雅鲁藏布江中游地区城乡居民点多尺度空间分异及自然因素影响分析

西藏高原土地面积广阔,但适宜人类居住的空间却高度集中于局部地区,其中雅鲁藏布江中游地区是西藏高原最重要的人口承载区。利用核密度、空间“热点”探测和地理探测器等方法,从“居民点斑块-样带-研究区全域”构成的点-线-面多尺度揭示了雅鲁藏布江中游地区城乡居民点的规模、形态和密度的空间分异特征,并分析了自然因素对城乡居民点空间分异的影响。结果表明：① 全域尺度上,雅鲁藏布江中游地区各乡镇居民点规模空间差异较大,基本形成以“彭措林乡-增期乡”为轴线的南北对称态势,居民点形态普遍规则,密度总体偏低;② 样带尺度上,仅有拉萨河样带的密度分布呈线性分布,雅鲁藏布江样带和湘曲-年楚河样带的规模、形态和密度以及拉萨河样带的形态和规模在各自方向上均呈现非线性分布,即居民点东西方向呈现分布规模和形态“两端大中间小”、分布密度“两端小中间大”的特征,而南北方向规模、形态和密度均呈现“南大北小”的特征;③ 斑块尺度上,居民点规模普遍较小,面积小于1000 m ²的数量高达19 099个,占比达到55.14%;斑块形态比较规则,形状为规则类型的数量有21 256个,占比为61.37%;分布密度整体偏低,全域仅为0.34个/km ²;④ 自然要素中,海拔对居民点规模和密度的影响最大,地势起伏度和河流邻近性对居民点形态影响显著,而降水量对居民点的规模、形态和密度影响均不显著。

Multiscale Spatial Differentiation and Physical Influencing Factors of Urban and Rural Settlements in the Middle Reaches of the Yarlung Zangbo River Basin

The Qinghai-Tibet Plateau has a vast land area, but the space suitable for human habitation is highly concentrated on parts of the plateau. The middle reaches of the Yarlung Zangbo River Basin is the most important population residing area on the Qinghai-Tibet Plateau. In this case study of the middle reaches of the Yarlung Zangbo River Basin, the kernel density analysis, space hotspot detection, the Geodetector, and other methods were applied to reveal the spatial differentiation characteristics of the size, shape, and density of urban and rural settlements and to detect the influence of physical factors from the perspective of multiscale feature units of "point-polyline-polygon". The results show that: (1) At the basin scale, there is a large difference in the scale of townships in the middle reaches of the Yarlung Zangbo River Basin, basically forming a North-South symmetry with "Pengcuolin-Zengshi Township" as the axis. Moreover, the pattern of the urban and rural settlements is generally regular and the density is generally low. (2) At the transect scale, only the density distribution of the Lhasa River strip is linear, while the size, shape, and density of the Yarlung Zangbo River and Xiangqu-Nianchu River, and the shape and scale of the Lhasa River are nonlinear in their respective directions. In other words, in the east-west direction of the residential area, the distribution scale and shape are characterized by "large and small at both ends" and the distribution density "small and large at both ends". However, the scale, shape, and density of the north-south direction are characterized by "large in south and small in north". (3) At the patch scale, the size of settlements is generally small, with an area of less than 1000 m ², up to 19 099, accounting for 55.14%. The shape of the settlement is relatively regular; there are 21 256 plaque shapes for the rule type, accounting for 61.37%. Finally, the overall distribution density is low (only 0.34/km ²). (4) The size, shape, and density of urban and rural settlements are affected by many physical factors, but the influence degree of each factor is different. Among them, precipitation has no significant impact on the size, shape, and density of residential areas, altitude has the greatest impact on the size and density of urban and rural settlements, while topography and river proximity have significant impact on the morphology. Our findings can provide theoretical basis for rational optimization of the population distribution pattern on the plateau and the formulation of scientific plateau development strategies, so as to better serve the national ecological security and the economic development of Tibet.