三江源地区“三区空间”时空演化及驱动机制分析（1992―2020年）

三江源地区是国家重要生态安全屏障和生态文明先行示范区。科学认知三江源地区生态空间、农业空间、城镇空间的空间格局演变特征及驱动机制,对于促进国土空间格局优化具有重要意义。首先从单一土地利用类型入手,分析1992―2020年的变化特征;然后结合土地分类和量化评价辨识出农牧空间,进而界定出“三区空间”并对其演变特征进行分析;最后,利用地理探测器分析变化背后的驱动机制。结果表明：① 三江源地区城镇空间增幅达774.56%;生态空间和农业空间以2005年和2015年为转折点,分别呈“U”字型和倒“U”字型变化趋势;② 研究区仅发生了4种交叉转换：生态空间转农业空间规模为1154.1 km²,多发生在气候变化主导区,转化量大但速度在逐步放缓;农业空间转生态空间规模为1140.8 km²,多分布在气候与人类活动共同作用区,转化速度呈明显变快趋势;农业空间和生态空间转为城镇空间的总量分别为41.0 km²和12.3 km²,多分布在县（市）驻地镇附近,转化速度在三个阶段表现为“缓慢增长―变快―减缓”的态势;③ 地理基础条件是“三区空间”格局演化的基本动力和前提,制约着交叉转换的位置和方向;社会经济因素是演化的关键驱动力,对交叉转换规模和速度均具有显著影响;生态保护政策在2005年之后驱动作用显著,尤其在“生态―农业”空间的相互置换过程中发挥着稳定作用。本研究可为牧业地区主体功能降尺度传导和国土空间用途管制提供新思路,可应用于三江源地区生态环境保护决策和各级国土空间规划编制工作。

Spatial-temporal Evolution Characteristics and Mechanism of “Three-Function Space” in the Three-Rivers Headwaters' Region from 1992 to 2020

The Three-River Headwaters region is an important national ecological security barrier and ecological civilization demonstration area. It is of great significance to quantify the evolution characteristics and driving mechanism of spatial patterns of the ecological space, agricultural space, and urban space in this area. Firstly, the change characteristics of every single land use type from 1992 to 2020 were analyzed. Secondly, combining with land classification and quantitative evaluation, the agriculture and animal husbandry space was identified, and the " three-function space " was further defined and its evolution characteristics were analyzed. Finally, the geodetector was used to analyze the driving mechanism behind the changes. The results show that: (1) The urban space growth rate in the Three-River Headwaters region was 774.56%. The decrease of ecological space and agricultural space was very small, but the dynamic transformation was obvious. The turning point of ecological space and agricultural space changes is 2005 and 2015, with a u-shaped trend and an inverted U-shaped trend, respectively; (2) There are four types of cross-transformation in the study area. The area of ecological space converted to agricultural space is 1154.1km², and most of the transformation occurred in the dominant climate change zone, with a large amount but a slow rate. The area of agricultural space to ecological space is 1140.8km², which is mainly distributed in areas with climate and human activities, and the transformation speed is obviously faster. The total amount of agricultural space and ecological space converted into urban space is 41.0 km² and 12.3 km², respectively, mostly distributed in central cities and towns. The transformation rate shows a trend of "slow growth, faster growth, and slower growth" in three stages; (3) The basic geographical condition is the primary driving force of the evolution of " three-function space ", which restricts the location and direction of the cross transformation. Social and economic factors are the key driving forces of evolution and have a significant impact on the scale and speed of cross transformation. After 2005, ecological protection policies began to play an important role, especially in the process of "ecology-agriculture" cross transformation. This study provides a new idea for the downscaling of the main function of animal husbandry areas and the control of territorial space usage, which can be applied to the decision-making of ecological environment protection and the formulation of territorial space planning at all levels in the Three-River Headwaters region.