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51.
藏北高寒草地生态系统服务价值评估   总被引:5,自引:0,他引:5  
刘兴元  冯琦胜 《环境科学学报》2012,32(12):3152-3160
藏北高寒草地是我国重要的畜牧业生产基地和生态安全屏障.然而,高寒草地退化使生态系统服务功能减弱,生态服务价值降低,不仅严重影响了藏北高原畜牧业生产和牧民生活,而且直接威胁到区域生态安全及东亚水资源安全.因此,本研究在综合考虑草地生态系统的地域差异性、空间异质性和区域经济发展水平差异性的基础上,选择了贡献率较高的12项指标,对藏北那曲不同类型和不同退化程度高寒草地的生态服务价值进行评估.结果表明,藏北那曲地区高寒草地生态系统的年总生态服务价值为1199.07亿元,其中,高寒草原、高寒荒漠、高寒荒漠草原和高寒草甸提供的生态服务价值分别占总生态服务价值的62.9%、1.5%、8.0%和28.1%.从退化程度上看,未退化、轻度退化、中度退化和严重退化草地提供的生态服务价值分别占总生态服务价值的54.9%、29.3%、11.0%和4.8%.  相似文献   
52.
北京地区暖温带森林土壤温室气体排放规律   总被引:30,自引:0,他引:30  
本研究利用静态箱法在北京市东灵山暖温带森林生长期选择3种不同类型的森林(阔叶混交林、辽东栎林和油松林)的土壤进行了温室气体(CH4、CO2和N2O)排放规律的野外原位观测.研究结果表明:暖温带主要代表森林类型的土壤作为CH4的汇吸收大气中的CH4,同时作为CO2和N2O的源向大气排放.观测结果显示:不同的森林土壤类型其温室气体排放通量、范围各不相同,阔叶混交林土壤CH4、CO2和N2O通量范围分别是:42~103μg/(m2·h),15~344mg/(m2·h)和-61~101μg/(m2·h);辽东栎林土壤3种气体通量范围分别是:13~182 μg/(m2·h),23~380mg/(m2·h)和-15~183 μg/(m2·h);油松林土壤3种气体通量范围分别是:12~128 μg/(m2·h),15~292mg/(m2·h) 和 -94~153 μg/(m2·h).观测期内阔叶混交林土壤CH4、CO2和N2O平均通量分别是:-66 μg/(m2·h),145mg/(m2·h)和22 μg/(m2·h);辽东栎林土壤3种气体平均通量分别是:-67 μg/(m2·h),146mg/(m2·h)和45μg/(m2·h);油松林土壤3种气体平均通量分别是:-79 μg/(m2·h),150mg/(m2·h)和31μg/(m2·h).本研究估算了不同类型的森林土壤不同的温室气体生长期内的排放总量,阔叶混交林土壤CH4、CO2和N2O排放总量分别是:-5.34kg/(hm2·a),13.9Mg/(hm2·a) 和2.58kg/(hm2·a); 辽东栎林土壤3种气体排放总量分别是:-6.20kg/(hm2·a), 14.07Mg/(hm2·a)和4.19kg/(hm2·a); 油松林土壤3种气体排放总量分别是-6.85kg/(hm2·a), 15.71Mg/(hm2·a)和4.30kg/(hm2·a).  相似文献   
53.
While fuzzy specialists commonly use homogeneous experts' knowledge to construct fuzzy models, it is much more difficult to deal with knowledge elicited from a heterogeneous group of experts. This issue is exemplified in the area of sustainable rangeland management (SRM). One way to deal with the diversity of opinions is to develop a fuzzy system for all experts and to combine all these, the so-called primary systems, into one multi-fuzzy model. To derive each of the primary fuzzy systems, several semi-structured interviews were held in three different areas of the Fars province in Southwest Iran using the knowledge of a group of administrative experts. To obtain the final output of the multi-fuzzy model, we applied different 'voting' methods. The first method simply uses the arithmetic average of the primary outputs as the final output of the multi-fuzzy model. This final output represents an estimation of the right rate of stocking (RRS). We also propose other (un)supervised voting methods. Most importantly, by harmonising the primary outputs such that outliers get less emphasis, we introduce an unsupervised voting method for calculating a weighted estimate of the RRS. This harmonising method is expected to provide a new useful tool for policymakers dealing with heterogenity in experts' opinions: it is especially useful where limited field data are available and one is forced to rely on experts' knowledge only. By constructing the three fuzzy models based on the elicitation of heterogeneous experts' knowledge, our study shows the multidimensional vaguenesses that exist in SRM. Finally, by comparing the final RRS with its common values, this study strongly points to the existence of overgrazing in pastures in the three regions of the Fars province in Southwest Iran.  相似文献   
54.
Increasing the density of natural reserves in the forest landscape may provide conservation benefits for biodiversity within and beyond reserve borders. We used 2 French data sets on saproxylic beetles and landscape cover of forest reserves (LCFR) to test this hypothesis: national standardized data derived from 252 assessment plots in managed and reserve stands in 9 lowland and 5 highland forests and data from the lowland Rambouillet forest, a forested landscape where a pioneer conservation policy led to creation of a dense network of reserves. Abundance of rare and common saproxylic species and total saproxylic species richness were higher in forest reserves than in adjacent managed stands only in highland forests. In the lowland regional case study, as LCFR increased total species richness and common species abundance in reserves increased. In this case study, when there were two or more reserve patches, rare species abundance inside reserves was higher and common species richness in managed stands was higher than when there was a single large reserve. Spillover and habitat amount affected ecological processes underlying these landscape reserve effects. When LCFR positively affected species richness and abundance in reserves or managed stands, >12‐20% reserve cover led to the highest species diversity and abundance. This result is consistent with the target of 17% forested land area in reserves set at the Nagoya biodiversity summit in 2010. Therefore, to preserve biodiversity we recommend at least doubling the current proportion of forest reserves in European forested landscapes.  相似文献   
55.
通过野外调查和历史文献及标本统计分析,确定并分析北洛河流域种子植物信息数据.结果表明:该区共有种子植物123科581属1671种,占黄土高原种子植物的83.67%、67.24%、51.83%,集中分布于大型科(>50种)、较大科(21~50种)和单种属(1种)、小型属(2~5种)内.11个干流流经的地理单元植物相似性聚类分为5组,较早分离的是黄龙县,最大类因子午岭山脉连接而包含4个地理单元(富县、合水县、宜君县、黄陵县).富县、合水县和黄龙县植物丰富度SD值最高,洛川县、华池县和甘泉县SD值最低.该区地理成分在属级水平上有15个分布区类型16个变型,以温带分布及其变型为主(287属,占49.40%),并与热带分布及其变型联系紧密(115属,占19.79%),植物丰富度SD值与温带成分显著正相关;黄陵县、洛川县、黄龙县R/T值最高,热带性质最强,华池县、定边县R/T值最低,热带性质最弱.R/T值受海拔影响,随温度和降水从东南向西北递减.该区植物起源古老,分化程度高,物种多样性丰富,地理成分复杂,是重要的植物种质资源库.植物物种多样性地带性格局过渡性明显,体现出这些类群的生态位需求.需加强保护该区原生环境和植物,合理开发利用,可选择6大优势科(菊科、禾本科、蔷薇科、豆科、唇形科和毛茛科)中适地适树适草的物种(温带性质),进行植被恢复和水土流失治理.  相似文献   
56.
Abstract: To understand how a highly contentious policy process influenced a major conservation effort, I examined the origins, compromises, and outcomes of the Alaska National Interest Lands Conservation Act of 1980 (ANILCA) for the Tongass National Forest. Tongass wilderness designation was among the most controversial issues in the ANILCA debate, and it faced strong opposition from influential lawmakers, land managers, and Alaska residents. To investigate the influence of this opposition on Tongass conservation outcomes, I conducted a gap analysis of Tongass reserves and a policy analysis of the ANILCA debate and traced the influence of specific interests through the amendments, negotiations, and resulting compromises needed to enact ANILCA. Overall, I found that Tongass reserves comprise a broadly representative cross‐section of ecosystems and species habitats in southeastern Alaska. Redrawn reserve boundaries, industry subsidies, and special access regulations reflected compromises to minimize the impact of wilderness conservation on mining, timber, and local stakeholder interests, respectively. Fragmentation of the Admiralty Island National Monument—the most ecologically valuable and politically controversial reserve—resulted from compromises with Alaskan Native (indigenous peoples of Alaska) corporations and timber interests. Despite language to accommodate “reasonable access” to wilderness reserves, ongoing access limitations highlight the concerns of Alaska residents that opposed ANILCA several decades ago. More broadly, the Tongass case suggests that early and ambitious conservation action may offset strong political opposition; compromises needed to establish key reserves often exacerbate development impacts in unprotected areas; and efforts to minimize social conflicts are needed to safeguard the long‐term viability of conservation measures.  相似文献   
57.
Abstract:  For many regions worldwide, multiple and often contrasting biogeographic classifications exist that are derived from a variety of taxa and techniques. This presents a challenge for managers who must choose appropriate large-scale spatial frameworks for systematic conservation planning. We demonstrate how systematically collected community data can be used to evaluate existing biogeographic classifications, identify the most appropriate metric for biogeographic patterns seen in other taxonomic groups, and develop an independent biogeographic classification scheme for systematic conservation planning. We evaluated 6 existing biogeographic classifications for New Zealand's nearshore marine environment with community-similarity metrics derived from abundance and presence–absence data for macroalgae (107 species) and mobile macroinvertebrates (44 species). The concordance between community metrics and the previous classifications was high, as indicated by a high multivariate classification success (CS) (74.3–98.3%). Subsequently, we carried out an independent classification analysis on each community metric to identify biogeographic units within a hierarchical spatial framework. The classification derived from macroalgal presence–absence data achieved the highest CS and could be used as a mesoscale classification scheme in which 11 regional groupings (i.e., bioregions) (CS = 73.8–84.8%) are nested within northern and southern biogeographic provinces (CS = 90.3–98.7%). These techniques can be used in systematic conservation planning to inform the design of representative and comprehensive networks of marine protected areas through evaluation of the current coverage of marine reserves in each bioregion. Currently, 0.22% of the territorial sea around mainland New Zealand is protected in no-take marine protected areas in which 0–1.5% of each bioregion represented.  相似文献   
58.
基于RUE的不同草地类生态评价研究——以河西走廊为例   总被引:1,自引:1,他引:0  
选择降水利用效率(RUE)作为评价指标,对河西走廊代表性草地类--温性荒漠、高寒草甸、温性草原进行生态评价研究。通过植被指数提取、降水Co-Kriging插值、图层叠加,得到河西走廊区域2006-2010年的RUE(NDVI)、RUE(PVI)、RUE(TSAVI)数据,并与地上生物量进行相关分析,筛选出适合不同草地类的RUE作为该区域生态评价的指标。结果表明:1)温性荒漠区RUE(PVI)与草地生物量风干重正相关性最高(R2=0.879),高寒草甸区RUE(NDVI)与草地生物量风干重的正相关性最高(R2=0.876),温性草原区RUE(TSAVI)与草地生物量风干重的正相关性最高(R2=0.895)。2)温性荒漠区、温性草原区生态均处于退化过程,高寒草甸区处于恢复过程。研究认为选择合适的RUE值可作为不同草地类生态评价指标,并具有理论的可行性和实践的可靠性。  相似文献   
59.
Water is the major food component for the maintenance of animals. Although Africa is endowed with diverse agricultural environments, the survival of animals in Sahelian and sub-Sahelian Africa is threatened by the lack of water. Animals need water as an essential nutrient, a component of the body, and for conductive or evaporative cooling. Water needs are met mainly through drinking free water and to a lesser extent by utilising water that forms part of the feed. However during the long dry season, surface water resources dwindle and the water content of available forage decreases, thereby increasing the animals’ demand for water. Consequently animals have to walk for long distances to obtain adequate forage and water, which in turn raises the demand for these resources. Water can be used to direct and regulate rangeland management in this open access environment, to maintain range resources and to improve their quality. Water development, which takes into consideration usable forage, despite some intra- or inter-annual variability, plays an important role and its spatial distribution will affect the grazing intensity of forage resources. Sound water development and management strategies integrating local communities in the decision-making will set up a firm basis for sustained range management in the free and open access environment of sub-Saharan Africa where lack of financial input, social and cultural habits and above all the environmental condition do not permit large scale fencing as in other parts of the world.  相似文献   
60.
Abstract:  This article reports on a survey of ranch owners in high amenity areas in southwestern Montana that have experienced marked ownership change over the last two decades. Specifically, we focus on findings from a set of questions targeting water resource and riparian area management. After reviewing the results, we consider how new owners may be managing water resources differently than longtime owners and what the ecological implications of this shift in management might be for Montana’s prized wild fisheries. Uses more closely associated with new owners than with longtime owners include water reallocation to instream uses, aquatic and riparian ecosystem restoration, and fish pond construction. These uses have both positive and negative impacts on the region’s fisheries. Our findings suggest that current laws and institutions guiding the management of water resources and the aquatic and riparian ecosystems they support may not be adequate to address emerging conservation opportunities and challenges.  相似文献   
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