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Volume 37,Issue 9
  • Environmental behavior of persistent organic pollutants in aquatic food web
  • Authors:FENG Qiuyuan, WAN Yi, LIU Xueqin and LIU Yong
  • Abstract:Food web is an import transfer path in aquatic ecosystem. It is essential to explore the environmental behavior of persistent organic pollutants (POPs) along the food web, which will provides cientific foundations for risk evaluation of ecological exposure. Here, we analyzed and summarized the environmental behavior of POPs in aquatic food web, including (a) relationships between trophic levels and food chain length and biomagnification; (b) POPs transfer along benthic and benthic-pelagic coupling food web; (c) adsorption and degradation of POPs by microbes; (d) influences of food web changes caused by several common environmental pressures on the environmental behavior of POPs. The results showed increased bioaccumulation in higher trophic levels, but exceptions were noted because of ecological and physiological factors, such as diet, prey abundance, POPs degradation and isotope enrichment by microbial loop, growth rate, and lipid content. Food chain length was positively correlated with bioaccumulation. When POPs were transferred from the sediment to top consumers, the coupling of pelagic-benthic food web would enhance the exposure risks of higher trophic level consumers to POPs. Controversies existed whether the biomagnification of POPs along benthic food web was greater than that along the pelagic food web. Microbes could adsorb POPs more efficiently because of having a larger surface area. Microbes in the sediment decomposed organic materials, recycling POPs into the water column. Microbial degradation is an important way for POPs leaving aquatic ecosystem. Food web changes caused by seasonal succession, eutrophication and exotic invasions could change the direction and efficiency of energy transfer, and further resulted in changes of the environmental behavior of POPs. Most current studies mainly focused on the environmental behavior of POPs in pelagic food web, especially on the higher trophic levels, lacking researches on the environmental behavior of POPs in benthic and pelagic-benthic coupling food webs and microbial loops. Furthermore, the studies on environmental behaviors of POPs were always restricted to parts of the food web on small temporal and spatial scales, lacking researches on dynamic changes of the environmental behavior of POPs from multiple perspectives and large scales. New POPs have been increasing in production and usage, but studies about its environmental behavior along food web were still scare. Future studies should be conducted considering the above.
  • DownLoad:Environmental behavior of persistent organic pollutants in aquatic food web.PDF
  • Advances in the study of the limitations of seedling recruitment for alpine timberline forests
  • Authors:SHEN Wei, ZHANG Lin and LUO Tianxiang
  • Abstract:Advances of alpine timberline forests during last century are not ubiquitous worldwide, suggesting additional factors and mechanisms likely affect the response of alpine timberline forests to climate warming. Upward shifts of treelines begin with seed dispersal and germination, and seedling establishment above the treeline and any limiting factors during these processes may affect treeline migration. Therefore, investigation of mechanisms controlling seedling recruitment at alpine treeline will be helpful to elucidate treeline formation and its response to future climate change. We reviewed recent advances in tree seedling recruitment at alpine treelines from the key seed and seedling stages. For the seed stage, the seed quantity and quality generally decreased with the sum temperature during summer; the seed dispersal to elevations above treeline was impeded by low wind speed, dense dwarf shrub and grass cover; the ability of seed germination above the treeline was impaired by frost and water stresses near the ground. Also, the allelochemical properties of shrubs had negative effects on seed germination. For the seedling stage, large temperature amplitudes and freezing events during the growing season, as well as the extremely low temperature during winter, were important factors affect seedling mortality. Also the low-temperature photoinhibition resulted from the combination of low temperature and high sunlight significantly decreased seedling photosynthesis during the growing season. Besides, frost-heave activity induced by large soil temperature amplitude and soil water deficits during summer impeded seedling establishment at and above the treeline. Snowpack could keep the seedlings away from the extremely low air temperature during the winter and supply snowmelt water in the early growing season. However, too long duration of the snowpack might increase the possibility of fungal infection that promote seedling mortality. Dense shrub and grass cover above the treeline and the presence of herbivores might decrease seedling survival. In all, the influence of climate warming on seedling establishment across the timberline ecotone is complex and uncertain. Further research is needed to explore the exact effects of warmth-induced environmental changes to seedling recruitment at the alpine treeline. Since the beginning of the growing season might advance under scenarios of climate warming, which in turn led to more early-season freezing events at and above the treeline, it is important to define the temperature threshold of freezing events to analyze the relationship between growing-season freezing events and increasing temperature in the future. Based on this threshold, we can further disclose the effects of growing-season freezing events on seedling establishment at alpine treeline, which will be helpful to elucidate treeline formation and predict treeline dynamics under future climate change.
  • DownLoad:Advances in the study of the limitations of seedling recruitment for alpine timberline forests.PDF
  • Future carbon emissions trends under carbon and sulfur taxation governance in China
  • Authors:HUANG Rui, LIU Changxin and WANG Zheng
  • Abstract:The effect of carbon and sulfur taxation on the economy and emission reduction has been simulated based on the climate governance in the present study. The results showed that under the baseline scenario, China's economy will keep growing, and the GDP will reach $69.95 trillion in 2100. Carbon emissions present Environmental Kuznets Curve characteristics, and a peak will appear in 2034 at a value of 3832 MtC. Under the taxation governance strategy, regardless of sulfur or carbon taxation, China's GDP will be affected; however, carbon emissions will be simultaneously reduced. Levying carbon and sulfur taxes simultaneously will reduce carbon emissions significantly. The peak carbon emissions value of 3111 MtC, decreased to 721 MtC from the carbon emissions peak value in the baseline scenario. Based on the current trend, the carbon emissions peak will appear in 2031. The carbon emissions are three years in advance of the baseline scenario, and, if they continue on the following trend, will fulfill the promise of carbon peak around 2030.
  • DownLoad:Future carbon emissions trends under carbon and sulfur taxation governance in China.PDF
  • Carbon source or sink of natural forested wetland ecosystem in Xiaoxing'anling region of China
  • Authors:LI Na, MU Changcheng, WANG Biao, ZHANG Yan and MA Li
  • Abstract:Carbon (CO2 and CH4) emission fluxes, annual net carbon sequestration of vegetation, were studied from seven kinds of natural wetlands (Carex schmidtii marsh-C, Betula ovalifolia-C. schmidtii shrub swamp-G, Alnus sibirica-C. schmidtii swamp-M, B. platyphylla-C. schmidtii swamp-B, Larix gmelinii-C. schmidtii swamp-L-T, L. gmelinii-moss swamp-L-X, and L. gmelinii-Sphagnum spp. swamp-L-N) in Xiaoxing'anling region of China using the static chamber gas chromatography method and the relative growth equation method to evaluate the carbon source or sink of natural forested wetlands based on net ecosystem carbon balance. The results showed that: 1) seasonal dynamics of CH4 emission fluxes from seven kinds of natural wetlands could be divided into three types (single-peak, multi-peak, and emission and absorption alternating type) and CH4 emission flux (0.006-7.756 mg m-2 h-1) exhibited a different trend in M (which was 1.0-1291.7 times greater than the others, P < 0.05) > C, G, B (17.7-649.0 times greater than L-T, L-X, and L-N; P > 0.05) > L-T, L-X, and L-N; 2)seasonal dynamics of CO2 emission fluxes from the seven kinds of natural wetlands could be divided into two types (single-peak and double peak), and CO2 emission flux (157.40-231.06 mg m-2 h-1) exhibited an different trend in G (which was greater 28.7%-46.8% than forested wetlands, P < 0.05) > C(7.4%-22.5% than forested wetlands, P > 0.05) > five kinds of forested wetlands; 3)CH4 emission fluxes from C, G, M, B, and L-N were controlled by soil temperature, but that of L-T and L-X had no significant correlation with soil temperature at 0-40 cm. CO2 emission fluxes from C, G, M, and L-T were controlled by air temperature and soil temperature, and that of B, L-X, and L-N were controlled by air temperature, soil temperature, and the water table level; 4) the annual net carbon sequestration of vegetation ((2.05±0.09)-(6.75±0.27) tC hm-2 a-1) had a different trend in C (greater than the others by 65.4%-229.3%,P < 0.05)> G, B, L-T, L-X, and L-N (greater than M by 80.0%-99.0%, P < 0.05) > M; and 5) the sources and sinks of carbon were significantly different among the seven kinds of natural wetland types (-2.32-2.09 tC hm-2 a-1). For example, C, B, and L-N exhibited varying degrees of carbon sinks, yet M, G, L-T, and L-X exhibited varying degrees of carbon sources. Therefore, marsh wetlands were greater carbon sinks and shrub wetlands were greater carbon sources, yet forested wetlands maintained overall carbon balance (except M) in the Xiaoxing'anling region of China.
  • DownLoad:Carbon source or sink of natural forested wetland ecosystem in Xiaoxing'anling region of China.PDF
  • Effects of forest thinning on soil CO2 emissions in a pine-oak mixed stand in the Qinling Mountains based on the Yasso07 model estimate
  • Authors:LUO Chunlin, HOU Lin, BAI Longlong, GENG Zengchao and HE Wenxiang
  • Abstract:Natural forest-protection programs have been implemented to increase stand volume and forest ecosystem diversity, and to improve forest resources. However, they have had some negative influences on forests, such as high stand density and poor growth, and these can easily lead to insect outbreaks and fire disasters. Forest thinning can effectively eliminate the negative influences caused by natural forest protection management. Forest thinning programs have been conducted for several years and these approaches have led to reduced tree mortality and accelerated natural regeneration. However, it has been demonstrated that forest micro-climates influence soil CO2 emissions. This study investigated the effects of forest thinning on soil CO2 emissions using the Yasso07 model to simulate a pine-oak mixed forest in the Huoditang forest zone area of the Qinling Mountains. The topography of the Qinling Mountains is complicated and fractured, so it is difficult to duplicate experimental plots in a randomized block design. Therefore, the quadratic general rotary design was applied, and thinning and residue-removed intensity were the factors in the experiment. Thirteen experimental plots were selected, including five control levels and nine treatment plots. Five litter-fall collection frames (1 m × 1 m) were laid in each experimental plot. The litter fall was collected each month from September 2012 to September 2014. The ethanol-soluble, water-soluble, acid-soluble, and non-soluble compound contents in the leaf litter fall were determined. Although the technology to measure soil CO2 emissions has continually improved, the soil spatial heterogeneity and strong soil carbon stability in undisturbed habitats has led to inaccuracies in the evaluation methods used in forest soil carbon dynamics research. Yasso07 is a soil-carbon decomposition model and is based on the assumption that there are four types of litter transformation. Yasso07 has been widely used in Europe and the United States because it can be operated easily; requires few parameters, which are easy to obtain; and the simulated results are reliable. However, there was no basis to determine if it could be applied in the Qinling Mountains. Therefore, this study validated the reliability of the Yasso07 model in this region. The soil CO2 emission traits under different thinning and residue-removed intensities were analyzed based on simulations by the model. The following results were obtained: (1) there was a significant difference between the conifer and broadleaf litter chemical compositions. The ethanol and water soluble compound contents were significantly higher in the conifer tree litter than in the broadleaf tree litter, and the non-soluble compound content was significantly lower in conifer litter than in broadleaf litter. (2) The chemical composition of the litter fall significantly affected soil CO2 emissions, and (3) thinning intensity was the key factor affecting CO2 emissions. Soil CO2 emissions increased after forest thinning, and when the thinning and residue-removed intensities were 12.38% and 53.18%, respectively, the soil CO2 emission fell to a minimum of -15.318 Mg hm-2 a-1.
  • DownLoad:Effects of forest thinning on soil CO2 emissions in a pine-oak mixed stand in the Qinling Mountains based on the Yasso07 model estimate.PDF
  • Dynamic changes in the carbon intensity and sustainability of farmland use: A case study in Pingdu County, Shandong Province, China
  • Authors:WU Jinfeng and WANG Xiuhong
  • Abstract:During 1995-2013, the carbon emissions for farmland uses in Pingdu County (in Shandong Province, China) were calculated by selecting the main sources of emissions and establishing a measurement system for the sources, including indirect carbon emissions for agrochemical inputs, direct N2O emissions for N fertilization, carbon emissions for energy consumption and straw burning, and CH4 and N2O emissions for livestock farming. The changes in carbon intensity were calculated based on the changes in agricultural output value, and the changes in the carbon sustainability index were calculated based on the carbon emissions of the main sources and carbon absorption by the main crops. The results were as follows: (1) The order of annual mean carbon emissions was agrochemical materials (22.50 ten thousand tons) > livestock farming (17.41 ten thousand tons) > straw burning (6.62 ten thousand tons). The carbon emissions for straw burning showed an increasing trend, whereas the emissions from the other sources showed a decreasing trend. (2) The increasing rate for the agricultural output value exceeded that of total carbon emissions, with the carbon emissions per agricultural output value decreasing from 1.24 t/Yuan in 1995 to 0.35 t/Yuan in 2013 (annual average decrease of 0.0459 t/Yuan). (3) The carbon sustainability index had an annual average increasing rate of 7.12%. This trend indicated that the carbon absorption by crops was greater than the carbon emissions from the farmland processes. Overall, this study not only provides an understanding of carbon emissions and a scientific basis for sustainable development of farmland in small-or medium-scale regions in eastern China, but it also promotes the reduction of agricultural carbon emissions in China. In addition, this study could provide basic information for the investigation of Land-Use and Land-Cover Change and Carbon Cycle of International Human Dimensions Programme on Global Environmental Change.
  • DownLoad:Dynamic changes in the carbon intensity and sustainability of farmland use: A case study in Pingdu County, Shandong Province, China.PDF
  • Morphological responses of six successional plant species in old-fields of the Loess Plateau to the pattern and level of nitrogen application in a pot experiment
  • Authors:WANG Yannan, DU Feng, SUI Yuanyuan, GAO Yan, LI Weiwei and WANG Yue
  • Abstract:How successional species differentially respond to nitrogen addition is of theoretical importance to understand the plant community-level consequences of China's accelerated nitrogen deposition amidst ongoing global climate change. Such research also has an immediate, practical significance for revegetation strategies through targeted fertilization. In this paper, a field potting experiment was carried out to test the biomass benefits and morphological responses of six successional seral species in the Loess Hilly Region of Northern Shaanxi. The factorial experimental design had two treatments: a nitrogen fertilization pattern (i.e., homogeneous vs. heterogeneous nitrogen) and nitrogen fertilization level (i.e., high, low, and zero nitrogen [the control]). The plant response variables measured were individual biomass (i.e., aboveground and belowground biomass, and root-branch ratio) and several root morphological features (i.e., root length, diameter, and surface area; specific-root length; and specific-root surface area). These eight response variables were tested separately for treatment effects using three-way ANOVAs; in addition, improved root morphological features in the fertilized patches were compared to those in the non-fertilized patches using a simple t-test. The results showed that (1) the aboveground biomass, belowground biomass, and root/branch ratio differed significantly among the six successional seral species; this may reflect their species-specific differences, as they were largely not affected by nitrogen fertilizer pattern or its level of application. Nevertheless, a significant interactive effect between fertilizer pattern and species upon the root/branch ratio between was found. This implied that some plant species-for example, Artemisia scoparia in our case-had a significant response to nitrogen pattern in terms of its root-branch ratio whereas others did not. (2) The specific root length, specific surface area, and root diameter also differed significantly among the six successional seral species. The nitrogen fertilization level significantly affected the specific root length; it was lower both at high and low levels of nitrogen fertilization in comparison to the controls (unfertilized plants). (3) Under the treatment of heterogeneous fertilization at high level, the proliferation of root biomass of Setaria viridis in the fertilized patches was significantly higher than in the non-fertilized patches. Similarly, under heterogeneous fertilization at low level, the root biomass of Artemisia sacrorum was significantly higher than its counterparts growing in the non-fertilized patches. Artemisia scoparia under heterogeneous fertilization at high level, more elongation, root length root surface area, specific root length, and specific surface area in the fertilized patches were significantly higher than in the non-fertilized patches. However, the root diameters of Artemisia scoparia and Setaria viridis in the patches of heterogeneous fertilization at high level, and the diameter of Bothriochloa ischaemum in the patches of heterogeneous fertilization at low level, were all significantly lower than those in the non-fertilized patches. From the perspective of morphological responsive sensitivity and a biomass benefit from fertilization, both of these plant traits exhibited an overall tendency to decrease along succession. That is to say, the early-successional seral species tend to respond more actively, and to assimilate more nitrogen in their formation of biomass, than the late-successional species do. This implies that for the successful revegetation of infertile fields, they should be fertilized as early as possible once been abandoned.
  • DownLoad:Morphological responses of six successional plant species in old-fields of the Loess Plateau to the pattern and level of nitrogen application in a pot experiment.PDF
  • Effect of straw application to soil nitrate leaching of paddy-upland rotation in the Yellow River irrigation area
  • Authors:YANG Shiqi, HAN Ruiyun, WANG Yongsheng, LIU Ruliang, XIE Xiaojun and YANG Zhengli
  • Abstract:The Yellow River irrigation area within Ningxia was a region severely polluted by non-point sources, where surface water quality in most drainage ditches was classified as Inferior Category V, and the primary pollutants were nitrate and ammonium. In this region a 5-year straw application and nitrate leaching experiment had been conducted, which consisted of 3 treatments: traditional fertilizing without rice straw amendment(CK), traditional fertilizing with 4500 kg/hm2 rice straw returning application (T1, semi), and traditional fertilizing with 9000 kg/hm2 rice straw amendment (T2, total). Nitrate nitrogen leaching losses within 10, 20, 30, 60, 90 cm soil layers were measured by the resin core method. Results indicated straw application could reduce soil nitrate leaching losses within the 30 cm layer. From the nitrate nitrogen loss of CK (15.76 kg/hm2), the loss of T1 (13.76 kg/hm2) and T2 (13.74 kg/hm2) all showed significant differences (P < 0.05), soil nitrate leaching losses were decreased by 12.71% and 12.84%, respectively. However no significant differences (P > 0.05) was detected between T1 and T2. The effects of straw application were only observed in plowing layer (30 cm depth soil layer), no significant difference was detected between experimental treatments and control (CK) in deeper layers (60 and 90 cm) and in topsoil (10 and 20 cm). Straw application could increase soil organic matter (SOM) and total nitrogen (TN) content: SOM of T1 and T2 were increased by 0.89 g/kg and 1.24 g/kg compared to CK (13.78 g/kg). TN of CK, T1 and T2 were 0.64, 0.66 and 0.69 respectively, at 0-30 cm layer, which were increased by 2.76% and 6.83%. Straw application could also increase crop yield,rice production of T1 and T2 were increased by 9.24% and 10.37%, and winter wheat yield were increased by 10.11% and 11.51%, respectively.
  • DownLoad:Effect of straw application to soil nitrate leaching of paddy-upland rotation in the Yellow River irrigation area.PDF
  • Influence of flue gas desulfurization gypsum on speciation of phosphorus in coastal cultivated soils
  • Authors:HE Kun, LI Xiaoping, ZHOU Chunliang, ZHOU Jian, DONG Longli and MAO Yumei
  • Abstract:To investigate the effect of the flue gas desulfurization gypsum (FGDG) on coastal cultivated soil, a field experiment was conducted to evaluate different application amounts at rates of 0, 15, 30, and 45 t/hm2. The effect of FGDG on soil total phosphorus (P), available P, and inorganic P fractions in coastal cultivated soils were measured. The results indicated that FGDG had no significant effect on soil total P in the cultivated soils. However, FGDG significantly reduced the soil available P and tile flow water soluble P. The inorganic P content was significantly increased by FGDG, especially calcium phosphorus (Ca8-P). The mean concentration of Ca8-P in the soil increased by 35.2%-66.3%, and the Ca10-P concentration in the soil was increased by 7.3%-17.8%. The ability of Echinacea to absorb P was not affected by the reduction of available P or increased Ca-P in fractions of inorganic P in the soil. FGDG application promoted plant growth and development. Therefore, FGDG could effectively fix the soil available P, control the excessive P accumulation of soil, and reduce the risk of eutrophication of the surrounding water bodies. The results provide a guideline for a reasonable rate of FGDG application in coastal cultivated soils.
  • DownLoad:Influence of flue gas desulfurization gypsum on speciation of phosphorus in coastal cultivated soils.PDF
  • Atmospheric CO2 variations and source estimation at the fourth ring road and roadside green-space system in Beijing
  • Authors:ZHANG Xiaobo, SUN Shoujia, ZHENG Ning, GUO Jia, SHU Jianhua and LI Chunyou
  • Abstract:Knowledge of variations and sources of urban atmospheric CO2 is important to determine energy saving and emission reduction policies. In the present study, air CO2 concentration and stable carbon (δ13C) isotope ratios on the Fourth Ring Road (FRR) and in the green-space system 100 m from FRR were measured using an off-axis integrated cavity output spectroscopy technique in heating and non-heating seasons. The CO2 variations and different source contributions were analyzed with the Keeling plot method and IsoSource software. The results showed CO2 from different sources had significantly different δ13C values. The δ13C values from high to low were noted from soil respiration (-18.92‰), plant respiration (-23.40‰), coal combustion exhaust gas (-24.10‰), motor vehicle exhaust gas (-28.14‰), and natural gas (-33.34‰). The CO2 concentrations of the FRR and green-space system in the heating season were 26.2% and 41.2% higher than those in the non-heating season, respectively. There was a significant difference of CO2 concentration between the FRR and green-space system in the non-heating season, but no difference in the heating season. The CO2 concentration had an obvious daily change and two peaks at 6:00 and 20:00 in the heating season. The CO2 concentration of FRR was highest at the bottom of the observation tower and decreased with increased height, but the CO2 concentration of the green-space system was highest at 8 m. In the heating season, the CO2 concentration had two peaks at 8:00 and 19:00, with a similar daily trend to that of traffic volume. CO2 concentrations of both the FRR and green-space system decreased with increasing height. However, there were obviously different sources between the FRR and green-space systems. The CO2 of the FRR was mainly from motor vehicle exhaust gases, but that of the green-space system mostly came from soil and plant respiration in the non-heating season. However, there was no difference in CO2 sources between the FRR and green-space system, and most sources were coal-fired emissions and motor vehicle exhaust gases.
  • DownLoad:Atmospheric CO2 variations and source estimation at the fourth ring road and roadside green-space system in Beijing.PDF
  • Spatiotemporal simulation of urban settlement morphology: a case study of Xiamen Island
  • Authors:WANG Jin, LIN Tao and ZHANG Guoqin
  • Abstract:Settlement morphology transition is constrained by population migration, settlement satisfaction, and low-carbon city policies. Many land use models poorly describe these transitions, rendering studies in this field relatively inadequate. Xiamen Island, a rapidly urbanizing area in the southeast of Fujian Province in China, was selected as a case study for settlement morphology transition. We generated a system dynamics (SD) model of the carbon footprint of this settlement based on settlement morphology transition and simulated the transition of settlement morphology using this SD model. In this model, the changing social needs of a residential area over the next 20 years were simulated, and the settlement carbon footprint was calculated under three different scenarios (basic, low-carbon, and compact city). We used the results of these simulations as the input of the non-spatial demand module in the CLUE-S (Conversion of Land use and its Effects at Small extent) model. In the study of settlement spatial allocation using the CLUE-S model, we simulated the transition of settlement morphology under three scenarios and depicted the spatial conversion of land use on Xiamen Island over the next 10 years. Next, we discussed the allocation characteristics of settlement types II and type III, which are predicted to be the major settlement types in decades. In summary, this study attempted to depict the transition of settlement morphology on Xiamen Island in multiple dimensions-time, space, quantity, and sequence. To address these issues, we clarified the development characteristics of the settlement in different ways, such as driving forces, structures, spatial allocation, and using various scenarios. The simulation results showed that the SD and CLUE-S models bridge the gap between non-spatial land use policies and the spatial characteristics. The simulation results of the SD model revealed that 1) the ratio of three types of settlement, I, II, and III, was 1:1.18:0.83 in 2009; type III will become predominant in 2018. 2) Over the next 20 years, the total population and the demand for land resources on Xiamen Island will continue to increase. The carbon footprint of Xiamen Island under different scenarios varied significantly. 3) In the basic scenario, the total population of Xiamen Island was predicted to reach 2.40 million in 2030, while the total settlement area was predicted to be 75.3 km2. The carbon footprint was predicted to increase and reach a plateau phase, at 4605 kg C/cap, in 2022. 4) In the low-carbon scenario, the total population of Xiamen Island was predicted to reach 2.44 million in 2030, while the total settlement area was predicted to be only 66.4 km2. The carbon footprint was predicted to increase and reach a plateau phase, at 3771 kg C/cap, in 2016. 5) In the compact-city scenario, the total population of Xiamen Island was predicted to reach 2.52 million in 2030, while the total settlement area was predicted to be 84.7 km2. The carbon footprint was predicted to increase and reach a plateau phase, at 5759 kg C/cap, in 2028. The simulation results of CLUE-S model indicated that settlement type II tends to distribute in areas with high population density, convenient traffic, and proximity to the city center, which can be summarized as the inertial development mode. In contrast, settlement type III tends to distribute in areas with low population density, low elevation, and proximity to commercial centers, which can be summarized as the low-land-cost development mode. Finally, we provide some recommendations to facilitate a balance between the low-carbon and compact-city scenarios. We hope that this study will contribute to the formulation of energy-saving measures as well as the construction of new settlement types. We also hope that it will provide scientific support for the sustainable development of urban settlements.
  • DownLoad:Spatiotemporal simulation of urban settlement morphology: a case study of Xiamen Island.PDF
  • Willingness-to-pay for recreation services of urban ecosystem and its value assessment: a case study in the Wenjiang district of Chengdu City, China
  • Authors:CAO Xianlei, LIU Gaohui, ZHANG Ying and LI Xiushan
  • Abstract:Urban ecosystems are mainly comprised of green infrastructure, such as green spaces, parks, forests, lakes, streams, and rivers, and are relatively small in China. Although economic evaluation of urban ecosystem services has attracted wide attention, little is known about the recreation value of urban ecosystems, an important benefit of urban ecosystems. Using modern consumer choice theory, residents in the Wenjiang district and Chengdu City accepting recreation services of urban ecosystem were assessed using a face to face questionnaire survey, which asked them to express their willingness to pay (WTP) for travelling to green infrastructure in the Wenjiang district. The residents' WTP for the recreation services of the urban ecosystem and its influencing factors were analyzed using the Logit and Oprobit models, and the economic value of the recreation service was calculated by the contingent valuation method (CVM). The results showed that: (1) respondents in the Wenjiang district and Chengdu City had different average probability of payment and amount of the residents' WTP for traveling to green space, forests, lakes, and rives in the Wenjiang disrict. The average probability of respondents expressing a WTP in Chengdu City and Wenjiang district were 60.3% and 69.1%, with an average WTP of 127.1 Yuan and 142.5 Yuan per year per person, respectively. (2) The probability and amount of the residents' WTP was not only influenced by respondent's income level, but also reflected the subjective evaluation of residents for internal infrastructure services in the urban ecosystem and degree of convenience, as well as the residents' willingness for the next availability of services. However, educational level and residents' willingness of next available services had a significant negative influence on the maximum WTP, which could correspond to variation in recognition and the act of paying, as well as "pick-up" psychology. (3) Based on the maximum WTP, the value of urban ecosystem services in recreation in the Wenjiang district was approximately 410 million Yuan per year. With growing residential income and increasing demand for the recreation entertainment services, this WTP might grow in the coming years. Finally, based on the respondents stated preferences, we suggest how ecological management could be used to protect urban green spaces, and promote sustainable city development to maximize these benefits to people.
  • DownLoad:Willingness-to-pay for recreation services of urban ecosystem and its value assessment: a case study in the Wenjiang district of Chengdu City, China.PDF
  • A nalysis of a land carrying capacity index based on an expanded three-dimensional ecological footprint model: a case study of Wenzhou
  • Authors:JIN Xiangmu and LIU Qiankun
  • Abstract:The ecological footprint method was initially proposed by Rees in the early 1990s, and Wackernagel and Niccolucci subsequently developed this method into two-and three-dimensional models. Ecological footprint models, as tools to estimate the appropriation of natural resources by humans, are important to evaluate the land carrying capacity. Using the three-dimension model, this paper expanded the footprint depth value range from ≥ 1 to ≥ 0, and the ecological deficit and remainder were then analyzed. Using a modified three-dimensional model, the ecological footprint, footprint depth, and ecological deficit (remainder) in Wenzhou City were calculated from 2000 to 2012. On this basis, the food pressure, water pressure, carbon sink pressure, construction pressure, and land comprehensive load indexes were introduced to the indicator system of land carrying capacity, and the condition of load carrying of Wenzhou City was determined. The results showed that from 2006 to 2012, the ecological footprint per capita increased annually, and since the biologically productive land remained unchanged, the ecological deficit worsened and a greater load was imposed on the land in Wenzhou City. The footprint depth value ranged from 4 to 6, which meant that natural resource flows could not meet the demand of everyday residential consumption, and natural resource stocks were extensively depleted. The food pressure, water pressure, carbon sink pressure, and land comprehensive load indexes were > 1, which indicated that arable land, sea, and forest were overloaded. Since 2000, the load, primarily from food and carbon sink pressures, imposed on biological productive land was three times greater than its carrying capacity.
  • DownLoad:A nalysis of a land carrying capacity index based on an expanded three-dimensional ecological footprint model: a case study of Wenzhou.PDF
  • Temporal-spatial dynamic change characteristics of evapotranspiration in arid region of Northwest China
  • Authors:DENG Xingyao, LIU Yang, LIU Zhihui and YAO Junqiang
  • Abstract:Using MODIS ET data of actual surface evapotranspiration products that were concentrated between 2000 to 2014, we used variable coefficients, the Theil-Sen median trend analysis, Mann-Kendall test, and Hurst index, to investigate the spatial pattern of evapotranspiration, spatial heterogeneity of different dimensionalities, characteristics of time variation, and future trends considering an arid region in Northwest China. The results showed the following: 1) Evapotranspiration over the entire region was very low from 2000 to 2014, and the area of evapotranspiration, less than 200 mm, accounts for 38.329% of the total area. Evapotranspiration decreases from mountainous areas to the plains. Evapotranspiration data were obtained for different land covers, which are forest land, cropland, grassland, and sparse vegetation, arranged from high to low. Mountain forests and grasslands that receive high rainfall have higher values of evapotranspiration (more than 400 mm) than sparse vegetation plains and grasslands that experience low rainfall (less than 200 mm). 2) The degree of variation in evapotranspiration over the past 15 years for the entire region is not obvious, but shows a slight fluctuation. The proportion of areas with slight fluctuations in each subregion ranged from large to small in the order of Northern Xinjiang, Tianshan Mountain, Qilian Mountain, Western Inner Mongolia, Hexi Corridor, and Southern Xinjiang. 3) The degree of variation in evapotranspiration over the past 15 years for the entire region shows changes in the fluctuations with a weakly decreasing trend, at a change rate of-0.9348 mm/a. An analysis based on the pixel scale also shows a mainly decreasing trend. The degree of decreases in each subregion ranged from large to small in the order of Tianshan Mountain, Western Inner Mongolia, Hexi Corridor, Northern Xinjiang, and Qilian Mountain. Only Southern Xinjiang showed an increasing tendency. 4) The Hurst index average of evapotranspiration for the entire region is 0.689. The area of the Hurst index greater than 0.5 accounts for 80.033% of the total area. The trend of changes in evapotranspiration in the future for the entire region is mainly towards a persistent decrease. However, the trend of changes for 22.003% of the area cannot be determined. The future trend of change in the degree of decreases for each subregion from large to small follows the order of Western Inner Mongolia, Tianshan Mountain, Hexi Corridor, Northern Xinjiang, Qilian Mountain, and Southern Xinjiang.
  • DownLoad:Temporal-spatial dynamic change characteristics of evapotranspiration in arid region of Northwest China.PDF
  • Assessment of soil salinization ecological environment change in the Manas river basin using remote sensing technology
  • Authors:ZHANG Tianyou, WANG Ling, WANG Hui, PENG Li and LUO Chong
  • Abstract:Soil salinization has become a serious global problem, which poses a grave threat to ecological environment and agricultural production. In order to assess the effect of soil salinization on ecological environment quickly and accurately in regional-scale, a new remote sensing ecological index was proposed to detect the ecological change in arid area based on the remote sensing method in this paper. Manas river basin, a typical arid inland basin in northwest of China, was selected for the study area. Firstly, four indicators (salinity, surface albedo, vegetation coverage and wetness) which closely related to soil salinization were calculated based on the Landsat image in the Manas river basin on August 25, 1989, August 7, 2000, and September 10, 2015. Then, these indicators were normalized using min-max normalization method. Lastly, the principal component analysis (PCA) method was introduced to couple the four indicators, and the soil salinization ecology index (SSEI) was obtained. This method is different from the previous index overlaid by weighting the indexes from remote sensing and other data. It depends on the data itself, instead of subjective human states. The result shows that there is a significant relationship between SSEI and salt content observed in the fields (R2=0.9035, P < 0.01). This indicates SSEI could be used for retrieving the soil salinization on ecological environment rapidly and quantitatively. Through PCA analysis, we found that the first principal component appears stable and its share of all indicators is greater than 85%. The properties of wetness index (WI), normalized difference vegetation index (NDVI), and salinity index (SI) are consistent with the general ecological environmental parameters. The index was applied to the irrigated area of the Manas river basin. Among the bad, comparatively bad, medium, good, excellent grades, the area of bad grade had increased from 491.6 km2 to 1031.4 km2 during 1989 to 2000, but it has been decreased from 1031.4 km2 to 636.9 km2 during 2000 to 2015. The area of medium grade also increased at first but then reduced. The change area ranges from 6354.3 km2 in 1989 to 2111.4 km2 in 2015. The good and excellent grades of ecological environment has been increased by 12.9% in the last 26years, which shows the ecology environment has improved in the irrigation area. The spatial distribution of SSEI shows that the desert area without influencing by human activities still keeps a poor level, and the ecological problem is still very serious. The function of artificial oasis has been improving. Assessment of soil salinization ecological environment change using remote sensing technology could provide insight for land resource development in arid areas.
  • DownLoad:Assessment of soil salinization ecological environment change in the Manas river basin using remote sensing technology.PDF
  • Effects of increased precipitation and nitrogen deposition on soil enzyme activities
  • Authors:YAN Zhongqing, QI Yuchun, PENG Qin, DONG Yunshe, GUO Shufang, He Yunlong, Wang Liqin and Li Zhaolin
  • Abstract:An in-situ field experiment was established to examine the effects of increased precipitation and nitrogen deposition on the activities of soil enzymes in the semi-arid Leymus chinensis grassland of inner Mongolia during the 2014 growing season. Water was added at two levels (W0, no additional water; and W15, a 15% surplus on average rainfall) and N was added at four levels (CK, 0 kg N hm-2a-1; LN, 25 kg N hm-2a-1; MN, 50 kg N hm-2a-1; and HN, 100 kg N hm-2a-1) to simulate increasing precipitation and N deposition in a future global change scenario. Effects of different water and nitrogen additions on the monthly dynamics of N cycle-related protease, urease, nitrate reductase, and nitrite reductase activities in grass topsoil were quantified. We also analyzed the correlations between all variables and soil physical and chemical properties. Results showed that, under natural rainfall conditions, there were no significant differences in protease, urease, and nitrate reductase activity between elevated nitrogen deposition levels, although nitrite reductase activity decreased significantly compared to the control. Under increased precipitation conditions, different nitrogen levels did not significantly affect protease or nitrate reductase activity, although high levels of nitrogen loading (HN) significantly reduced nitrite reductase activity. Additional precipitation increased protease activity in the low nitrogen (LN) treatment and nitrate reductase activity in the medium and high nitrogen (MN, HN) treatments; it also reduced urease activity in the high nitrogen treatment (HN). Individually, precipitation had major effects on protease and nitrate reductase activity, while nitrogen deposition had a major effect on nitrite reductase activity, however, precipitation and nitrogen treatments did not show any significant interactive effects on all the enzyme activity. Finally, soil nitrate reductase activity was significantly, positively correlated with soil C/N ratio and NH4+-N content, and positively correlated with NO3--N content.
  • DownLoad:Effects of increased precipitation and nitrogen deposition on soil enzyme activities.PDF
  • Heavy metal absorption characteristics of epiphytic moss on coarse woody debris in an alpine forest
  • Authors:WANG zhuang, YANG Wanqin, WU Fuzhong, CHANG Chenhui, LI Jun, TANG Guoqing and WANG Qin
  • Abstract:Coarse woody debris (logs, branches, snags, and stumps) constitutes a large component of forest biomass, and plays an essential role in many alpine forests. Coarse woody debris not only participates in material cycling and energy flow in the ecosystem, but also provides a suitable environment and abundant nutrients for the growth of epiphytic moss. Many studies have focused on the importance of moss as an absorber as well as indicator of heavy metal pollutants, especially pollutants from anthropogenic activities. Moss can absorb heavy metals from precipitation/wet deposition and directly from the substrate, and the concentrations of heavy metals in epiphytic moss are related to the local environmental conditions; total storage can be affected by the heavy metal content in the epiphytic moss and the biomass of the moss. However, the effect of the interaction between epiphytic moss and coarse woody debris on the sequestering of heavy metals in forest ecosystems remains unknown. In July 2015, the cadmium (Cd), lead (Pb), copper (Cu), and zinc (Zn) content and storage in epiphytic mosses on different types (logs, branches, snags, and stumps) and decay classes (Ⅰ-Ⅴ) of coarse woody debris were investigated in an alpine fir (Abies faxoniana) forest in western Sichuan. Results showed that an average of 4700 mg/hm2 of Cd, 21236 mg/hm2 of Pb, 6179 mg/hm2 of Cu, and 2622 mg/hm2 of Zn were sequestrated in the epiphytic mosses on the coarse woody debris in this region. The total storage of the four heavy metals in the epiphytic mosses was in the following order for coarse woody debris: logs > branches > snags > stumps. Cd, Pb, Cu, and Zn storage in the epiphytic mosses on the logs accounted for 54.53%, 66.08%, 51.13%, and 66.30% of total storage, respectively; Cd, Pb, Cu, and Zn storage in the epiphytic mosses on the roots accounted for less than 3% of total storage. The characteristics of the heavy metal elements in the epiphytic moss was affected by the type and decay level of coarse woody debris. The content and storage of both Cd and Pb in the epiphytic mosses of the logs and large branches showed an "accumulation-release" pattern, and the highest values were observed in decay classes Ⅱ or decay classes Ⅲ. In contrast, the content and storage of Zn and Cu in the epiphytic mosses for all decay classes were insignificant. Overall, these results suggest that epiphytic moss on coarse woody debris greatly contributes to the sequestration of heavy metals in alpine forests; the results provide new insight into the cycling and transportation of heavy metals, as well as the role played by coarse woody debris in these alpine forest ecosystems.
  • DownLoad:Heavy metal absorption characteristics of epiphytic moss on coarse woody debris in an alpine forest.PDF
  • Ecological stoichiometry characteristics of leaves and litter in plant communities in the Yongli colliery reclamation area
  • Authors:ZHAO Junfeng, XIAO Li, AN Shaoshan, FANG Ying, MA Rentian and HUANG Yimei
  • Abstract:The objective of this study was to clarify the ecological stoichiometry characteristics of leaves and litter in different plant communities in the Yongli colliery reclamation area. Leaves and litter were collected, and organic carbon (C), total nitrogen (N), total phosphorous (P), and total potassium (K) content were measured.Plant nutrient values and restriction factors for the reclamation area were determined and nutrient cycling between leaves and litter was investigated. The results indicated that: (1) There were significant differences in leaf C content among the different plant types. C content was the highest in shrubs (Platycladus orientalis (L.) Franco, 537.96 g/kg) and the lowest in herbs (Astragalus adsurgens Pall., 423.73 g/kg). Leaf N, P, and K content did not differ significantly between plant types. In contrast, there were significant differences between plant types for the N and P content of the litter. C content was significantly higher in Hippophae rhamnoides Linn. (417.84 g/kg) than in A. adsurgens and Caragana korshinskii Kom. N content was the highest in A. adsurgens (20.30 g/kg) and the lowest in C. korshinskii, whereas P content was the highest in A. adsurgens (1.57 g/kg) and the lowest in H. rhamnoides. K content was significantly higher in A. adsurgens (6.31 g/kg) than in H. rhamnoides and C. korshinskii. C, N, P, and K content were higher in the leaves than in the litter. The resorption efficiencies of N, P, and K was in the range of 5.17-50.16%, 4.19-6.41%, and 11.27-23.24%, respectively. N resorption was significantly higher in H. rhamnoides than in C. korshinskii and A. adsurgens, P resorption was the highest in A. adsurgens and the lowest in C. korshinskii, and K resorption was the highest in H. rhamnoides (23.24%) and the lowest in C. korshinskii; and (2) Shrubs and herbs had an N/P ratio > 16. This finding indicates that the growth of these plants was primarily limited by P. In contrast, macrophanerophytes had an N/P ratio < 14, which indicates that growth was primarily limited by N. Combined with C, N, and P content in the soil, leguminous plants should be planted in the early stage of vegetation restoration, followed by shrubs or macrophanerophytes.
  • DownLoad:Ecological stoichiometry characteristics of leaves and litter in plant communities in the Yongli colliery reclamation area.PDF
  • Data assimilation for leaf area index of tobacco on the basis of the ensemble Kalman filter in Nanxiong
  • Authors:CHEN Hao and FAN Fenglei
  • Abstract:Leaf area index (LAI) can be used as a monitoring index for assessing tobacco health in different growing periods. Hence, acquiring and updating accurate LAI data in a timely manner are necessary for managing the growth of tobacco. Growth information for tobacco in different seasons could provide valuable information for management on a national scale. Accurate and continuous tobacco LAI dynamics data are based on the data fusion framework of the ensemble Kalman filter (EnKF), which is an efficient recursive filter to estimate the state of a dynamic system from a series of incomplete and noise measurements, can be used to obtain optimal results. Nanxiong City in Guangdong Province was selected as the study area to extract LAI data for tobacco and test the effect of EnKF method on the basis of quantitative remote sensing data for the growing state of tobacco in 2014. Tobacco canopy hyperspectral reflectance data in different growing seasons were collected every 15 days by using AvaSpec-ULS2048 HandHeld spectroradiometer made by Avantes company in the Netherlands. Tobacco LAI data were retrieved using the Normalized Difference Vegetation Index (NDVI), which was calculated using the reflectance data. An improved tobacco growth model (LOGISTIC) was established using the LAI data collected around Nanxiong. This improved model used LAI and accumulated temperature to reveal the changes in LAI in different growing seasons. On the basis of integration of LAI data (obtained using remote sensing data) and LAI data (obtained using the simplified LOGISTIC model and EnKF method), continuous LAI data were obtained in the time series during the tobacco growing season in Nanxiong. Finally, we compared three different LAI computing methods in tobacco study: (a) calculated by NDVI, (b) simulated by the LOGISTIC model and (c) data assimilation was based on EnKF. The results indicated that these three methods could describe the growth status of tobacco to a certain extent, especially in the mature growth period, however, the LAI assimilation method was the best, which was able to adjust measured values and model values dynamically, LAI data were more consistent with the practical growth conditions of tobacco. Method (a) was imperfect at early and late growth seasons of tobacco (in these two seasons, the LAI data were either less or more), and method (b) was more dependent on accumulated temperature data (LOGISTIC model could not effectively describe the unexpected changes in tobacco LAI). The results showed that the EnKF algorithm could obtain better estimation on the basis of the dynamic model, and assimilate remote sensing data into the dynamic model to obtain optimal estimation for LAI. The assimilated LAI data were closer to the real values, and the LAI curve was more consistent with actual tobacco growth status.
  • DownLoad:Data assimilation for leaf area index of tobacco on the basis of the ensemble Kalman filter in Nanxiong.PDF
  • Effects of drought stress on Bothriochloa ischaemum water-use efficiency based on stable carbon isotope
  • Authors:LIU Ying, LI Peng, SHEN Bing, FENG Zhaohong, LIU Qi and ZHANG Yi
  • Abstract:Owing to low precipitation and high inter-annual variability, the Loess hilly and valley region experiences frequent drought, which significantly affects plant growth. Studying the response mechanism of plants to water stress is important with respect to improving water-use efficiency (WUE) in this arid and semi-arid area. In the present research, Bothriochloa ischaemum (L.) Keng., a typical native species in the Loess hilly-gully region, was selected to investigate biomass accumulation and allocation, instantaneous WUE, stable carbon isotope composition (δ13C), and stable carbon isotope discrimination (Δ13C) in different organs under three water regimes: control [CK, 80% field capacity (FC)], mild water stress (MS, 60% FC), and severe stress (SS, 40% FC). Photosynthetic parameters of B. ischaemum were measured at 09:00-11:00 on sunny windless days (Aug 3, 10, and 13,2014), using a portable photosynthesis determination system (Li-6400; Li-Cor, USA). On Nov 11, when the experiment ended, the new leaf, old leaf, stem, fine root, and coarse root parts of seedlings were sampled carefully and weighed (with accuracy 0.001 g) after drying at 65℃. The root-to-shoot ratio was then calculated as the ratio of the belowground dry biomass to aboveground dry biomass. The δ13C of different plant parts was measured using a CCIA-36d-EP Carbon isotope ratio mass spectrometer (Los Gatos Research, USA). The Δ13C of different plant parts was calculated based on δ13C and the carbon isotope ratio of atmospheric CO2. Many environmental factors that might affect WUE were analyzed to explore the response mechanisms of B. ischaemum under drought conditions. The following results were obtained. (1) The total biomass of B. ischaemum was significantly decreased under the SS condition, whereas the root-to-shoot ratio and fine root biomass were significantly increased under this water regime. (2) The δ13C and Δ13C in different plant parts showed different trends. Drought stress led to an increase in the δ13C value and decrease in the Δ13C value. There was no significant difference in the δ13C and Δ13C of different plant parts under the SS condition. The δ13C values under CK and MS conditions were in the order of fine root > coarse root > old leaf > new leaf > stem, and fine root > new leaf > old leaf > coarse root > stem, respectively. Furthermore, the Δ13C values under CK and MS conditions were all in the order of root < leaf δ13C and Δ13C values of new leaves had the highest correlation coefficients with respect to WUE, which indicated that the stable carbon isotope technique is suitable for the determination of the WUE of B. ischaemum. (4) The WUE was affected by different environmental factors under different water regimes. Leaf temperature, atmospheric water vapor pressure, and air temperature were the most important factors affecting WUE under CK, MS, and SS conditions, respectively. This research provides a theoretical basis for the feasibility of using the stable carbon isotope method to determine the WUE of B. ischaemum, and for elucidating the mechanism underlying the response of B. ischaemum to water stress.
  • DownLoad:Effects of drought stress on Bothriochloa ischaemum water-use efficiency based on stable carbon isotope.PDF
  • Effects of thinning intensity on fine root biomass and morphological characteristics of middle-aged Pinus tabulaeformis plantations in the Huanglong Mountains
  • Authors:YOU Jianjian, ZHANG Wenhui, DENG Lei, YU Biyun, LI Gang, HE Ting and FAN Rongrong
  • Abstract:Pinus tabulaeformis plantations play an important role in local water and soil conservation and ecological protection in the Loess Plateau. Because of the large surface area, short life span, and rapid turnover, fine root systems were considered an important part in material cycling, energy transportation, and soil and water conservation of the forest ecosystem. This study was conducted in a middle-aged P. tabulaeformis plantation, located in the Huanglong Mountains, south of Loess Plateau, China. Thinning was performed on three occasions in 2008 following afforestation: light thinning, medium thinning, and heavy thinning. Three replicates of thinned and un-thinned treatments (20 m×30 m) were selected in our research. Basic data of fine root biomass and morphological characteristics were collected from three soil depths (0-20 cm, 20-40 cm, and 40-60 cm) via root drilling methods. The results showed that fine root biomass increased with increasing thinning intensity up to the medium thinning treatment and then decreased in the heavy thinning treatment. Fine root biomass in the 0-20cm soil layer decreased significantly (P < 0.05) under heavy thinning intensity compare with other treatments. The proportions of fine root biomass in the 20-40-cm and 40-60-cm soil layers increased with increasing thinning intensity. The differences in root length density and root surface area density between different thinning intensities and different soil layers were significant (P < 0.05), and exhibited a similar trend as the fine root biomass. With increased thinning intensity, specific root length and specific surface area of fine roots increased, and the differences were significant under heavy thinning (P < 0.05). Light and medium thinning had a significant effect on finest diameter fine roots (0-1.0 mm), but no significant effect on fine roots (1.0-2.0 mm) (P < 0.05), whereas heavy thinning had a significant effect on all roots (0-20 cm) (P < 0.05). Fine roots may be distributed in the deep soil layer after thinning. Compared with fine roots, the finest ones were more sensitive to different thinning intensities. In this study, fine root biomass (1022.43 g/m2), along with the root length density and root surface area, peaked at the medium thinning intensity, which could be the appropriate silviculture practice for tree growth.
  • DownLoad:Effects of thinning intensity on fine root biomass and morphological characteristics of middle-aged Pinus tabulaeformis plantations in the Huanglong Mountains.PDF
  • Effects of grazing on plant biomass and the carbon density of vegetation and soil in the Artemisia ordosica shrubland of the Ordos Plateau
  • Authors:GAO Li, ZHU Qingfang, YAN Zhijian, WANG Yuqing, HOU Xiangyang and DAI Yating
  • Abstract:Plant biomass and the carbon density of vegetation and soil in enclosed and grazed Artemisia ordosica shrubland of the Ordos Plateau were studied in the field and in the laboratory. The results revealed that the grazed plots supported plant communities with a higher the number of species yet lower vegetation coverage than did the enclosure plots. Grazing, moreover, reduced the overall above-and below-ground biomass of plant communities, as well as the proportion of above-and below-ground biomass consisting of A. ordosica. Nevertheless, during the growing season the grazed plots produced significantly more litter biomass than did the enclosure plots (P < 0.05). When protected by enclosures, however, the carbon density of the vegetation was higher, whereas that of the soil was lower, than that under grazing; although their seasonal averages did not differ significantly between the two plot treatments (P > 0.05). Ninety percent of carbon storage was in the soil in A. ordosica shrubland. The percentages of carbon density of soil accounting for the vegetation-soil system were 91% in enclosed plot and 93% in grazed plot, respectively. The carbon density of A. ordosica shrubland was 2.29 kg/m2 in enclosed plot and 2.68 kg/m2 in grazed plot. Grazing had little impact on carbon density of vegetation-soil in A. ordosica shrubland.
  • DownLoad:Effects of grazing on plant biomass and the carbon density of vegetation and soil in the Artemisia ordosica shrubland of the Ordos Plateau.PDF
  • Tempo-spatial variations and driving factors analysis of net primary productivity in the Hengduan mountain area from 2004 to 2014
  • Authors:WANG Qiang, ZHANG Tingbin, YI Guihua, CHEN Tiantian, BIE Xiaojuan and HE Yixuan
  • Abstract:The Hengduan mountain area is acting as the essential ecological barrier for the upper reaches of the Yangtze River, which exerts profound influences to the climate and ecological environment of its surrounding areas as well as the Middle West part of our country. As the core of carbon budget climate changes, NPP functions as the crucial indicator in measuring the health status and sustainable development of the ecological system. Therefore, based on the NPP statistics of MODIS C6, vegetation map (1:1000000), meteorological data as well as topographic data, this paper is intended to utilize trend line analytical method and other related analysis methods to perform study on the spatial pattern, variation rules and the driving factors to NPP in Hengduan mountain area during year 2004-2014. Detailed research results indicate that: ①total NPP for Hengduan mountain area during 2004-2014 falls between 183.768-223.239 TgC with average of annual NPP total value as 208.498 TgC and annual NPP mean value per unit area as 463 gC m-2 a-1. On the whole, overall NPP is showing an increasing trend with distinct local disparity. ②average annual NPP change rate is within -53-97 gC m-2 a-1. And regions with a rising NPP tendency are mainly distributed at the north part, east of middle part as well as east and west of the south part; whereas regions with a decreasing tendency mainly concentrates on Wenchuan-Yingxiu areas which belong to the northwest and middle part. ③The regions with NPP changes resulted from climate factors take up 8.42% of the total coverage of the Hengduan mountain area. These regions mainly sit at the mountainous areas at Daxue Mountain-Shaluli Mountain. By contrast, those subject to non-climate factors occupy 91.58% of the Hengduan mountain area. And they are mainly located at Aba areas in the north and broad regions in the south part with lower altitude. As far as the significance of this paper is concerned, it will provide instructions to the ecological environment construction and the sustainable growth for Hengduan mountain area.
  • DownLoad:Tempo-spatial variations and driving factors analysis of net primary productivity in the Hengduan mountain area from 2004 to 2014.PDF
  • Effects of environmental conditions on ash dynamics during foliar litter decomposition in an alpine forest
  • Authors:YUE Kai, YANG Wanqin, ZHANG Chuan, PENG Yan, HUANG Chunping and WU Fuzhong
  • Abstract:Ash is an important component of foliar litter, the concentration of which is closely related to the process of litter decomposition and the concomitant organic matter dynamics. Ash dynamics in decomposing litter may be affected by environmental conditions and decomposition period. However, currently there is little information about the dynamics of ash concentration in decomposing litter. To fill this knowledge gap, we investigated the dynamics of ash mass and concentration in decomposing foliar litter (litterbag method) of four dominant species (Salix paraplesia, Rhododendron lapponicum, Sabina saltuaria, and Larix mastersiana) under different environmental conditions (forest floor, stream, and riparian zone) in an alpine forest in the upper reaches of the Minjiang River. The results indicated that ash mass in decomposing foliar litter generally decreased over the 2-year experiment, regardless of litter species and environmental conditions, but that there was variation in the magnitude of the decrease. In contrast, ash concentration in all litter species showed a general increasing trend (5.86%-72.15%), except for S. paraplesia foliar litter in streams, which decreased approximately 0.99% over the two years. Changes in ash concentration varied significantly among different decomposition periods, and were significantly affected by initial litter quality and environmental factors. Overall, our results are inconsistent with the historical opinion that ash concentration is relatively stable during litter decomposition, which suggests that the method for calculating ash-free mass loss, using the initial ash concentration value based on the assumption that ash concentration is relatively stable during litter decomposition, is incorrect. The results of this study can provide the basis for a better understanding of ash dynamics during litter decomposition, and the correct method for calculating litter mass loss.
  • DownLoad:Effects of environmental conditions on ash dynamics during foliar litter decomposition in an alpine forest.PDF
  • Variation in sap flow density among levels of tree dominance in Picea crassifolia in the Qilian Mountains
  • Authors:WAN Yanfang, YU Pengtao, LIU Xiande, WANG Shunli, WANG Yanhui and XIONG Wei
  • Abstract:Tree transpiration plays a determining role in water balance for forest stands and in water yield from forested catchments. In the present study, an experiment was conducted in the Pailugou watershed in the Qilian Mountains, in the arid region of Northwest China. In a 86-year-old Picea crassifolia forest stand, 3-5 trees from each of dominant, subdominant, intermediate and suppressed trees were chosen as sample trees. The sap flux density for these trees was measured using the thermal dissipation probe (TDP) method from June 16 to October 14, 2015. Furthermore, the related meteorological factors, including solar radiation (Rs), air temperature (T), air relative humidity (Rh), and precipitation (P) were simultaneously monitored by an automatic meteorological station in the outer forest. The results showed that: (1) Daily sap flow density was higher during the day than during the night. On sunny days, daily variation in sap flow density exhibited large amplitudes, whereas it exhibited little variation on cloudy and rainy days. (2) On sunny days, daily sap flow density began earlier in the morning, ended later at night, and exhibited a larger maximum of sap flow density as tree dominance class increased. The value of the mean sap flow density of dominant trees was (0.0758 ± 0.0475) mL cm-2 min-1, which was 1.5 times of that of subdominant trees and 1.68 times that of intermediate and suppressed trees. (3) Mean daily sap flow density for all dominant trees showed that the maximum values were achieved in June, with the next highest values in August, and decreasing values in September and October. In addition, sap flow density exhibited the following order: dominant > subdominant > intermediate > suppressed trees. (4) Correlation and stepwise regression analyses indicated that mean daily sap flow density was significantly correlated with solar radiation, vapor pressure deficit, and air temperature, and was negatively correlated with air relative humidity and precipitation. Solar radiation was the main meteorological factor influencing mean daily sap flow density of dominant, subdominant, and intermediate trees, whereas air relative humidity primarily influenced suppressed trees.
  • DownLoad:Variation in sap flow density among levels of tree dominance in Picea crassifolia in the Qilian Mountains.PDF
  • History of growth suppression and release events in forests in Changzhi Prefecture, Shanxi Province, China
  • Authors:ZHANG Qi, YAN Ming and LIANG Hanxue
  • Abstract:Forest growth is closely associated with climate change, and understanding the history of growth disturbances can help predict potential changes in forest growth caused by global warming. In this study, we utilized dendrochronological methods to study growth release and suppression events of trees in order to reconstruct the disturbance history of forests. A total of 27 samples were collected from one Pinus tabuliformis forest and two Pinus bungeana forests in Changzhi Prefecture (southeast of Loess Plateau). After measuring and cross-dating the tree ring width, we found that the oldest trees in the Licheng, Pingshun, and Tunliu sampling sites were 227, 185, and 102 years old, respectively. Percentage of growth change (GC%) was calculated to identify the disturbance events. Growth release was defined as an average GC% (five years) of more than 0.25, while growth suppression was defined as an average GC% (five years) of less than-0.25. In this study, the results indicated that in the past 150 years, growth suppression occurred three times (1873-1877, 1925-1930, and 1994-1997), while growth release occurred five times (1867-1871, 1878-1884, 1930-1935, 1980-1985, and 1999-2004). Although the three forests had similarities in their disturbance histories, there were also differences in their spatial and temporal scales. These differences may be caused by the genetic characteristics of the different species and local environmental variations. To further understand the causes of the disturbances, a correlation analysis was performed for the first order difference of the three tree ring width chronologies and the meteorological records. The correlation coefficients showed that forest growth was negatively correlated with June temperature and positively correlated with April-May precipitation. This suggested that the historical growth suppression events might be related to extreme drought events, caused by precipitation reduction or excessive water evapotranspiration, whereas the growth release events might be related to an abundant supply of water. To validate these results, we compared our study with historical records and local paleoclimate studies. The drought events recorded in the historical materials, and reconstructed using other paleoclimate studies reasonably fit our results, which indicates that our study successfully rebuilt the historical growth history and that dendrochronological methods could be used in forest disturbance research in the east edge of the Loess Plateau. This study provided useful information for forestry management. For example, forest plantations should be carried out in moist conditions during the growing season. The old growth trees that survived multiple disturbance events have strong resilience and contain valuable information about historical environmental changes; identifying and protecting old growth trees is important for maintaining efficient and healthy forest ecosystem services.
  • DownLoad:History of growth suppression and release events in forests in Changzhi Prefecture, Shanxi Province, China.PDF
  • Identifying priority areas for monitoring the invasion of Solidago canadensis based on MAXENT and ZONATION
  • Authors:LI Lihe, LIU Huiyu, LIN Zhenshan, JIA Junhe and LIU Xiang
  • Abstract:The invasion of alien plants poses serious threats to local ecosystems and biodiversity. To control plants invasion effectively, the relative importance of influencing factors and the areas with high invasion risk must be identified. In the present study, MAXENT was applied to simulate the potential distribution of Solidago canadensis and explore its response to major impact factors in east China including Anhui, Jiangsu, Zhejiang and Shanghai. This was based on occurrence records and environmental factors including land use change, human disturbance, soil characteristics, climate, and topography. ZONATION was combined with the results from MAXENT to identify priority areas with high invasion risks for monitoring. The results showed that (1) the five most important factors influencing the distribution of S. canadensis were the distance to major roads (29.4%), land use change (16.9%), precipitation seasonality (15.9%), population density (9.5%), and mean temperature of the driest quarter (6.2%), respectively; (2) the occurrence probability of S. canadensis decreased rapidly with increased distance from major roads. The occurrence probability was dramatically higher in areas where cropland was transformed to construction land, aquatic areas to grassland, construction land to woodland; mutual conversion between grassland and construction land occurred; and construction land remained unchanged. As precipitation seasonality increased, the probability initially decreased quickly and then slowly. With an increase of population density, the occurrence probability initially increased rapidly and then decreased very slowly. As the mean temperature of the driest quarter increased, the probability decreased initially and then increased gradually; (3) the area of invasion risk of S. canadensis was 130,433 km2. The primary risk area was mainly distributed in the Taihu basin, the area surrounding Hangzhou Bay, and the Zhejiang coast and its inland crop-and construction land. The secondary risk area was mainly distributed outside the primary risk area, particularly along the Yangtze River in southern Jiangsu. The third-level risk area was widely distributed in the south and east of Jiangsu, the middle and east of Anhui, and the north and east of Zhejiang.
  • DownLoad:Identifying priority areas for monitoring the invasion of Solidago canadensis based on MAXENT and ZONATION.PDF
  • Research on data mining of salinization information based on phenological characters
  • Authors:HE Baozhong, DING Jianli, WANG Fei, ZHANG Zhe and LIU Bohua
  • Abstract:Soil salinization is an important factor that affects crop and vegetation growth condition and can result in environmental impacts with considerable economic consequences. Therefore, it is necessary to determine an effective method to monitor spatiotemporal salinity distribution. We used MOD13A1 time-series NDVI data to determine the vegetation phenology, including start of season (SOS), end of season (EOS), length of season (LEN), etc., and calculated several vegetation, salinity, terrain, and drought indexes, and spatial models. These were used as input parameters for the BP-ANN model. Meanwhile, we predict the soil salinity through vegetation and geomorphological partitioning, which described the correlations between vegetation or geomorphic type and salinization. The main conclusions are as follows: salinity is influenced by many factors, and many of them show non-linear relationships between phenological indicators and salinization, so we utilized artificial neural networks to predict soil salinity than mathematical equations; through a combination of phenology parameters, the precision of inversion salinity R2 improved from 0.68 (no phenologcial indicators were included) to 0.79 (phenological indicators were included). However, additional auxiliary data to predict soil salinity, such as terrain, image, and soil moisture parameters should also be included. After the classification of the vegetation, the inversion precision improved obviously, where R2 increased to 0.88. Phenological characters, such as large seasonal integrals (LSIs) and small seasonal integrals (SSIs) are good indicators to represent soil salinity. After geomorphological partitioning, R2 increased to 0.85, indicating that it could be a good salinity predictor, but the ability of comprehensive inversion was lower than vegetation type partitioning. In farmland, the salinity level was low. The low, intermediate, and high salinization was 53.42, 13.71, and 32.87% respectively. Generally, salinization was higher at lower altitudes, and the salinity level was affected by terrain and geomorphological factors. The above conclusions indicate an effective method for the inversion of salinization levels that combines phenology and other parameters for comprehensively determining the effect of phenological information on salinity monitoring ability in data mining. The inversion of soil salinity is enhanced by the inclusion of phenological parameters.
  • DownLoad:Research on data mining of salinization information based on phenological characters.PDF
  • Spatial-temporal variation of vegetation and its correlation with climate change in Central Asia during the period of 1982-2012
  • Authors:YIN Gang, MENG Xianyong, WANG Hao, HU Zengyun and SUN Zhiqun
  • Abstract:Dry-land plant ecosystems are particularly sensitive to climate change. Despite their importance in the global carbon cycle, the responses of vegetation dynamics to climate change in recent decades in Central Asian dry-lands remain unclear. In this study, we used normalized difference vegetation index (NDVI) data to analyze spatial-temporal changes in vegetation and to determine the correlation between vegetation and climatic variables over the period of 1982-2012 in Central Asia using the empirical orthogonal function (EOF) and least square methods. The results showed that the annual NDVI in Central Asia experienced an overall weak increasing trend during the study period, and a sharp decrease since 1994, especially in the grasslands of northern Kazakhstan, which might have been caused by decreased precipitation during the last three decades. In terms of seasonal variation, the NDVI in spring had a greater increasing trend than did the other three seasons. A significantly declining trend (P < 0.05) was found in winter. Compared to a weak increase in the NDVI in the plains areas, the mountainous areas experienced the greater increasing trend and the trend was significant at the annual and seasonal scales (P < 0.05). The EOF results illustrated that the annual NDVI showed a uniform spatial pattern during 1982-2012. Further, the NDVI showed long-range dependence characteristics, which indicated the increasing trend may be continuous in the future. In terms of the relationships between the NDVI and climate variables over Central Asia, the annual NDVI was positively correlated with annual precipitation, and a weak negative correlation between annual NDVI and temperature was detected. The positive correlation coefficient center appeared between the annual NDVI and annual temperature over the southern Central Asia, and the negative center appeared over the areas between Kazakhstan, Turkmenistan, and Uzbekistan. However, the opposite correlation coefficients were found over these areas between the annual NDVI and annual precipitation. In addition, one-month time lags were found between NDVI and temperature from June to September in Central Asia during 1982-2012. Our study provides important information on vegetation variation and would facilitate better understanding of the natural ecosystem changes over Central Asia for the past three decades.
  • DownLoad:Spatial-temporal variation of vegetation and its correlation with climate change in Central Asia during the period of 1982-2012.PDF
  • Spatial point pattern analysis of Alchornea trewioides population clonal growth in the karst area of Guilin
  • Authors:MEI Junlin, ZHUANG Fenghong, MA Jiangming, QIN Yanghui, LIANG Shichu and JIANG Yong
  • Abstract:The spatial distribution patterns and associations of plant species result from both abiotic and biotic interactions, which may reflect factors and processes that nearly all plants experience; namely resource availability constraints, limits to propagule dispersal, and intra-or inter-specific competitive interactions. In the karst area of Guilin, China, Alchornea trewioides (Benth.) Muell. Arg. is a common pioneer species; to determine the importance of its ecological function in this community, it is critical to analyze the spatial patterns of its individuals. To this end, the spatial patterns of A. trewioides were investigated in situ and analyzed with three objectives: (1) to describe the spatial patterns and individual-association changes among the different diameter classes; (2) to quantify and reveal the relationship between the spatial scale and the spatial patterns for this species; and (3) to analyze the effects of different diameter classes on the spatial patterns and the individual associations. In this study, we set up six plots, each 10 m × 10 m, in the karst habitat (i.e., calcium-rich, alkaline soil with low water-holding capacity, high ratio of exposed(80%), and prone to periodic flooding), wherein we recorded and mapped all live individuals of A. trewioides. To identify the differences and associations between these individual plants, they were divided into three diameter classes Ⅰ (diameter ≤ 0.5 cm), Ⅱ (0.5 cm < diameter ≤ 1.0 cm), and Ⅲ (diameter > 1.0 cm). The point-pattern analytical approach has proven effective and useful elsewhere to study the plant population characteristics and the community structure underlying ecological processes. On the basis of Ripley's K function, we used the g(r) function statistic to explore differences in the distribution patterns. We also used the L(r) function statistic to examine the spatial associations among the three diameter classes. The results showed that the spatial patterns and their individual associations were closely related to the spatial scale and diameter class tested: (1) At the scale of 2 m, the A. trewioides population had a clumped distribution, whereas at a much larger scale it had a random distribution. (2) The different diameter classes were another important factor that affected the spatial associations. As the diameter classes of individuals were gradually increased, the changing spatial associations between individuals went from positive, to independent, and then to a negative correlation. (3) On a large spatial scale, the mother plants Ⅲ played a significant role in inhibiting the cloning of other smaller ramet plants. However, as the differences among the three diameter classes increased, the spatial association gradually showed a correlation that was independent, or even a negative. Comparing the spatial distribution patterns among diameter classes Ⅰ and Ⅱ, Ⅱ and Ⅲ, and Ⅰ and Ⅲ, the last class showed the strongest negative association in the population that we studied.
  • DownLoad:Spatial point pattern analysis of Alchornea trewioides population clonal growth in the karst area of Guilin.PDF
  • Structure and diversity of fish communities in the waters south of Nanri Island
  • Authors:GUAN Wei, XU Zhaoli and CHEN Jiajie
  • Abstract:To explore the characteristics and diversity of fish communities in the waters south of the Nanri Island, three comprehensive surveys of fishery resources were conducted in the winter of 2009 and the spring and summer of 2010. Bray-Curtis cluster was used to classify the fish communities in the surveyed area, and the number of species, density, ecological groups, and diversity of fish species were analyzed on the basis of the division of fish communities. The effects of the changes in water masses on fish communities' classification and diversity were discussed in detail. The results indicate that in spring, the fish communities comprise two different groups: the northern coastal community and the southern nearshore community. The number of species, density, and the individual diversity index (H') of the northern coastal community were 27 species, 7.47 × 103 individuals/km2, and 2.71, respectively, and the corresponding values of the southern nearshore community were 32 species, 24.34 × 103 individuals/km2, and 1.97, respectively. The number of species and density of warm water species of the southern offshore community were higher than the corresponding values of the northern offshore community. In contrast, the warm temperate species exhibited the opposite scenario-0. In summer,the number of species, density, and H' of the western coastal community were 55 species, 329.24 × 103 individuals/km2, and 1.97, respectively, while the respective values of the eastern nearshore community were 27 species, 106.47 × 103 individuals/km2, and 1.62, respectively. The individual density of both coastal species and nearshore species of the western coastal communities were higher than those of the eastern nearshore community. In winter, the fish communities were divided into northern coastal community and southern nearshore community. The number of species, density, and H' in the northern coastal community were 25, 9.96 × 103 individuals/km2, and 2.71, whereas the corresponding values in the southern nearshore community were 32 species, 28.85 × 103 individuals/km2, and 1.97, respectively. The individual density of warm water species and warm temperate species in the southern coastal community were higher than those in the northern nearshore community. In winter and spring, the number of fish species, individual density, and diversity, of the warm water species in the area controlled by the Taiwan Strait warm waters were higher than those of the species dominated in the Fujian-Zhejiang coastal waters. In summer, with the influence of the Taiwan Strait warm water and overland runoff, the corresponding values of the fish community in the western region of the study area were higher than those in the eastern region. We conclude that the demarcation and characteristics of the fish communities were closely related to the seasonal changes of water masses.
  • DownLoad:Structure and diversity of fish communities in the waters south of Nanri Island.PDF
  • Spatial patterns of fish diversity and distribution in the Pearl River
  • Authors:SHUAI Fangmin, LI Xinhui, LIU Qianfu, LI Yuefei, YANG Jiping, LI Jie and CHEN Fangchan
  • Abstract:The Pearl River, which is 2400 km long and flows into the South China Sea, is the longest river in subtropical southern China. The warm humid climate of the region, which promotes high species diversity, has resulted in significant aquatic biodiversity and the development of lucrative commercial fisheries. Nevertheless, studies on the spatial distribution of fish communities in the Pearl River system are limited, especially, considering the decline in global fishery resources due to numerous anthropogenic stressors, such as overfishing, dam construction, introduction of invasive species, and climate change. Thus, studies on the spatial distribution of fish species in the Pearl River are urgently needed. This study investigated the spatial patterns of fish diversity and distribution in the Pearl River Basin based on an investigation of 13 sample sites. A total of 10,119 individual fishes were collected during the study period, comprising 94 taxa representing 17 families and 72 genera. The Cyprinidae family, representing 49 taxa, accounted for 52% of the total number of fish species collected. Cyprinidae were the dominant family in the Pearl River, followed by Bagridae (7%; seven species) and Cobitidae (4%; four species). Non-metric multidimensional scaling (NMDS) was applied to the collected data and three separate groups were identified. The spatial variation in upstream fish assemblages differed significantly from that in downstream assemblages (P < 0.05), although clustering and diversity showed a significant spatial autocorrelation. A significantly high species diversity was recorded in the Pearl River, but low species diversity existed in the up and downstream reaches. Redundancy analysis was used to describe the relationship between the diversity patterns of fish species and associated environmental factors. Temperature, precipitation, water discharge, river width, and water chemistry play important roles in species diversity, with the average annual temperature accounting for the largest proportion of variance. A comparison with historical data for the Pearl River revealed a dramatic decline in fish species and a significant change in the spatial distribution of fish communities. Currently, the most serious threat to the ecology of the Pearl River network is the invasion of alien species. For example, non-native tilapia are now widely distributed in most of the Pearl River system, even surviving in the cooler, upper reaches of the Nanpanjiang River. In the Hongshuihe, Beijiang, and Dongjiang Rivers, tilapia is the dominant species recorded and has frequently been collected in the middle and lower reaches of the Pearl River. The present study is part of a long-term investigation into the wild fishery resources of the Pearl River. Therefore, understanding the processes outlined in this study will assist in the conservation of fish community diversity, which is critical to the success and sustainability of commercial fisheries in the Pearl River. Regularized discriminant analysis (RDA) is used by ecologists to relate a dataset (Y) of response variables (such as species abundance) to a second dataset (X) of explanatory variables (often environmental factors) and consistently outperformed other statistical tests using all the data in this study.
  • DownLoad:Spatial patterns of fish diversity and distribution in the Pearl River.PDF
  • Effect of urea on the growth of Skeletonema costatum and Karenia mikimotoi
  • Authors:LI Zhilin, ZHOU Yanlei, WANG Xuejing, SHI Xiaoyong and ZHANG Chuansong
  • Abstract:With rich nutrients, suitable temperature, light, and weather conditions, large-scale harmful algal blooms (HABs) have frequently occurred in the East China Sea in recent years. According to datas from the State Bureau of Oceanic Administration of China from 2009 to 2014, there were 367 instances of HABs in the coastal waters of China and 195 instances in the East China Sea, accounting for 53%. It is generally believed that the occurrence of algal blooms is linked to eutrophication of coastal waters. Nutrients are the basic material for the growth and reproduction of organisms. As an important kind of DON(Dissolved Organic Nitrogen), urea has high biological activity. Many studies have reported that urea could serve as the sole nitrogen source for a variety of phytoplankton. As such, studying the effect of urea on the organisms that induce red tides is very important. To determine the different responses of diatoms and dinoflagelattes to DON, the effect of urea on the growth of Skeletonema costatum and Karenia mikimotoi, which are the dominant algae in China, were determined using a batch of culture experiments in the laboratory. Results indicated that the two algae could grow under different ratios of urea to nitrate, but their kinetic parameters were different. With the increase of the proportion of urea in the mixed nitrogen source in the culture solution, the growth rate(0.91-0.82/d) of Skeletonema costatum and its maximum biomass(2.0×105-1.2×105 cells/mL) in the plateau phase of the growth curve gradually decreased. However, the growth rate (0.36-0.51/d) of Karenia mikimotoi gradually increased and its maximum biomass (1.1×104cells/mL) in the plateau phase remained relatively unchanged. In plateau phase, the concentration of nitrogen in the Skeletonema costatum culture solution declined to 2.5μmol/L, and in Karenia mikimotoi it declined to 1.0 μmol/L. In the exponential phase, the concentrations of DON increased with the growth of algae, and reached the maximum values (5-6 μmol/L), then remained constant in the cultural of Skeletonema costatum. For Karenia mikimotoi, the concentrations of DON declined after reaching maximum values (2-3 μmol/L) in the culture solution. The content of particulate organic nitrogen in each cell of Skeletonema costatum (approximately 10-6 μmol in the exponential phase, 10-7 μmol in the plateau phase) were much less than that of Karenia mikimotoi (10-4 μmol in the exponential phase, 10-6 μmol in the plateau phase). In an environment with lower inorganic nitrogen and higher DON concentration, dinoflagellates exhibit better adaptability than diatoms. This research can provide references on the interpretation of the succession between diatoms and dinoflagelattes in the Yangtze River Estuary in spring.
  • DownLoad:Effect of urea on the growth of Skeletonema costatum and Karenia mikimotoi.PDF
  • Response of food resources and trophic niche of Apis cerana cerana to an altitudinal gradient in the north valley of the Lancang River
  • Authors:CHEN Shun'an, ZHANG Qiang, WAN Rong, ZHAO Shiwen, LIU Zhitao, LUO Jiancheng, YE Yinlong and ZHANG Xuewen
  • Abstract:To further understand the distribution of Apis cerana cerana in the north valley of the Lancang River, as well as variations in food resources and trophic niche, we investigated honeybee distribution at different altitudes. Using melissopalynology, we studied pollen composition of the honey samples collected from different altitudes. We analyzed the correlations between altitude, food resources, and trophic niche. The associations between the natural environment and A. cerana cerana distribution, altitude, nectar and pollen plants, food resources, and trophic niche were addressed in this study. The results showed that food resources were abundant in the north valley of the Lancang River, and A. cerana cerana mainly inhabited areas between 2,200 to 2,800 m above sea level. The types and quantities of pollen consumed by A. cerana cerana differed by altitude. At the altitude that most A. cerana cerana inhabited, pollen was rich in type but low in quantity. With altitude increasing, the quantity of pollen first decreased and then increased, where as the types first increased and then decreased. Trophic niches of A. cerana cerana were different according to altitude, which might be caused by the differences in plants, pollinating insects, and herbivorous animals. No significant correlations were detected between altitude and trophic niches (r=0.051), altitude and pollen quantity (r=0.047), or altitude and pollen types (r=0.144). Trophic niches were positively correlated with pollen types (r=-0.305, P < 0.05), but not with pollen quantity (r=-0.064). Pollen types in the honey sample were positively correlated with pollen quantity (r=-0.303, P < 0.05).
  • DownLoad:Response of food resources and trophic niche of Apis cerana cerana to an altitudinal gradient in the north valley of the Lancang River.PDF
  • Springtime utilization of farmland habitat by red-crowned cranes in the Zhalong Nature Reserve
  • Authors:WU Qingming, YANG Yubo, ZOU Hongfei, TAO Rui and LI Quanliang
  • Abstract:In order to deepen our understanding of the springtime utilization of farmland habitat by migratory red-crowned cranes (Grus japonensis), and to provide scientific data to support crane monitoring and farmland monitoring, the characteristics of the farmland habitat used by red-crowned crane during their spring migration (May, 2002-2015) was analyzed using the fixed-point observation method, the two-dimensional coordinate method, the sample method, GPS positioning, and factor analysis. The results showed that: (1) In terms of farmland habitat type, red-crowned cranes preferred maize crops (absolute foraging preference choice, 100%), preferred maize seedlings with 2 to 5 leaves (94.32%), and avoided seedlings with l leaf or more than 6 leaves (100%); (2) Selection criterion of farmland habitat were effective food factors and disturbance factors; (3) Important food factors included crop height, crop density, crop area, distance from lakes, and distance from reed marshes. For these factors, the preferred choices were 8-10 plants/m2 for crop density, 6-7 cm for crop height, 4-50 hm2 for crop area, and approximately 0.4 km for the distance from the lakes and reed marches; and (4) Disturbance factors included strong disturbance factors and weak disturbance factors. For residential areas (strong factor), red-crowned cranes avoided it by at least 1.20 km; for roads (weak factor), red-crowned crane did not avoid it, the disturbance to the weak disturbance areas was greater above 0.20 km. Based on the results of our study, we suggest that during the spring resource patrol and protection period of the Zhalong Nature Reserve, there should be more focus on the residential areas and farmland.
  • DownLoad:Springtime utilization of farmland habitat by red-crowned cranes in the Zhalong Nature Reserve.PDF

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