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Volume 37,Issue 11
  • Ecological distribution of arbuscular mycorrhizal fungi and the influencing factors
  • Authors:XIANG Dan, XU Tianle, LI Huan and CHEN Baodong
  • Abstract:Arbuscular mycorrhizal (AM) fungi are ubiquitous soil fungi that can form symbiotic associations with the majority of terrestrial plant. AM fungi play key roles in plant resistance to various environmental stresses, such as nutrient deficiency, drought, and soil contaminations. Through the common mycorrhizal network, AM fungi can regulate plant community structure and succession, influence material cycling, energy flow, and signal transduction, and substantially affect ecosystem stability and function. Because the physiological and ecological functions of AM fungi could be predetermined by their ecological adaptability, understanding the AM fungal biodiversity in different ecosystems and their response to various environmental factors is important for the exploration and utilization of these biological resources. To date, many studies have revealed the influences of different ecological factors on AM fungal diversity, however, systematic studies on the ecological distribution patterns of AM fungi and the underlying mechanisms are still lacking. This paper summarized available knowledge regarding the influences of biotic and abiotic factors on AM fungal diversity and ecological distribution, and discussed AM fungal biogeography compared to macroorganisms. Prospects in this research area were also proposed to promote future research.
  • DownLoad:Ecological distribution of arbuscular mycorrhizal fungi and the influencing factors.PDF
  • Symbiosis network for municipal waste recycling: concept, characteristics, and architecture analysis
  • Authors:ZHANG Qichun and XI Yongqin
  • Abstract:Mining valuable resources in municipal waste is often used to exploit and manage waste across the world. Industrial symbiosis is a strategic tool that can promote green economic development and improve resource efficiency, which has become important aspects of waste resource utilization. This study introduces industrial symbiosis theory to municipal waste resource recycling, promotes the concept of municipal waste recycling symbiosis network, and summarizes the typical characteristics of a municipal waste recycling symbiosis network into "four unifications". These are the unification of the value network and the responsibility network, unification of cluster symbiosis and virtual symbiosis, unification of robustness and vulnerability, and unification of self-organization and subject constructiveness. A theoretical model, based on super network theory, was built to architecturally analyze a municipal waste recycling symbiosis network. In order to gain a comprehensive understanding of the model, this study undertook a detailed analysis of the model using the symbiotic unit, the symbiotic mode, the symbiotic interface, and the symbiotic environment. The model suggests that the symbiosis network for municipal waste recycling can be divided into two networks: the core network and the peripheral network. The core network consists of suppliers, recyclers, resource enterprises, and regeneration enterprises, whereas the peripheral network consists of governments, financial institutions, university research institutes, media outlets, industrial associations, and intermediary agencies. There is a comprehensive and multi-level cooperation mechanism between the two networks. Furthermore, the symbiotic unit is very diverse and has multi-level characteristics. There are different types of symbiotic relationships between symbiotic units with varying efficiency. Consequently, it is important to move primary symbiosis towards symmetric reciprocal and integrated symbiosis when attempting to solve municipal waste recycling problems. In the symbiosis network for municipal waste recycling, the symbiotic interface has material exchange, energy transfer, information sharing, knowledge dissemination, and interest coordination functions. The evolution of the symbiosis relationship and the functional efficiency of the symbiosis interface rely on a good quality symbiotic environment. In addition, there are four operation modes for a municipal waste recycling symbiosis network. These are the reliant, equal, nested, and virtual modes. A typical case analysis in China showed that these four operation modes coexist over the longer term.
  • DownLoad:Symbiosis network for municipal waste recycling: concept, characteristics, and architecture analysis.PDF
  • Forewarned is forearmed: limitations and prospects of early warning indicators of regime shifts in shallow lakes
  • Authors:YU Ruihong, ZHANG Xiaoxin, LIU Tingxi and HAO Yanling
  • Abstract:In shallow lake ecosystems, the exchange rate between water and sediment is high and can be easily disturbed by anthropogenic pressures. Additionally, catastrophic shifts occur when a threshold is reached; however, effective methods for detecting regime shifts can contribute to the timely control and restoration of eutrophication. Regime shifts of key variables, including chlorophyll, dissolved oxygen, and biomass of zooplankton and fishes, may be detected either through time series analysis, early warning signals provided by the abrupt changes of indicators, or identification of thresholds of explanatory variables, in which early warning signals can provide the most useful forecasting information. Thus far, the most widely used early warning indicators, such as autocorrelation and variance, are usually applied to lake ecosystems subject to the phenomenon of critical slowing down (CSD). However, under conditions of high stochasticity, strong external perturbation, and extreme events, these measures may underperform or subject to misinterpretation. Thus, in terms of driving mechanisms, the applicability and limitations of CSD indicators are herein discussed, as well as their prospects. The aim of this study is to synthesize what is currently known about the early warning detection of regime shifts in shallow lake ecosystems.
  • DownLoad:Forewarned is forearmed: limitations and prospects of early warning indicators of regime shifts in shallow lakes.PDF
  • Effects of nitrogen fertilizer application on abundance and community structure of ammonia oxidizing bacteria and archaea in a North China agricultural soil
  • Authors:YANG Yadong, ZHANG Mingcai, HU Junwei, ZHANG Kai, HU Yuegao and ZENG Zhaohai
  • Abstract:The abundance and community structure of total bacteria ammonia oxidizing bacteria, and archaea were investigated by real-time PCR, T-RFLP, and cloning library approaches in a wheat field under different N fertilization rates (no N fertilization, 0 kg N/hm2, CK; low N fertilization rate, 75 kg N/hm2, N1; moderate N fertilization rate, 150 kg N/hm2, N2; high N fertilization rate, 225 kg N/hm2, N3) in North China. The population sizes of total bacteria, AOB and AOA were 5.74×109-7.50×109, 8.89×106-2.66×107 and 3.83×108-7.78×108 copies/g dry soil, respectively. The population numbers of AOA were higher than that of AOB in all treatments, with AOA to AOB ratios ranged from 81.72 to 14.38. Significant higher numbers for AOB were detected for the high level of N fertilization soil (P < 0.05), but not in the population of total bacteria and AOA. The population numbers of AOB observed in N1, N2 and N3 were 1.64, 2.50 and 2.99 times greater than that in the CK treatment, respectively. The N fertilization rates significantly changed the communities of both AOB and AOA, and more variation was observed in the community of AOB. Phylogenetic results showed that the majority AOB sequences fell into two branches of Cluster 3, affiliated with Nitrosospira species, and all AOA sequences fell within four branches in Cluster S. Significant positive correlations were observed among the population sizes of AOB to total nitrogen and ammonium, and the population sizes of AOA to soil pH and nitrate (P < 0.05). Significant negative correlations were observed among the population sizes of AOB to soil pH and C/N ratio, and the population sizes of AOA to ammonium (P < 0.05). These results demonstrated that AOB were more sensitive than AOA to N fertilization in alkaline wheat fields in North China.
  • DownLoad:Effects of nitrogen fertilizer application on abundance and community structure of ammonia oxidizing bacteria and archaea in a North China agricultural soil.PDF
  • Characteristics of, and the correlation between, vegetation and N-fixing soil bacteria in alpine grassland showing various degrees of degradation
  • Authors:LI Jianhong, LI Xueping, LU Hu, YAO Tuo, WANG Lide, GUO Chunxiu and SHI Shangli
  • Abstract:China has some of the most serious grassland degradation in the world, with about 90% of the available grassland being subject to various degrees of degradation. The grassland shows surface vegetation degradation, and there is a close relationship with soil degradation. Self N-fixing bacteria have an important impact on soil quality. In this study, alpine grasslands that had suffered different levels of degradation were selected as study areas in the east Chi-lien mountains. The plant species, coverage, average height, and above ground biomass were investigated, and the population of aerobic N-fixing bacteria and anaerobic N-fixing bacteria in the soil were measured. The levels of soil N-fixing bacteria relative to total soil bacteria were determined by the levels of real-time PCR-amplified nifH gene present in the different degraded grasslands. These methods showed how vegetation and soil N-fixing bacteria changed and how these changes were regulated as the degradation process progressed. The results showed that plant species abundance decreased; the dominant species varied; poisonous weed numbers gradually increased; and the height, coverage, and above ground biomass of the vegetation all decreased as the degradation process progressed. The lightly degraded grassland had up to 20 species, whereas there were only 11 in the severely degraded grassland. At first, there was only one dominant species, Elymus nutans, but this gradually evolved into two species, Elymus nutans and Potentilla chinensis, as degradation progressed. The poisonous weeds that appeared included Achnatherum inebrians and Stellera chamaejasme. The medially degraded and severely degraded grassland ground biomass was lower by 47.2% and 92%, respectively, than that of the lightly degraded grassland, and the average height of the severely degraded grassland decreased by 42.3 cm. Vegetation coverage also showed similar trends. The population of aerobic self N-fixing bacteria and anaerobic N-fixing bacteria was affected by the degree of degradation and the soil depth. The further grassland degradation had progressed and the deeper the soil layer, the lower were the number of self N-fixing bacteria. The examination of genetically amplified nifH showed that the ratio of soil self N-fixing bacteria to total soil bacteria declined. In the surface soil, the proportion of the bacteria made up of self N-fixing bacteria in the medium degraded grassland was lower by 26.9% than that of the lightly degraded grassland. In the severely degraded grassland, the proportion of self N-fixing bacteria was lower by 13.2% than that in the relatively medially degraded grassland, and the proportions were similar across all soil layers. This showed that the population of soil self N-fixing reduced, and that there was a degradation of community structure. The correlation analysis indicated a significant correlation between the vegetation characteristics and the population of soil self N-fixing bacteria. In summary, grassland degradation gradually reduced ground vegetation height, coverage, and aboveground biomass, and increased the numbers of poisonous weeds. It also reduced the numbers of soil self N-fixing bacteria numbers and had negative effects on soil microbial community structure. This jndicates a correlation between the grassland degradation process and soil self N-fixing bacteria. These results show that the soil functional flora, especially the role of soil self N-fixing bacteria, must be considered when researching and managing grassland degradation.
  • DownLoad:Characteristics of, and the correlation between, vegetation and N-fixing soil bacteria in alpine grassland showing various degrees of degradation.PDF
  • Effects of cattle fertilizer on community structure of nirK- and nirS- type denitrifying bacteria in soil
  • Authors:WANG Ting, LIU Lili, ZHANG Keqiang, WANG Feng, DU Huiying and GAO Wenxuan
  • Abstract:Field experiments of winter wheat-summer maize rotation were conducted in Xushui, Hebei Province, North China Plain irrigation area, to explore the effects of dairy effluent irrigation on diversity and community structure of nirK- and nirS- type denitrifying bacteria through terminal restriction fragment length polymorphism (T-RFLP) analysis and gene sequence analysis. Five treatments were designed, including no fertilizers treatment (CK), conventional fertilization (CF) and dairy effluent irrigations with 3 fertilizer levels (T4, T5 and T11). The results showed that no significantly differences were noted in diversity indexes of nirK- and nirS- denitrifying bacteria in all treatments. And T-RFLP analysis of nirK and nirS genes addressed significant differences in community composition: both fertilizer type and amount affected the relative abundance of nirK- T-RFs significantly, especially for dominant T-RFs, and therefore affected nirK- community composition; organic and inorganic fertilizer treatments increased or decreased different nirS- T-RFs' relative abundance, resulting in significant differences in nirS- community composition. Phylogenetic analysis of nirK and nirS gene indicated that the nirK- type denitrifiers were mainly composed of Pseudomonas, Alcaligeneand and Rhizobium, nirS- type denitrifiers were mainly composed of Ralstonia and Rubrivivax. Most of these identified denitrifying bacteria were belong to families of aerobic denitrifying bacteria. A possible reason was that samples for biological analysis were taken from topsoil.
  • DownLoad:Effects of cattle fertilizer on community structure of nirK- and nirS- type denitrifying bacteria in soil.PDF
  • Effects of the return of organic materials on soil physical and chemical properties and bacterial number in sandy soil
  • Authors:LI Peipei, WANG Qiang, WEN Qian, LI Hui, WU Chuanfa, XIONG Weidong and HAN Yanlai
  • Abstract:Sandy soils have limitations for growing crops. In general, those soils have poor structural traits, low fertility, and little organic matter. Agricultural practices influence the physical and chemical characteristics of soil and induce changes in soil microbial structure and function. It was important to determine a conventional agricultural practice to improve the quality of soil and solve the problem of the reduced productivity. The effects of different tillage practices on physical, chemical, and microbial properties of the soil have been studied. Organic matter is crucial for soil productivity and its quantity depends heavily on soil management systems. Returning crop straw to fields is one of the common practices to improve soil organic matter and achieve sustainable development of agriculture. Biochar, a solid elemental carbonaceous material, formed from the thermochemical conversion of biomass in an oxygen-limited environment, is a much more durable form of C than parent plant biomass or most forms of C in soil organic matter. Hence, the application of biochar to soil has been proposed for increasing the stable C pool and improving physical and chemical properties of soil. No-tillage and direct seeding are believed to be more sustainable than conventional practices, mainly because they improve nutrient status and water conservation. Although there have been many studies that referred to no-tillage and straw return or biochar application separately, the combined effects of various tillage and organic materials returned to sandy soil in the Huanghuaihai Plain requires further research. To address the adverse physical and chemical characteristics of the soil, a field experiment was conducted in a sandy fluvo-aquic soil in a village near Xinzheng City, Henan Province, to assess the effect of five methods of organic material return. The five methods were equivalent in the amount of carbon application, and included conventional tillage combined with straw return (TS), conventional tillage combined with biochar application (TB), conventional tillage combined with half straw and half biochar application (TSB), no-tillage combined with straw cover (NTSB), and no-tillage combined with half straw and half biochar cover (NTSB). The results indicated that compared with TS, the most popular local agricultural practice, TB significantly decreased soil bulk density, and increased soil water content and pH value. The soil quality index of soil organic matter increased by 16.4%. However, TB decreased the soil macroaggregate number and bacterial gene copy number by 21.2% and 16.1%, respectively. Compared with the available carbon component of straw, the chemical stability of biochar decreased microbial growth to some extent. TSB without any significant effect on soil chemicals or microbial shifts could significantly decrease soil macroaggregate number. NTS and NTSB, the two no-tillage practices could significantly increase the soil water content in the maize growing stages, bell mouth and ripening, separately, and NTSB dramatically increased bacterial number and soil organic matter by 53.7% and 14.9%, respectively, and decreased the soil fractal dimension, which increased the amount of macroaggregates and its stability. Compared with the common practice of conventional tillage with straw return, no-tillage combined with straw and biochar return is an effective way to change physical, chemical, and microbial properties of sandy soil, and the results will provide some theoretical basis for improving other low-yield soils.
  • DownLoad:Effects of the return of organic materials on soil physical and chemical properties and bacterial number in sandy soil.PDF
  • Effect of pavement on the leaf photosynthetic characteristics of saplings of three common tree species (Pinus tabulaeformis, Fraxinus chinensis, and Acer truncatum) in Beijing
  • Authors:CHEN Yuanyuan, JIANG Bo, WANG Xiaoke and LI Li
  • Abstract:Pavement is one of the most important factors causing environmental changes in urban areas. In this study, saplings of three common tree species (pine, Pinus tabulaeformis; ash, Fraxinus chinensis; and maple, Acer truncatum) were planted in three different treatment plots: pervious brick pavement with a permeability coefficient of more than 0.4 mm/s, impervious brick pavement with a permeability coefficient near zero, and non-pavement (control). In response to the pavement treatments, leaf photosynthetic characteristics of the pine, ash, and maple trees were determined by measuring surface temperature, soil moisture content (20 cm), and photosynthetic parameters. The results showed that surface temperature was significantly higher in the pavement treatments than in the control treatment (P < 0.01), with a higher surface temperature noted for the pervious pavement than for the impervious pavement. For all the tree species (especially ash), soil moisture content was significantly lower in the impervious pavement treatment than in the pervious pavement and control treatments (P < 0.01). Soil moisture content was significantly higher for pine and maple in the pervious pavement treatment than in the impervious pavement and control treatments (P < 0.01). For pine and maple, the total number of days with a maximum surface temperature exceeding 40℃ accounted for 53.3% (pervious pavement treatment) and 36.1% (impervious pavement treatment) of the entire growing period. For ash, the total number of days with daily mean soil moisture content less than 15% accounted for 88.5% (impervious pavement treatment) of the entire growing period. The pavement caused heat stress on pine and maple growth, and the impervious pavement caused drought stress on ash growth, leading to a decrease in net photosynthetic rate, transpiration rate, and stomatal conductance, and, subsequently, a decrease in tree height and basal diameter. For pine, significantly lower tree height (12.6% and 18.5%) and basal diameter (18.5% and 17.1%) were noted for the pervious and impervious pavement treatments, respectively, than for the control treatment. For maple, significantly lower tree height (45.1% and 26.8%) and basal diameter (40.9% and 20.3%) were noted for the pervious and impervious pavement treatments, respectively, than for the control treatment. For ash, significantly lower tree height (11.1% and 14.6%) and basal diameter (9.4% and 11.3%) were noted for the impervious pavement treatment, than for the pervious pavement and control treatments. In conclusion, it is necessary to select heat and drought tolerant tree species, and manage land with shadowing or irrigation, in order to guarantee tree growth in paved urban environments.
  • DownLoad:Effect of pavement on the leaf photosynthetic characteristics of saplings of three common tree species (Pinus tabulaeformis, Fraxinus chinensis, and Acer truncatum) in Beijing.PDF
  • Relationship between forest communities and the environment in the Xiaowutai Mountain National Nature Reserve, Hebei
  • Authors:BAI Xiaohang, ZHANG Jintun, CAO Ke, WANG Yunquan, Sehrish Sadia and CAO Ge
  • Abstract:The relationship of plants and the environment is a complex evolution process. We discuss species composition of forest communities, ecological characteristics of the population, and the relationship between different plant communities and the environment with quantitative ecology method to protect the stability of forest communities and biodiversity in the area. The forest communities in the Xiaowutai Mountain National Nature Reserve in Hebei province were investigated with a two-way indicator species analysis (TWINSPAN) and canonical correspondence analysis (CCA). All quadrats (n=148) were classified into 20 groups representing 20 plant communities. The results of the CCA ordination clearly reflected the pattern of community distribution, and it was obvious in the gradients of the first and second axis, which mainly represented altitude, slope position, litter layer thickness, soil electrical conductivity, soil temperature, soil moisture, soil thickness, and disturbance. All environmental factors influenced the forest community distribution pattern and the formation of different vegetation types. The CCA ordination of dominant species in tree layer revealed a high degree of similarity between environmental gradients and the distributions of community types. A two-dimensional t-value diagram clarified that altitude, litter layer thickness, soil temperature, and disturbance played an important role in dominant species in the tree layer of forest communities. In this study, we used TWINSPAN classification and CCA ordination to explain the relationships between forest communities and environmental factors. The purpose was to provide a theoretical basis for scientific management of the Xiaowutai Mountain area and to analyze the results that can be used as a reference for research and protection of forest ecosystems in similar areas.
  • DownLoad:Relationship between forest communities and the environment in the Xiaowutai Mountain National Nature Reserve, Hebei.PDF
  • Water use strategy of Platycladus orientalis in Beijing mountainous area
  • Authors:LIU Ziqiang, YU Xinxiao, LOU Yuanhai, LI Hanzhi, JIA Guodong and LU Weiwei
  • Abstract:In order to understand water source of the dominant tree species Platycladus orientalis and its eco-physiological adaptation during growing season in Beijing mountainous area, the Platycladus orientalis of water use strategy under different soil moisture conditions during growing season was studied. We employed the Iso-source software and measured the δD and δ18O in branches of trees, soil and groundwater to clarify their water source during growing season, and analysis combined with eco-physiological factors,such as leaf water potential (ψ), stomatal conductance (GS) and water use efficiency (WUE). Results show that Platycladus orientalis water use strategy with seasonal fluctuations, the in different seasons of different depths of soil moisture utilization ratio are different. In the dry season, Platycladus orientalis absorbed water in 0-20cm soil layer, the average utilization rate between 27.6-31.3%, at the same time, it utilization of 80-100 cm deep soil water and groundwater are in the range of 27.0%-33.7% and 22.0%-28.9% respectively. In the rainy season, the ratio of Platycladus orientalis absorbed 0-20cm soil water increased range of 47.2%-60.9%, the ratio of absorbed water in 80-100 cm deep soil layer and groundwater is decreased, range of 10.5%-16.2% and 15.2%-19.8% respectively. In dry season, the drought and water shortage of Platycladus orientalis is more serious, leaf water potential 44.5% less than in the rainy season; the peak of Platycladus orientalis stomatal conductance appeared at 10:00 am in the dry season, but 51.67% less than in rainy season, the photosynthetic rate and transpiration rate of peak also corresponding fell 22.3% and 37.0% respectively. Platycladus orientalis can reduce stomatal conductance decrease water loss to obtain higher carbon assimilation rate and maintain higher water use efficiency to adapt the arid condition, showed high adaptability to arid condition.
  • DownLoad:Water use strategy of Platycladus orientalis in Beijing mountainous area.PDF
  • Phenotypic variations in populations of Rosa rugosa
  • Authors:TONG Ran, WU Xiaolong, JIANG Lina, SI Qianqian and ZANG Dekui
  • Abstract:To determine the phenotypic variation in Rosa rugosa populations and the relationships between phenotypic variation and different distribution areas, 24 phenotypic traits from 5 representative populations were chosen as research subjects. Analysis of variance, multi-comparison, principal component analysis, correlation analysis, and cluster analysis were used to analyze these data. The results showed the following. (1) There were highly significant differences in the 24 phenotypic traits among and within the populations, and the variation was high. The mean phenotypic differentiation coefficient (VST) among populations was 0.2952, which indicated the phenotypic variation was great. The variation within populations (27.18%) was greater than that among populations (16.79%), which indicated that the former was the main source of the phenotypic variation in the species. The mean phenotypic variation coefficient (CV) was 18.48%, and the variation range of the 24 phenotypic traits was 6.67%-26.79%. The variation coefficients of leaves, fruits, flowers, and seeds were 21.40%, 17.42%, 12.54% and 6.67% respectively, which indicated that seeds exhibited the greatest stability, whereas leaves exhibited the least. The principle component analysis also showed that the phenotypic variation of leaves and fruits contributed the most variation. (2) The correlation analysis showed that there was significant correlation between some traits and geographic ecological factors. With the decrease of latitude and longitude, the length of stipule decreased, but when annual temperature and the average July temperature increased, the length of stipule became even greater. Increases in annual precipitation resulted in larger fruit diameters, and the ratio of the transverse and longitudinal diameter of fruits and also increased, which indicated that the shape of fruit varied from broadly orbicular to oblong. A decrease in average July temperature and an increase in latitude and longitude resulted in an increase in thousand-grain weight. (3) The five populations of R. rugosa investigated could be divided into three groups according to the UPGMA cluster analysis; the phenotypic traits gathered were based on geographic distance, and it was noteworthy that the population of Chengshan town in Shandong Province and the population of Mingyang Town in Liaoning Province were in the same group.
  • DownLoad:Phenotypic variations in populations of Rosa rugosa.PDF
  • Distribution variations of dominant plant species in degraded shrub tundra on the western slope of the Changbai Mountains
  • Authors:JIN Yinghua, XU Jiawei, WANG Shaoxian, WANG Ailin, ZHANG Yingjie, JIN Hui, ZHAO Ying, LIU Lijie, YIN Hang and HE Hongshi
  • Abstract:Tundra vegetation of the Changbai Mountains is undergoing significant changes. In the alpine tundra on the western slopes of the mountain, the area of distribution of shrubs is shrinking and the importance of shrubs as dominant plant species is reducing significantly. This study analyzed changes of dominant plant species in the shrub tundra, distribution pattern variations of shrubs and characteristics of shrub community structure at different elevations using plot survey data, revealed regional differentiation of degradation in shrub tundra and the degradation mechanisms of shrub communities. The results showed the following: (1) The shrub community in the alpine tundra on the western slopes has been severely degraded. Various herbs have invaded the area and became the dominant species. Five herbs and two shrub species were the dominant species of alpine tundra, which indicated a decrease in the number and importance value of dominant shrub species compared to the results of the survey conducted in 1979. The aggregated distribution was the dominant pattern of distribution of the seven dominant species, whereas the distribution of each dominant species occurred in separated patches; the shrub tundra faced fragmentation. In shrub communities of alpine tundra, herbs appeared and gradually became dominant. The herbs were taller than the shrubs in alpine tundra at lower elevations, and the species composition and community form were nearing those of the herb-shrub tundra. (2) Shrubs were widely distributed at different elevations, but their spatial distribution patterns were distinct. Below 2300 m a.s.l., the distribution of shrubs appeared aggregated, especially at elevations below 2100 m a.s.l. The shrubs did not aggregate above 2300 m a.s.l. (3) Regional differentiation of the degraded alpine tundra on the western slopes was significant. Below 2100 m a.s.l., the number of herbs was more abundant than that of shrubs, and the coverage and height of the shrubs were decreased; so the degradation is the most serious in this region, which developed into herb-shrub tundra. Between 2100 and 2300 m a.s.l., the degradation was significant, but the number of shrubs were more abundant than that of herbs; this region developed into shrub-herb tundra. Above 2300 m a.s.l., the degradation of shrubs was not significant and shrub tundra was preserved. It can be inferred that the degradation mechanism of the shrub tundra includes two aspects: herb invasion of the shrub tundra, resulting in interspecific competition, and environmental changes of tundra zone, which could be attributed to global climate change.
  • DownLoad:Distribution variations of dominant plant species in degraded shrub tundra on the western slope of the Changbai Mountains.PDF
  • Responses of soil respiration of moss-dominated biological soil crusts to simulated rainfall on loess and aeolian soils in the Loess Plateau of China
  • Authors:XIAO Bo, GUO Chengjiu, ZHAO Dongyang, HU Kelin and JIA Yuhua
  • Abstract:The respiration of biological soil crusts is an important contribution to carbon cycling in arid and semiarid ecosystems, but soil crust responses to rainfall have not yet been fully investigated. In this study, we conducted a series of simulated rainfall experiments with different rainfall intensities (2, 4, 6, 10, 20, 30, 40 mm) for moss-dominated biological soil crusts (hereafter moss crusts) on loess and aeolian soils in the Loess Plateau of China. The soil respiration rates of the moss crusts were measured before and after the simulated rainfall with a portable CO2/H2O Analyzer (LI-COR LI-840). Afterwards, the soil respiration rates of the moss crusts with 40 mm rainfall were continually measured at 0-24 h (0, 0.25, 0.5, 1, 2, 12, 24 h) after the rainfall. Finally, the soil respiration responses of the moss crusts to rainfall were determined from rainfall intensity and time after rainfall. The following results were obtained in this study. (1) The soil respiration rates of the moss crusts were consistently and significantly increased after the simulated rainfall. Compared with the soil respiration rates before the rainfall, the soil respiration rates of the moss crusts on loess soil were increased by 2.89-6.38 times, whereas the soil respiration rates of the moss crusts on aeolian soil were increased by 0.73-4.38 times. (2) In the 0-6 mm rainfall experiments, the soil respiration rates of the moss crusts, both on loess and aeolian soils, linearly increased with increasing rainfall. Correspondingly, in the 6-40 mm rainfall experiments, the soil respiration rates of the moss crusts on loess soil slightly increased with increasing rainfall, whereas the soil respiration rates of the moss crusts on aeolian soil sharply decreased with increasing rainfall. (3) Changes in soil respiration rates during 0-24 h after the rainfall event were similar for the moss crusts on loess and aeolian soils; they both rapidly increased immediately after the rainfall and then gradually decreased to their original levels before the rainfall during 0-24 h. The soil respiration rates of the moss crusts on loess soil reached their maximum values almost immediately after the rainfall event; however, the soil respiration rates of the moss crusts on aeolian soil reached their maximum values approximately 30 min after the rainfall event. (4) The soil respiration rates of the moss crusts on loess soil were 150.0% and 59.6% higher than that on aeolian soil under different rainfall intensities and at different times after the rainfall, respectively. (5) The soil respiration rates of the moss crusts were significantly positively correlated with surface soil water content (0-5 cm) when soil was dry ( < 4%). However, when soil was wet ( > 4%), the soil respiration rates of the moss crusts on loess soil were positively correlated with surface soil water content, but that on aeolian soil were negatively correlated with surface soil water content. From this study, we concluded that the soil respiration of the moss crusts on the Loess Plateau of China responded directly and sensitively to rainfall events, but the responses were different for the moss crusts on loess and aeolian soils. It appeared that the moss crusts on loess soil responded more efficiently to rainfall compared with that on aeolian soil.
  • DownLoad:Responses of soil respiration of moss-dominated biological soil crusts to simulated rainfall on loess and aeolian soils in the Loess Plateau of China.PDF
  • Quantitative assessment of water conservation function of the natural spruce forest in the central Tianshan Mountains: a case study of the Urumqi River Basin
  • Authors:DING Chengfeng, ZHANG Huifang, LI Xia, LI Weitao and GAO Yaqi
  • Abstract:To quantitatively investigate the water conservation function of the natural spruce forest at the watershed scale in the central Tianshan Mountains, the Urumqi River Basin was chosen as a study area. The InVEST model was used to investigate the capacity for water conservation of the spruce forest and other land use types, as well as quantitatively analyze water conservation changes of the spruce forest under the conditions of different distribution areas and terrain factors. The results showed that: (1) The InVEST model could adequately assess water conservation at the watershed scale. The InVEST model simulation showed that the total water conservation of the spruce forest in the Urumqi River Basin was 4.93×106 m3, which accounted for 20.46% of the total water conservation in the study area (2.41×107 m3). In addition, the average water conservation depth of forest area was 54.25 mm. (2) The contribution rate of water conservation in the slope, aspect, and elevation was consistent with the spatial distribution pattern of the spruce forest. At first, per hectare water conservation increased with altitude and then decreased, and it decreased with an increase in slope. The water conservation ability in the shade slope was greatest. (3) The spruce forest showed the greatest capacity, which reached 544.78 m3/hm2. The total, average depth and unit area of water conservation exhibited an increasing trend with increasing spruce forest coverage. (4) The contribution rate of water conservation in the spruce forest was closely related to forest area. Total water conservation in study area and spruce area increased to 0.437×106 m3 and 0.522×106 m3 with a 1% increase of spruce forest area, respectively. Therefore, the forest plays a vital role in maintaining sustainable and stable water conservation and ecological service functions, which necessitate effective measures to strengthen the protection and management of spruce forests.
  • DownLoad:Quantitative assessment of water conservation function of the natural spruce forest in the central Tianshan Mountains: a case study of the Urumqi River Basin.PDF
  • Analysis of wetland plant-soil relationships and population niches in Chayegang marshland near Henghu farm in the Poyang Lake region during the dry season
  • Authors:DUAN Houlang, ZHAO An and YAO Zhong
  • Abstract:Interactive effects exist among soil, vegetation, hydrology and climate in wetland areas, affecting the charateristics of wetland ecosystems. Wetland soil is usually a product of long-term interactions between ecological environment factors and plays a vital role in preserving the regional ecological balance. The factors that influencewetland vegetation include biological and abiological variables, which soil of abiological variable has the most profound effect on wetland plant growth. Relationships between wetland plants and soil have always been a hot topic in ecology and also form the basis for plant population niches research. Based on a sample plot-species matrix of Importance Value (IV) of 20 species at 19 sampling plots in the Chayegang marshland of the Poyang Lake region near Henghu farm, we used the Ward cluster method of hierarchical clustering to divide the plants in the study area into 3 community types-Com. Carex cinerascens, Com. Phalaris arundinacea and Com. Triarrhena lutarioriparia. Spearman rank correlations results revealed that, when considering biodiversity indices (Shannon Wiener diversity index H', species richness index S and Pielou evenness index J) and soil factors (soil pH, electrical conductivity, moisture and organic matter), there were significant positive correlations (P < 0.05) between H' and soil pH, and highly significant positive correlations (P < 0.01) between S and soil pH; However, there were significant negative correlations (P < 0.05) between H' and soil organic matter and highly significant negative correlations (P < 0.01) between S and soil organic matter. However, the Pielou evenness index J had no discernible correlation with soil factors. The relationships of plant species distribution with soil pH, electrical conductivity, moisture and organic matter were assessed using redundancy analysis (RDA); Results revealed significant relationships of plant distribution with soil pH and soil organic matter (P=0.042 and 0.048), which were regarded as the key soil factors that controlled species distribution.As soil pH and organic matter were determined to be the principal environmental factors that had a considerable influence on plant species distribution, both were divided into 10 gradient levelsto analyze the plant population niches. The results showed that the dominant species, C. cinerascens and P. arundinacea, had larger niche breadths, while Veronica peregrina, Nymphodes peltatum, and other specieshad smaller niche breadths. All plant species in the study area had relatively small niche overlaps on the whole, suggesting that the population niches had obvious differentiation in soil pH and soil organic matter gradients.
  • DownLoad:Analysis of wetland plant-soil relationships and population niches in Chayegang marshland near Henghu farm in the Poyang Lake region during the dry season.PDF
  • Characteristics of N and P stoichiometry of plants in different functional groups in the Qinghai-Tibet Plateau regions
  • Authors:YU Hailing, FAN Jiangwen, ZHONG Huaping and LI Yuzhe
  • Abstract:Ecological stoichiometry provides an important method for the determination of plant nutrient utilization and plant environmental adaptation strategies. Nitrogen (N) and phosphorus (P) stoichiometries play critical roles in the functions and structures of ecosystems by affecting important ecological processes. Studying the contributions of different functional groups to ecological stoichiometry could help to reveal the formation mechanisms of plant elements on a regional scale. Currently, most studies focus on comparison of ecological stoichiometry characteristics among different functional groups, but fail to discuss the variation in element contents among different plant functional groups with regard to geographic and climatic factors. The Qinghai-Tibet Plateau alpine region has a much higher elevation and lower temperature than the other regions in the same latitude. Thus, this region could provide ideal research conditions for investigating the relationship between plant element characteristics and variations in geographic and climatic factors. Using ecological stoichiometry theory, we analyzed the patterns of N and P contents among different functional groups (legumes, grasses, sedges and forbs) and how these varied with geographical factors (latitude and altitude) and climatic factors (mean annual precipitation and mean annual temperature) in the Qinghai-Tibet Plateau alpine region. We used these data to explore the formation mechanisms of plant N and P features in this region. The results showed that: 1) N and P contents were significantly higher in legumes and much lower in grasses, and that no obvious differences in N/P were found between the four groups. 2) As the latitude increased, the P contents of sedge folia decreased, while the N contents of forb folia increased. The P contents of all sample pool folia were found to decrease. As the altitude increased, the N contents of legume, grass, and forb folia decreased significantly, and the N contents of all plant folia also decreased. As the mean annual precipitation (MAP) increased, the N contents of sedge and forb folia, as well as that of all plant folia increased. As the mean annual temperature (MAT) increased, the N contents of sedge folia decreased, while their P contents increased. All plant folia element contents were found to have no correlation with MAT. 3) Folia N and P contents varied with latitude and MAP in sedges, and with altitude and MAT in legumes, grasses and forbs. These results are consistent with the patterns observed on a regional scale. These results indicate that the characteristics of element contents in different plant functional groups vary with geographic factors and climatic factors, and that plant species composition plays an important role in the regional-scale ecological stoichiometry. These results also show that the combination of different functional group plants can offset or cover up the characteristics of some groups, thereby affecting ecological stoichiometry on a regional scale.
  • DownLoad:Characteristics of N and P stoichiometry of plants in different functional groups in the Qinghai-Tibet Plateau regions.PDF
  • Spatial distribution of poisonous weed invasion based on inter-species competition models
  • Authors:LIU Hua, JIN Xin, SHI Lei, JIANG Rui and WEI Yumei
  • Abstract:In the present study, a spatial diffusion model of poisonous weed invasion by using inter-species competition model was developed based on poisonous weeds and edible forage in native pastures. Using the cellular automata theory, the competition model was extended to the spatial network to simulate and study the spatial distribution patterns of poisonous weeds, which will provide data supporting their control. The results showed that (1) under the influence of invasion and diffusion, the coexistence equilibrium point of the poisonous weeds and the edible grass could be increased by an increase of two, which increased the possibility of coexistence; and (2) the spatial distribution of the weed population was affected by invasion and diffusion, and the aggregation of the spatial distribution of the population was reduced.
  • DownLoad:Spatial distribution of poisonous weed invasion based on inter-species competition models.PDF
  • Impact of climate warming on heat resources and freezing injuries in wine grapes at the east foot of the Helan Mountains of Ningxia
  • Authors:WANG Suyan, ZHENG Guangfen, LI Xin, YANG Jianling, ZHANG Xiaoyu, LI Jianping and MA Liwen
  • Abstract:Using meteorological data collected from the east foot of the Helan Mountains of Ningxia since 1981, we analyzed the impact of climate warming on heat resources and freezing injuries in wine grapes. The results show that the average temperatures from April to September increased significantly during this period, with an abrupt climate warming trend beginning around 1997. Temperature anomalies were higher than 1℃ in some years after 1997. The trend of average temperatures in April, when wine grapes are in their bud germinating stage, increased rapidly, but there were also greater fluctuations, and the risk of frost or of strong cooling periods also increased. Low-temperature injury events were more likely to appear between July and August, which is the period during which wine grape berries grow and mature. With the active accumulated temperature above 10℃ increased significantly, the probability of mid- or late-maturation was 100%, and the probability of temperatures of 3300℃ (the critical value of high maturity and quality) between April and September improved. With the frost-free period was prolonged the probability of late-maturation increased; the accumulated temperatures and frost-free periods could result in extreme late-maturation trends in many years. The factors affecting low temperature freezing-disasters in winter had no distinct trend. As the number of sustained days at which the minimum temperature dropped below -17℃ (the freezing-disaster critical temperature) decreased, the extreme minimum temperature was raised, although it was still below -17℃, and the days at which the minimum temperature was lower than -4℃ at a depth of 20 cm decreased in Huinong, Helan, Pingluo, and Yinchuan. The frequency of frost appearing after the appropriate time in spring was also reduced, but the number of days with frost increased. Although the minimum temperature decreased, Both the years and days with frost appearing after the appropriate time in spring increased. Climate warming has both advantages and disadvantages for wine grapes, and different cultivars adapt to these effects differently. Thus, there is still a need to increase monitoring of temperature and to prevent extreme climate events and meteorological disasters during the key periods of wine grape development in order to reduce or avoid the negative effects of climate change on wine grapes.
  • DownLoad:Impact of climate warming on heat resources and freezing injuries in wine grapes at the east foot of the Helan Mountains of Ningxia.PDF
  • Applicability analysis of SPEI for drought research in Northeast China
  • Authors:SHEN Guoqiang, ZHENG Haifeng and LEI Zhenfeng
  • Abstract:Determining the applicability of a drought index to a specific area is a prerequisite for drought quantification and mapping on a regional scale. In this paper, we explored the effectiveness of the Standardized Precipitation Evapotranspiration Index (SPEI) in northeast China. SPEI values at a time scale of 1, 3, 6, and 12 months were calculated using a daily climate dataset that had been collected by 90 meteorological stations in northeast China from 1961 to 2014. The climate variables analyzed included daily temperature, precipitation, atmospheric pressure, wind speed, relative humidity, and sunshine duration. The applicability of the SPEI for drought quantification in northeast China was investigated using Kolmogorov-Smirnov (K-S) test, validation analysis from specific drought events and soil moisture, and correlation analyses between SPEI and the statistics of the area suffering from drought.The results showed that our null hypothesis was rejected by the K-S Test at a 0.05 significance level for each station, and that the Log-logistic distribution matched very well to the water surplus or deficit series for all four time scales at each station. The drought-affected areas showed a significant negative relationship to the SPEI during the growing season (April to September) at these four time scales during 1971-2013. The index of SPEI01 was found to be more suitable for predicting the time, location, and intensity of drought events. There was a strong positive correlation between soil moisture at a depth of 20 cm and the SPEI for most of the climate stations (90.2% of stations for SPEI01, 92.16% of stations for SPEI03, 90.2% of stations for SPEI06 and 88.24% of stations for SPEI12). In addition, the number of climate stations decreased as the time scale increased. Our results indicate that the SPEI is suitable for quantifying droughts, and therefore, should be widely used in scientific drought prediction research in Northeast China.
  • DownLoad:Applicability analysis of SPEI for drought research in Northeast China.PDF
  • Response of radial growth of three conifer species to climate at their respective upper distributional limits on Yulong snow Mountain
  • Authors:ZHANG Weiguo, XIAO Derong, TIAN Kun, CHEN Guanglei, HE Ronghua and ZHANG Yun
  • Abstract:The Northwestern Yunnan Plateau is located on the southeastern margin of the Tibetan Plateau, which is an area sensitive to climate change. In this area, forests have remained undisturbed due to their remote location, and many tree species have grown to their upper distributional limits. Accordingly, it is an ideal location for dendroclimatological study. Although some dendrochronological research has been carried out on the Northwestern Yunnan Plateau, few studies have been conducted on Yulong snow Mountain, which is a typical snow mountain and supports growth of the main tree species in the area. In order to detect the response of tree growth to climate change on the Northwestern Yunnan Plateau, we used the tree-ring width index of three major conifers, Abies georgei, Picea likiangensis, and Larix potaninii Batal var. macrocarpa Law, at their upper distributional limits on Yulong Snow Mountain. Specifically, we focused on the characteristics of residual chronologies and the relationships between radial growth and climatic factors (temperature and precipitation). We aimed to identify the main climatic factors limiting tree growth in the area and detect differences in growth responses to climate among the studied species. The following results were obtained (1) Temperature and precipitation were the main factors affecting tree growth at the upper distributional limits on Yulong snow Mountain, but the effects varied according to tree species. (2) The radial growth of L. potaninii Batal var. macrocarpa Law was mainly limited by temperature and precipitation during the early growing season (May-June) of the current year, and was positively and negatively correlated with temperature and precipitation in May and June, respectively. (3) Precipitation during the early growing season of the current year was the main factor limiting the radial growth of A. georgei, with a significantly negative correlation between the residual chronology and May-June precipitation, whereas higher temperature during the growing season (July-August) of the current year positively affected its growth. (4) The radial growth of P. likiangensis was mainly limited by climatic factors before the start of the growing season, showing a significantly negative correlation between growth and mean temperature of the previous December and current May, and a significantly positive correlation between growth and precipitation during the current January. Our research represents a reference tree-ring study of the Northwestern Yunnan Plateau, and can provide a scientific basis for climate reconstruction in the area.
  • DownLoad:Response of radial growth of three conifer species to climate at their respective upper distributional limits on Yulong snow Mountain.PDF
  • An ecological vulnerability evaluation method for arid pasturing areas based on the SWAT model: a case study in the Aibugai Basin
  • Authors:SONG Yifan, GUO Zhongxiao, LU Yajing, LIAO Zilong and XU Xiaomin
  • Abstract:Ecological vulnerability evaluation is a prerequisite to conducting ecological restoration. The common ecological vulnerability evaluation methods have some applicability problems in arid pasturing areas: 1) the evaluation indicators are numerous, and the data are usually difficult to obtain; 2) an administrative region, such as a city or a country, is often used as the evaluation unit, which is too large and lacks specific significance. Commonly used data, such as meteorological data, soil data, land-use data, and water resource development and utilization data, as well as the simulation results in the SWAT model, are used in this research to build an ecological vulnerability evaluation of arid pasturing areas based on the SWAT model. Ecological vulnerability of arid pasturing areas has been divided into ecological vulnerability of the natural ecosystem and ecological vulnerability of the human-nature coupling system. Drought index, vegetation coverage, soil bulk density, and evapotranspiration capacity of soil water are used to depict ecological vulnerability of natural ecosystem; evenness index, contagion index, ecological suitability index, and water utilization modulus are used to depict the human-nature coupling system. Firstly, the SWAT model has been used to divide sub-basins and hydrological simulations by the combination of observed data and simulated data, and the association of the statistic data with spatial land type. All indicators have been set based on GIS, linear piecewise membership functions have been adopted to calculate index values, and analytic hierarchy process (AHP) is adopted to determine the weighs of criteria layers and index layer. The ecological vulnerabilities of the research area are divided into five levels. This evaluation model was used in the Aibugai Basin (which is located in arid pasturing areas in Northwest China) to evaluate the change in ecological vulnerability caused by land-use variation between 1990 and 2010, and 17 sub-basins were divided according to demand. The results showed that, during a period of 20 years, both the entire research area and each sub-basin went through a CIEV (comprehensive index of ecological vulnerability) decrease to some degree. Sub-basin 9, 10, 11, 12, and 15 developed a moderate vulnerability level from a slight vulnerability level in 1990, and sub-basin 16 and17 have changed to a sever vulnerability level from a moderate vulnerability level in 1990. The CIEV of the entire research area decreased to 0.59 in 2010 from 0.70 in 1990. The northwestern part of the research area had better ecological stability, and the degradation in ecological vulnerability levels took place mainly in the agro-pastoral ecotone located in the southeast of the research area. With the expanding demands of grain and cattle, agricultural areas have gradually expanded northward in the past 20 years. Declines in grassland areas and overdeveloped water resources caused by farmland expansion were the main reasons that caused the ecological degradation in the research area. Closely tied to the relationship with water, grass and cattle in arid pasturing areas to establish indicators, this evaluation model effectively reflected the aggravation of ecological vulnerability caused by cropland expansion in the research area from 1990 to 2010.
  • DownLoad:An ecological vulnerability evaluation method for arid pasturing areas based on the SWAT model: a case study in the Aibugai Basin.PDF
  • Seasonal variation of the edge influence of soil temperature on cultivated grassland-cropland boundaries in Karst areas of Guizhou Province
  • Authors:HAO Jun, CHEN Chao, WANG Jianli, YANG Feng and LIU Honglai
  • Abstract:The landscape boundary is a transition zone between two or more adjacent ecosystems, or an interface that exists between an organism and abiotic environment; it is also extremely sensitive to climate change and human interference, and plays an essential role in the structure, processes, and functions of ecosystems. Soil temperature affects vegetation growth, and plays an important role in environmental microclimates and plant production, and affects various chemical reactions of soil organic matter and nitrogen accumulation; therefore, it affects plant growth, seed germination, and crop output. Cultivated grassland-cropland boundaries (Maiping County, Guiyang) in Karst areas of Guizhou Province were analyzed, and the surface soil temperature (0-20 cm) of the interface was monitored seasonally. Moving-split window technology (MSWT) was used to compute the variables in adjacent samples along transect data, which was a simple and reliable method for determining the boundary, and MSWT could be used for any type of variable reaction. The width of the cultivated grassland-cropland boundary was determined based on soil temperature by combining the field measurement, indoor statistics, and MSWT in this study. The soil temperature of three functional areas in the study area was compared and analyzed. The results showed that the average annual soil temperature of the cultivated grassland-cropland boundary in Guizhou was 9.8, 26.5, 15.4, and 4.8℃ for spring, summer, autumn, and winter, respectively. The width variation of the soil temperature boundary in cultivated grassland-cropland varied with seasonal shifts and soil temperature, from wide to narrow: 37, 32, 27, and 24 m in spring, summer, autumn, and winter, respectively. This also indicated that the soil temperature-interface width in cultivated grassland systems varied consistently with the total width of the cultivated grassland-cropland boundary, which was categorized as a gradual changing boundary type. The average soil temperature of the cropland functional area, cultivated grassland-cropland compound functional area, and the grassland functional area was 14.0, 14.1, and 13.9℃, respectively, and the soil temperature of the three functional areas was significantly different in spring, summer, and winter; and the soil temperature in the grassland functional area system and cultivated grassland-cropland compound functional area were not significantly different in autumn, and the soil temperature in the farmland functional area system and cultivated grassland-cropland compound functional area were significantly different to the grassland functional area system. Based on these results, regarding the policy of "returning cropland to grassland", an optimal width of 12-18 m could be set for grassland-cropland intercropping in the studied area, and this study provides reference values for the sustainable development of southern grassland animal husbandry, and theoretical references and practical measures for enriching the boundary theory and the project of "returning cropland to grassland".
  • DownLoad:Seasonal variation of the edge influence of soil temperature on cultivated grassland-cropland boundaries in Karst areas of Guizhou Province.PDF
  • Effects of root pruning and shallow plowing on soil properties and plant communities in deteriorated steppe
  • Authors:GAO Zhicheng, TIAN Jiani, HUO Yanshuang, SHU Kai and BAOYIN Taogetao
  • Abstract:Grassland degradation is one of the main ecological problems in the arid and semi-arid areas of China. Nitrogen content, which is typically reflected by the mineralization rate of soil nitrate nitrogen, plays a very significant role in plant life in deteriorated steppe regions. The key to addressing the limitation of soil nitrogen content is determining how to increase the exchange speed of soil nitrate nitrogen mineralization using different ameliorative treatments. Furthermore, biomass, the accumulation of organic matter per unit leaf area, is also a vital evaluation factor for primary productivity. Species diversity, the index of which generally increases with an increase of biomass, is an indicator of ecosystem stability. The species diversity of deteriorated steppe communities reflects the restoration status of grassland and changes in soil physical and chemical properties. The aim of the present study was to provide a scientific basis for the development of deteriorated steppe restoration by determining the effective use of different ameliorative treatments. In this regard, we examined the effects of two typical ameliorative treatments, namely, shallow plowing and root pruning of deteriorated grassland, in Inner Mongolia in order to determine the effects of different treatments on soil properties (the mineralization rate of soil nitrate nitrogen) and the character of Leymus chinensis communities (biomass and biodiversity). The data was obtained at the research base of the School of Life Science, Inner Mongolia University of Mao Deng grassland, Xilin Gol, Inner Mongolia. The research focused on the relationship between different treatments and biodiversity, biomass, and the mineralization rate of soil nitrate nitrogen. Compared with the control treatment, our results indicate that the mineralization rate of soil nitrate nitrogen was reduced by shallow plowing (P < 0.05). This might be attributable to changes in soil structure and the natural habitat of most plant caused by shallow plowing, which often causes marked disturbance to the soil in the first and second years after plowing. The mineralization rate of soil nitrate nitrogen was increased by root pruning but the effect was not significant. This might be due to the reduction in certain species whose growth requires a high content of nitrite nitrogen, although the total biomass increased. The mineralization rate of soil nitrate nitrogen differed according to the time of year. The lowest nitrification rate was in June, whereas the highest was in September. Shallow plowing significantly reduced the diversity and biomass of the L. chinensis community, whereas root pruning significantly increased the diversity of this community (P < 0.05). This is because the growth of annuals is more rapid in seasons with high precipitation. Root pruning reduced the competition between short-lived plants and other plants. Accordingly, annuals could grow very well and increased in number. This might be closely related to the increase in biomass. Although the biomass of the L. chinensis community was incr eased by root pruning, the difference was not significant. The data show that different treatments have a marked impact on soil properties and biota. Furthermore, root pruning treatment, but not shallow plowing, contributes to the biodiversity of deteriorated steppe in the short term.
  • DownLoad:Effects of root pruning and shallow plowing on soil properties and plant communities in deteriorated steppe.PDF
  • Regional ecosystem service value evaluation based on land use changes: A case study in Dezhou, Shandong Provience,China
  • Authors:WEI Hui, ZHAO Wenwu, ZHANG Xiao and WANG Xinzhi
  • Abstract:Land use change conditions were analyzed using the data for land use change in Dezhou City from 2006 to 2014 and land use dynamics indicators. The ecosystem service values per unit area of different terrestrial ecosystems in China were used as a basis to analyze the spatial and temporal variations in the ecosystem service values for Dezhou from 2006 to 2014, after applying a correcting coefficient to the level of economic development. The results indicated that the overall ecosystem service value in Dezhou City decreased by 3.78% from 46.092 billion Yuan in 2006 to 44.347 billion Yuan in 2014. The decrease in forest land and the water covered area were the main reasons for the decrease in ecosystem service value. The spatial differences in ecosystem service values for Dezhou City were significant. The ecosystem service value for Qihe County was the highest because of the wide distribution of forest and water covered areas, which have high ecosystem service values. The ecosystem service value reduction in Decheng District was the greatest. This was mainly due to land use change caused by socioeconomic development. With the same trend of the total ecosystem service value change, the single ecosystem service value showed a declining trend in Dezhou City during the study period. Therefore, the influence of land use change on ecosystem service value is an important factor that needs to be considered in the new round of general land use planning. Furthermore, optimizing and adjusting the land use structure and increasing the ecological land area also need to be considered when attempting to improve the regional ecosystem service value.
  • DownLoad:Regional ecosystem service value evaluation based on land use changes: A case study in Dezhou, Shandong Provience,China.PDF
  • A case study of a novel sustainable agricultural development evaluation method based on Euclidean distance theory
  • Authors:YANG Shiqi
  • Abstract:A novel evaluation theory for sustainable agricultural development was developed using the standardized Euclidean distance method. It contains an agriculture sustainable development model, an evaluation function, and agriculture sustainable development ranks. It includes a goal system, a zero system, and an index frame. Wuzhong County in Ningxia Hui Autonomous Region (WZC) was used as a case study area between 2000 and 2012. The results showed that the agricultural sustainable development exponent (ASDE) in WZC slowly increased over the period from 0.65 to 0.70. The positive features of the method are: (1) the methodology was reliable; (2) the agriculture sustainable development model was constructed using the goal system and the zero system, which provides a reference system for sustainable agricultural development and improves evaluation controllability; (3) the index weights were embedded in the evaluation function, which removes the errors or mistakes made by the expert scoring method and avoids having to reassign index weights because of indicator addition or subtraction; and (4) the agriculture sustainable development exponent was related to the centesimal system by a function model transformation, which gives a very clear figure conception because the primitive value from the Euclidean distance is difficult to understand. It is important to compare systems and method application, and this model suggests that the low ASDE in WZC is mainly due to high nitrogen fertilizer application rates, low straw application rates, the compound or special fertilizer ratios, the proportion of the land taken up by conservation farming areas, soil organic matter levels, and income per rural person.
  • DownLoad:A case study of a novel sustainable agricultural development evaluation method based on Euclidean distance theory.PDF
  • Soil conservation service zoning in the Inner Mongolia Autonomous Region based on PSR framework
  • Authors:PENG Jian, WU Wenhuan, LIU Yanxu and HU Yina
  • Abstract:Soil erosion has been a critical ecological issue in northern China. Inner Mongolia Autonomous Region is located in the arid and semi-arid area, which is a typical soil erosion area in northern China. Based on the analytical framework of pressure-state-response (PSR), this study takes the Inner Mongolia Autonomous Region as the study area, and constructs the index system from three aspects: climatic background, soil conservation, and vegetation condition. It aims at addressing the remaining issue of complexity and subjectiveness in weigh specification towards ecological function zoning in the previous studies. In the study, self-organizing feature map (SOFM) neural network and GIS spatial analysis technique were applied to carry out the soil conservation service zoning with the 1280 small watersheds as the basic unit and the schemes were optimized according to the aggregation degree of the zoning units. The Inner Mongolia Autonomous Region was divided into three ecological functional zones and eleven sub-zones based on the principle of regional conjugation. The three ecological functional zones include Soil Conservation Services Protection Area, Soil Conservation Services Controlling Area, and Soil Conservation Services Rehabilitation Area. According to the characteristics of zoning, the results clearly indicate the zonal distribution of climatic background, soil conservation service and vegetation condition in Inner Mongolia, and quantify the characteristics and spatial differences of the ecological functions at watershed scale more comprehensively. The result of the optimal soil conservation service zoning was compared to the annual average temperature contours and annual precipitation contours in Inner Mongolia. It shows that the ecological function zoning results obtained by SOFM neural network model were in good agreement with the spatial patterns of basic ecological elements. The zoning scheme indicates a significant gradient and is consistent with changes in temperature and precipitation.
  • DownLoad:Soil conservation service zoning in the Inner Mongolia Autonomous Region based on PSR framework.PDF
  • Analysis of the industrial carbon emission effect based on the Net Primary Productivity Model, its influencing factors and scene simulation
  • Authors:XIA Chuyu, LI Yan, YE Yanmei, SHI Zhou and LIU Jingming
  • Abstract:At present, there are serious environmental problems caused by global warming, primarily resulting from the interaction of industrial fossil fuel emissions and Land-Use and Land-Cover Change (LUCC). According to IPCC reports, the industrial sector is the most important source of fossil fuel consumption, which accounts for 78.75% of the carbon emission to the atmosphere. In China, the annual growth rate of carbon emissions from fossil fuel combustion has been 5.2% since 1978, and the future growth trend is difficult to reverse. Moreover, a lack of ecological security in the implementation of the cultivated land balance policy, the principle of "occupying one up one", can easily lead local governments to incorrectly understand infinite cultivated land reserve resources. Thus, to explore how natural resources, industrial development, and restricted cultivated land protection policies affect the ecological pressure of industrial carbon emission in different cities, the present study uses Dongying and Binzhou as examples. Both cities, located in the Yellow River delta, were used to research the ecological pressure of industrial carbon emission based on the Net Primary Productivity Model (NPPM); the elastic coefficient model was applied to analyze changes of influencing factors from 2005 to 2014; and finally, the potential of low-carbon sustainable development using the scene simulation method was measured. Net Primary Productivity (NPP) is employed as a common indicator of biological productivity and the Net Primary Productivity Model (NPPM) can illustrate the interaction between carbon emissions and land carbon sequestration. The following conclusions were reached: (1) carbon emissions and carbon emission intensities of Dongying were significantly higher than that of Binzhou, and the ecological footprint of carbon emissions annually increased by 12.79 and 6.16%, respectively. This is related to the difference of industrial development between the two cities. (2) After analyzing the results of the elastic coefficient model, we found the combination of critical factors of the industrial carbon emission ecological footprint of Dongying changed from a "cultivated land-land urbanization rate-energy structure coefficient" to "cultivated land-population size-energy structure coefficient" to "cultivated land-population size-the proportion of the second industry" from 2005-2008 to 2008-2011 and 2011-2014; that of Binzhou remained a "population size-land urbanization rate-energy structure coefficient" from 2005 to 2014. (3) Through the situational simulation analysis until 2020, we found that under the baseline scenario, the carbon emission ecological deficit of Binzhou was approximately ten times than that of Dongying; under the low carbon scenario, that of Binzhou was only 2.6 times that of Dongying. Regarding the emission reduction potential (the distance between the carbon emission ecological deficit under the baseline scenario and low carbon scenario), the potential of Binzhou was significantly higher than that of Dongying. However, the low carbon scenario of Binzhou is at the expense of a serious slowdown from 20.6 to 6.5% in industry GDP, which needs to forcibly eliminate high energy-consuming enterprises, and economic growth mainly relies on the completion of the third industry. Therefore, there is a very high demand for the readjustment of the industrial structure. Regarding Dongying, the low carbon scenario needs to improve the energy use efficiency by double, and ensure the restoration of large numbers of "carbon sink" resources.
  • DownLoad:Analysis of the industrial carbon emission effect based on the Net Primary Productivity Model, its influencing factors and scene simulation.PDF
  • A network efficiency analysis approach to habitat network optimization: a case study of the little egret (Egretta garzetta) in the Su-Xi-Chang area, China
  • Authors:WU Wei, FAN Shiwei and OU Minghao
  • Abstract:The network efficiency analysis method is used to study network systematization and integrity, which are important for the assessment of ecological networks. However, this method has rarely been applied in habitat network optimization studies. The objective of the present study was to use the network efficiency analysis method to develop a new approach to optimize habitat network analysis. A small-scale area of 1.75×105 km2 was selected in the Su-Xi-Chang region as the case study; and 12 neighboring cities, together with the Su-Xi-Chang area, covering 11.91×105 km2, were selected as the large-scale study area. The little egret (Egretta garzetta) was chosen as a regionally representative species in the study area. The method included three steps: 1) a conceptual framework for the network efficiency analysis was built to optimize the habitat network, in which the small-world and scale-free network concepts were introduced, with their network structural characteristics, which included average path length, cluster coefficients, and the probability distributions of node degrees. These structural characteristics were applied in step 3 as the assessment indicators; 2) the little egret habitat patches and small- and large-scale habitat networks were identified and simulated. The present status of the small-scale habitat network was obtained from previous research results. In the large-scale area analysis, the observation sites were obtained from a dataset for 2003-2015 on the China Bird Report website. These were regarded as the habitats and those sites where > 20 little egrets were observed simultaneously were identified and transferred to habitat patches. Then, a large-scale habitat network was simulated using the same method used in the previous research; and 3) the present status of the small-scale habitat network was optimized using the large-scale habitat network and was designated as network A. Network B was generated by adjusting the network A structure and transferring its network structural characteristics. The network connectivity indexes α, β, and γ of the present status small-scale habitat network were used to calculate and compare networks A and B. The results showed that 1) the A and B networks represented the optimized results of the present status small-scale habitat network; 2) the increased average path length value, decreased cluster coefficient value, and increased goodness-of-fit of probability distribution of node degree for network B compared to that of network A showed that the network B small-world network characteristics had decreased, but its scale-free network characteristics had increased. This suggests that network B has a better fit to the large-scale habitat network than network A; and 3) the number of newly-added habitat nodes and the migration corridor for network B were smaller than network A, but its corresponding values for the network connectivity indexes α, β, and γ were greater. This suggests that network B results were better than those for network A, and therefore are the recommended, optimized results. The present study indicated that optimizing habitat networks using the network efficiency analysis method improved effectiveness, enriched network structure optimization methodology, and provided a theoretical basis for improved goodness-of-fit when undertaking spatial planning among upper- and lower-levels. However, further studies are required to improve conceptual frameworks, including aspects of network hierarchical analysis, scaling, and network quality assessment indicators.
  • DownLoad:A network efficiency analysis approach to habitat network optimization: a case study of the little egret (Egretta garzetta) in the Su-Xi-Chang area, China.PDF
  • Ecological land classification protection based on the landscape security pattern in Yixing City
  • Authors:WEN Bo, ZHU Gaoli, XIA Min, ZHANG Kailiang, LIU Youzhao and WANG Wei
  • Abstract:Ecological land is a major supplier of ecosystem services, and plays a key role in controlling regional eco-environmental quality. Protection of ecological land significantly promotes the sustainable development of society, the economy, ecology, and regional ecological security. The present research used Yixing city as a case study area, which is located in the southern part of Jiangsu Province. Firstly, following previous research into the relationships between ecological land use classification and current land use classification, the vector data for ecological land were acquired from the current land use vector data for Yixing. Secondly, the landscape security pattern theory and the model of minimum cumulative resistance were used to construct a comprehensive landscape security pattern after systematic analysis of the soil and water conservation, biodiversity protection, vernacular culture protection, and natural landscape protection processes related to ecological land. The overall landscape was then classified into four grades. Finally, the comprehensive landscape security pattern and the current ecological land maps were overlaid. The current ecological land areas were classified into lower, low, middle, and high security pattern levels, and these areas covered 50528.29 hm2, 69942.53 hm2, 34777.44 hm2 and 2335.07 hm2, respectively, which accounted for 32.07%, 44.38%, 22.07%, and 1.48% of the total ecological land area, respectively. In the lower security pattern level ecological land, forest land and cultivated land, located in the southern hilly area, were the priority use types. In the low security pattern level ecological land, cultivated land, and water surrounding the city were the priority use types. In the middle security pattern level ecological land, water and cultivated land that was away from the city were the priority use types, and in the high security pattern level ecological land, water that was located far from the west bank of Taihu Lake was the only land use type. This study makes recommendations for improving ecological land based on the condition of the different land use types found in the ecological land areas. Identifying the landscape security pattern levels for ecological land and giving priority to protecting ecological land are the main approaches used to expand ecological land in urban construction areas in regions that are undergoing accelerated urbanization. This study provides scientific guidance that will aid urban sustainable development decision making, and land use planning and management in Yixing. It also provides scientific methods for ecological land planning that could be used in other areas with similar land conditions.
  • DownLoad:Ecological land classification protection based on the landscape security pattern in Yixing City.PDF
  • Effects of vegetation coverage on soil moisture: Evidence from subtropical lakeside sandy lands in South China
  • Authors:LI Lanhui, DING Mingjun, HUANG Qi, SHI Guangxun and ZHENG Lin
  • Abstract:Lakeside desertification is a common type of desertification in South China. Soil moisture dynamics of lakeside sandy land have important implications for regional vegetation restoration and reconstruction. Using soil moisture data from the Duobao Sand Hills of Poyang Lake recorded from February 2013 to February 2014, we investigated soil moisture dynamics under different vegetation coverage and extreme weather conditions. We found that (1) soil moisture levels of lakeside sandy land in the rainy season were significantly different from the levels in the drought season. Soil moisture, mainly affected by precipitation, was maintained at a higher level ( > 0.063 cm3/cm3) and was less sensitive to the type of underlying surface in the rainy season. However, different types of vegetation cover affected soil moisture differently. Soil moisture in the presence of Pinus elliottii was relatively low ( < 0.035 cm3/cm3) during the drought period. (2) Under high temperatures and drought conditions, shallow-soil moisture of desertified lands dropped rapidly at first, then remained exceptionally low ( < 0.01 cm3/cm3). With the increase in soil depth, the differences in soil moisture among soils with Pinus elliottii, Vitex trifolia Linn., or bare sandy lands became more significant. (3) 17-year-old Pinus elliottii effectively increased the water-holding capacity of the soil surface during the rainy season. However, due to water absorption and obstruction of rainfall, Pinus elliottii affected groundwater recharge during the drought period in terms of the amount of water and soil depth. Therefore, the shallow-soil water of a 17-year-old Pinus elliottii stand is difficult to recharge when precipitation intensity is low. Based on our findings, we suggest to increasing the initial planting density of Pinus elliottii then decreasing mature Pinus elliottii density in subtropical sandy land in South China to neutralize the effects of more frequent extreme droughts and to induce continuous positive succession in desertified areas.
  • DownLoad:Effects of vegetation coverage on soil moisture: Evidence from subtropical lakeside sandy lands in South China.PDF
  • Factors influencing spatial heterogeneity of soil moisture content in a small catchment of Mount Taiyue, Shanxi Province
  • Authors:WANG Tian, KANG Fengfeng, HAN Hairong, CHENG Xiaoqin, BAI Yingchen, MA Junyong and GUI Zhihong
  • Abstract:Soil moisture is a hydrological characteristic that plays a crucial role in the soil-plant-atmosphere continuum. The spatial distribution of soil moisture and factors that influence this distribution are extremely important to many ecological processes, especially in temperate mountain forest regions such as those in northern China. Nonetheless, little is known about soil moisture heterogeneity in typical subalpine forest lands or the controlling factors of soil moisture change. In this study, soil moisture content (SMC) was measured for depths of 0 to 60 cm in a typical watershed forest, dominated by Larix principis-rupprechtii, in Taiyue Mountain, Shanxi Province. We used Geographic Information System (GIS) data and geostatistical methods to examine the spatial heterogeneity of SMC and the factors (i.e., vegetation and topography) that influence it. SMC and its coefficient of variation (CV) decreased with increasing soil layer depth, exhibiting high to moderate variation under an assumption of time stability. At this small watershed scale, the best-fit model for SMC of the three layers (0-20 cm, 20-40 cm, and 40-60 cm) is the spherical model; the spatial autocorrelation distance ranged from 1.1 to 1.4 km. The distribution of SMC has strong spatial autocorrelation in all three layers. The degree of spatial heterogeneity of soil moisture in the 0-20 cm and 20-40 cm soil layers was higher than that in 40-60 cm layer. The structural characteristics of the middle layer accounted for the largest proportion of the total variation. Spatial variability of soil moisture was mainly (81.4% to 91.3%) controlled by natural structure factors such as topography, parent material, vegetation properties, and soil properties, while the influences of random factors such as sampling error, human disturbance, plant root distribution, and absorption were relatively small (8.7% to 18.6%). Moran's I values indicated that soil moisture had moderately aggregated distributions (0.44-0.51) across soil depths. The overall trend of SMC spatial distribution gradually transitioned from high to low values from west to east along with the waterline, an obvious gradient change. We also found that the spatial heterogeneity of soil moisture was mainly controlled by terrain factors in this mountainous catchment with homogeneous vegetation cover. Spatial variability of soil moisture was significantly correlated with topographic factors (such as aspect, slope, and elevation) and soil chemical properties (such as soil organic carbon and total nitrogen) (P < 0.01). However, it was weakly and negatively correlated with the normalized difference vegetation index (NDVI). Overlay analysis suggested that SMC was relatively high in regions where the three attributes of shady slope, smooth slope (<15 degrees), and high altitude overlapped. Moreover, soil moisture variation nearly matched the color depth change in a superimposed terrain map. Taken together, the results of this study provide data for planning the use of soil water resources in artificial vegetation restoration and construction of temperate subalpine forests and a theoretical basis for devising water management strategies.
  • DownLoad:Factors influencing spatial heterogeneity of soil moisture content in a small catchment of Mount Taiyue, Shanxi Province.PDF
  • Heavy metal spatial distribution and contamination assessment of Hadoxylon and Reaummuria soongorica in an industrial area south of Kalamali
  • Authors:XIA Nan, TIYIP·Tashpolat, NURMEMET·Ilyas, ZHANG Dong and LI Yun
  • Abstract:Hadoxylon and Reaummuria soongorica, two species of desert vegetation that occur near Juggar coal, were studied. Six kinds of heavy metals were detected in them, including Zn, Cu, Cr, Pb, As, and Hg. Conventional statistics and geostatistical analysis methods were used to determine the spatial distribution characteristics of heavy metals. The heavy metals in plants were assessed by the Nemerow integrated index to understand the current pollution status and potential ecological risk. The results suggested that maximum Hg (0.224 mg/kg), mean Hg (0.069 mg/kg) in stems and leaves, and mean Hg (0.215 mg/kg) in roots of Hadoxylon were all higher than the national baseline value in soil (0.065 mg/kg). Its maximum (0.92 mg/kg) and mean (0.066 mg/kg) in stems and leaves, and maximum (0.637 mg/kg) and mean (0.072 mg/kg) in roots of Reaummuria soongorica indicated similar results. In the whole body of Reaummuria soongorica, maximum Cr (72.62 mg/kg) and that of Zn (97.61 mg/kg) were higher than the soil baseline in Xinjiang (49.3 mg/kg) and nationally (61 mg/kg). Pb was not found. Interpolated precision was better for Hg and Cu, but worse for Zn. Spatial analysis of Reaummuria soongorica revealed that Zn, Cr, As, and Hg exhibited large artificial disturbances. Hg moderately contaminated Hadoxylon and mildly contaminated Reaummuria soongorica. Zn in stems and leaves of Reaummuria soongorica was a potential risk, whereas the others were in the safe range. It is worth mentioning that Hg was at a moderately hazardous level, higher than the other four elements. Over time, research into metal pollution in plants will be intensified.
  • DownLoad:Heavy metal spatial distribution and contamination assessment of Hadoxylon and Reaummuria soongorica in an industrial area south of Kalamali.PDF
  • Assessing habitat suitability for Cervuselaphus in the Ebinur Lake National Nature Reserve
  • Authors:Akbar Muhtar, Rahmutulla Abdukerim and Mahmut Halik
  • Abstract:Habitat assessing and prediction is important when attempting to protect endangered species. In the Ebinur Lake National Nature Reserve, Xinjiang, A total of 92 recorded GPS coordinates showed that Cervuselaphus was present in the reserve in September 2013 and October 2014. We grouped 23 habitat predictor variables into three classes-terrain, vegetation structure, and climatic factors. We used the MAXENT model to predict the potentially suitable autumn habitat distribution for C. elaphus and determined the contribution each habitat factor made to the distribution characteristics. The accuracy of our prediction models was accessed by the area under the curve (AUC) values for a receiver operating characteristic (ROC) curve, and the validation showed that the results had high average AUC of 0.976. The results of a Jackknife test indicated that the maximum temperature in the warmest month had the strongest influence on autumn C. elaphus habitat suitability, followed by altitude, annual precipitation, mean diurnal range, and mean temperature during the warmest quarter. Vegetation type and slope had little effect on habitat distribution. The simulated habitat was divided into four classes-the most suitable habitat, moderate suitability habitat, low suitability habitat, and unsuitable habitat. The most suitable habitats for C. elaphus were mainly distributed in the northern parts of the study area, and habitats with moderate and low suitability were in the marginal areas of the most suitable habitats. In contrast, the western and eastern parts of the study area were classified as unsuitable habitats for C. elaphus. This study provides information on the actual distribution of C. elaphus in the Ebinur Lake National Nature Reserve and identifies important indicators that could be investigated by future studieson this species and its habitat.
  • DownLoad:Assessing habitat suitability for Cervuselaphus in the Ebinur Lake National Nature Reserve.PDF
  • Habitat assessment of red deer (Cervus alashanicus) in the Helan Mountains, China
  • Authors:GAO Hui, TENG Liwei, WANG Yang, WANG Jifei and LIU Zhensheng
  • Abstract:Cervus alashanicus only occurs in the Helan Mountains. Evaluating the habitat suitability of Cervus alashanicus is the premise and foundation of effective protection for this population. We used a Geographic Information Systems (GIS) and the Maximum Entropy (MaxEnt) model to predict habitat suitability for Cervus alashanicus in the Helan Mountains. The data needed in this research, included occurrence records of Cervus alashanicus and environmental factors. We collected 86 GPS coordinates for Cervus alashanicus occurrance obtained by line transect surveys and patrol data from the Helan Mountain National Nature Reserve from 2013 to 2014. Environmental factors were grouped into three categories, including topographic data (elevation, slope, and aspect) extracted from the Digital Elevation Model (DEM), six vegetation factors extracted from the Thematic Mapper (TM) image of the Helan Mountains (2007), and water resources and human interference factors, including roads, mining, and forest protection points extracted from the 1 : 50000 vector maps of the Helan Mountains. GIS was used to produce the data needed in the model. The distribution of Cervus alashanicus was predicted using the model of MaxEnt. The area under the curve (AUC) values of a Receiver Operating Characteristic (ROC) curve was used to assess the accuracy of the MaxEnt model, and the Youden Index was applied to determine the threshold value for habitat classification in the MaxEnt model. The simulated habitat was divided into two categories, including suitable and unsuitable habitat using a threshold value of 0.31. Finally, the distribution map of habitat suitability of Cervus alashanicus in the Helan Mountains was generated from the data and software, and the AUC value for training data and test data were 0.956 and 0.898 respectively, which indicated that the result of the assessment was excellent. The results showed that suitable habitat for Cervus alashanicus was primarily distributed in the central and southern regions of the Ningxia Helan Mountain National Nature Reserve (eastern part) and to a lesser extent in the northern region of the Inner-Mongolia Helan Mountain National Nature Reserve (western part), with a total area of 667.87 km2, accounting for 18.2% of the total assessment area. Most northern areas of Helan Mountains were unsuitable habitat for Cervus alashanicus because of lower precipitation and more mining. Jackknife tests and the contribution of environmental variables indicated that mining (30.4%), slope (26%), altitude (10.8%), and aspect (8.4%) were the main factors affecting habitat selection of Cervus alashanicus, followed by the forest protection points (5.7%), grasslands (4.2%), roads (4.2%), shrubs (4%), alpine meadows (3.8%), broad-leaved forests (1.3%), and water resources (0.9%). Coniferous forest and desert had little effect on the habitat selection of Cervus alashanicus. The response curves showed that habitat suitability increased gradually with the increase of distance from mine and road, and decreased when the slop was more than 30°. Results from our study suggested that mining was the most serious human interference for the Cervus alashanicus. Managers need to take more regulatory actions to protect the suitable habitat areas of Cervus alashanicus in order to promote the conservation of this population.
  • DownLoad:Habitat assessment of red deer (Cervus alashanicus) in the Helan Mountains, China.PDF
  • Effects of conspecific rivals on male courtship and mating in the monandrous wolf spider Pardosa astrigera
  • Authors:CHEN Bo, WEN Lelei, ZHAO Jupeng, LIANG Honghe, CHEN Jian and JIAO Xiaoguo
  • Abstract:Male sperm or semen production is costly across diverse taxa. Consequently, depending on mate quality and the competitive intensity of rivals, males are predicted to adaptively invest their courtship and mating efforts to maximize their reproductive success, while prudently allocating their sperm. Presently, most studies on male plastic behavioral responses to rivals have mainly focused on polyandrous females. Recent studies provide evidence that male plastic behavioral responses are plentiful and varied, found in a wide range of taxa, and comprise behaviors that occur pre- or post-copulation. It is predicted that males altered aspects of their mating behavior when indirectly exposed to rival chemical cues, and directly exposed to the sex ratio or the presence, number, or density of rivals. Generally, males exhibit adaptively behavioral responses to rival cues to maximize their reproductive fitness. In contrast, we have limited information about male behavioral responses to rival cues in monandrous species. In the present study, we used the monandrous wolf spider, Pardosa astrigera, as a model system to test male plastic behavioral responses to rival chemical cues and different operational sex ratios. It is generally accepted that in wandering spiders, males depend on female silk-mediated chemical substances to search and locate mates. Besides encountering the silk of females of different periods, such as immature and mature virgin females, and mated females, males may also encounter male silk and a mix of female and male silk. Given that males gain mating opportunities via pre-copulatory mate choice, it is predicted that males may invest more courtship intensity in the silk of virgin females than those of males and/or a mix of female and male silk. When male P. astrigera individuals were exposed to the female silk previously occupied by themselves or other males, we compared the differences in male courtship latency, courtship duration, courtship intensity, and mating duration across mating treatments. Our results showed that male courtship intensity (foreleg raises per second and body shakes per second) was significantly reduced when they were exposed to female silk previously occupied by their own silk or by other males than female silk not previously occupied by males; however, there were no significant differences in male courtship latency, courtship duration, and mating duration. Although, when male P. astrigera individuals were directly exposed to different operational sex ratios, our results indicated that varied sex ratios showed a small effect on male courtship and mating behaviors. The present study concurs with our prediction, which shows that male P. astrigera possessed pre-copulatory adaptive responses to rival chemical cues, but showed limited plastic behavioral responses to operational sex ratios. To our knowledge, this is the first study to determine male plastic behavioral responses to conspecific rivals in monandrous spiders.
  • DownLoad:Effects of conspecific rivals on male courtship and mating in the monandrous wolf spider Pardosa astrigera.PDF
  • Effects of short-term heat stress on survival and fecundity of two plant bugs: Apolygus lucorum (Meyer-Dür) and Adelphocoris suturalis Jakovlev (Hemiptera: Miridae)
  • Authors:LI Guoping, FENG Hongqiang, HUANG Bo, ZHONG Jing, TIAN Caihong, QIU Feng and HUANG Jianrong
  • Abstract:Apolygus lucorum (Meyer-Dür) and Adelphocoris suturalis Jakovlev (Hemiptera: Miridae) are the major pests of cotton because of the widespread adoption of Bt transgenic cotton in China and an associated reduction in pesticide use. The effects of short-term heat stress on the survival and fecundity of the two plant bugs were studied to understand changes in the biological characteristics of plant bugs encountering high temperature stress. The egg hatch rate, nymph survival rate, and reproduction of A. lucorum and A. suturalis in incubators were evaluated after the eggs and nymphs were exposed to 27, 30, 33, 36, or 40℃ for 4 h each day. Within the range of 27 to 40℃, the egg hatch rate of A. lucorum increased from 84.25% at 27℃ to 94.69% at 30℃, then decreased to 44.30% at 40℃; whereas the egg hatch rate of A. suturalis increased from 79.27% at 27℃ to 87.90% at 30℃, then decreased to 60.24% at 40℃. After exposure to 40℃ for 4 h, the egg hatch rate of A. suturalis was higher than that of A. lucorum; this indicated that the heat tolerance of A. suturalis eggs was significantly higher than that of A. lucorum. The nymph survival rates of both species decreased with an increase in temperature. Within the range of 30 to 40℃, the nymph survival rate of A. lucorum decreased from 70.47% to 0%, whereas that of A. suturalis varied from 69.65% to 16.74%. Furthermore, female reproduction of both species was affected by high temperature. The mean egg number of A. lucorum adult females increased from 64.78 at 27℃ to 70.03 at 30℃, then decreased slowly. A. lucorum did not lay eggs at 40℃. There was not a significant difference among the mean numbers of eggs laid by A. suturalis females from 27℃ to 36℃. However, exposure to 40℃ for 4 h each day resulted in a mean egg number of 20.75 for A. suturalis. In addition, duration of the nymphal stadia of A. lucorum was extended from 11.01 days at 27℃ to 13.67 days at 36℃ exposure. For A. suturalis, the duration of the nymphal stadia was extended from 13.05 days at 27℃ to 16.58 days at 40℃ exposure. The longevity of both sexes of A. lucorum adults decreased 2 to 4 days with exposure to 27℃ and 36℃, respectively, whereas the longevity of both sexes of A. suturalis adults decreased 11 to 13 days with exposure to 27℃ and 40℃, respectively. In conclusion, the egg hatch rate, survival rate, and reproduction of A. lucorum and A. suturalis significantly decreased after exposure to higher temperatures. However, A. suturalis was more adapted to 40℃ than A. lucorum when both survival and fecundity were considered. The adaptive divergence of tolerance to extreme high temperature may be an important factor differentiating seasonal dynamics and distribution of these species in cotton fields.
  • DownLoad:Effects of short-term heat stress on survival and fecundity of two plant bugs: Apolygus lucorum (Meyer-Dür) and Adelphocoris suturalis Jakovlev (Hemiptera: Miridae).PDF

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