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Volume 37,Issue 3
  • Stimulation on the impact of afforestation on the groundwater table in arid and semi-arid areas in northern China
  • Authors:LU Chenxi, CAO Shixiong and SHI Xiaoliang
  • Abstract:Water scarcity is a global environmental problem that jeopardizes human safety and socioeconomic development. In China, it has also become a potentially major obstacle for socioeconomic development, where 164 major groundwater areas are being exploited unsustainably. As a result, the depth of the groundwater table has increased by an average of 1.5 m per year in the arid and semi-arid regions of the north. Since 1952, China has implemented an unprecedented large-scale tree-planting program that focused on arid and semi-arid regions. The goal was to use trees to conserve water and combat desertification. Unfortunately, there is a serious risk that this program could exacerbate water shortages and lower the groundwater table because the trees were not chosen based on local environmental constraints, and their evapotranspiration is greater than the regional precipitation. Since precipitation is the major source of groundwater recharge in these semi-arid and arid areas of northern China, this imbalance will intensify the decline of the groundwater resource. Despite this risk, there has been limited research on the effect of afforestation on the groundwater table in China. In the present study, we selected nine provinces and provincial-level regions (Beijing, Hebei, Henan, Shanxi, Shaanxi, Ningxia, Inner Mongolia, Gansu, and Xinjiang) in China that focused on the tree-planting program, and are environmentally fragile arid or semi-arid regions facing a serious water scarcity. We calculated the influence of the afforestation program on groundwater based on two assumptions using seven evapotranspiration models, without considering evapotranspiration of the underlying vegetation or accounting for differences among the tree species used in afforestation. We confirmed that there is a serious risk that afforestation will cause the groundwater table to decline, independent of any other human withdrawals of this water. Based on our assumptions that afforestation plots had insignificant groundwater recharge or losses as a result of lateral inputs from adjacent land via subsurface or surface flows and that all planted trees survived, the groundwater table would decline most dramatically in Gansu, Ningxia, and Xinjiang regions. When we extended our analysis to assume that groundwater exchanges would possibly occur in land adjacent to the afforestation plots, and that this recharge is affected by the distance between the two plots, we found that the groundwater table in Beijing decreased most. Together, our results suggest that implementing such an afforestation program in arid and semi-arid areas without considering its influence on the groundwater supply will cause potentially severe damage to local ecosystems. In China, this will possibly compromise the goals of the national environmental policy, and damaging local socioeconomic conditions. In contrast, acknowledging the effects of this program will support efforts to utilize groundwater resources more efficiently, decrease the impact on the ecological services provided by these regions, and will mitigate the social and economic impacts on residents in these regions. In planning future ecological restoration practices, the impacts on the groundwater resource must be considered and calculated. In particular, environmental managers should select native tree species with high water-use efficiency and consider alternatives to trees, such as shrubs, sub-shrubs, and grassland or steppe vegetation. In addition, a broader variety of trees and other plant types should be considered; to determine an appropriate scale for afforestation that accounts for local moisture conditions, and determine methods to utilize the groundwater resource more efficiently and sustainably. This afforestation approach will improve the successful ecological restoration and sustainability of arid and semi-arid regions in China.
  • DownLoad:Stimulation on the impact of afforestation on the groundwater table in arid and semi-arid areas in northern China.PDF
  • The cooling effect of plain afforestation in the Beijing Project and its remote sensing-based valuation
  • Authors:JIA Baoquan and QIU Kuanbiao
  • Abstract:With the rapid development of urbanization, the urban heat island effect has exerted a great influence on the lives and productivity of urban residents. Many research has suggested that the cooling effect caused by vegetation and water bodies is an economic way to efficiently and substantially mitigate the urban heat island effects at a local scale. However, because the previous studies mainly concentrated on a limited number of urban parks, the past result might have a large uncertainty. Since plain afforestationwas implemented in the Beijing Project from 2012 to 2014, 10,648 forest patches have been constructed, therefore providing a great sample for examining the cooling effects of artificial forests.We analyzed the cooling effects of these artificial forests using the land surface brightness temperature as an indicator of urban heat islands. For this, we used the LANDSAT-8 images of 4 September 2014 and additional information about the originally afforested patches. The artificial forests in this project decreased inbrightness temperature by 1.023℃,despitethe short afforestation period. The latter can be explained by the large young plants that were used for the afforestation, as well as the special implementation mode used. A buffer zone analysis showed that the influence of this cooling effect reached as far as 350m from the edge of the artificial forests. The strongest cooling effect was found within 100m from the forest edges, with a decrease in brightness temperature of 0.392℃.In addition, a zonal analysis showed that the artificial forests had the most significant cooling effects in the Yanqing Basin, with a cooling of 3.519℃. The smallest significant decrease, 0.111℃, was found within the 6th Ring Road. An analysis between different years showed that the landscape pattern of artificial forest patches, as well as wetland protection and construction,were important for establishing the cooling effects. According to a patch size frequency analysis, the small patches had the highest frequency, whereas the middle and small patches covered a large part of the total area. Nevertheless, the large artificial forest patches had a larger significant cooling effect compared with the small ones. According to the primary valuation,the cooling effect of this project had a value as high as 488 millionCNY. Approximately 54% of this total value was caused by cooling within the forest patches, whereas cooling within the influential range from the forest patch edges caused approximately 46%.For further afforestation intended for effective mitigation of the urban heat island effects, several factors should receive careful attention. First, large artificial forest patches are preferablein terms of forest patch design. Second, for the configuration of the forest patches,two adjacent forest patches should be between 100 and 500m apart, in order to benefit from the cooling effects of the forest patches'influential range.
  • DownLoad:The cooling effect of plain afforestation in the Beijing Project and its remote sensing-based valuation.PDF
  • Leaf functional trait distribution and controlling factors of Pinus tabuliformis
  • Authors:ZHANG Kai, HOU Jihua and HE Nianpeng
  • Abstract:Leaf functional traits can directly or indirectly reflect the adaptation strategy of plants to the environment, influencing their survival, growth, and reproduction. Until recently, there have been many studies on the relationship between leaf functional traits and environment, but most have used the single or mean value of the traits to represent one species, ignoring considerable intraspecific variations.Pinus tabuliformis is one of the main afforestation tree species in China, playing an important role in terrestrial ecosystems. Thus, the relationship between the leaf functional traits of P. tabuliformis and environmental factors could elucidate the relationship between intraspecific variations and environmental factors. The results of this study could provide a theoretical basis for better protection, development, and utilization of P. tabuliformis forests under global climate change. In the present paper, we analyzed the environment factors and distribution of eight leaf functional traits of P. tabuliformis in its natural distribution range, including leaf length (LL), leaf thickness (LT), specific leaf area (SLA), leaf dry matter content (LDMC), stomatal density (SD), leaf nitrogen concentration (LNC), leaf phosphorus concentration (LPC), and leaf carbon concentration (LCC), from leaves collected in Inner Mongolia, Liaoning, Beijing, Shanxi, Shaanxi, Ningxia and Qinghai Provinces, from June to September 2014. The results showed that 1) The leaf functional traits of P. tabuliformis showed significant intraspecific variations, and the variation coefficient was between 4.82% and 25.85%. The traits, except the LCC of annual leaves, showed significant differences between different research sites (P < 0.05), the intraspecific variation of LPC was the highest (23.29% for annual leaves and 25.85% for perennial leaves), and the intraspecific variation of LDMC was the lowest (5.91% for annual leaves and 4.82% for perennial leaves). 2) There were significant correlations between the leaf trait and the longitude and latitude (P < 0.05). LL, LT, SLA, SD, and LNC of P. tabuliformis leaves exhibited a weak longitude distribution pattern, and LT, SD, and LNC exhibited a weak latitude distribution pattern. The combined effect of changing hydrothermal conditions along longitude and latitude and strong local effects could contribute to the formation of these patterns. There was also significant variation among different individuals at the same site, suggesting large local effects, which could weaken the longitude and latitude distribution pattern on the large scale, leading to a small R value (0.05 < R2 < 0.3). 3) The pattern of leaf functional traits was affected by various environmental factors, and each leaf trait of P. tabuliformis was affected by several factors. Further, the main controlling factors of different traits were different; the controlling factors of annual and perennial leaves were different in some traits. In the present study, we found that the LL was mainly affected by the mean annual precipitation and altitude, LT was mainly affected by the mean annual temperature and volumetric soil water content, SLA was mainly affected by the mean annual precipitation and soil nitrogen content, LDMC was mainly affected by water factors, SD was mainly affected by altitude, LNC was mainly affected by altitude and water factors, and LPC was mainly affected by soil phosphorus content.
  • DownLoad:Leaf functional trait distribution and controlling factors of Pinus tabuliformis.PDF
  • Responses of leaf traits to submergence stress and analysis of the economic spectrum of plant species in an aquatic-terrestrial ecotone, the Li River
  • Authors:HUANG Duan, WANG Dongmei, REN Yuan, QIN Yunbin and WU Linchuan
  • Abstract:Five leaf traits were analyzed in different plant species in an aquatic-terrestrial ecotone, Li River, to investigate differences in these traits between different types of functional plants in severe and mild inundation zones, and to explore the physiological responses of plants suffering from long-term submergence stress. By analyzing the relationships between leaf traits in plants subjected to severe inundation, differences between the results of this study and those on the global scale are also discussed. The five leaf traits analyzed were:leaf mass per area (LMA), leaf maximum net photosynthesis rate (Amax), leaf nitrogen content per mass (Nmass), leaf phosphorus content per mass (Pmass), and leaf potassium content per mass (Kmass). The results were as follows:(1) The values of Amass, Nmass, and Pmass under severe submergence were significantly higher than those under mild submergence. (2) The LMA value for grasses was relatively lower than that for trees and shrubs, whereas Amax and PNUE (photosynthetic nitrogen use efficiency) were higher for grasses. (3) The Nmass, Pmass, and PNUE values for grasses in the severe inundation zone were significantly higher than those in the mild inundation zone, while there were no significant differences in leaf traits for trees and shrubs between the two zones. (4) The relationships between leaf traits in the severe inundation zone were similar to those on the global scale, and the species in the severe inundation zone had lower LMA, higher Amass, Nmass, and Pmass. These results suggest that improving photosynthetic capacity and increasing the levels of relevant leaf nutrients may be involved in the adaptation of plants to aquatic-terrestrial ecotone conditions. Compared with trees and shrubs, grasses showed stronger adaptability to submergence, which illustrates the differences in adaptability between different types of functional plants. The results of this study indicate that a spectrum of leaf economics also exists in plant species in the severe inundation zone, and that these represent species with a fast investment-return on the leaf economic spectrum.
  • DownLoad:Responses of leaf traits to submergence stress and analysis of the economic spectrum of plant species in an aquatic-terrestrial ecotone, the Li River.PDF
  • Inter- and intra-annual dynamics in litter production for six temperate forests
  • Authors:WU Qiqian, WANG Chuankuan and ZHANG Quanzhi
  • Abstract:Litter production and its composition in temperate forests show seasonal dynamics due to changes in the ecosystem structure and environment, which directly affect the nutrient cycling and ecological services in the ecosystems. In this study, we investigated seasonal dynamics in the litter production and its composition for six forest types in Maoershan region for six continuous years in order to reveal the factors driving the inter- and intra-annual variability of the litter production. The results showed that annual litterfall (t/hm2) decreased in the order of:Quercus mongolica stand (4.60) > mixed deciduous stand (4.21) > hardwood stand (4.03) > Pinus koraiensis plantation (3.95) > Populus-Betula stand (3.89) > Larix gmelinii plantation (3.85). There was a significant difference in total litterfall among the six stands. The litter production fluctuated interannually and showed an overall increasing tendency. The interannual variation in the litter composition depended upon its compoents:the litter production of woody tissues was relatively stable; that of foliages was consistent with the total litter production; and that of reproductive tissues and others increased with stand age. The production of total litter showed a mono-peak seasonal pattern for all the stands, and the occurrence of the peak varied with forest type. The litter production of woody tissues displayed a bimodal seasonal course; that of foliages was a mono-peak curve; and that of reproductive tissues and others was relatively stable intra-annually. Total rainfall significantly influenced the inter-annual litter production (P < 0.05), and explained 90% and 87% of the variability in the total litter production and the production of woody tissues, respectively. Mean temperature, cumulative temperature and total rainfall significantly affected intra-annual variability in litter production, among which the effect of total rainfall was dominant. In conclusion, rainfall, in addition to the biological characteristics of the forests, was a key factor driving the inter- and intra-annual dynamics in litter productions.
  • DownLoad:Inter- and intra-annual dynamics in litter production for six temperate forests.PDF
  • Distinctive responses of photosynthetic characteristics to warming of invasive Alternanthera philoxeroides and native Sambucus chinensis
  • Authors:WANG Qiong, TANG Ya, XIE Tao and WANG Hui
  • Abstract:Global climate change could exacerbate biological invasions by changing competitive interactions, and hence, threaten ecosystem biodiversity and stability. Replacement control, which relies on the growth advantage of native plants, is one of the most effective methods to suppress invasion. In the present study, distinctive photosynthetic responses to warming of invasive (Alternanthera philoxeroides) and native (Sambucus chinensis) plants were compared to determine the invasive potential of alien plants, and to screen native species for replacement control under climate change scenarios. Plants were grown in two different air temperatures (unwarmed or ambient temperature and warmed at (0.76±0.10)℃ by using an infrared heater) for a 5-month short-term period, and photosynthetic pigment concentrations and gas exchange characteristics were determined. The results showed that warming significantly and positively improved the chlorophyll a/b ratio by 6.21% in A. philoxeroides(P < 0.01), but negatively by 5.55% in S. chinensis(P < 0.05). Meanwhile, chlorophyll b, rather than both chlorophyll a and carotenoid, was significantly higher in S. chinensis than in A. philoxeroides, at ambient (P < 0.001) and increased temperatures (P < 0.05). Increased temperatures significantly increased the net photosynthetic rate by 9.23% in A. philoxeroides(P < 0.01), but decreased the water use efficiency by 10.64% (P < 0.01) due to a respective increase in stomatal conductance by 11.10% (P < 0.05) and transpiration rate by 21.46% (P < 0.001). In contrast, increased temperatures significantly enhanced stomatal conductance by 10.95% in S. chinensis(P < 0.001), but had no effect on other gas exchange traits. Under the control conditions, the stomatal conductance and intercellular CO2 concentration were 7.03% (P < 0.05) and 4.57% (P < 0.001) higher, but the net photosynthetic rate and water use efficiency were 10.30% (P < 0.001) and 11.92% (P < 0.05) lower in A. philoxeroides than in S. chinensis, respectively. However, under increased temperatures no significant differences in net photosynthetic rate and stomatal conductance were observed between the two plant species. In contrast, under increased temperatures, water use efficiency was 26.45% higher in S. chinensis than in A. philoxeroides(P < 0.001), possibly because of lower transpiration rates in S. chinensis. Increased temperatures, species, and their interactions did not have significant effects on photosynthetic-light curve parameters. In general, S. chinensis had a stronger photosynthetic capacity than the invasive A. philoxeroides in terms of chlorophyll b content, net photosynthetic rate, and water use efficiency, especially in control conditions. However, the photosynthetic advantage of S. chinensis was eliminated with increased temperatures. Collectively, our results suggested that S. chinensis could potentially be used in ecological restoration to replace A. philoxeroides in invaded habitats.
  • DownLoad:Distinctive responses of photosynthetic characteristics to warming of invasive Alternanthera philoxeroides and native Sambucus chinensis.PDF
  • The response of Cleistogenes squarrosa and Stipa grandis root characteristics to nitrogen adding gradient and removal of function groups
  • Authors:QIN Jie, BAO Yajing, LI Zhenghai, ZHANG Jing, MENGGEN Qiqige and LI Mengjiao
  • Abstract:Overgrazing has severely degraded the grassland of Northern China causing serious loss of soil nitrogen (N). Along with the degraded steppe, Cleistogenes squarrosa will replace Stipa grandis, which was the original dominant species, to become the dominant plant in the community. In order to understand this transition, a study was made to examine the effect of N and selected functional plant groups on the rooting characterisitics of S. grandis and C. squarrosa. Two experiments were conducted in degraded grassland communities that were dominated by C. squarrosa.on the Xilingol steppe.on a degraded community. In Experiment 1 involved N addition along an increasing gradient (0, 10.5, 17.5, 28g N/m2) while in Experiment 2, two of three functional groups (high-energy, middle-energy and low-energy functional groups) were removed (1, 0, 0; 0, 2, 0; and 0, 0, 3) and adding N fertilizer(0, 17.5 g N/m2) in a factorial arrangement. After two years, the root length, diameter, area, and volume of S. grandis and C. squarrosa were measured using a Delta-T SCAN analyzer. Root response to N fertilizer as well as to the removal of functional groups, with two N levels, were analyzed. Under pressure from competition by other functional groups, the root length, area, and volume of S. grandis significantly increased under high N fertilizer (28 gN/m2) while root diameter and volume of C. squarrosa with 17.5 gN/m2 were significantly higher than the other three N application rates. In Experiment 2, we did not detect a response in S. grandis to nitrogen addition(17.5 gN/m2)while removing functional groups but the root diameter of C. squarrosa increased significantly. In general removal of plant functional groups affects the root length and area of S. grandis and the root length, diameter and area of C. squarrosa. While the interaction between nitrogen addition and removal of plant functional groups affects the root diameter and volume of C. squarrosa, and it did not affect S. grandis.
  • DownLoad:The response of Cleistogenes squarrosa and Stipa grandis root characteristics to nitrogen adding gradient and removal of function groups.PDF
  • The dynamics and main driving factors of coastal vegetation in Guangxi based on MODIS NDVI
  • Authors:CHENG Fangyan, LIU Shiliang, YIN Yijie, LÜ Yihe, AN Nannan and LIU Xinming
  • Abstract:The normalized difference vegetation index (NDVI) can be used to characterize a region's vegetation status, however, there have been few studies on the NDVI dynamics of coastal wetland areas. Using MODIS NDVI as the data source, we analyzed the vegetation dynamics, NDVI trend, and the main driving factors of NDVI in the coastal wetland areas of Guangxi from 2000 to 2014. The results showed that in the coastal wetland area with a 10-km buffer, the mean NDVI value was relatively high (0.71). However, annual fluctuations were more stable (SD=0.02). Spatially, NDVI showed a higher trend in terrestrial land and a lower trend in coastal and estuarine areas. The NDVI values of various vegetation types were significantly different, and the highest value was recorded for woodland, which is widely distributed in the terrace (0.76), and the lowest value was found for coastal wetland (0.52) and other vegetation types (e.g., bare land) (0.50). The vegetation trend (slope k) showed that 57% of the woodland was improving (k≥0.002), and 52% of the coastal wetland was degrading (k ≤-0.002). The Hurst index of the sustainability of vegetation showed that forest land and dry land have been continuously improving, while the coastal wetland showed a trend of continuous degradation. The influence of meteorological factors on NDVI dynamics was not significant, and the NDVI was mainly affected by topographic characteristics and human activities. NDVI and its trend were negatively correlated with comprehensive topographic indexes and the distance from the river, and positively correlated with slope, altitude, and the distance from roads and valleys. Altogether, most regions showed positive development, but the coastal wetland exhibited degradation and needed to be improved.
  • DownLoad:The dynamics and main driving factors of coastal vegetation in Guangxi based on MODIS NDVI.PDF
  • Effects of mulching materials and furrow-to-ridge ratios on soil moisture and alfalfa forage yield
  • Authors:SONG Xingyang, WANG Qi, LI Fuchun, HU Guangrong, ZHANG Dengkui, ZHANG Enhe, LIU Qinglin and WANG Heling
  • Abstract:To determine the optimum furrow-to-ridge ratio and a suitable ridge-mulching material for alfalfa production in a ridge-furrow rainwater harvesting system in the semi-arid Loess Plateau, a field experiment with a randomized complete block design was conducted during the 2012 and 2013 alfalfa growing seasons. The experiment was designed to investigate the effects of different mulching materials (manually compacted soil crust, biodegradable mulch film, and common plastic film) and furrow to ridge ratios (60:30, 60:45, and 60:60[cm:cm]) on soil moisture and alfalfa forage yield, with traditional flat planting (TFP) as a control. The average number of ineffective rainfall events (53) was greater than that of effective rainfall events (27) over these two years, and the contribution rate (19%) of the ineffective rainfall to annual rainfall was less than that (81%) of the effective rainfall. Compared with TFP, increases in the soil water storage at depths of 0-140 cm were 12.8, 19.2, 24.4, 26.0, 30.7, 40.5, 29.9, 37.1, and 47.7 mm in SR30, SR45, SR60, BMR30, BMR45, BMR60, CMR30, CMR45, and CMR60 (SR, BMR, and CMR were ridges with manually compacted soil, covered with bio-degradable mulch film, and covered with common plastic film, respectively, and subscripts 30, 45, and 60 refer to ridge widths (cm), all with 60 cm furrow width), respectively. There was no distinctive dry soil layer found within the root zone among ridge-furrow rainwater harvesting treatments during 2 consecutive years. Compared with TFP, forage yields decreased by 3%, 8%, and 13% for SR30, SR45, and SR60, respectively, while water use efficiency (WUE) increased by 52%, 58%, and 55% over the two years in these ridge-furrow systems. Forage yields increased by 14%, 12%, 7%, 17%, 19%, and 9% for BMR30, BMR45, BMR60, CMR30, CMR45, and CMR60, respectively, while WUE increased by 49%, 62%, 59%, 51%, 67%, and 56% in these ridge-furrow systems in the same period. Optimum furrow width was 35-36 cm for BMR and CMR in the ridge-furrow rainwater harvesting system with 60 cm furrows for alfalfa production in this region that has an annual 380.7-427.6 mm rainfall. This information is useful for alfalfa production in ridge-furrow rainwater harvesting systems in this region.
  • DownLoad:Effects of mulching materials and furrow-to-ridge ratios on soil moisture and alfalfa forage yield.PDF
  • Multi-scale spatial pattern analysis of Korean pine based on presence/absence data
  • Authors:NIE Zhiwen, BU Rencang and LI Binglun
  • Abstract:Spatial patterns reflect the distribution characteristics of populations and the adaptions of populations to environmental resources and ecological processes. Dispersal limitation, inter- and intraspecific competition, and habitat heterogeneity all influence species distribution. In addition, species are affected by local temperature, precipitation, and terrain. Therefore, the relationship among species distribution patterns, landscape indices, and environmental factors are important in population studies affected by changing climates. To reveal these relationships, Korean pine, the dominant species in the Small Khingan Mountains, at the northern boundary of its distribution range, was selected to analyze its distribution patterns at multi-spatial scales. The point pattern analysis and landscape pattern metrics were calculated at eight spatial scales (90 m×90 m resolution) using R package (Spatstat 1.42-1) and FRAGSTATS (Version 4.2), based on presence/absence data derived from forest inventory maps and attributed data. The results from the point pattern analysis showed that Korean pine was aggregated in small scales, random distribution areas surround an aggregated pattern, and uniform distribution areas were often mosaicked in aggregated pattern areas. However, the distribution pattern of Korean pine was more aggregated with an increasing spatial scale because the aggregated distribution area increased, especially in the core area of this region. Meanwhile, random distribution areas occurred at the edge of aggregated distribution areas, and uniform distribution areas disappeared from the core area. The results from the landscape pattern analysis indicated that landscape pattern indices could be used to describe an aggregated distribution at multi-spatial scales since the landscape metrics were most stable, or changes were logarithmic; whereas landscape pattern indices dramatically fluctuated with changing spatial scales for the others. The analyses also revealed that Korean pine was sensitive to slope and elevation; most individuals were distributed on flat slopes or elevations between 200 and 800 m. Korean pine distribution was not affected by this aspect. Based on the above results, we concluded that 1) Korean pine was primarily aggregated in the core area of its distribution, and was randomly distributed at the borders or ecotones; 2) presence/absence data of specie was more likely to be implemented in analysis of population distribution type at multi-spatial scales; 3) with changing spatial scales (or extents), species distribution patterns changed, e.g., the random and uniform distribution areas at small scales often merged into aggregated distribution areas at large scales; 4) landscape pattern indices could not completely describe species distribution patterns at a single scale, but at a multi-spatial scale, stable changes in landscape indices indicated an aggregated distribution, while unstable changes resulted in uniform or random distribution; 5) Korean pine was sensitive to slope and elevation. Elucidation of the spatial patterns of Korean pine aids in understanding its distribution mechanisms, future migration, climate change effects, and promotes strategies for its effective conservation and management.
  • DownLoad:Multi-scale spatial pattern analysis of Korean pine based on presence/absence data.PDF
  • Spatial heterogeneity of soil nutrients and salinization risk assessment of a small-scale farmland in Ebinur Basin in northwest China
  • Authors:ZHANG Zhaoyong, LI Juying, ZULPIYA·Mamat and YE Qingfu
  • Abstract:Our objective was to investigate the soil nutrient and salinization status of small-scale surface farmland within the Ebinur Basin, a typical rump lake basin in Xinjiang, which experienced recent economic success. We analyzed the spatial distribution and factors influencing soil nutrient composition, as well as conducted a soil salinization environmental risk assessment in the basin. The results indicated that:(1) there were relatively high amounts of OM, AN, RP, and RK in the farmland surface soil. Among these five elements, the total salt content was highly variable, while the contents in the other four elements demonstrated low variation. (2) The semi-variance function analysis showed that the spatial distributions of AN, RP, and RK were mainly influenced by random factors, such as fertilization and irrigation, while the spatial distributions of OM and TS in the Ebinur Basin farmland were influenced by both random factors, such as fertilization and irrigation, and structural elements, such as vegetation coverage and soil texture. (3) The Spatial interpolation analysis revealed that, in general, the areas with high OM, AN, RP, and RK soil content were mainly distributed in the central and northern parts of the research area, and they were mainly influenced by the fertilization method, irrigation method, and the vegetation coverage; while the areas with high TS were mainly distributed in the southern and surrounding parts of the research area, and they were mainly influenced by the topography, soil texture, and the vegetation coverage. (4) The correlation analysis showed that soil OM, RK, RP, and AN have a negative correlation with the total salt content. The salinization risk assessment revealed that the whole area was within a low to moderate range of salinization risk, which will not influence the growth of the main crop, such as cotton, in the research area. However, in the future we should improve the irrigation and cropping system methods by increasing the application of organic manure and returning crop stalks to the field, thereby achieving a stable and high crop yield.
  • DownLoad:Spatial heterogeneity of soil nutrients and salinization risk assessment of a small-scale farmland in Ebinur Basin in northwest China.PDF
  • Water sources of dominant desert species in ebinur lake wetland nature reserve, Xinjiang, China
  • Authors:MA Huiying, YANG Xiaodong, LÜ Guanghui, HE Xuemin, ZHANG Xueni, WANG Xiyuan and LI Yan
  • Abstract:The proportions of water sources in plants are related to plant adaptation, and reflect the mechanisms of niche differentiation and diversity in arid desert regions. At present, traditional physical methods is hard to determine the proportions of water sources in plants. But, due to the stable isotopes does not existed fractionation when it transported from the roots to the leaves, the stable hydrogen-oxygen isotope content (δ18O and δD) were essentially unchanged among roots, xylem, and the water sources. This resulted in the hydrogen-oxygen stable isotope analysis as a tool for accurately identifying the proportions of water sources in plants. In the present study, δ18O of the xylem of 14 dominant desert species in 8 families (including Apocynaceae, Chenopodiaceae, Tamaricaceae, Leguminosae, Salicaceae, Zygophyllaceae, Compositae and Polygonaceae), river water, groundwater, and 4 layers soil water (including 0-40, 40-70, 70-100, and 100-150 cm) were measured respectively in desert, riparian forest, salt marsh, and sand dunes of Ebinur Lake Wetland Nature Reserve, Xinjiang, China. Based on the roots distribution and δ18O, 14 dominant desert species were firstly classified into 13 deep-rooted species and 1 shallow-rooted species, and then the proportions of water sources in plants, the differences of water utilization strategies between the deep- and shallow-rooted plants, and the replenishment relationships among water sources were analyzed. The results showed that:(1) the proportions of water sources in plants were different among species and families in the Ebinur Lake Wetland Nature Reserve; (2) groundwater occupied the largest proportion in water sources in plants, whereas the 0-40-cm layer soil water was rarely used; (3) the proportions of water sources in plants differed between deep- and shallow-rooted plants. Groundwater and river water were the main sources for deep-rooted plants, whereas the soil water was the primary source for shallow-rooted plants; (4) groundwater contributed to river supply, and subsequently, these two waters were discharged into the soil waters from deep to shallow soil layers; (5) atmospheric condensed waters as a special precipitation in arid desert, to some extent, it also discharged into the soil water, river water and groundwater. Overall, in the arid desert region, the diversity of availability in water sources showed a large variation in the proportions of water sources in plants among species and families. Additionally, under the comprehensive influences of the distance from habitat to riverbank, groundwater levels, and soil salinization levels, the perennials and halophytes mainly absorbed the groundwater, river water, and deep soil water. On the contrary, the annuals and ephemeral plants utilized all water sources that could be reached and absorbed by their roots.
  • DownLoad:Water sources of dominant desert species in ebinur lake wetland nature reserve, Xinjiang, China.PDF
  • Maximum carboxylation rates of reed in the Wuliangsuhai wetland using hyperspectral remote sensing
  • Authors:WEI Yaxing and WANG Liwen
  • Abstract:Studies on wetland vegetation productivity and their carbon sequestration potential are becoming an important focus of the global carbon cycle and global climate change research. The photosynthetic capacity of wetland vegetation can indicate the health status of its growth. In addition, an accurate estimate of maximum carboxylation rate (Vcmax) is important for accurately simulating wetland vegetation photosynthesis and carbon sequestration processes with a gas exchange model. Here, the wetland of Wuliangsuhai (Inner Mongolia) was chosen as the study area, and the photosynthetic parameters and spectral reflectance of reed leaves were measured. Based on the Farquhar model of photosynthesis, reed leaf Vcmax values were calculated from A-Ci curves, and subsequently standardized to 25℃. Estimation models of Vcmax for reed leaves in the wetland were constructed with a bootstrap PLSR model and single band and hyperspectral vegetation indices (e.g., simple ratio index (SR) and normalized difference index (ND)). Based on hyperspectral remote sensing images from HJ-1A HSI, the bands of 702 and 756 nm, which had a higher estimation accuracy for Vcmax, were selected from the ND hyperspectral indices. Subsequently, a spatial distribution map of Vcmax for wetland reed was acquired for the study area. The results showed that the spectral characteristics of wetland vegetation, combined with hyperspectral vegetation indices, could be used effectively to accurately estimate reed Vcmax in the wetland. The highest accuracy was produced from the modeling method based on a bootstrap PLSR model (R2=0.87,RMSECV=3.90,RPD=2.72). Furthermore, the accuracy of Vcmax estimations from the ND hyperspectral indices was higher than that from the SR hyperspectral indices. Overall, the estimated values extracted from the spatial distribution map of Vcmax had a good correlation with the measured values (R2=0.80,RMSE=4.74).
  • DownLoad:Maximum carboxylation rates of reed in the Wuliangsuhai wetland using hyperspectral remote sensing.PDF
  • Effects of grazing on the emission of CH4 flux in the Zoige Plateau wetland
  • Authors:ZHOU Wenchang, CUI Lijuan, WANG Yifei and LI Wei
  • Abstract:Wetland ecosystems, as the main source of atmospheric methane (CH4), could seriously affect the concentration of atmospheric CH4 and further climate change. Presently, wetland ecosystems have been severely affected by human actives (i.e., drainage, grazing, and harvesting). However, the effects of grazing on the CH4 emission of wetland ecosystems have not been well investigated. Therefore, to evaluate the effects of grazing on the emission of CH4 flux, we performed the field experiments in the Zoige Plateau wetland, southwestern China, from June to October 2013. We also performed field experiments to investigate the effects of simulated increased in sheep or yak grazing by the clipping on CH4 emission in the same studied sites from May to October 2014. CH4 emission was measured using a dark static chamber and the fast greenhouse gas analyzer (FGGA) during the two growing season. We observed an obvious seasonal variation in CH4 emission at the studied sites. The CH4 emission varied from -0.42 to 18.06 mg m-2 h-1 and its maximum value occurring in summer and/or autumn. These results showed that the CH4 emission in the grazing and fencing plot was (31.32±19.57) g/m2 and (30.31±23.46) g/m2, respectively, during the growing season, and there were no significant differences in CH4 emission between grazing and fencing plots (P > 0.05).However, the CH4 emission in the grazing plot was (21.01±12.35) g/m2 during heavy grazing periods (from July to September 2013), which was 54.3% higher than that in the fencing plot (un-grazed plot). Moreover, the results revealed that the CH4 emission in the two clipping plots with 8 cm and 4 cm of vegetation height after clipping were (5.01±5.37) g/m2 and (4.69±5.99) g/m2, respectively, during the growing season, which were significantly higher in the 8 cm vegetation height in the clipping plot (335.9%) than that in the non-clipping plot (1.15±1.89) g/m2 (P < 0.05), and 308.0% higher in the 4 cm vegetation height in the clipping plot than that in the non-clipping plot. Furthermore, we also measured the aboveground biomass in both the grazing and clipping plots. The results indicated that grazing decreased the aboveground biomass, which was 37.5% lower than the control plot ((525.88±103.47) g/m2 vs. (886.09±124.46) g/m2) (P < 0.05). We also found a significantly negative correlation between aboveground biomass and CH4 emission in August (P < 0.05), which may imply that CH4 flux emissions decrease due to the reduced height of herbaceous vegetation. In summary, the results of the present study suggested that the sheep or yak grazing and clipping disturbance increased CH4 emission in plateau wetland, via the reduction of the transporting distance from soil to the atmosphere due to significantly decreased aboveground biomass. This result provides the basic date for habitat protection and management in the plateau wetland in China.
  • DownLoad:Effects of grazing on the emission of CH4 flux in the Zoige Plateau wetland.PDF
  • Spatio-temporal variations of soil moisture in the root zone of Haloxylon ammodendron at different life stages
  • Authors:ZHU Hai, HU Shunjun, LIU Xiang, LI Hao and LI Yike
  • Abstract:Soil water, as a major factor limiting vegetation in deserts, does not only affect the survival and growth of plants, but also the species abundance and distribution. To research the spatiotemporal variations of soil moisture content in root zone is vital for understanding the recovery, maintenance and the stability of plant communities in deserts. In the Gurbantunggut desert in northwestern China, Haloxylon ammodendron as the dominant species plays an important role in dune stabilization. However, little is known about the effects of plant life stage on the variations of soil moisture content in the root zone for Haloxylon ammodendron. In our study, soil water dynamics were monitored for eight typical Haloxylon ammodendrons individuals in an inter-dune low land at the southern edge of Gurbantunggut Desert, each with a soil moisture monitoring point 20-30 cm away from the stem base. Another two points were set in the inter-shrub bare soil. In addition, 16 points were positioned two individuals with 10 meters away from each other. Thus there were totally 26 points. From February 2014 to November 2014, in-situ observations for soil moisture within 0-400 cm soil were performed by neutron probe method in combination with oven-drying method to explore the spatiotemporal variations of soil moisture in the root zone of Haloxylon ammodendron individuals at different life stages. Results show that (1) the annual variation of soil water underwent 4 periods, i.e., recharging period (from later February to early March), equilibrium period (from early April to late May), discharging period (from early June to late October), and stable period (from early November to middle February of the following year); (2) soil water dynamics differed within profiles, with a higher coefficient of variation that decreases rapidly with depth in the top 50 cm soil layer, and a relatively constant coefficient for 50-400 cm soil layers; (3) the averaged soil moisture content at different life stages in spring, summer, fall, as well as in the whole year displayed a pattern in order of dead individual > adult individulal > young individual > bare soil; (4) soil moisture decreased gradually with the increasing distance to the Haloxylon ammodendron base stem within 5 meters; and (5) following rainfall events, the soil moisture content in 10 cm soil increased more in the root zone than in the bare soil.
  • DownLoad:Spatio-temporal variations of soil moisture in the root zone of Haloxylon ammodendron at different life stages.PDF
  • Effects of precipitation change on soil microbial functional diversity in the primitive Korean pine and broadleaved forests
  • Authors:WANG Nannan, HAN Dongxue, SUN Xue, GUO Wei, MA Hongyu and FENG Fujuan
  • Abstract:Global climate change and sustainable development are the two most important challenges worldwide. Patterns of precipitation, includes quantity, intensity and distribution, are expected to change. Subsequently, soil moisture content is expected to followed the precipitation pattern changes, which would affect the aboveground biomass and soil microorganisms activity. The latter would consequently affect the structure and functioning of terrestrial ecosystem. Therefore, it is critical to understand how ecosystem structure and function will respond to the expected changes of precipitation pattern. Many large controlled field experiments modify the precipitation pattern change. Most of those studies have been focusing on species composition, productivity and soil respiration. Soil microorganisms are sensitive to micro-environmental changes, which drive the soil nutrient cycling, as well as ecosystem processes such as soil material conversion and energy flow. Therefore, they have been recognized as sensitive indicator of soil ecosystem. As a consequence, soil microorganisms have been a popular research topic in pedology, and have become an extremely important and relatively quick growing research field. Forest ecosystem can contribute greatly to adjust of global climate change. Broad-leaved Korean pine mixed forest is zonal climax vegetation in northeastern China, and it plays a significant ecological role in this region. We selected Changbai Mountain to study the microbial feedbacks to the precipitation changes. Soil microbial functional diversity and its changes driven by precipitation change (30% increase and decrease) were measured in different layer soil (0-5cm, 5-10cm and Korean pine rhizosphere soil), using the Biolog microplate. Our results showed that the average well color development (AWCD) value were highest in the increased precipitation plots, and lowest in the control plot at the beginning of the cultivation. however, it did not have an obvious pattern with precipitation regime at the end of cultivation. Throughout the whole incubation periods, the AWCD value in rhizosphere soil was higher than in surface soil. Shannon-Wiener, Simpson, and McIntosh diversity indices showed no significant difference between different layers and precipitation patterns. This suggest that precipitation increasing or decreasing with 30% had no significant effect on functional diversity of different layers or the rhizosphere soil in broad-leaved Korean pine mixed forest. However, the utilization intensity of six categories carbon sources types were specified. Amino acids, carbohydrate and polymers were the main carbon sources with a high utilization rate, especially the amino acids. The microbial functional diversity under different precipitation conditions showed that the spatial heterogeneity was reflected the use of amino acids and carbohydrate by microrganisms. N-Acetyl-D-Glucosamine, D-cellobiose, and α-D-Lactose was the most specified carbon sources to microbes. This evaluation of microbial functional diversity in bulk soil and rhizosphere soil under different precipitation patterns can help other researchers to summarize the patterns and mechanism of microorganism responses to precipitation change. It is also provide a scientific reference for further study on climate change.
  • DownLoad:Effects of precipitation change on soil microbial functional diversity in the primitive Korean pine and broadleaved forests.PDF
  • Effects of corn stover cultivation on the population dynamics and genus composition of soil nematode community
  • Authors:MOU Wenya, JIA Yifan, CHEN Xiaoyun, LIU Manqing, ZHOU Kexin, LI Junsheng and CHEN Fajun
  • Abstract:In this study, the impact of corn stover cultivation, (i.e., CR) in contrast with not cultivating core stover (i.e., CK), on the population dynamics, genera, and structure of the soil nematodes community was examined in the field. The results indicated that a total of 36 genera of nematodes were found and identified for the two treatments of corn-straw-return/non-return cultivation (CR:36,CK:30) during the eight sampling dates between 2013-2014, including 12 genera of plant-parasites (CR:12,CK:10), 15 genera of bacterivores (CR:15,CK:14), 5 genera of fungivores (CR:5,CK:4), and 4 genera of omnivores-predators (CR:4,CK:2). Compared with not cultivating core stover, corn stover cultivation decreased the percentage of plant-parasites and fungivores, while noticeably enhanced the percentage of bacterivores and omnivorespredators. A significant increase in the percentage of bacterivores (about 42.95%) was recorded for the corn stover cultivation, than that with not cultivating core stover. Moreover, the total number of nematodes was higher in the corn stover cultivation field than that in the not cultivating core stover field, while no significant difference was found between the two treatments. Additionally, significant increases in bacterivore abundance (16.3%-125.6%) was found for the corn stover cultivation treatment relative to that in the corn stover cultivation. Furthermore, the corn-straw-return cultivation demonstrated significantly enhanced Shannon-Wiener index (H'), Richness index (S), and Nematode Channel Ratio (NCR), but did not markedly affect the Evenness index (J), the Wasilewska index (WI), and the Total Maturity index (∑MI), when compared to those of not cultivating core stover. In conclusion, corn stover cultivation has important ecological impacts on the agroecosystem, and it can enhance the abundance and genera diversity of soil nematodes, thereby creating a stable and healthy soil ecosystem.
  • DownLoad:Effects of corn stover cultivation on the population dynamics and genus composition of soil nematode community.PDF
  • Biomass and stoichiometry of dead branches of standing trees in Populus euphratica forests with different ages
  • Authors:SHI Junhui, LIU Maoxiu, WANG Xinying and MA Xuexi
  • Abstract:The temporal and spatial variations of stoichiometry and carbon (C) storage of the dead branches were revealed in the natural forest trees after having investigated their biomass. The results indicated that:(1) the biomass of the dead branches from a single tree, increased with the forest age and the average annual cumulative biomass of the dead branches, was 0.22 kg per tree; The biomass of the dead branches increased with the enhancing diameters, and the larger diameter grades would induce the easier dead branches. Biomass of the dead branches originally increased and then decreased with increasing forest age, and the highest biomass value was 10.93 t/hm2 contributing 17.79% of the total ground living biomass in the mature forests; (2) the C, N, P, K contents of the dead branches were 491.01, 4.13, 2.75 g/kg and 1.83 g/kg, respectively, and were higher than those on the living branches, whereas the K content showed the opposite trend. The ratios of C:N, C:P, and N:P in dead branches of different forests were 128.58, 232.79, and 1.95, respectively, and were higher than those in the living branches. Forest age had little effect on element contents and stoichiometry, which could indicate that element content of dead branches of the standing trees varied slightly; and (3) the C density of the dead branches first increased and then decreased with forest age, and was highest in the mature forests. The average carbon density of different aged forests was 2.63 t/hm2, which was 20.74% of that of the living forests. It was considered the variation law that the biomass and carbon density of the dead branches increased with forest age, resulting in a potentially huge carbon sink. This is a fundamental factor to consider for environmental and forestry management.
  • DownLoad:Biomass and stoichiometry of dead branches of standing trees in Populus euphratica forests with different ages.PDF
  • Ecological stoichiometric characteristics of plants, soil, and microbes of Pennisetum purpureum cv. Guimu-1 pastures at different rehabilitation ages in a karst rocky desertification region
  • Authors:HU Peilei, WANG Kelin, ZENG Zhaoxia, ZHANG Hao, LI Shasha and SONG Xijuan
  • Abstract:Ecological stoichiometry has become the focus of research in ecological sciences in recent years and many studies have examined the carbon:nitrogen:phosphorus (C:N:P) stoichiometry of plants, soil, or litter in forest communities. However, few studies have explored the stoichiometric characteristics of herbs at different ages. Elephant grass, Pennisetum purpureum cv. Guimu-1, is a tall perennial C4 grass that can withstand repeated cutting and regenerates rapidly, and has been widely cultivated in northwest Guangxi, China because of the "grain for green" policy. For enhanced understanding of the nutrient cycling characteristics of artificial forage at different time scales in fragile karst ecosystems, we investigated the C:N:P stoichiometric characteristics of plant-soil-microbe interactions in Guimu-1 pastures of different growth ages. Corn and three different restoration stage pastures (1-, 5-, and 7-y-old Guimu-1 pastures, representing initial restoration, vigorous restoration, and degenerating stages, respectively, after returning farmland to grassland) were chosen in northwest Guangxi, China to determine the C, N, and P contents and the C:N:P stoichiometry. The results showed that:(1) the C, N, P contents and C:N:P ratios in the aerial portion of plants varied with different artificial Guimu-1 pasture ages. The N and P contents of the plant aerial portion in different years all followed the same order:5-y-old < 1-y-old < 7-y-old pastures, whereas the C content followed the reverse order. Plant C:N, C:P, and N:P ratios, which varied over a large range from 26.50 to 33.91, 631.70 to 2254.33, and 23.89 to 67.21, respectively, were all in the order of 7-y-old < 1-y-old < 5-y-old pastures. (2) Soil C, N, and P in the topsoil layer (0-10 cm) all showed the same order:corn field < 5-y-old < 1-y-old < 7-y-old pastures. However, there were no significant differences among the soil C:N, C:P, and N:P ratios for the four herb types (P > 0.05), with average values of 9.20, 27.88, 3.38, respectively. (3) Soil microbial C biomass (MBC), microbial N biomass (MBN), and microbial P biomass (MBP) showed significant differences among the different plant types (P < 0.05). The corn field had the highest MBC/soil organic C, MBN/total N, and MBP/total P ratios among the four plant types, while the 5-y-old pasture had the highest ratios among the three different aged pastures. (4) Correlation analysis showed that:(a) there were significant positive linear correlations between MBC and soil C, and MBP and soil P (P < 0.05); (b) there were highly significant negative linear correlations between plant and soil C, plant C and soil N, plant C:N and soil C, and plant C:N and soil N (P < 0.01); and (c) there were highly significant positive linear correlations between plant N and soil C, and plant and soil N (P < 0.01). Thus, the determination of C, N, and P stoichiometric characteristics of plant-soil-microbe interactions in the present study showed that in karst ecosystems, croplands were more limited by N than by P, whereas artificial pastures in rehabilitated land were mainly limited by P, especially during the vigorous restoration stage. Plant C:N:P stoichiometric characteristics in pastures at different ages showed a higher temporal variability than those of soil.
  • DownLoad:Ecological stoichiometric characteristics of plants, soil, and microbes of Pennisetum purpureum cv. Guimu-1 pastures at different rehabilitation ages in a karst rocky desertification region.PDF
  • The response of plant alpha diversity to different grazer stocking rate in a Stipa breviflora. desert steppe
  • Authors:ZHANG Ruiyang, WANG Zhongwu, HAN Guodong, PAN Zhanlei, LIU Fang, WU Qian and AMUER Sana
  • Abstract:Plant diversity is a crucial component of biodiversity, and it has attracted growing attention in recent years. For desert steppes, however, how grazing and the sample area used in these studies affect species diversity, and through what mechanisms, is still unclear. Stipa breviflora grasslands typically represent desert steppes, which in turn occupy a special place among the grassland ecosystems. In this study, a long-term (11 years) grazing experiment with four levels of grazer stocking rate in the S. breviflora desert steppe in Siziwang Banner of Inner Mongolia was used. The study aims to provide a scientific basis for grassland biodiversity protection and sustainable development, and therefore explored the influence of different grazer stocking rates on plant diversity (using four alpha diversity indexes:the Margalef, Shannon-Wiener, Simpson, and Pielou index). Grassland alpha diversity and species composition change was assessed for different stocking rates, and the sample area sizes (from 0.01 m2 to 650 m2) were analyzed to determine the optimal sampling area for this desert grassland.The results showed that:(1) The number of species and alpha diversity indices declined with increasing stocking rate. (2) Compared with the relative density of the dominant species (e.g. S. breviflora and Cleistogenes songorica), grazing reduced the relative density of non-dominant species. Dominant species have a strong adaptability and endurance, whereas non-dominant species have a sensitive response to grazing. Moreover, a decrease in non-dominant species resulted in a lower alpha diversity index. This suggests that non-dominant species are important indicators that reflect how plant species respond to grazer stocking rate changes, and underline the variety in adaptive strategies for resources changes. (3) The best sampling area size to investigate the species number and alpha diversity was 40 m2. (4) The species-area relations and alpha diversity index-area relations both conformed to a logarithmic growth model. (5) Sampling area influenced the analyses of the different alpha diversity indices. With increasing scale area, the differences among the alpha diversity indices increased gradually with stocking rate gradients. Sampling areas between 0.16 m2 to 0.64 m2 (small scale) detected significant different levels of alpha diversity indices between zero and low, and moderate and high stocking rate levels. However, sampling areas larger than 160 m2 (large scales) could detect significant differences in alpha diversity indices among high and all stocking rate levels over the sampling area.
  • DownLoad:The response of plant alpha diversity to different grazer stocking rate in a Stipa breviflora. desert steppe.PDF
  • Effects of snowfall on physiological and biochemical characteristics of Bryum argenteum distributed in desert moss crusts
  • Authors:XIE Min, HUI Rong, LIU Lichao, GAO Yanhong, LI Gang, WANG Yanli and WEI Wenfei
  • Abstract:Biological soil crusts (BSCs) endure the most extreme habitats in the world. They grow on the soil surface in desert regions and withstand extreme temperature, drought and intense radiation. BSCs comprise many kinds of micro-organisms, such as bacteria, algae, lichen and moss. Water is the main limiting factor in the growth of BSCs, and winter snowfall is likely to be one of their important water resources. However, few studies have explored the effects of snowfall on BSCs untill now. In this study, moss crust (Bryum argenteum) was sampled from a revegetated area in Shapotou, at the southeastern fringe of the Tengger Desert. The effects of snowfall on the content of photosynthetic pigment, water-soluble sugar, water-soluble protein, proline and malondialdehyde (MDA) in B. argenteum were measured. Four snowfall treatments were applied:non-snowfall (control, 0S), half of the ambient conditions (0.5S), ambient snowfall (1S), and double ambient conditions (2S). The 0S samples were each covered with a euphotic plastic disc of 10 cm diameter to exclude all snowfall. The remaining treatments accepted natural snowfall, then half of the natural snowfall was removed from 0.5S samples and an additional mass of snowfall equivalent to natural snowfall was added to the 2S samples. The results show that with an increase in snowfall, the chlorophyll and water-soluble proteins increase significantly, while the water-soluble sugars, proline, and MDA decrease. Snowfall results in an increase in the chlorophyll and water-soluble protein content, hence, leads to a pontential promotion of the ability of photosynthesis and metabolism. At the same time, increased snowfall reduces the soluble sugar, proline, and MDA content, thus affecting B. argentum's osmotic adjustment and membrane lipid peroxidation. This study elucidates the physiological and biochemical activities of B. argenteum under snowfall, and has academic and practical significance in maintaining the stability of desert ecosystem.
  • DownLoad:Effects of snowfall on physiological and biochemical characteristics of Bryum argenteum distributed in desert moss crusts.PDF
  • Spatio-temporal change in desertification of the Maqu Plateau based on RS and GIS
  • Authors:HU Mengjun, PAN Ninghui, ZUO Hailing and LI Xiangfeng
  • Abstract:The Maqu plateau, an important part of the Qinghai-Tibet plateau, is the main water conservation area in the upper reaches of the Yellow River. In recent years, under the influence of natural environmental and human activities, the ecologically sensitive Maqu plateau area has experienced environmental problems such as glacier retreat, permafrost degradation, aeolian desertification, and grassland degradation. The Maqu plateau is one of the largest pasture lands in Asia, with a rangeland area of 8.58×107hm2. In the past decade, the eco-environmental problems of the Qinghai-Tibetan plateau have received increasing attention owing to global warming and intensifying regional development. The aim of this study was to quantify the developmental processes in these region, as well as any changes in the spatial distribution of land desertification. We used remote sensing (RS) and geographic information system (GIS) technologies, and applied multi-temporal Landsat imagery to investigate the spatio-temporal development of land desertification in the Maqu Plateau during 1977-2014. The remote-sensing data used in this study include:Landsat multi-spectral scanner images from 1977; Thematic Mapper images from 1989, 1995, 2006, and 2014; and Enhanced Thematic Mapper images from 2001 and 2010. We mainly selected images recorded between June and October, because aeolian desertified lands are more easily recognized during this period of greater vegetation growth. Our results indicated that the area of desertified land in the Maqu plateau had experienced five main phases:rapid development, where the area of aeolian desertified land increased at a rate of 2004.6 hm2/a between 1977 and 1989; slow development, where it increased at a rate of 57 hm2/a between 1989 and 1995; rapid reverse, where it decreased at a rate of 3868 hm2/a between 1995 and 2006; slow reverse, where it decreased at a rate of 893.4 hm2/a between 2006 and 2010; and, fast reverse, where it decreased at a rate of 2129.3 hm2/a between 2010 and 2014. The area of desertified land expanded rapidly between 1977 and 1995, with an average growth rate of 3.01% per year. An obvious decrease in the area of desertified land was observed from 1995 to 2014, with an average reversal rate of 4.14% per year. The areas affected by the development and reversal of aeolian desertification were mainly distributed alongside the Yellow River, including near the Oulaxiuma and Nima villages of the northeastern region, the marshlands of the Cairuma and Manrima villages in the southeastern region, and the riversides of tributaries to the Yellow River near the Qihama and Awancang villages of the southwestern region. We found that the spatial distribution of aeolian desertification changed significantly over time, with fragmentation of the desertified land increasing rapidly between 1977 and 1995. Aeolian desertification in the Maqu Plateau has not been progressive, but instead, it has been an alternating process of development and reversal approximately every 15 to 20 years. There was an abrupt change in the desertification level of lands in different levels of the plateau. Overall, we found that the trend of aeolian desertification in the Maqu plateau had been reversed and the local environment had improved since 1995.
  • DownLoad:Spatio-temporal change in desertification of the Maqu Plateau based on RS and GIS.PDF
  • Health assessment of watershed ecosystems: the Chao River and Bai River Basins as a case study
  • Authors:XU Fei, WANG Yonggang, ZHANG Nan, WANG Xu and FAN Qing
  • Abstract:From the perspective of adaptive river basin management, health assessment based on an eco-environmental investigation was used to determine the health state, analyze the pressure influence and diagnose the main problems of watershed ecosystems. The Chao River and Bai River basins, located upstream of the important drinking water source of Beijing (the Miyun Reservoir), were selected as an example for such an assessment. The established index system for the assessment includes 13 indicators, which cover aspects of habitat structure, aquatic organisms, ecological patterns, ecological functioning, and ecological pressure. The health states of water and land areas of the studied basins were evaluated by comparing their state indicator scores, to consequently determine the weakness of the basins' ecosystems. In addition, the major cause for ecosystem health degradation was analyzed by contrasting the ecological pressure indicator scores. The results show that the health states of water land areas of the Chao River and Bai River basins were good. However, the aquatic organisms and ecological patterns were in a poor state. Furthermore, the indices of organism diversity and landscape fragmentation in the Bai River basin acquired a relatively low score, whereas organism diversity, landscape fragmentation, and forest cover score were comparatively low in the Chao River basin. The health pressure assessment showed that indices of aquatic habitat disturbance and pollution load discharge scored low. This observation indicates that in the Chao River and Bai River basins, river habitat damage resulting from anthropogenic disturbances and pollutants are the dominant pressures on ecosystem health. The comprehensive indices of watershed health for the Chao River and Bai River basins have been 78 and 71, respectively, indicating the health levels of both are in relatively good condition. There were a few differences among the health states of 14 sub-basins. Sub-basins of the Liuli River, downstream of the Bai River, and upstream of the Tang River, displayed a relatively better health state. In contrast, the health state of sub-basins of the Chao River (middle-downstream), and Xiaotang River were relatively worse. According to field investigation, excessive livestock breeding, bankside planting, and local tourism in the basin were the main causes of the degradation of watershed health. In order to improve the watershed health state, control on the pollution load and supervision of wading activities that disturb the aquatic habitat should be enhanced. Furthermore, for the Chao River and Bai River basins, the biological index is a more effective indicator than physical and chemical indices. The diversity of benthic animals is very closely related to the condition of river habitat, because some benthic species are sensitive to river habitat destruction caused by excessive wading activities. Therefore, to realize sustainable and adaptive watershed management, and to guarantee the water ecological security of the Miyun Reservoir, more attention should be paid to biotic indices that can effectively indicate the early stages of ecosystem degradation.
  • DownLoad:Health assessment of watershed ecosystems: the Chao River and Bai River Basins as a case study.PDF
  • Assessment of the ecosystem health of the Yellow River Estuary based on the pressure-state-response model
  • Authors:NIU Mingxiang, WANG Jun and XU Binduo
  • Abstract:As the main channel of matter exchange between riverine and marine environments, estuarine ecosystems have been subjected to growing environmental interference and disturbance. Anthropogenic activities and the interactions between land and sea considerably affect estuarine ecosystems and health, and they have resulted in challenges for ecosystem management. Ecosystem health assessment, a new method of ecosystem assessment, determines the current ecosystem structure and function, and provides substantial information necessary for effective ecosystem management. Therefore, for the management of the Yellow River Estuary, a pressure-state-response (PSR) method was used to assess the health status of the ecosystem. The estuary and the adjacent marine and terrestrial ecosystems were considered an entity under the broad definition of estuarine ecosystems. An ecosystem health assessment indicator system was developed, taking external pressure, ecosystem state, and response parameters into consideration to calculate indicators of regional ecosystem health. The health status of the Yellow River estuarine ecosystem was then assessed using a comprehensive evaluation index (CEI), including historical data from 1991. The results showed that the overall index of the Yellow River Estuary was 0.7427 in October 2013. In detail, the response index was 0.9055, which indicates that the Yellow River estuarine ecosystem was "very healthy," suggesting the policy and behavior of local government, relevant departments, and individuals reduced the pressure on the regional environment to a certain extent. The pressure index was 0.8288, which indicates that the ecosystem was at a "good status," but has been under growing pressure and its health has deteriorated. The state index was 0.6458, suggesting that the ecosystem is "unhealthy" and is under considerable pressure, requiring improvement. Overall, the current status of the Yellow River estuarine ecosystem was reasonably "healthy" as compared to that in 1991, but it has deteriorated. The state index showed the most serious decline among pressure, state, and response indexes. The main reasons for the health degradation of the Yellow River estuarine ecosystem were investigated by analyzing the index variation and its weight. The factors resulting in the deterioration included overfishing, unreasonable wetland development, over-farming in shallow seawater, and pollution. Therefore, actions should be taken to prevent further deterioration through ecological restoration and appropriate management of the Yellow River estuarine ecosystem. Any future development should be based on scientific planning for the sustainability of the ecosystem.
  • DownLoad:Assessment of the ecosystem health of the Yellow River Estuary based on the pressure-state-response model.PDF
  • The impact of vehicle emissions on microclimate in Beijing metropolis
  • Authors:WANG Yening, SUN Ranhao and CHEN Liding
  • Abstract:The urban heat island effect is worsening with the rapid urbanization of Beijing. Vehicle heat emissions are regarded as one of the most significant factors affecting the urban thermal environment. The intensity and scale of the impact of vehicle heat should not be ignored given the sharp increase in car ownership in recent years. Taking the region inside Beijing 5th ring road as the study area, this paper proposes a feasible method to calculate vehicle heat intensity through the data of transportation index, traffic density, road length, etc. The microclimate data were collected through field sampling at several typical sites. These temperature and humidity data were used to explore the quantitative relationship with vehicle heat intensity in the Beijing metropolis. The results show that vehicle heat intensity distributes in radial pattern in Beijing. The mean heat intensity ranges from 8.6 to 10.8 W/m2 and reaches 32.2-53.9 W/m2 inside the 3th ring road. The average vehicle heat intensity at daytime is 2-10 times the intensity at nighttime. The maximum value of vehicle heat appears in the mornings and evenings. Interestingly, the spatial pattern of vehicle heat has no significant difference between weekends and weekdays. The vehicle heat intensity at 8:00 a.m. shows a significant correlation with its temperature difference on main roads. The temperature amplification reaches 0.91℃/10 W/m2 at 8:00 a.m. At some points, we observe a significantly positive correlation between vehicle heat intensity and its temperature difference. We also notice a lag effect (10-20 min) of vehicle heat on temperature amplification. This study could provide useful information for the scientific planning of roads and urban landscapes.
  • DownLoad:The impact of vehicle emissions on microclimate in Beijing metropolis.PDF
  • Nitrogen flow associated with food production and consumption in Nanjing City
  • Authors:ZHOU Di, XIE Biao, YANG Hao, SUN Panpan, SONG Yimin and WANG Xueye
  • Abstract:With rapid urbanization, the food production-consumption system is associated with increased nitrogen (N) flow resulting in environmental problems. However, quantitative analyses of N flow during urban expansion and information about their drivers and trajectories are limited, especially at the city level. In the present study, we analyzed the changes in N flow and environmental load in the food production and consumption system of Nanjing, which experienced remarkable population and economic growth between 1995 and 2012, using a combination of statistical databases, literature surveys, and the mass balance model. The results showed that population density increased at the expense of agricultural land and livestock breeding. Food production transformed from self-sufficiency to deficiency, resulting in increased food imports. The rapid increase of the migrant population coincided with a rapid increase in gross domestic production, with changes in food demand and consumption patterns. The structure of food consumption in Nanjing transformed from grain-oriented to grain-vegetable-meat-oriented, and the per capita N consumption of food decreased from 1995 to 2012. In addition, due to different living standards and food consumption patterns between rural and urban residents, the percentage of the per capita decline for N consumption of food was different. The rural and urban per capita N consumption decreased from 5.09 kg person-1 a-1 and 3.04 kg person-1 a-1 in 1995 to 4.11 kg person-1 a-1 and 2.65 kg person-1 a-1 in 2012, respectively. The N cost of food consumption of Nanjing decreased from 8.40 kg/kg in 1995 to 5.10 kg/kg in 2012, and declined by 39.29%. The N cost of the food consumption was relatively low when compared to the mean in China, and decreased over time. Mean N use efficiency in food production increased from 18.71% in 1995 to 24.34% in 2012; however, it was still lower than the mean national level. A large amount of N entered the environment and caused severe air, water, and soil pollution. The decrease of total N input, combined with increased N use efficiency in crop and animal production systems, resulted in a decreased environmental N load from food production and consumption of 30.44%, from 100.49 GgN/a in1995 to 69.90 GgN/a in 2012. Regarding food production in Nanjing, environmental N load could be efficiently reduced by optimizing N fertilizer management and using slow-release fertilizer. Regarding food consumption, environmental N load is produced primarily from food waste and human sewage discharge. The effective collection and treatment of these wastes and the utilization of these in rural areas is urgently needed. The rapid increase in the urban population from 1995 onwards has greatly contributed to the increasing import of food and apparent low food N cost. As food imports increased with rapid growth of urban areas in Nanjing, the N cost associated with the production and processing of imported food and feed was transferred to areas where it was produced. Other regions with increased food production will be affected by large increases in N load.
  • DownLoad:Nitrogen flow associated with food production and consumption in Nanjing City.PDF
  • Urban expansion modes and regional ecological footprints in the Shandong Peninsula Urban Agglomeration
  • Authors:XIE Wenxuan, HUANG Qingxu and HE Chunyang
  • Abstract:Understanding the relationship between urban expansion modes and regional ecological footprints is an important objective in regional sustainability research, and can provide crucial guidance for achieving urban sustainable development. However, empirical research on the relationship between urban expansion modes and ecological footprints is limited. Taking the Shandong Peninsula Urban Agglomeration as an example, the goals of the present study are to examine the characteristics of urban expansion modes and ecological footprint dynamics from 2000 to 2010, and to analyze the relationship between them. We quantified the urban expansion modes and ecological footprint dynamics using the landscape expansion index and ecological footprint model. Then, we divided the 44 counties in the study area into 4 types, and analyzed the relationship between urban expansion modes and ecological footprint dynamics among them using a correlation analysis. The results showed that urban land area of the Shandong Peninsula Urban Agglomeration increased by 1.2×105 hm2 (19.4%), and the average ecological deficit increased by 1.26 hm2 per capita from 2000 to 2010. In all 44 counties, the area of edge-expansion growth was the largest and the ecological deficit increased. There was a significant positive correlation between epitaxial expansion areas and the ecological deficit increment in 27 counties, such as Kenli. However, 17 counties did not show significant correlations. In the future, for sustainable development in this region, controlling the area of outlying and edge-expansion growth, utilizing new clean energy, and limiting the fossil fuel footprints in several counties, such as Kenli, Zibo, and Qingdao, should be the focus.
  • DownLoad:Urban expansion modes and regional ecological footprints in the Shandong Peninsula Urban Agglomeration.PDF
  • Simulation and verification of land surface soil temperatures in the Xinjiang Region by the CLM3.5 model forced by CLDAS
  • Authors:MENG Xianyong, WANG Hao, LIU Zhihui, SHI Chunxiang, LIU Shiyin, CHEN Xi and GONG Weiwei
  • Abstract:This study modeled the spatial and temporal distribution of soil temperatures in the Xinjiang region of China, using atmospheric surface forcing data in the China Meteorological Administration Land Data Assimilation System (CLDAS, NMIC of China Meteorological Administration) to drive the Community Land Model (CLM3.5, National Center of Atmospheric Research USA) for hourly off-line simulations (from 2009 to 2012). To verify the CLM3.5 simulated soil temperatures, data from national automatic soil-temperature stations (105 in the Xinjiang region) were used at three soil layers (5 cm, 20 cm, and 80 cm). For monthly variation, simulated top layer (5cm) soil temperatures differed substantially from measured values, with the largest difference (±5℃) reaching the maximum in July each year. The difference (±3℃) between modeled and observed soil temperatures at the second layer (20 cm) reached the maximum in July for all years, whereas for the third layer (80 cm), simulated annual July soil temperatures were in accordance with the observed values. The large discrepancies in July soil temperatures in the top surface layers can be explained by the drastic surface temperature changes in the Xinjiang region during that month. With day-time temperatures that can reach above 30℃, combined with large diurnal temperature differences, it becomes very difficult to accurately capture surface temperature variation by using the model. In contrast, in January and December, the 80 cm soil depth simulations were less accurate than the results of simulations at the first two soil layers. Furthermore, simulated values of soil temperature at the top two layers (5 cm and 20 cm) did not fit well with observed values for the summer and autumn. However, similar to monthly variation, the daily variation in modeled soil temperature at 80 cm showed a bad fit with observed data in January and December, whereas the fit was good in other periods. For hourly variation at 5 cm soil depth, the simulated soil temperature values were higher than the observed ones from January to April and September to November between 03 UTC and 21 UTC the next day. In contrast, simulated results were slightly lower than the observed values between 21 UTC and 00 UTC the next day for this same layer and period. From May to August of every year, day-time simulated values are slightly lower, reaching a maximum at 09UTC. At 20 cm depth, simulated soil temperature had smaller deviations (between -1℃ and 1℃) for most months, and the daily maximum occurred at 12UTC, which is earlier than the observed values. At the 80 cm soil layer, little daily variation was simulated or observed in soil temperatures, giving this soil layer hardly any influence on the overall daily variation. In the Xinjiang region, the diurnal temperature difference is large from May to August and September to November, which can explain why the upper two soil layers show differences between modeled and observed hourly soil temperatures. Soil temperature at deep soil layers, however, will vary less with temperature differences, giving this layer a better fit than the other two. Overall, this study shows that the CLM3.5 model forced by a CLDAS driving field can simulate the multi-year spatial and temporal distribution of average soil temperatures in Xinjiang region precisely. It furthermore showed that this method could simulate and reflect the hourly, daily, monthly, and yearly patterns of soil temperature in the Xinjiang region. Finally, the poor simulation of temperatures at the surface layer may be caused by the parameterization scheme of the surface parameters in this model, which will be addressed and corrected in a later phase.
  • DownLoad:Simulation and verification of land surface soil temperatures in the Xinjiang Region by the CLM3.5 model forced by CLDAS.PDF
  • Temporal and spatial patterns of climate drought-wet and drought event based on Standard Precipitation Index in Shiyang River Basin
  • Authors:ZHANG Lili, ZHOU Junju, ZHANG Hengwei, WANG Bei and CAO Jianjun
  • Abstract:Shiyang River Basin is located in the northwest China, and it is a typical fragile ecosystem area. This region is extremely sensitive to climatic changes, and therefore, monitoring these changes can provide an important evidence for revealing trends indrought-wet transition mechanisms in drought-prone and arid regions of Northwestern China, this study aimed to investigate monthly precipitation data obtained from four stations in Shiyang River Basin. In particular, the Standard Precipitation Index (SPI) and Theory of Runs were adopted to analyze changes in climate drought-wet and space-time evolution of drought events on different time scale during a period of 54 years i.e., from 1960 to 2013. The main results of this study suggest that SPI characteristics at different time scale lead to SPI values were substantial sensitive to precipitation changes, and a smaller time scale resulted in a more sensitive response to one precipitation event. The inter-decadal, inter-annual and seasonal SPI showed an increasing trend. The wetting rate was the fastest in winter, which makes the largest contribution to annual wetting. The drought event duration, drought severity and drought intensity on different time scales showed a decreasing trend, and the fluctuations noticedwere gradually mild. The most serious agricultural drought and hydrological drought occurred during 1964 to 1965 and 1962 to1964, respectively. The drought event duration during two time scales reduced gradually from upstream to downstream, and the longest agricultural drought occurred in Wushaoling areas, whereas the longest hydrological drought occurred in Yongchang and Minqin region. Drought severity of the drought events during the two time scales reduced the fastest in Wushaoling areas. Except for the three-month scale for drought intensity showing a slight increase in Wuwei and Minqin regions, the intensity of drought events showed a decreasing trend in other regions on different time scales. More frequent drought events and relatively higher drought intensity were noted in the middle reaches of the river, especially in Yongchang region.
  • DownLoad:Temporal and spatial patterns of climate drought-wet and drought event based on Standard Precipitation Index in Shiyang River Basin.PDF
  • Study on eco-environmental water requirement in the middle-reach oasis of Shulehe River Basin based on ecological protection target
  • Authors:SUN Dongyuan, YANG Jun, HU Xiangquan, JIN Yanzhao and ZHANG Yunliang
  • Abstract:The study of eco-environmental water requirements is the hotspot of ecology and water science. It is also the basis of the rational allocation and sustainable utilization of water resources. The results of such a study could provide guidance as to the optimal allocation of regional water resources and utilization, and ultimately provide a regional, economical, ecological, and environmental water system of balanced and sustainable development. The eco-environmental water requirements of an arid inland river basin are a key scientific problem facing the reasonable allocation and management of water resources as well as the eco-environmental protection and construction of arid regions. The Shulehe River Basin, as the third largest inland river basin in Hexi Corridor, Gansu province, is an important ecological security barrier for northwestern China. Recently however, increasing human activity and global climate change has led to a series of ecological and environmental issues and water crises in Shulehe River Basin. Specifically, the degenerated vegetation caused a rapid decline of the groundwater water table. In recent years, ecological water requirements have often been overshadowed by the socioeconomic use of water. This led to great changes in the oasis of the middle reaches. The oasis of the middle reaches, as a societal, economical, and human activity main zone, is a vital ecological subject for protection in the Shulehe River Basin. Considering these issues, this study utilized the oasis of the middle reaches of Shulehe River Basin as its study area. Using Remote Sensing (RS) and Geographic Information System (GIS) technology, the results of Thematic mapper/Enhanced Thematic Mapper (TM/ETM) images of the oasis of the middle reaches of the Shulehe River Basin in 1990, 2000, and 2013 were selected to be used as basic data in order to study ecological evolution, and determine the ecological protection target of the oasis of the middle reaches of the Shulehe River Basin in 2020 and 2030. According to different types of eco-environmental water requirements in the oasis of the middle reaches of the Shulehe river basin, a quantification model for such water requirements was established and the current status and protection targets of eco-environmental water requirements were estimated. This would provide reference for the rational allocation of regional water resources and the coordinated development of an ecological system. These results indicate that the eco-environmental water requirements of natural vegetation, basic eco-environmental water requirements, transportation sand eco-environmental water requirements, recharge of watercourse seepage water requirements, water surface evaporation eco-environmental water requirements, marsh eco-environmental water requirements and combating salinization of farmlands eco-environmental water requirements of the oasis of the middle reaches of the Shulehe river basin were 1.90×108, 0.98×108, 1.11×108, 0.83×108, 0.68×108, 2.70×108, 0.20×108, 2.24×108, 0.98×108, 1.11×108, 0.83×108, 0.73×108, 3.13×108, 0.20×108 m3 and 2.47×108, 0.98×108, 1.11×108, 0.83×108, 0.80×108, 3.71×108, 0.20×108 m3 in 2013, 2020 and 2030, respectively. At the same time, the maximum of eco-environmental water requirements, minimum of eco-environmental water requirements, and optimum eco-environmental water requirements of the oasis of the middle reaches of the Shulehe river basin were 7.42×108, 7.09×108, 7.29×108, 8.24×108, 7.91×108, 8.11×108 m3 and 9.12×108, 8.79×108, 8.99×108 m3 in 2013, 2020 and 2030, respectively. The annual variation of eco-environmental water requirement was concentrated mainly from May to August and proportion of cumulative eco-environmental water requirements of the total ecological environment water demand were 58.01%, 58.08% and 58.13% in 2013, 2020 and 2030, respectively. The water requirements of Guazhou County eco-environmental water requirements were relatively greater than those of Yumen City and Dunhuang City. The study results will provide a basis for the management program of Dunhuang water resources reasonable utilization and ecological protection. Additionally, it will be an important source for promoting the research of ecological water rights, allocation of water quantity, and coordinated and sustainable development among ecological protection, reasonable configuration of water resources and economic society in Shulehe river basin. http://www.ecologica.cn
  • DownLoad:Study on eco-environmental water requirement in the middle-reach oasis of Shulehe River Basin based on ecological protection target.PDF
  • The strategy adopted by Upland buzzard (Buteo hemilasius) to Prey on Meriones unguiculatus family group, in Autumn
  • Authors:LI Yaheng, MAN Li, HONG Liguo, GAO Lijun, WU Yunqiqige, QING Gelitu, BI Ligebayaer and WANG Yong
  • Abstract:Between september 10-15 of 2003, we focused on the grasslands in Inner Mongolia that are heavily populated with rodents, to understand the strategy adopted by the upland buzzard (Buteo hemilasius) to prey on the Mongolian gerbil (Meriones unguiculatus) in a typical steppe environment. Autumn is the season when M. unguiculatus are most active, therefore, the number of rodent holes in this season was used as a measure to determine the abundance of M. unguiculatus. Based on a previous study on M. unguiculatus community behavior, we found that when the rodents cluster in autumn, on an average, there is only 1 M. unguiculatus per 6.3 rat holes. Therefore, to reduce the interference of the temporary M. unguiculatus holes in autumn, we defined the groups that had fewer than five rodent holes as temporary, ineffective groups. This study only analyzed the groups with more than five rodent holes as a base group to assess the predation risk. The predation preference of B. hemilasius on different-sized M. unguiculatus clusters was analyzed. This study focused on 3 square meter of grassland, and the number of M. unguiculatus groups, based on the statistics, was 87. To determine the predation strategy of B. hemilasius, two researchers recorded the location and frequency of B. hemilasius within the sample area at different locations using telescopes. For 5 d B. hemilasius was observed swooping down 29 times within the sample area, which was inhabited 23 M. unguiculatus groups. The number of holes that B. hemilasius visited, and the frequency of B. hemilasius visits to each of the groups, was analyzed using the Mann-Whitney test for nonparametric data. From the results, we determined that B. hemilasius visited 2,569.5 holes, while 1,258.5 holes were not visited by B. hemilasius (U value=489.5, Adjusted Z Value=-2.37459), indicating a significant difference between the two (P=0.017574). This indicated that B. hemilasius was obviously biased towards the survey groups with more rodent holes, possibly for increased predation success rate. From the analysis that the correlation between the number of B. hemilasius visits (F) and the group size of another rodent, Brandt's vole (Lasiopodomys brandtii, (S)), was also determined as follows:F=-0.0559+0.023S (r=0.2707, P < 0.05). From these results, we concluded that the upland buzzard first chose the M. unguiculatus groups that have a higher number of rodent holes as potential prey before it chose the L. brandtii groups. During the winter, the number of M. unguiculatus individuals in clusters will become restricted, and may form an optimal number in the cluster model. The results of the present study may support the theory that prey species form an optimal cluster to reduce predation risk. M. unguiculatus may use rodent holes to escape predation, or autumn swarming behavior to reduce the density of individuals in clusters, to reduce predation risk.
  • DownLoad:The strategy adopted by Upland buzzard (Buteo hemilasius) to Prey on Meriones unguiculatus family group, in Autumn.PDF
  • Nest building duration and its contributing factors for black-necked cranes (Grus nigricollis) at Ruoergai, Sichuan, China
  • Authors:JIANG Zhengquan, LI Fengshan, RAN Jianghong, LIU Wei, ZHAO Chenhao, ZHANG Bo and LI Hua
  • Abstract:The black-necked crane Grus nigricollis is the only alpine crane species, and its distribution is restricted to the Tibetan-Qinghai Plateau and the adjacent high altitude areas of China, Bhutan, and India. With a world population of 10000-10200 birds, this species is classified as vulnerable under the IUCN Red List Categories. The Ruoergai wetland is situated at the headwaters of the Yellow River on the northeastern edge of the Tibetan Plateau in western China, and it is one of the largest wetlands in China. With over 2,000 cranes, the marsh is the most important breeding area for the black-necked crane in the world. The Ruoergai National Nature Reserve, a wetland site of international importance and accounting for only 8.3% of the Ruoergai wetland, hosts over 1/3 of the total black-necked cranes population breeding in the Ruoergai wetland. Nest building is a significant strategy for many bird species to secure breeding success, and many species spend considerable time and energy in nest building activities. For birds, nest building is one of the key indicators for parental investment during the breeding period, and the duration of nest building greatly reflects the birds' adaptation to the environment. To enhance knowledge of the black-necked crane breeding biology, and better understand its ecological adaption and conservation strategy, we studied the behavior at the Ruoergai National Nature Reserve from March-July in 2013 and 2014. The specific objectives of this study were to determine the duration of nest building of this species and its relation to:(1) nest type; (2) starting date of nest building; (3) nest size; and (4) nesting habitat. All potentially nesting black-necked cranes pairs in the study area were located with field surveys and data from previous observations. We checked these pairs every day, accessing the site with field vehicles. Once arrived in an area where a pair of cranes was sighted, we watched from a distance with a spotting scope, and recorded the date, time, and nest building activity. Immediately after the hatching of crane chicks, we walked to the nest and recorded the nest type, size of the nest (length, width, and height), and nesting habitat. There were four types of nests:grass mound, natural island, dirt mound, and floating grass mound. Nesting habitats included lake, river, and shallow water marsh. A total of 55 nests of black-necked cranes were studied. From these 55, 41 were grass mounds, five were natural islands, five were dirt mounds, and four were floating grass mounds. Twenty-five nests were located in swampy habitats, 17 in lake habitats, and 13 near rivers. The cranes spent (6.7±9.3) days on nest building, ranging from 0.5 to 40 days. From the four types of nests built or used by the cranes, nest building period was from longest to shortest:dirt mound > grass mound > floating grass mound > natural island. Nest building time and nest types correlated significantly (r=0.728). As for habitat type, nest building took the longest time in the lake habitat. Most nests were built in April, when cranes also spent more days building their nests, than in May and June. Finally, the larger the nest, the longer it took the cranes to build it.
  • DownLoad:Nest building duration and its contributing factors for black-necked cranes (Grus nigricollis) at Ruoergai, Sichuan, China.PDF
  • Effects of vision obstruction on the foraging behavior in voles (Microtus fortis)
  • Authors:TANG Xianjiang, TAO Shuanglun, MA Jing, ZHANG Li, WU Shuailing and LI Junnian
  • Abstract:The foraging behavior of small mammalian herbivores is the outcome of adaption to specific habitats. It is unknown whether vision obstruction caused by plants surrounding food patches affects foraging vigilance in small mammalian herbivores, resulting in variations in their intake rates. To evaluate the effects of the height of surrounding obstructs on the behavior sequence and intake rate of voles (Microtus fortis), we devised concentrated food patches of fresh leaves of clover (Trifolium repens) that were obstructed by three heights of brown paper to imitate the vegetation obstruction to vole vision around the food patches. The sequence and parameters of vole foraging behavior were measured to examine the effect of vegetation heights on their intake rate. No significant difference was detected in the foraging subject with different heights of obstruction in foraging behavior. The dynamic analysis of variation in foraging behavior parameters showed that in each biting bout, individuals maintained the total foraging interruption time by modulating the frequency and duration of vigilance behavior in each foraging bout, thus maintaining a steady ingestion time. The results also indicated that the voles maintained their intake rates at different levels of vision obstruction via altering and optimizing their behavior. These results verified the instantaneously dynamic change of energy gain by measuring the actual foraging interruption time caused by vigilant behavior. The variation in vigilance intensity, i.e., vigilance frequency, in voles did not reflect the cost of decreasing food intake caused by foraging interruption, rather the duration of vigilance action in foraging processes was a reliable indicator of dynamic change in intake rates. Consequently, investigating the effects of vigilance behavior on intake rates by measuring the foraging cost caused by the foraging interruption time as an indicator could be an effective way to evaluate adaptive foraging strategies in different situations in small mammalian herbivores.
  • DownLoad:Effects of vision obstruction on the foraging behavior in voles (Microtus fortis).PDF
  • A wavelet theory based remote sensing inversion of chlorophyll a concentrations for inland lakes in arid areas using TM image data
  • Authors:SHI Rui, ZHANG Hong, YUE Rong, ZHANG Xiaoyu, WANG Meiping and SHI Wei
  • Abstract:Chlorophyll a (Chl-a) concentration is an important indicator for measuring eutrophication and lake water quality. Therefore, a fast and sensitive remote sensing method for Chl-a concentrations is urgently needed, as this will enable real-time spatio-temporal monitoring of Chl-a distribution in large inland lakes, which will enhance water quality management and protection. Using Wuliangsuhai Lake (Inner Mongolia) as an example, this study established an effective remote sensing inversion method for Chl-a concentrations, based on Landsat Thematic Mapper (TM) image data. Chl-a concentration data from January 2010 to November 2014 was collected by the Environmental Monitoring Station of Bayannur city. TM images were acquired by the Information Center of the Chinese Academy of Sciences. After pre-treatment, the Wuliangsuhai TM images were de-noised and reconstructed based on a wavelet analysis. A neural network method was subsequently used to construct a model that relates the TM spectral reflectance ratios and Chl-a concentrations. The results indicated that the proposed method of combining wavelet analysis with a neural network model is suitable for inversely remote sensing Chl-a concentrations. The correlation coefficient between the wavelet de-noised spectral signal and the Chl-a concentration (-0.575) was higher than when the original spectral signal was used (-0.417). Furthermore, the negative correlation between the de\oised spectral signal and water sample Chl-a concentrations was stronger than the original one. This demonstrated that the de\oised monitoring values could further reduce the interference of random errors and noise. Furthermore, the remotely sensed Chl-a values could approach the sampled Chl-a concentrations. In addition, the de\oised reconstruction of the TM images had a narrower reconstructed spectral than before, and part of the signals were enhanced. Nonetheless, the basic cross\sectional structure of the images did not change notably. The mean relative error (MRE) of the proposed method was 0.142, and differed little from other models. In addition, the distribution of Chl-a concentration based on the TM inversion method was consistent with the distribution of the Wuliangsuhai Lake pollution sources. The spatio\temporal distribution of Chl-a concentrations showed some variability. In the wet season, the Chl-a concentrations in shallow water areas were higher than those in the central area, whereas the Chl-a concentrations in the inlet area were higher than those in other areas. In the dry season, the Chl-a concentration decreased gradually from west to east in the middle of the lake, and showed a homogeneous pattern in the west of the lake. Overall, the precision of the TM remote sensing inversion method achieved a satisfactory prediction accuracy. However, given the lack of sufficient Chl-a monitoring sites and monitoring data, some factors that influenced the spectral reflectance ratio of TM image could not be removed or controlled for. Some improvements on TM image data acquisition, such as algorithm optimization and model verification, should therefore be a priority for the future. Alternatively, high\esolution remote sensing image data could be used to acquire the spectral reflectance ratio of lake water, instead of TM images. In conclusion, this study could be used to improve lake water quality monitoring technologies, as well as contribute to real\time water quality monitoring. The proposed method for Wuliangsuhai Lake could be applied in other areas as well, and for other water pollutants.
  • DownLoad:A wavelet theory based remote sensing inversion of chlorophyll a concentrations for inland lakes in arid areas using TM image data.PDF
  • Spatial variation of phytoplankton community structure and its relationship with environmental factors at the Mangshan pumping station
  • Authors:HU Jun, YANG Yuxia, CHI Shiyun, SHEN Qiang and HU Juxiang
  • Abstract:The Mangshan pumping station is one of the most important water sources in the Yellow River basin, and it has been included in the list of national drinking water sources. When water from the Yellow River is pumped, desilted, and transferred to the waterworks at the Mangshan pumping station, the aquatic biotope dramatically changes throughout these steps. To better understand how these artificial actions influence the phytoplankton by changing the biotope, the changes in phytoplankton from the river intake to the entry of the waterworks were investigated in June 2014. Overall, 7 sampling sites were set up along the path of the water. The measured water quality parameters included, among others, water temperature, dissolved oxygen, and total phosphorus, and all were monitored simultaneously. Structural changes in phytoplankton community and the relationship with the environmental factors were analyzed using two multivariate analysis techniques:Polar Ordination Analysis (POA) and Redundancy Analysis (RDA). The phytoplankton community structure, their density, and the biomass changed significantly from the river intakes to the waterworks. The phytoplankton biomass and biodiversity showed a decreasing trend along the path of the water. Furthermore, POA analyses indicated that the 7 sampling sites could be divided into three biotopes, and that these three biotopes reflected the change along the way. Finally, RDA analyses showed a significant influence of the environmental factors on the community structure, which differed from the influence these factors have in the lake and other natural water bodies.
  • DownLoad:Spatial variation of phytoplankton community structure and its relationship with environmental factors at the Mangshan pumping station.PDF

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