青藏高原城乡建设用地和生态用地转移时空格局

青藏高原作为中国重要的生态环境保护地,城镇化和生态环境的变化受到广泛关注。本文基于1990-2015年土地利用数据,进行生态用地和城乡建设用地之间的转移分析,通过核密度以及标准差椭圆分析进行空间转移强度的定性研究。结果表明：① 1990-2015年青藏高原生态用地显著地向城乡建设用地转移,是城乡建设用地向生态用地转移量的54.6倍,其中2000-2005年和2010-2015年是用地转移的热点时期;② 城乡建设用地与生态用地之间的转换在空间上呈现逆向状态,生态用地向城乡建设用地的转移分布逐渐从青藏高原的周边区域向腹地蔓延;城乡建设用地向生态用地的转移最初出现在青藏高原的腹地,逐渐向外围扩张;③ 生态服务功能越大的生态用地,越容易被人类占用,随之发生用地类型的转移,侵占后的土地很难反向转移为具有高生态服务功能的生态用地。

Spatio-temporal Dynamics of the Urban-Rural Construction Land and Ecological Land on Qinghai-Tibet Plateau

With the development of urbanization, more and more urban and rural construction land has been converted to ecological land on Qinghai-Tibet Plateau. Land use change is a key component for global environment change, it also reflects the impacts of human activities on the environment. To some extent, urban and rural construction land can represent the intensity of human activities. Based on the land use data of 1990, 2000, 2005, 2010, and 2015 on Qinghai-Tibet Plateau, the conversation of ecological land to urban and rural construction land in the past decades were analyzed by land-use conversion matrix. Using kernel density and standard deviational ellipse, the spatial mechanism of the conversion was analyzed. The results show that: (1) In the past 25 years, lots of ecological land have been converted to urban and rural construction land. It is over 50 times the conversation of urban and rural construction land to ecological land. The conversion concentrated in two periods, 2000-2005 and 2010-2015. (2) Through experiments, 10km grid can reflect the spatial distribution regularities more obviously. The conversion between urban and rural construction land and ecological land presented a spatial reverse. The conversion of ecological land to urban and rural construction land occurred in just marginal areas. As time went by, urban and rural construction land gradually invaded the hinterland of Qinghai-Tibet Plateau. On the contrary, the conservation of urban and rural construction land to ecological land appeared in the hinterland of Qinghai-Tibet Plateau, and it gradually spread outward. (3) The towns, the hot spots of land conversion, can be divided into four 4 types. Type one is provincial capitals, located in river valleys; type two is industrial towns; type three towns are always located in natural ecological protection areas; and type four is tourism towns with good natural environment and convenient transportation. (4) Ecological lands that have higher ecological services are more likely to be converted to urban and rural construction land more easily. Nevertheless, it is very difficult for urban and rural construction land to transfer to ecological land. Reverse conversion usually transfers from urban and rural construction land to some low ecological service land. In general, the area of urban and rural construction land has increased a lot during the 25 years. Because of the large area of ecological land, ecological land use dynamic index is very low. On Qinghai-Tibet Plateau urbanization did not have a negative effect on eco-environment. So sustainable urbanization is still a significant development trend on Qinghai-Tibet Plateau in the future.