The dynamic changes of ecosystem spatial pattern and structure in the Three-River Headwaters region in Qinghai Province during recent 30 years
The dynamic changes of ecosystem spatial pattern and structure in the Three-River Headwaters region in Qinghai Province during recent 30 years
复制标题
作者：
Jiangwen Fan
以20世纪70年代中后期的MSS影像、90年代初的TM影像和2004年的TM/ETM影像为支持，通过分析和整理，获得了生态系统类型的空间分布数据集，然后分析了长江三角洲生态系统空间格局和结构的动态变化，对三江源区20世纪70年代以来的草地生态系统进行了分析，结果表明：三江源区以高寒草地面积最大，湿地、冰川和山地永久积雪是三江源区的特色生态系统，沼泽面积占水域和湿地生态系统总面积的26.09%，冰川和高山积雪面积占水和湿地生态系统总面积的9.02%，作为三江源地区的特色生态系统，湿地、冰川和高山积雪在提供稳定的水资源方面发挥着重要作用，近30年来，三江源区生态系统空间格局变化稳定而缓慢，耕地、森林、草地、水域和湿地的年变化率较高，荒漠化生态系统的比例均小于0.5%，在长江、黄河流域乃至全国范围内最小，但较为稳定。水和湿地生态系统在三大生态系统中占据主导地位，河源区草地变化主要发生在中东部，以开垦草地和将草地转化为裸地、桑迪和盐碱地等未利用地为主，水和湿地生态系统的变化主要发生在西部和北方广大地区，以水体转化为海滩地、湿地转化为草地为代表。
Supported by MSS images in the mid and late 1970s,TM images in the early 1990s and TM/ETM images in 2004,the spatial distribution data set of ecosystem types was acquired through analysis and distinguishment,then the dynamic changes of spatial pattern and structure of ecosystems in the Three-River Headwaters region were analyzed since the 1970s.The results showed that alpine grassland occupied the largest area in the Three-River Headwaters region,and the area of alpine grassland occupied 64.68% of the total land area and 99.58% of the total grassland area.Wetland,glacier and mountain permanent snow-cover were characteristic ecosystems in the Three-River Headwaters region,with marsh area occupying 26.09% of the total area of water and wetland ecosystem,and glacier and mountain permanent snow-cover area 9.02% of the total area of water and wetland ecosystem.As the characteristic ecosystems in the Three-River Headwaters region,wetland,glacier and mountain permanent snow-cover played important roles in providing stable water resource.During recent 30 years,the changes of ecosystem spatial pattern in the Three-River Headwaters region have been stable and rather slow,with an annual changing rate of farmland,forest,grassland,water and wetland,and hungriness ecosystem being less than 0.5% respectively,the least but stable in the Yangtze and Yellow river basins,even the whole country.The changes of grassland,water and wetland ecosystem have occupied a dominant position in the Three-River Headwaters region since the mid and late 1970s.The changes of grassland mainly occurred in the central and eastern parts of the region,dominated by reclamation of grassland and conversion of grassland into unused land such as bare land,sandy and salt land.And the changes of water and wetland ecosystem mainly occurred in the vast western and northern parts of the region,represented by conversion of water body into beach land and conversion of wetland into grassland.