期刊文献+
共找到3篇文章
< 1 >
每页显示 20 50 100
对指数体系中共变影响部分的分解
1
作者 王伟真 苏敏邦 《统计与决策》 北大核心 2002年第7期68-68,共1页
关键词 指数体系 共变影响 物值指数 分解方法
下载PDF
Valuation of Lake and Marsh Wetlands Ecosystem Services in China 被引量:14
2
作者 ZHANG Yiran ZHOU Demin +1 位作者 NIU Zhenguo XU Fengjiao 《Chinese Geographical Science》 SCIE CSCD 2014年第3期269-278,共10页
Wetlands are highly productive natural ecosystems, providing valuable goods and services. There is growing interest in transferring ecosystem service value from the existing wetlands studied to other wetlands ecosyste... Wetlands are highly productive natural ecosystems, providing valuable goods and services. There is growing interest in transferring ecosystem service value from the existing wetlands studied to other wetlands ecosystems at a large geographic scale. The benefit transfer method uses the known values from wetlands to predict the value of other wetland sites. This methodology requires only limited time and resources. The present study calculated the value of the ecological services provided by lake and marsh wetlands in China in terms of biodiversity indices, water quality indices and economic indices. Basic data on wetlands were obtained through remote sensing images. The results show that: 1) The total ecosystem service value of the lake and marsh wetlands in 2008 was calculated to be 8.1841 × 1010 United States Dollars(USD), with the marsh and lake wetlands contributing 5.6329 × 1010 and 2.5512 × 1010 USD, respectively. Values of marsh ecosystem service were concentrated in Heilongjiang Province(2.5516 × 1010 USD), Qinghai Province(1.2014 × 1010 USD), and Inner Mongolia Autonomous Region(1.1884 × 1010 USD). The value of the lakes were concentrated in Tibet Autonomous Region(6.223 × 109 USD), Heilongjiang(5.810 × 109 USD), and Qinghai(5.500 × 109 USD). 2) Waste treatment and climate regulation services contributed to 26.29% and 24.74% respectively, of the total ecosystem service value of the marsh wetlands. Hydrological regulation and waste treatment contributed to 41.39% and 32.75%, respectively, of the total ecosystem service value of the lake wetlands. 3) The total ecological service value of the lake and marsh wetlands was 54.64% of the total service value of natural grassland ecosystems and 30.34% of the total service value of forests ecosystems in China. 展开更多
关键词 lake wetlands marsh wetlands ecosystem services
下载PDF
Assessment and analysis of microwave emissivity and transmissivity of a deciduous forest towards the estimate of vegetation biomass 被引量:2
3
作者 ZHANG ZhongJun YU XianChuan +1 位作者 ZHAO ShaoJie CHAI LinNa 《Science China Earth Sciences》 SCIE EI CAS 2014年第3期534-541,共8页
Forests play an important role in the global carbon cycle and have a potential impact on global climatic change.Monitoring forest biomass is of considerable importance in understanding the hydrological cycle.Because o... Forests play an important role in the global carbon cycle and have a potential impact on global climatic change.Monitoring forest biomass is of considerable importance in understanding the hydrological cycle.Because of the problem of dense forest cover,no reliable method with which to retrieve soil moisture in forest areas from the microwave emission signature has been established.All of these issues relate to the microwave emissivity and transmissivity characteristics of a forest.The microwave emission contribution received by a sensor above a forest canopy comes from both the soil surface and the vegetation layer.To analyze the relationship of forest biomass and forest emission and transmissivity,a high-order emission model,the matrix-doubling model,which consists of both soil and vegetation models,was developed and then validated for a young deciduous forest stand in a field experiment.To simulate the emissivity and transmissivity of a deciduous forest in the L and X bands using the matrix-doubling model,the parameters of components of deciduous trees when the leaf area index varies from 1 to10 were generated by an L-system and a forest growth model.The emissivity and transmissivity of a forest and the relationships of these parameters to forest biomass are presented and analyzed in this paper.Emissivity in the L band when the leaf area index is less than 6 and at viewing angles less than 40°,and transmissivity in the L band are the most sensitive parameters in deciduous forest biomass estimation. 展开更多
关键词 forest biomass matrix-doubling microwave emission TRANSMISSIVITY L-SYSTEM
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部