耕地整理现实潜力评价研究——以重庆市为例   总被引：2，自引：1，他引：1  

史娟  姜开勤  叶公强 《水土保持通报》2008,28(5):122-127

耕地整理潜力评价是耕地整理中的一项基础性工作,是省域及市域范围划定耕地整理重点区域的依据,其准确性直接影响区域内耕地整理的布局安排。耕地整理现实潜力评价是一项复杂的工程,影响耕地整理现实潜力的因素很多,建立科学、合理的耕地整理潜力评价指标体系和评价方法对指导耕地整理的实践具有重要意义。选取重庆市为研究区域,采用特尔斐法构建包含自然、经济、社会多方面因素的评价指标体系。采用数轴法,划定重庆市耕地整理现实潜力级别,确定了重庆市耕地整理3大重点区域：渝东北、渝东南、渝西。  相似文献   

Assessing the collapse risk of Stipa bungeana grassland in China based on its distribution changes     

QIAO Xianguo  GUO Ke  LI Guoqing  ZHAO Liqing  LI Frank Yonghong  GAO Chenguang 《干旱区科学》2020,12(2):303-317

The criteria used by International Union for Conservation of Nature(IUCN) for its Red List of Ecosystems(RLE) are the global standards for ecosystem-level risk assessment, and they have been increasingly used for biodiversity conservation. The changed distribution area of an ecosystem is one of the key criteria in such assessments. The Stipa bungeana grassland is one of the most widely distributed grasslands in the warm-temperate semi-arid regions of China. However, the total distribution area of this grassland was noted to have shrunk and become fragmented because of its conversion to cropland and grazing-induced degradation. Following the IUCN-RLE standards, here we analyzed changes in the geographical distribution of this degraded grassland, to evaluate its degradation and risk of collapse. Past(1950-1980) distribution areas were extracted from the Vegetation Map of China(1:1,000,000). Present realizable distribution areas were equated to these past areas minus any habitat area losses. We then predicted the grassland’s present and future(under the Representative Concentration Pathway 8.5 scenario) potential distribution areas using maximum entropy algorithm(MaxEnt), based on field survey data and nine environmental layers. Our results showed that the S. bungeana grassland was mainly distributed in the Loess Plateau, Hexi Corridor, and low altitudes of the Qilian Mountains and Longshou Mountain. This ecosystem occurred mainly on loess soils, kastanozems, steppe aeolian soils and sierozems. Thermal and edaphic factors were the most important factors limiting the distribution of S. bungeana grassland across China. Since 56.1% of its past distribution area(4.9×10~4 km^2) disappeared in the last 50 a, the present realizable distribution area only amounts to 2.2×10~4 km^2. But only 15.7% of its present potential distribution area(14.0×10~4 km^2) is actually occupied by the S. bungeana grassland. The future potential distribution of S. bungeana grassland was predicted to shift towards northwest, and the total area of this ecosystem will shrink by 12.4% over the next 50 a under the most pessimistic climate change scenario. Accordingly, following the IUCN-RLE criteria, we deemed the S. bungeana grassland ecosystem in China to be endangered(EN). Revegetation projects and the establishment of protected areas are recommended as effective ways to avert this looming crisis. This empirical modeling study provides an example of how IUCN-RLE categories and criteria may be valuably used for ecosystem assessments in China and abroad.  相似文献