岷江上游植被在汶川地震中的损毁及灾后恢复状况

岷江上游是四川盆地和长江干流的重要生态屏障，其植被资源在汶川地震中遭受了严重破坏。以震前（2006年）和震后（2008年和2010年）的遥感影像数据为基础，研究了该区域植被在地震中的受损情况及灾后恢复状况。研究表明：受地震影响，岷江上游森林、灌木、草地和荒漠植被面积在2006～2008年分别下降23 124、15 409、7 482 和2 656 hm2，降幅依次为273%、253%、104%和412%，而沼泽面积变化不大；经过灾后恢复，森林、灌木、草地和荒漠植被面积在2008～2010年分别恢复12 104、21 283、10 554 和2 847 hm2，分别占受损面积的52%、138%、141%和107%，而沼泽面积变化依然不大。植被的这些变化对区域的生态服务功能产生了深远影响。对合理开发利用区域资源、妥善处理经济建设和生态环境保护矛盾以及科学保障长江流域的生态安全都具有一定的指导意义     

岷江上游脆弱生态环境刍论

岷江上游地区位于长江上游四川省西北部。该地区既是长江上游生态屏障的重要组成部分，又是成都平原的水源生命线。但几十年来，该区域植被的大量砍伐和土地的不合理利用，引起了一系列生态失调问题，被列为南方山地典型脆弱生态环境区。在分析岷江上游地区脆弱生态环境现状的基础上，探讨了其形成的自然因素：地质条件的不稳定性、地貌状况和地面组成物质的脆弱性以及气候类型的多样性和人为因素：土地的过度垦殖、土地资源的不合理利用以及草场的过度放牧等，提出了改善该区脆弱生态环境的对策。结果表明，科学利用与发展林草植被，提高林草植被覆盖率、加大坡耕地的坡改梯力度，合理利用土地、重视干旱河谷的治理、聚落的重建与迁建以及农村剩余劳动力的转移等既可改善该区生态环境，又可促进资源的合理利用与开发，最终使该区甚至整个川西地区的经济朝着良性循环的方向发展。     

岷江上游山地生态系统退化机理研究的核心——关键种群的作用

岷江上游地区在我国长江上游同山峡谷区代表性，由于近几十年来人为活动加剧，该区生态系统严重退化。简要介绍了岷上游山地生态系统的概况，讨论了关键种群在退化生态系统研究中的作用和意义。在此基础上进一步认为，岷江上游山地系统退化机理研究应以典型的干旱河谷灌丛，亚高山森林和亚高山草甸等主要生态为对象，以关键种群为核心和切入点，重点研究了干旱河谷批示植物种群动态有其与环境退化的关系、主要动植物种群在变化在草地生态系统退化过程中的作用、亚高山关键种苗木定居及对退化产生理生态适应机制、土壤微生物区系变化有其对系统中氮素归还的影响等，进而有助于在理论上阐述关键种群的生态功能，探讨关键种群变化导致生态系统退化的作用机理；在实践上为目前国家实施西部大开发生态环境建设的重大需求提供理论依据，推动恢复生态学的发展和该区域的生态建设。     

恢复退化草地生态功能与可持续发展--以浑善达克沙地为例

草地生态系统既是我国北方众多自然生态系统中的重要组成部分，又是我国北疆一座天然的“绿色生态屏障”，但这一“绿色生态屏障”却遭到了前所未有的干扰和破坏，草地生态系统退化的面积，程度和速度都在进一步加剧。天然草地植被的人为干扰和破坏是草地退化的根本因素，本文基于此对恢复退化草地植被的生态功能进行初步的讨论，进而提出：草 草≠草原。     

天然草地退化的社会经济原因与可持续利用对策--以甘肃省肃南县为例

天然草地是人类生存和发展的重要物质基础，又是重要的生态屏障。长期以来。天然草地因疏于管理与保护．加之不合理的放牧利用．致使我国天然草地陷于面积缩减．草地组成退化．生产力下降．草地生境日趋恶化的困境．草原退化已成为我国重大的资源和环境问题之一。本文以祁连山区的肃南县为例，通过对天然草地退化现状的调查研究．剖析了天然草地退化的社会经济原因。通过分析我们认为．草地退化虽然是自然因素和人为因素共同作用的结果。但是制度不完善．过度放牧．农户经营封闭、生产结构单一等人为因素才是造成草地生态急剧退化的主要原因。并依此为依据，提出了完善草原法体系、加强管理、创新草业发展镧度等天然草地可持续利用对策。     

基于土地利用变化的生态服务价值损益估算——以岷江上游地区为例

为了定量分析和比较区域生态服务功能及其价值变化,运用中国生态系统服务价值当量因子表和岷江上游流域单位面积农田生态系统提供的食物生产服务的经济价值,以及分析1986、1995和2000年三期TM遥感影像所得到的土地利用情况,对岷江上游地区不同年代的生态服务价值变化进行了估算和比较。并初步分析了生态服务价值变化的原因。1986~1995年,农田面积增加了60 801 hm2,比1986年增长了477%。林地面积减少了89 01217 hm2,占原来面积的497%。总的生态服务价值从1986年到2000年减少了1199×108元。主要是由于人口的增加和森林的砍伐,导致森林面积减少,转变为草地、农田等土地利用类型。通过1995年和2000年对比得出：自从1998年实施“天然林保护工程”政策以来,到2000年森林生态系统面积与1995年相差约4 16528 hm2,生态服务价值相差约79亿元,可见国家政策在保护生态系统服务功能上虽起到了一定的作用,但与1986年相比还相差甚远,天然林保护工程任重而道远。     

黄浦江上游地区水环境污染负荷特征

通过调查黄浦江上游地区的水环境污染来源、污染负荷及其特征，为管理部门控制污染、提高上游地区水环境质量提供科学依据。调查中了解到污染源种类主要有4类：工业、事业、生活和畜禽污染源；水源保护区内年用水量为22196万t．污水量为17755万t／a，其中工业污染源352个，排放量占46．3％，事业污染源4108个。排放量占22．3％，生活污水排放量占30．6％．畜禽污水排放量占0．8％；黄浦江上游水源保护区污染源排放去向主要分4种：直排河道（占40．4％），进入市政泵站后排出（占3．9％）。经污水处理厂处理后排出（占20．5％），通过合流污水收集系统排出（占35．3％）。根据黄浦江上游地区水环境污染负荷特征，建议黄浦江上游区域进一步调整和完善不同区域的功能定位，优化产业结构和布局，构建利于水源保护的区域发展模式和格局；通过采取污染控制和生态环境建设并重的一系列措施，有效抑制生态环境恶化趋势，促进黄浦江上游上游水环境质量的改善。确保上海市的饮用水安全。     

近16年金沙江流域植被覆盖时空特征及其对气候的响应

植被覆盖度是生态系统变化的主要指标之一.改善植被观测的时空尺度和植被动态变化及其驱动因素的方法,能够为我们提供更多植被变化的信息,有利于更好地了解该地区生态环境的特征和变化.基于MODIS-EVI数据,使用Sen和Mann-Kendall模型,结合偏相关分析和灰色关联分析(GRA)等方法,探索了金沙江流域近16年植被覆盖的时空演变特征及其气候驱动力.结果表明:(1)在近16年中,金沙江流域的植被覆盖总体上呈增加的趋势,EVI增速为0.011/10a;(2)植被覆盖改善区和退化区面积分别占总面积的55.53％和28.95％;(3)植被覆盖受气温和降水驱动的区域分别占总面积的32.627％和28.265％.在半干旱区,植被覆盖变化主要受降水的影响,而在半湿润和湿润区主要受温度的影响,但地形和植被类型会改变气候与植被覆盖之间的相关性;(4)半干旱区植被覆盖对气候的响应不明显,在半湿润和湿润区植被覆盖对温度的响应要慢于降水,响应时间也随海拔和植被类型的不同而变化.高海拔地区的植被对气候因素的响应要快于低海拔地区,农作物和草地对气候的响应更快,针叶林和混交林对温度的响应要快于降水.     

岷江上游生态环境脆弱性评价

生态环境脆弱性评价是全球生态问题和可持续发展研究中的重要内容之一。岷江上游因地质构造复杂、人地矛盾突出、生态系统异常脆弱和灵敏而备受关注。本文以岷江上游生态环境脆弱性为研究对象,选取证据权重法(WOE)进行滑坡脆弱性评价,层次分析法(AHP)进行水力侵蚀、景观破坏与污染脆弱性评价;在此基础上,进行了研究区各生态主题脆弱性的空间叠加分析;探讨了岷江上游生态环境脆弱性及其在不同影响因子作用下的空间分异特征。结果表明:研究区的滑坡脆弱性、水力侵蚀脆弱性、景观破坏与污染脆弱性均以轻微度为主,分别占研究区面积的80.43%、71.89%、75.55%;各生态环境主题脆弱性综合分析表明,54.70%的区域至少面临一种生态问题,面临两种及以上环境问题的区域占15.43%,同时面临三种环境问题的占1.35%。研究结果探讨了岷江上游生态环境存在的主要问题和影响因子,对岷江流域乃至长江流域的生态安全和可持续发展具有积极意义,未来应持续关注生态环境脆弱区的生态环境问题。     

气候变化对青藏高原腹地可持续发展的影响

受全球变暖影响，青藏高原气候呈现出暖干化趋势。气温升高，降水量减少对高原腹地植被生长具有消极意义，导致该区牧草质量和数量的下降。人口和牲畜数量的增加，更加重了资源环境与经济（牧业经济）发展的对立。本文对受气候和人为因素共同作用下，青藏高原腹地高寒草地逆行演替的原因及方式进行了分析。在些基础上，对气候暖干化模式下可持续的利用高寒草地资源提出了建议。     

江河源区主要自然生物资源概述

广袤的草地、特有的高寒湿地以及丰富而有又独特的生物多样性是江河源区重要的自然生物资源。草地占江河源区总土地面积的84.53%,是源区畜牧业经济发展的基础,同时也是长江、黄河和澜沧江三大江河的源头区域,为江河中、下游地区生态环境稳定和经济持续发展提供无可替代的服务。江河源区是世界上海拔最高的高寒湿地主要分布区,湿地总面积达8 000 km2。江河源区独特的生态环境孕育了种类繁多的特有动、植物种类,源区约有哺乳动物、鸟类和鱼类133、249和219种,牧草植物、药用植物、食用植物和观赏植物约800、808、80和400种,是世界海拔最高的生物多样性集中分布区。然而,由于超载放牧、盲目采挖、盗猎等不合理的开发和利用以及气候变化等诸多因素的综合影响,江河源区草地生态系统退化、高寒湿地萎缩、生物多样性锐减等生态环境危机不断加剧。正确权衡江河源区自然生物资源的短期经济价值及其所拥有的巨大生态公益和潜在开发价值,科学决策,保护江河源区自然生物资源迫在眉睫。     

基于土地利用的三峡库区生态系统服务价值时空格局分析

生态服务价值评估是对生态功能的一种经济性量化评价。以三峡库区为研究区,结合净初级生产力(NPP)、土地利用/土地覆盖变化(LUCC)、遥感(RS)、气候、国家统计数据和GIS技术,采用替代花费法、影子工程法、碳税法、市场价值法和水量平衡法对三峡库区蓄水前后4个时期(2000、2005、2010和2015年)的生态系统服务价值进行量化评估,分析库区生态系统服务价值时空变异格局。结果显示:(1)从2000年到2015年,三峡库区生态服务总价值增加了269.37亿元,增长率为15.32%。(2)其中林地生态系统贡献较高,占48.14%,耕地次之,占44.04%。(3)林地生态系统服务价值随其面积的增长而增加。耕地生态系统面积减少了4.64%,但生态系统服务总价值却增加了14.54%,耕地存在不合理利用的现象。草地生态系统面积减少了16.57%,生态系统服务总价值减少了5.01%,应加强对草地生态系统的保护。总之,三峡工程的实施在整个研究区尺度上对库区生态系统服务功能的影响是利大于弊。在未来的发展中,应合理规划土地利用,制定区域发展和环境保护计划,确保三峡库区生态环境的改善和可持续发展。     

川中丘陵区植被遥感动态监测及其驱动力分析

川中丘陵区是长江上游重要的生态屏障,也是国家退耕还林还草和天然林资源保护工程重点实施区。近年来,由于气候变化与人类活动的影响,该区植被覆盖及生态发生了较大变化。利用该地区2000～2015年MODIS NDVI数据、气象和土地利用数据以及研究区统计数据,采用最大值合成法(MVC)、趋势分析法和相关系数法,分析了川中丘陵区经国家生态工程建设后的植被动态变化特征,并探讨了气候变化和人类活动对植被覆盖的影响。研究结果表明:近15年,川中丘陵区植被呈增加的趋势,增速为5. 84/10 a(P0. 01);31. 58%的区域植被NDVI显著增加,主要分布在嘉陵江中游和岷江中下游,2. 90%的区域植被NDVI显著减少,主要分布在城市中心及周边;研究区植被对降水的敏感性较气温更强,22. 08%的区域面积NDVI与降水是呈显著相关的,仅7. 69%区域面积NDVI与气温是显著的;森林、灌木和草地的NDVI增加明显,各自增加比例超过60%,而建设用地和湿地是NDVI减少最明显的土地利用类型;退耕还林还草和天然林资源保护工程的建设,对川中丘陵区植被覆盖的增长起到了积极作用。     

Radioactive contamination of tropical rainforest soils in Southern Costa Rica

Radionuclide content in soils from four locations in a tropical rainforest near Golfito in Southern Costa Rica was investigated. For comparison, two nearby locations in open grassland were also studied. From each site 5 soil cores down to a depth of 15 cm were taken. The median contamination with 137Cs was 584 Bq m-2 (reference date 1 January 1996) and the coefficient of variation (CV) was 50%. This contamination can be attributed to global fallout from atmospheric nuclear weapon tests between 1945 and 1980. The mean contamination is slightly lower than the value expected for the latitude (8 degrees 42': 700 Bq m-2), which may be explained by migration of radiocaesium to subsoil below 15 cm or by uptake into the living biomass. Out of the total variability of 50%, around 20% can be attributed to the sampling and measuring process uncertainties, thus leaving a 45% contribution of spatial variability. A significant difference between forest and meadow sites could be detected: the meadow sites showed lower radiocaesium soil inventories (median: 291 Bq m-2) than the forest sites (643 Bq m-2). This may be explained by the agricultural activities carried out on meadow sites which lead to an increased redistribution of caesium in the soil profile and therefore a larger fraction of the total 137Cs lying below 15 cm. Another reason for higher contamination levels under forest can be attributed to the high interception potential of dense tree canopies for dry deposition. Extrapolating the 137Cs concentration below the sampling horizon, i.e. accounting for the cut-off of the profiles by the sampling technique, results in an estimated mean of 710 Bq m-2 for the forest sites, which is very close to the expected figure. The mainly mineral part of the forest soil profiles was analysed for the 137Cs transport parameters, apparent convection velocity (v = 0.14 +/- 0.09 cm a-1) and apparent diffusion constant (D = 0.79 +/- 0.49 cm2 a-1). The maximum concentration can be found at 5.3 +/- 2.9 cm depth, the half-value depth being 7.4 +/- 1.3 cm. The mean 40K activity concentration was 175 Bq kg-1 dry matter (CV = 69%) and 226Ra and 228Ra concentrations of 9.90 Bq kg-1 (CV = 23%) and 7.93 Bq kg-1 (CV = 20%) have been found, respectively.     

Impacts of snow disaster on meat production and adaptation: an empirical analysis in the yellow river source region

The Yellow River source region is located in the hinterland of the Qinghai-Tibetan Plateau, and has a sensitive response to global change due to its unique cryosphere processes. Any slight changes in natural elements and human activity can have a magnified effect on grassland ecosystem, animal husbandry, and pastoral livelihoods since its economy is exclusively dominated by grassland animal husbandry. Because snow disaster has been one of the major natural disasters in the source region, it is crucial to explore the economic impact of snow disaster on animal husbandry and identify effective adaptation measures. A nonlinear model of meat production was established in relation to snow disaster, grassland productivity, and disaster prevention by introducing a snow level index, and selecting three key indicators of grassland productivity and disaster prevention, including grass growing season precipitation concentration, sown grassland area, and warm barn area. This is an inverse of negative correlation, less meat when there is more snow. Per unit increase in snow level in the source region led to a decrease of 0.213 units in meat production. However, production losses caused by the snow disaster could be effectively suppressed by the increase in scale and intensity of sown grassland and warm barn construction. Per unit increase in sown grassland and warm barn area led to an increase of 0.240 and 0.610 units in meat production, respectively. The effects of sown grassland and warm barn area in reducing snow damage at different snow levels were analyzed. Snow disaster adaptation in the source region should include acceleration of the construction of meteorological disaster prevention and mitigation system, to ensure balanced forage supply between winter and spring, to prioritize the development of warm barn, and reduce the proportion of self-financed construction warm barn to encourage active participation of pastoralists, and to develop insurance mechanism for livestock.     

最近10年鄱阳湖区土地利用格局的时空变化

利用1988和1998年4月份的TM遥感数据,采用最大似然法对翻阳湖区的土地利用进行机助分类。把研究区土地利用分成7种类型：林地、灌草坡、水体、湖滩洲地、耕地、城镇用地和裸地。采用空间叠加的方法得到研究区土地利用的转移短阵。结果显示,林地、水体、城镇的面积增加,灌草坡的面积减少。1998年耕地面积比1988年面积减少11．3％,湖滩洲地面积减少42．7％。对不同高程的土地利用变化分析表明,耕地、灌草坡的面积都有所减少;城镇的面积增加,林地的面积增加明显,尤其在丘陵山区。土地利用的变化受到自然和人文因子的双重影响。水体面积增加的主要因于是降水量的增大;林地、灌草坡的变化明显受到政策等因素的影响,湖滩洲地减少的主要原因是水位的升高。     

Regional specialization and market integration: agroecosystem energy transitions in Upper Austria

We investigate agroecosystem energy flows in two Upper Austrian regions, the lowland region Sankt Florian and the prealpine region Grünburg, at five time points between 1830 and 2000. Energetic agroecosystem productivity (energy contents of crops, livestock products, and wood per unit area) is compared to different types of energy inputs, i.e., external inputs from society (labor, industrial inputs, and external biomass inputs) and biomass reused from the local agroecosystem (feed, litter, and seeds). Energy transfers between different compartments of the agroecosystem (agricultural land, forest, and livestock) are also quantified. This allows for delineating an agroecosystem energy transition: In the first stage of this transition, i.e., in the nineteenth century, agroecosystem productivity was low (final produce ranged between 14 and 27 GJ/ha/yr), and local biomass reused made up 97% of total energy inputs in both regions (25–61 GJ/ha/yr). In this period, agroecosystem productivity increase was achieved primarily through more recycling of energy flows within the agroecosystems. In the second stage of the agroecosystem energy transition, i.e., after World War II, external energy inputs increased by factors 2.5 (Sankt Florian) and 5.0 (Grünburg), partly replacing local energy transfers. Final produce per area increased by factors 6.1 (Sankt Florian) and 2.9 (Grünburg). The difference in the resulting energy returns on investment (EROI) owes to regional specialization on cropping versus livestock rearing and to increasing market integration. Our results suggest that sustainable land-use intensification may benefit from some regional specialization harnessing local production potentials based on a mix of local and external inputs.

     

Effects of grazing and fencing on carbon and nitrogen reserves in plants and soils of alpine meadow in the three headwater resource regions

Knowledge about carbon and nitrogen in plants and soils and response to fence and graze in alpine ecosystems is still rudimentary because of extremely geographic situation. The purpose of this study was to compare the difference among carbon, nitrogen concentration, and content of unit area and dynamics of above- and below-ground biomass, soil organic carbon and total nitrogen between fencing and grazing alpine meadow. The results showed that total carbon and C: N radio in the aboveground tissue were significantly higher in fenced and ungrazing grassland (FU) than those in free grazing grassland (FG). In addition, the order of total carbon and nitrogen concentration of aboveground tissue of different function groups were not identical between them; The total carbon storage (TCS) per unit of aboveground tissue, roots and 0–30 cm soil layer increased after being fenced for 5 years from free grazing grassland (9255.17 g/m²) to fenced and ungrazing grassland (12637.10 g/m²) by 26.79%. The corresponding total nitrogen storage (TNS) increased by 751.42 g/m². Furthermore over 95% TCS (TNS) come from 0–30 cm soil layer. However there were no significant differences between fenced and ungrazing grasslands of 10 years and 5 years. Therefore fenced to exclude grazing by Tibetan sheep and yaks was an alternative approach to sequester C to the soil in alpine meadow systems.     

汉江流域土地利用变化及空间格局分析

土地利用变化是人类活动对自然环境施加影响的显著表现形式,已成为全球环境变化研究的重要内容。基于遥感和地理信息系统技术,利用三期Landsat TM图像的解译成果,分析了安康市1985～2000年土地利用变化的结构特征及其空间差异格局。研究表明,近15年来,安康市土地利用转移量主要发生在耕地、林地、草地和水域之间．建设用地和未利用土地的转移趋势不明显。三个时段内各土地利用类型的净变化量差异比较明显。1985～1995年．耕地变化以转入为主,其中由草地转入的比重最大,占耕地总转入量的96．02％。1995～2000年,耕地以大量转出为主,共有1503．21hm2的耕地转为其它用地,其中转向林地和草地的量占耕地总转移量的比例分别是15．46％和78．77％。在行政区尺度上各种用地类型的净变化量分布比较均衡,而在垂直带空间尺度上耕地、林地和草地的净变化随海拔高度的分异较为明显。大致以1600m为界,耕地随海拔高度升高而递减,林地、草地随海拔高度升高而递增．     

Availability and immobilization of 137Cs in subtropical high mountain forest and grassland soils

To understand the behavior of (137)Cs in undisturbed soils after nuclear fallout deposition between the 1940s and 1980s, we investigated the speciation of (137)Cs in soils in forest and its adjacent grassland from a volcano and subalpine area in Taiwan. We performed sequential extraction of (137)Cs (i.e., fractions readily exchangeable, bound to microbial biomass, bound to Fe-Mn oxides, bound to organic matter, persistently bound and residual). For both the forest and grassland soils, (137)Cs was mainly present in the persistently bound (31-41%) and residual (22-62%) fractions. The proportions of (137)Cs labile fractions--bound to exchangeable sites, microbial biomass, Mn-Fe oxides, and organic matter--were lower than those of the recalcitrant fractions. The labile fractions in the forest soils were also higher than those in the grassland soils, especially in the volcanic soil. The results suggest that the labile form of (137)Cs was mostly transferred to the persistently bound and resistant fractions after long-term deposition of fallout. The readily exchangeable (137)Cs fraction was higher in soils with higher organic matter content or minor amounts of 2:1 silicate clay minerals.