基于空间自相关的1975—2015年玛纳斯河流域耕地时空特征变化分析

为揭示耕地空间分布特征与变化趋势,本研究以玛纳斯河流域为例,基于7期（1975年、1990年、1995年、2000年、2005年、2010年和2015年）土地利用数据提取流域耕地信息,采用空间自相关、重心模型、标准差椭圆、地学信息图谱等方法,分析1975-2015年流域耕地空间格局演变特征。结果表明：耕地空间分布存在显著全局正相关,局部空间异质性较强,耕地在时间序列上呈现先减弱后增强再减弱的集聚态势,最终形成以沙湾县商户地乡与石河子市北泉镇为左、右核心的"高-高"集聚分布。耕地空间变化总体呈现西北方向的明显偏移,耕地重心迁移速度经历"缓慢（1975-1995年）-加速（1995-2005年）-减速（2005-2015年）"过程。1995年后标准差椭圆空间分布格局在西北方向愈加明显,椭圆面积大幅增长,耕地涨幅不断增强,并有继续向流域北部荒漠区扩张的趋势。LISA频率图谱中稳定不变与低频区域占比合计达84.58%,耕地空间格局相对稳定。1975-2015年耕地聚集状态主要变化特征表现为"低-低"集聚和"低-高"集聚向"高-高"集聚的转变,流域耕地呈现高密度扩增式发展。通过构建LISA频率图谱,结合重心模型与标准差椭圆较为全面地、动态地掌握了区域耕地空间演变趋势,为耕地资源的科学管理与有效保护提供理论基础与决策依据。

Spatial distribution pattern and change characteristics analysis of cultivated land in the Manas River Basin from 1975 to 2015

The objective of this study was to reveal the spatial distribution characteristics and change trend of cultivated land, taking the Manas River as the study area, by extracting the cultivated land information based on 1975, 1990, 1995, 2000, 2005, 2010, and 2015 series of land use data, via spatial autocorrelation, gravity center mode, standard deviational ellipse, and geography informatic spectrum analysis. The results revealed that there was significant global positive correlation and strong local spatial heterogeneity in the spatial distribution of cultivated land. The cultivated land showed an aggregated time series trend, which first weakened, then strengthened, and then weakened again across the study period. The land formed a high-high agglomerate distribution situation with a left core in Shanghudi Township of Shawan County, and a right core in Beiquan Town of Shihezi City. The overall spatial change in the cultivated land showed a clear, significant shift to the northwest, and the moving speed of the cultivated land''s center of gravity experienced a process of "slowed (1975-1995)-accelerated (1995-2005)-decelerated (2005-2015)". The spatial distribution pattern of the standard deviation ellipse appeared more obvious in the northwest direction after 1995, and the area of ellipse increased substantially. The growth range of the cultivated land was constantly strengthened and had a trend of expansion to the northern desert area of the basin. Through LISA frequency geo-spectrum analysis, we found that the total proportions of stable invariant and low frequency types accounted for 84.58%, and the spatial pattern of cultivated land was relatively stable. The overall spatial aggregation of the cultivated land generally shifted from a state of "Low-Low" aggregation "Low-High" aggregation to a state of "High-High" aggregation, which showed high-density expansion of cultivated land in the Manas River Basin from 1975 to 2015. By constructing the geo-spectrum of LISA frequency and combining the gravity center model and standard deviation ellipse, spatial evolution trends in the regional cultivated land were comprehensively and dynamically outlined, and the theoretical basis and decision-making foundations for scientific management and effective protection of cultivated land resources were provided.