Simulating potential vegetation distribution in a mountainous region of the Eastern Tibetan Plateau:A case study of Barkam County

The main objective of this study is to simulate the potential vegetation types on the basis of environmental parameters.The paper took Barkam County in a mountainous region of the Eastern Tibetan Plateau as the study area.The vegetation distribution was mapped in 1994 and 2007 based on TM remote sensing images by object-oriented interpretation method.We overlaid the two maps to find out the vegetation patches which have not changed,and took them as stable types.Fifty per cent of the stable patches were randomly sampled to operate the logistic regression with related environmental parameters;others were used as test data of simulated results.Seven environmental parameters were mapped,including elevation,slope,aspect,surface curvature,solar radiation,temperature and precipitation,based on DEM data and meteorological site data by GIS technology.The relationship between the spatial distribution of vegetation and environmental variables were quantified by logistic regression.The distribution probabilities of each vegetation type were calculated.Finally,the spatial distribution of potential vegetation was simulated.This research can provide a scientific basis for vegetation restoration and ecological construction in this area.     

鄱阳湖区景观格局季相变化及其优化调控研究

论文以自然属性确定的鄱阳湖区为例,基于景观生态学理论和GIS空间分析技术,定量描述和分析了鄱阳湖区景观格局的季相变化特征。研究结果表明：鄱阳湖区整体景观格局季节变化明显,枯水期较丰水期景观更加破碎,形状更加复杂,聚集程度更低,异质性水平更高;类别水平上,以滩地景观变化最为显著。枯水期和丰水期生态连通性也有较明显差异,枯水期景观生态连通性更差,景观单元间的生态阻力更大,生态流运行更加困难。在此基础上,借助最小累积耗费阻力模型和GIS空间分析模块,识别和构建了不同季相鄱阳湖区的源地、廊道（三类）、节点等生态组分,形成了“斑块-廊道-基质”模式的生态功能网络;并通过对不同季相景观格局优化组分的对比分析,辨识了年内能够持续发挥重大生态效益的景观组分,构建了更为合理的景观格局优化调控方案,以期增强鄱阳湖区景观网络的连通性,保障生态流的畅通运行,加强湖区生态系统的稳定性和可持续性,为鄱阳湖区生态规划和管理提供借鉴和参考。     

50年长江源区域植被净初级生产力及其影响因素变化特征

基于长江源区1959—2008年月平均气温、最高气温、最低气温、相对湿度、降水量、风速和日照时数等气候要素资料,应用修订的Thornthwaite Memorial模型计算了50年植被净初级生产力,分析其年际和年代际变化特征及其主要气象因子的影响。结果表明：1959—2008年间,研究区年降水量呈增加趋势,降水量变化曲线线性拟合倾向率每10年为5.685~13.047 mm,春夏季增幅较大;年平均气温呈极显著上升趋势,气温变化曲线线性拟合倾向率每10年在0.240~0.248℃之间,增温率以秋冬季最大;最大蒸散呈增加趋势,年最大蒸散变化曲线线性拟合倾向率每10年在5.073~5.366 mm,春季增幅最大;地表湿润指数也呈增加趋势,年地表湿润指数变化曲线线性拟合倾向率每10年为0.013~0.020,冬季增幅最大,在10年周期时间频率附近,出现了6~8个干湿交替期,20世纪90年代之后为偏湿期,在低频区,1998—2005年有偏干振荡;近50年年NPP变化呈显著上升趋势,NPP变化曲线线性拟合倾向率每10年在97.901~197.01 kg.hm-2之间,2001—2008年NPP较高。影响长江源区NPP变化的主要气候因子是降水量、最大蒸散量和平均最低气温。     

黄浦江上游水源保护区水质评价与分析

黄浦江上游保护区是上海环境保护工作的重点,其水质状况直接影响上海的饮水安全,分析影响该区域水质的主要水质因子。研究水质的分布特点和近年（2000年-2004年）的发展变化趋势,本文使用因子分析法通过对2000年-2004年黄浦江上游水源保护区的常设监测断面水质进行了分析,得出了黄浦江上游水质保护区的特征污染因子,再使用幂指数法、加权平均法、向量模法等水质综合评价方法对该区域的水质进行了评价,并得到了该区域的水质分布特点。     

Seasonal and interannual variation of soil respiration in four vegetation types in the loess hilly region北大核心CSCD

Soit carbon (C) stock is the largest C pool in terrestrial ecosystems, and the emission of CO2 through soil respiration contributes to the majority of soil C expenditure and atmospheric C. Soil respiration is also one of the major processes controlling the C budget of terrestrial ecosystems. A slight change in soil CO2 emission might cause drastic variations in global C balance. Therefore, it is of great significance to investigate the characteristics of soil respiration of soils growing different types of vegetation over a long period, and determine its relationship with variables such as soil temperature and moisture. The rate of soil respiration was measured each month in the growing seasons (from April to October) of 2011, 2013, and 2014 using the Li-8100 CO2 flux measurement system in the central Loess Plateau. Four types of vegetation (Quercus liaotungensis, Platycladus orientalis, Robinia pseudoacacia, and a natural shrub) were chosen for the periodical measurements. A permanent sample plot was established for each type of vegetation, and five polyvinyl chloride (PVC) collars were placed in each plot for the measurements. The temperature and water content of the soil in the upper 12 cm near the collar were measured using a digital soil temperature probe and a TDR 200 soil moisture meter at the same time when the soil respiration was measured. The soil respiration rates were fitted to the soil temperature and moisture with an exponential function, power function, linear function, and an equation combining the two variables. The results showed that: (1) the seasonal variation in the rates of soil respiration in the soils growing the four types of vegetation were almost the same, and were lower in the earlier period and then increased to high levels in the middle and later periods; (2) the rates of soil respiration in the same month varied with the type of vegetation grown, and were in the descending order: Q. liaotungensis > P. orientalis > shrub > R. pseudoacacia; (3) the average values of the rates of soil respiration in 2011, 2013, and 2014 were 2.77, 3.48, and 5.08 μmol m-2 s-1, respectively. The variation in soil respiration was higher across the three years than the variation for the types of vegetation grown; and (4) the rate of soil respiration was positively correlated to soil temperature and moisture for all the types of vegetation. A better fit was obtained by using the equation that included both the variables, soil temperature and moisture, than by an equation that included a single factor. Our results suggested that both seasonal and inter-annual variations of soil respiration occurred in the soils growing the four types of vegetation in the region. The temperature and water content of soils are the major regulating factors, and soil respiration in the Loess Plateau is more greatly affected by environment factors than by the type of vegetation. © 2018 Science Press. All rights reserved.     

西北地区农村生活污水处理技术研究

西北地区农村生活污水处理工作是中国环境保护工作的重要组成部分.针对西北地区农村生活污水处理目前没有专门设计的处理工艺,结合西北地区农村污水处理的实际特点,在对比分析了几种常用农村生活污水处理工艺特点及适用范围基础上,选择了四套家用型污水处理技术,为建立西北农村生活污水处理新模式提供借鉴与科技支撑,为西北地区农业面源污染的控制提供技术支持.     

云南地区种子植物东亚分布成分的地理分布格局

植物区系分析是理解植被起源、性质和分布的基础.本研究利用大尺度的区系分布信息,结合地理信息系统平台和统计分析方法,探讨了云南地区种子植物东亚分布成分的地理分布格局以及"田中线"的生物地理意义.结果表明,东亚分布成分及其亚型所占比重均随着纬度的升高呈递增趋势.在经度梯度上,中国-日本植物分布亚型所占的比重从东到西呈递减趋势,而中国-喜马拉雅分布亚型所占比重的经度格局则与此相反.东亚分布成分在云南地区的扩散方向以由北到南为主,其次为经度梯度上的双向迁移.与过去的研究不同,本研究结果表明,东亚分布成分在云南地区的起源中心更可能为滇西北.我们未能证实"田中线"对中国-喜马拉雅分布亚型的分布具有限制意义,但对东亚分布成分(总体)和中国-日本分布亚型在云南地区的分布具有严格的限制意义.     

黄河源区植被生长季NDVI时空特征及其对气候变化的响应

利用黄河源区MODIS/NDVI数据、1∶100万植被类型图和气象资料,分析了该区不同植被类型生长季NDVI时空特征以及与气候因子的关系。结果表明,1）2000—2011年,黄河源区植被生长呈改善趋势,生长季NDVI年际变化率每10 a为＋2.75%,高寒草原、高寒草甸、高寒灌丛生长季NDVI年际变化率分别为每10 a＋2.84%、＋2.65%、＋2.77%。2）黄河源区植被改善面积占全区总面积的29.39%,主要分布在卡日曲和玛曲上游、扎曲流域、布青山南麓、扎陵湖北部和鄂陵湖周边地区。植被退化面积仅占全区总面积的0.98%,主要分布在约古宗列曲东南部山地和卡日曲北部山地。受水热条件控制,植被改善表现为：①植被改善面积南坡大于北坡;②植被改善面积随海拔升高先增加后减小;③植被改善面积随坡度增加迅速减小。3）黄河源区植被生长季NDVI与同期气温和降水分别存在显著正相关性,其中高寒草原和高寒草甸生长受降水影响更为明显,而高寒灌丛生长受气温影响更为明显。气候的暖湿化趋势可能是促使黄河源区植被生长改善的主要原因。     

Nitrogen leaching under corn cultivation stabilized after four years application of pig manure to red soil in subtropical China

The impact of long-term pig manure application to a red soil in subtropical China on nitrate leaching was investigated in a field lysimeter experiment from 2002 to 2009. Simultaneously, nitrate leaching was simulated by water and nitrogen management model (WNMM) basing on these observed data to determine the environmental threshold of manure application. Nitrate concentrations in the drainage and nitrate leaching under low manure application (150 kg N ha⁻¹ y⁻¹) did not increase during the study period. Interestingly, the nitrate concentrations in drainage water following high manure application (600 kg N ha⁻¹ y⁻¹) increased exponentially in the first four years and then remained at 13 mg l⁻¹ for the next four years. Addition of lime based on high manure application had no significant effect on nitrate concentrations or total nitrate leaching. WNMM simulated the variation in corn yields and nitrate leaching well. The environmentally safe threshold for long-term application of pig manure was 360 kg N ha⁻¹.     

陕北水蚀风蚀交错区生物结皮对土壤酶活性及养分含量的影响

论文以陕北水蚀风蚀交错区六道沟小流域的生物结皮为对象,研究分析了其对土壤酶活性和土壤养分特征的影响。结果表明:生物结皮对土壤酶活性和土壤养分的影响主要体现在结皮层。结皮层的土壤脲酶和过氧化氢酶活性分别为下层(0～2 cm)土壤的1.56和1.31倍,碱性磷酸酶活性提高幅度最大,为结皮下层的3.72倍;生物结皮能显著提高结皮层土壤有机质、全氮及速效氮含量(P0.05),研究中结皮层土壤有机质、全氮、速效氮含量分别为15.67 g.kg-1、0.65 g.kg-1和22.51 mg.kg-1,而其下0～2 cm层土壤则分别为5.54 g.kg-1、0.30 g.kg-1和14.6 mg.kg-1;生物结皮对土壤速效磷和速效钾的影响不明显(P0.05);生物结皮层土壤pH值为8.08,低于其下0～2 cm层土壤(pH值为8.32,P0.05)。总之,生物结皮的形成和发育可以改善表层土壤的生物化学性质,对该区植被的恢复与重建具有积极意义。