基于RS和GIS的喀斯特山区生态系统构成与格局及转化分析--以贵州毕节地区为例

摘要

Bijie City,Guizhou Province is located in slope zone between the eastern Yunnan plateau and Qianzhong tableland and hills,which is a typical karst area.Bijie region consists of Dafang,Qianxi,Jinsha, Zhijin,Nayong,Hezhang and Weining counties and Bijie City.It has a fragile ecological environment.In or-der to better understand Bijie ecosystem composition,structure and change characteristics,in this paper, based on obj ect-oriented classification and spatial statistics and analysis technology,the ecological system of Bijie prefecture in 2000 and 2010 was extracted from Landsat TM image,and the ecosystem composition, structure and characteristics were analyzed quantitatively.The results showed that:from the view of the e-cosystem composition and structure,the study area in 2010 was mainly composed of forest land and farmland ecosystem types,accounting for 42.65 % and 42.65 % respectively;in 2000 and 2010,the region had a higher number of patches and the smaller average patches area,indicating a higher degree of landscape frag-mentation in the region.Number of patches in 2010 was less than that in 2000,indicating that the study area landscape connectivity was improved totally,the whole landscape tended to be neat.The dry land patches and the average plaque area decreased in 2010,while the coniferous forest and grassland increased,showing that the Grain for Green proj ect worked;The dry land and coniferous forest concentration increased,which indicated that connectivity was enhanced and the landscape became more concentrated.Depending on the sta-tistics of conversion area of ecosystem during 2000 and 2010,the total conversion area of all ecosystem types in the study area was 1 298.25 km2 ,the upland and paddy field area decreased significantly,the woodland and grassland increased obviously,the land transfer matrix displayed that dryland mainly became forestland or grassland.Due to larger drought area,the area in Bij ie,Qianxi,Dafang changed greatly and the ecological transformation intensiy are high,the ecological system type transformation intensity values of eight adminis-trative area were positive,showing that the ecosystem cover types tended to be improving.%为了更好地了解贵州省毕节地区生态系统类型的构成、格局与转化特征,本文基于面向对象分类和空间统计与分析技术,对毕节地区2000年和2010年生态系统类型进行提取,并对生态系统构成、格局和转化特征进行定量分析。结果表明：从生态系统构成和格局看,2010年研究区生态系统类型以林地和耕地为主,分别占研究区面积的42.65%和42.51%；2000 和2010年该区均具有较高的斑块数和较小的平均斑块面积,说明该地区景观破碎化程度较高；2010年斑块总数较2000有所减少,表明研究区景观连通性得到改善,景观整体趋于规整化；2010年旱地斑块总面积和平均斑块面积有所减少,针叶林、草地则增加,显示该地区退耕还林还草项目的实施有所成效；旱地和针叶林的聚集度都增加,表明二者连通性增强、景观更加集中。从生态系统转化特征看,2000-2010年,研究区生态系统类型间转化总面积为1298.25 km2,面积明显减少的是旱地和水田,明显增加的主要为林地、草地,土地面积转移矩阵显示旱地主要向林地、草地转化；受旱地面积较大影响,毕节、黔西、大方的面积变化和生态系统转化剧烈程度都较大,8个县(市)的生态系统类型相互转化强度值均为正值,可见生态系统覆被类型均向着较好的方向发展。