降雨与植被耦合关系对土壤侵蚀的影响分析——以密云水库上游为例

基于TRMM降雨降雨资料时间序列数据和MODIS-NDVI16d合成产品的时间序列数据,分析密云水库上游降雨与植被的耦合关系对侵蚀的影响。结果表明：（1）侵蚀将发生在降雨强度大,同时植被覆盖差的时段,而密云水库上游地区植被的年内生长曲线形态与降雨的分布形态相似性较大,表明研究区的植被具有较好的保护水土能力;（2）研究区侵蚀主要发生在7—8月,而在1—3月以及11—12月几乎不会发生侵蚀;（3）研究区侵蚀的发生与植被覆盖有很紧密的联系,大部分的侵蚀发生在植被覆盖差的＂其他＂类内。研究方法可以清楚地了解研究区内降雨与植被的耦合关系及对侵蚀的影响,研究的结果将为在年内选择具有代表性的时段分析侵蚀状况提供很好的参考资料。     

密云水库流域植被覆盖度变化对输沙量的影响

封闭流域中,泥沙的产生是多种因素相互作用,相互制约的结果,而在这些众多的环境影响因素中,植被是土壤侵蚀中最重要的环境控制因子,目前,植被覆盖度变化对输沙量的影响一直是区域生态环境研究中比较热门的话题。文章使用遥感(Remote Sensing(RS))、地理信息系统(Geographic Information System(GIS))与统计分析相结合的方法评价了密云水库流域内2个子流域出口处2002年至2005年植被覆盖度变化对输沙量的影响。密云水库流域多为山地,其降雨具有明显的季节性。本文的主要目的在于分析2002年至2005年植被覆盖度变化对流域输沙量的影响,并分析了植被覆盖度变化对气候改变及人类活动的综合影响,结果表明:在密云水库流域内,输沙量是降雨情况和人为因素引起的地表植被覆盖度变化情况的综合反映,人口增长、经济发展和城市化是密云水库流域内引起土地利用变化和地表植被覆盖度变化的主要驱动力。并且,输沙量可以被看作是一个很好的指标来定量分离出生物生理和人为的影响,并从中能够找出在流域生态系统中获得显著结果关键的临界点。研究结果对制定流域的合理开发和管理计划将有所帮助。     

Ecological issues and risk assessment in China

As a result of economic development and population explosion, global ecological environments have been severely disturbed and markedly changed. An ecological crisis involving desertification, soil erosion, degradation of land quality, loss of biodiversity and global climate change has been brought about all over the world. In order to manage ecosystems efficiently, it is necessary to assess ecological risk at multiple scales. Ecological risk is the probability that a region and/or site will experience defined ecological or environmental problems. In this paper, the ecological risks of soil erosion, desertification, and acid deposition have been assessed on a national scale according to natural and human factors, such as topography, soil, vegetation and climate. This assessment has provided very useful information for ecological environmental management in China.     

基于RS-GIS的湖北丹江库区土壤水力侵蚀定量分析

湖北丹江库区是南水北调中线工程的主要淹没区和水源区,土壤水力侵蚀是影响水质安全和工程实施的重要因素。以1998年和2003年的TM遥感影像为主要信息源,建立了以植被覆盖度、坡度和土地利用为指标的水力侵蚀遥感分析方法,将水力侵蚀强度分为六级,并结合GIS的空间分析功能对1998年和2003年库区水力侵蚀强度变化及空间分布进行了划分。结果表明五年间库区微度侵蚀、中度侵蚀和强度侵蚀面积呈增加趋势,而轻度侵蚀和极强度侵蚀面积呈减少趋势;并将库区水力侵蚀空间分布划分为北部中低山丘陵中强度侵蚀区和中部河谷城区轻度流失区。分析结果对库区土壤侵蚀的治理和生态环境的改善具有指导意义。     

西南环境移民安置地的生态环境状况研究初报

以桂西北环江县肯福环境移民安置示范区为例，对我国西南喀斯特地区环境移民安置区的气候、地貌、土壤与植被等主要生态因子进行了调查研究和取样分析。研究表明，环境移民安置地由于地处亚热带季风气候区，具有气候温暖，雨量充沛，日照充足，且雨热同季的特点；地貌破碎，土地以坡地为主，但有一定量可开垦利用的土地；土壤主要为红壤，土壤剖面发育良好，土壤质地和结构尚可，有机质和氮含量相对丰富，但磷、钾缺乏，土壤酸度大；植被以先锋植物为主。     

华南红壤坡面侵蚀水动力学机制试验研究

华南红壤区是我国发生潜在水土流失危害的重点区域之一,红壤坡地的水土流失现象较为严重。华南红壤地区气候温暖,雨量丰沛,降雨特点通常表现为强度大、历时长,暴雨或大暴雨事件频发,因此暴雨驱动因子影响作用更为显著,研究探讨华南红壤坡面侵蚀过程及动力特征有着重要的现实意义。通过室内35场不同雨强（30、60、90、120、180、210、270 mm·h-1）、不同坡度（5°、10°、15°、20°、25°）的人工模拟降雨试验,研究了华南红壤侵蚀的水动力学机制。主要取得以下研究结果：（1）红壤坡面侵蚀水流的流态大部分均处于＂层流—缓流区＂,除平均流速随着模拟雨强的增加而增加外,其他水动力参数（坡面侵蚀水流的阻力、曼宁糙率、径流剪切力、以及水流功）均会受到雨强和坡度改变的影响,但是不呈现特定的函数关系,规律不明显;（2）从水动力学角度解析了红壤坡面水蚀过程,得出了相对水深和曼宁糙率系数两种水动力因子共同组成的复合水动力特征参数,可作为表征不同雨强及坡度下的坡面水蚀侵蚀产沙的特征水动力参数指标。     

Assessment of land degradation and its impact on crop production in the Dry Zone of Myanmar

Land degradation in terms of soil degradation is a major environmental issue posing threat to sustainable livelihood in the semi-arid region of Central Myanmar. However, the studies on soil degradation status and its impacts in this region are very scanty. The objective of this study was to determine the impact of land degradation on crop production both in terms of area and yield in the Dry Zone of Myanmar. Remote sensing and geographic information system-based modelling was utilized to assess and map soil erosion rates. Household survey was conducted to understand the causes of land degradation and its impacts on crop productivity and livelihoods. It has been found out that the current rate of soil erosion ranged from 0 to 114 t ha^–1 yr^–1, and that the average rate of soil erosion increased from 14.2 to 54.6 t ha^–1 yr^–1 over a period from 2000 to 2012. The major types of land degradation were physical and chemical soil degradation. Farmers identified topographic condition, soil types, improper crop management practices and climatic factors as the main causes of soil erosion. The observed crop yields of monsoon rice, groundnut, sesame and cotton in the highly degraded area were 3–12 times lower compared with the yields of these crops grown in less degraded area. Livelihoods of the farmers in the high-degraded area were affected by crop yield reduction, increased cultivation cost and increased uncultivable land area. The impact of land degradation on crop production was dependent on the severity of degradation. This suggests that advanced conservation measures are immediately required and the supportive policy strategies need to be implemented to educate farmers and to strengthen extension services for sustainable land management in the Dry Zone of Myanmar.     

1980—2015年青藏高原植被变化研究

青藏高原地形复杂,气候类型独特,是北半球气候变化的调节器。全球气候变化直接影响植被变化,探讨植被变化对了解青藏高原的环境状况及环境保护与恢复具有重要意义。选取青藏高原作为研究区域,基于1980年和2015年的1 km土地利用数据利用转移矩阵研究植被的转换变化,利用1981—2015年的GIMMS-NDVI数据借助趋势分析法分析土地利用未变化区域的植被覆被变化,并通过相关分析法研究植被变化与气候因子的关系。研究表明:1980—2015年,青藏高原植被的转换变化表现为转入面积大于转出面积,植被面积整体增加。植被类型变化的主要表现形式为农作物和草地面积增加,乔木林地和灌木林面积减少;草地的面积变化最大,农作物、乔木林地和灌木林面积变化很小。从不同植被类型和生态分区来看,植被覆被变化表现为农作物面积较小,分布于半干旱地区,NDVI呈上升趋势;乔木林地位于东南部湿润半湿润地区,生长状况呈现退化趋势;灌木林位于东部边缘和东南部的湿润半湿润和半干旱地区,呈退化趋势;草地分布范围最大,生长情况趋于改善。近35年来,青藏高原的植被覆盖整体趋于好转,低覆盖度、干旱半干旱地区趋于改善,高覆盖度、湿润半湿润地区出现退化。研究时段内,青藏高原趋于暖湿化,NDVI变化与年平均气温、年降水量变化呈正相关,对降水变化更为敏感。不同植被类型对气候变化响应不同,农作物相关系数最高。乔木林地与气温和降水变化呈负相关,农作物和草地则呈正相关,灌木林与降水变化呈正相关,与气温变化呈负相关。     

Influence of slope aspect on soil physico-chemical and biological properties in the mid hills of central Nepal

This study assessed the influence of slope aspect and land use on soil physio-chemical and biological properties (soil quality indicators) on contiguous south- and north-facing slopes of the mid hills in central Nepal, having the same climate, vegetation and parent material. In each aspect, two treatments (agriculture and forest) were chosen and four replicates taken for each treatment. Soil sample collection and microarthropod extraction was done according to the standard methodology: soil core samples (10 × 10 × 5 cm) and extraction with the modified Berlese–Tullgren funnel. The investigated soil variables were temperature, moisture, faunal abundance and diversity, organic matter, organic carbon, bulk density and pH. Except in a few cases, all considered soil properties showed significant differences between aspects and land use. Soils of the north-facing slope had higher SOC content, moisture, faunal abundance and diversity, and lower temperature and pH. Variations due to topographic aspect induced varied microclimates, causing differences in faunal abundance and diversity; soil moisture, temperature and organic matter trends affected soil fertility and ultimately soil quality. Further studies are required to clarify the complex interactions between soil properties (physio-chemical and biological), vegetation and slope aspect in Nepal, as well as to develop soil biological indicators as a tool to assist in sustainable land management.     

基于Meta分析的土壤呼吸对凋落物输入的响应

凋落物输入是影响土壤呼吸的一个重要因素,然而从国内外目前研究结果来看,土壤呼吸响应凋落物输入的影响因素尚不清楚。利用国内外已发表的30篇研究论文共1393对有效数据,通过Meta分析,从凋落物管理措施、气候、植被、地形、土壤理化性质等因素揭示凋落物输入对土壤呼吸的影响程度。研究发现:与清除凋落物处理相比较而言,(1)凋落物输入后显著增加了土壤呼吸,且土壤呼吸的增加程度呈现出倍增凋落物处理是自然凋落物处理的1.33倍;(2)不同气候条件下的土壤呼吸增加程度呈现出强降雨(>1000 mm)是微弱降雨(<1000 mm)的1.34倍,以及高温气候(>20℃)是低温气候(<20℃)的1.7倍;(3)土壤呼吸的增加程度在不同植被带下呈现出针叶林带(34.1%)>阔叶林带(28%)>混交林带(22%)>草地(17.3%)的趋势;(4)不同海拔梯度条件下土壤呼吸的增加程度呈现出高海拔(59.6%)>中海拔(34.2%)>低海拔(26.7%)的趋势;(5)不同土壤理化性质条件下的土壤呼吸增量呈现出低容重(77.5%)分别是中容重(26.9%)和高容重(18.0%)的2.9倍和4.3倍,同时中性土壤(79.6%)的呼吸增量远远大于酸性(28.2%)和碱性(24.1%)土壤的呼吸增量,以及高土壤碳氮比(81.2%)的土壤呼吸增量远远大于低土壤碳氮比(19.4%)和中土壤碳氮比(29.6%)的土壤呼吸增量。由此可见,凋落物输入后会导致土壤呼吸的显著增加,但是不同气候、不同植被、不同地形、不同土壤理化性质等条件下其土壤呼吸增加的幅度不同。     

Afghanistan: Environmental degradation in a fragile ecological setting

SUMMARY

Currently, only 6% of the 15% of land in Afghanistan is usable and, if all the refugees were to return, problems of land ownership and adequacy of available land are inevitable. Natural forests have been severely degraded. Due to the nature of the topography and the arid climate, vast areas are subject to soil erosion. Loss of vegetation and soil humus have created ever more arid conditions. Abandoning the lands, poor reclamation schemes, overgrazing and destruction of vegetation for fuelwood have all caused desertifkation. The biological productivity of pastures has also deteriorated. This reduced productivity has affected livestock and has caused dramatic changes to the patterns of wildlife populations. Soil salinization and waterlogged lands are common. Farmland and pastures have been contaminated by landmines. Heavy concentrations of air-borne particulates and considerable amounts of transboundary pollutants from the Aral Sea have been found. Use of chemicals and the machinery of war have damaged the ecosystems.

Collection of plants and animals is unregulated and has resulted in excessive removal or extermination of some species endemic to the Hindu Kush. Uprooting of some plants and dynamite fishing are increasing and a disturbing number of fauna and flora are endangered. Agriculture is traditional, and natural resources are not being used in a sustainable way. A sound environmental strategy needs to be formulated and adopted.     

红壤丘陵区LAI与土壤侵蚀分布特征的关系

叶面积指数(LAI)是常用的一个用于描述植被覆盖的方面指数,土壤侵蚀的分布又与植被的覆盖状况息息相关,这就意味着LAI与土壤侵蚀有一定的相关性,目前有关这二者的相关性研究还鲜有文献报道。基于这此,本研究首先利用2000年的遥感影像(TM)解释出该年度的土壤侵蚀强度图,再利用该遥感影像通过图像的代数运算得出该地区的NDVI栅格图,通过实测该县不同典型植被条件的LAI值,得出实测的LAI与图像NDVI值之间的函数关系式,由图像的代数运算把NDVI图转换成LAI图,即实现了遥感图像的实测LAI纠正。在GIS软件的帮助下,通过将LAI栅格图与土壤侵蚀强度图的空间叠加分析,得到不同LAI条件下的土壤侵蚀分布。结果表明,LAI与土壤侵蚀的分布表现为:大致以LAI=2为分界线,当LAI<2时,土壤侵蚀并未随LAI的增加而迅速减少,LAI>2时,土壤侵蚀的分布随植被指数的增加而减少,当LAI=2左右时,土壤侵蚀的面积最大。这种情况对于轻度、中度及强度土壤侵蚀的影响是类似的,都呈类正态分布的曲线形式,但在曲线的两侧土壤侵蚀类型是有本质区别的,在曲线的左侧土壤侵蚀类型的分布是中度和强度为主,而在曲线右侧则以轻度为主。表明LAI这个指标与土壤侵蚀有很好的相关性,可以用于土壤侵蚀方面的相关研究工作。     

紫色土区裸露地植被恢复技术

通过现场调查和样方调查法,分别调查衡阳市紫色岩裸露地的地形、地貌、气候、母岩、土壤等因子,以及植被分布、生态环境、植物生长等.在此基础上,采用对比研究法,有选择地进行植物及其配置模式的适宜性试验、整地方式的对比试验、宜林型紫色土经济林树种选择试验,评价不同立地条件类型下的植物适宜性与不同配置模式群落的生态适宜性及水土保持能力,最终筛选出不同立地条件类型下适宜的植物及其配置模式与整地方式,为紫色土裸露地植被恢复与宜林地经济开发提供理论依据和技术基础.表18,参11.     

植被-侵蚀动力学模型参数的确定及在黄土高原的应用

植被-侵蚀动力学是研究流域植被与侵蚀在人类活动影响下演变规律的一门新的边缘学科。由植被-侵蚀动力学模型可绘制植被-侵蚀状态图,以预测停止人为干扰后植被及侵蚀变化趋势,评价水土保持措施成效,提出小流域优化治理方略。植被-侵蚀动力学模型4个参数a、c、b、f是流域重要特征参数,其值的确定是进行植被-侵蚀动力学模拟及绘制植被-侵蚀状态图的前提和基础。它们依赖于流域气候、土壤和地形地貌。本文以黄土高原典型小流域为例,采用试算法确定了它们的取值,通过相关分析发现参数a与P、T,参数c、b、f与D50、S之间存在明显的相关关系,并得到了相关关系式。将其用于吕二沟小流域植被-侵蚀动力学模拟,结果与实际情况符合较好。绘制了各参数的取值分布图。最后以燕儿沟小流域为例,将以上相关关系式用于植被-侵蚀状态图的绘制,及小流域自然状况、植被-侵蚀状态及水土保持效果的评价。     

雷州半岛地表水体非点源污染物时空变化特征研究

以雷州半岛为研究区，利用2000-2003年问南渡河与九洲江，以及赤坎水库与鹤地水库的4年常规监测数据，结合实地调查，利用数理统计分析，对雷州半岛地表水体非点源污染物及其时空变化规律进行了初步研究。研究发现，河流与水库的水质均是以氮污染为主，水体有富营养化现象发生，同时，两河流在雨季都不同程度受到了非点源污染的影响，而只有赤坎水库明显受到了非点源污染的影响。究其原因，主要是由于土地利用方式的不同在一定程度上决定了雷州半岛地表水体非点源污染物质量浓度的时空变化特征。因此，只有合理调整流域和库区的土地利用方式、加强区域的水土流失治理工作，才能有效降低非点源污染所带来的地表水体环境污染问题。     

榆林地区植被时空分异特征及其影响因素研究

植被作为反映陆地生态系统和气候的重要指标,对研究全球或区域生态环境变化具有重要作用.以地处黄土高原生态脆弱区的榆林市为研究区,基于地理探测器模型,选取坡向、坡度、气温、降水和土壤类型5类自然因子,土地利用类型、人口密度和GDP 3类人文因子,分析榆林地区植被空间分异特征及其驱动力,并揭示了促进植被生长影响因子的最适宜特...     

基于遥感与GIS的土壤侵蚀强度快速估测方法

针对土壤侵蚀问题,提出了一种基于遥感数据、气象数据、土壤数据的区域土壤侵蚀快速估测方法。首先,通过对土壤侵蚀问题形成原因和影响因素的分析,确定土壤侵蚀敏感性因子;其次,利用遥感(RS)、GIS技术提取土壤侵蚀敏感性因子信息;然后,在GIS系统支持下,运用主成分分析方法,进行土壤侵蚀强度分级;以北京密云水库周边区域为例,进行了土壤侵蚀估测方法的应用,并对该区域的土壤侵蚀空间特征进行分析。研究结果表明:(1)区域土壤侵蚀快速估测方法与实际情况有较好的一致性;(2)密云水库周边地区土壤侵蚀以微度和轻度侵蚀为主,所占面积比例为67.51%,中度以上侵蚀仅占面积的1.46%;(3)土壤侵蚀受坡度、地貌影响明显,中度侵蚀主要发生在低山、丘陵区以耕地为主的土地利用上以及坡度在大于25°的阳坡地带。     

Understanding Interaction Effects of Climate Change and Fire Management on Bird Distributions through Combined Process and Habitat Models

Abstract: Avian conservation efforts must account for changes in vegetation composition and structure associated with climate change. We modeled vegetation change and the probability of occurrence of birds to project changes in winter bird distributions associated with climate change and fire management in the northern Chihuahuan Desert (southwestern U.S.A.). We simulated vegetation change in a process‐based model (Landscape and Fire Simulator) in which anticipated climate change was associated with doubling of current atmospheric carbon dioxide over the next 50 years. We estimated the relative probability of bird occurrence on the basis of statistical models derived from field observations of birds and data on vegetation type, topography, and roads. We selected 3 focal species, Scaled Quail (Callipepla squamata), Loggerhead Shrike (Lanius ludovicianus), and Rock Wren (Salpinctes obsoletus), that had a range of probabilities of occurrence for our study area. Our simulations projected increases in relative probability of bird occurrence in shrubland and decreases in grassland and Yucca spp. and ocotillo (Fouquieria splendens) vegetation. Generally, the relative probability of occurrence of all 3 species was highest in shrubland because leaf‐area index values were lower in shrubland. This high probability of occurrence likely is related to the species’ use of open vegetation for foraging. Fire suppression had little effect on projected vegetation composition because as climate changed there was less fuel and burned area. Our results show that if future water limits on plant type are considered, models that incorporate spatial data may suggest how and where different species of birds may respond to vegetation changes.     

洞庭湖区地表温度反演及其时空变化特征

洞庭湖是我国第二大的淡水湖,对区域气候的调节起着极其关键的作用,然而受全球变暖及其他因素的影响,洞庭湖区范围内对气候变化的响应并不一致。为了更好地认识洞庭湖区的地表温度变化及其对全球变暖的响应情况,同时为准确的判断该区温度未来的变化趋势奠定基础,利用1995年、2004年和2013年12景冬季Landsat TM/ETM＋遥感影像的热红外波段数据反演了洞庭湖区地表温度,并对反演的地表温度值进行标准化处理,采用标准差分类法得到地表温度等级图。通过三时相温度等级图的面积统计与直观对比,分析了洞庭湖区在三峡蓄水前后的温度时空变化特征;并结合归一化植被指数（NDVI）、降雨资料、DEM、坡度等数据对洞庭湖区的温度变化影响因素进行了统计分析。结果表明,（1）洞庭湖区各温度等级面积成正态分布,主要以中温区、较高温区和较低温区为主。从空间分布上来看,低温区主要分布在水体,而高温区则没有明显的分布特征。（2）受雨雪天气影响,2004年的高温范围减少,减少情况为西洞庭湖区〉南洞庭湖区〉东洞庭湖区,面积变化比例分别是5.38%、2.12%、0.71%,表明冷气流对西洞庭湖区的温度变化影响最强,而东洞庭湖区最弱。（3）2013年高温范围增加,且变化强度呈现出西洞庭湖区〈南洞庭湖区〈东洞庭湖区的空间特征,面积变化比例分别是2.21%、2.38%、2.68%,表明在三峡水库蓄水之后,东洞庭湖区的地表温度受到较大影响。（4）植被的覆盖情况与温度相关性不明显,而坡度、海拔与温度呈正相关关系,这表明坡度可以有效的减少冷气流对温度的影响,地势较高地区与阳坡出现高温情况则表明地表温度受太阳辐射影响较大。     

Assessment of soil salinisation in the Ejina Oasis located in the lower reaches of Heihe River,Northwestern China

Recognition of the spatial-temporal distribution characteristics of soil salinity has become an important basis for the formulation of strategies required in the utilisation and sustainable development of soil resources in arid and semi-arid area. In this paper, based on vegetation cover dataset during 1998–2015 in Ejina region combined with the collected soil salinity data, geostatistical methods were used to explore the temporal and spatial dynamic characteristics of soil salinity and its impact on vegetation in the study area. The results showed significant differences in soil salinisation characteristics with a large variability in the soil salinity among the different soil depths, with a variation coefficient ranging from about 0.97–1.47. Soils are represented by a continuous variation, both in space and time. Soil salinity showed an obvious spatial autocorrelation, with a plaque type distribution. The areas of the salinised soil found for the years 2003, 2011 and 2015 were approximately 18,565, 23,206 and 17,721?km², respectively. From the relationships deduced between the normalised difference vegetation index (NDVI) and soil moisture and salt content in different soil depths, the present study ascertains that the soil moisture content is the most important limiting factor of vegetation growth in Ejina Oasis.