*3.1. Spatiotemporal Pattern Analysis of Urban–Rural Construction Land*

3.1.1. Structure and Spatial Pattern of Urban–Rural Construction Land

As seen from the change in the time-series law of scale structure, the area of urban– rural construction land in Qixingguan District increased from 10,034.97 hm2 in 2009 to 22,879.86 hm<sup>2</sup> in 2020, thus more than doubling in those 10 years (Table 2). Using the natural breakpoint method, the quantity change of urban–rural construction land was divided into five zones: low, medium low, medium, medium high, and high density (Figure 2). The spatial distribution of urban–rural construction land changes in Qixingguan District during the four monitoring periods had similar uniformity, expanding outward from the central urban area and gradually increasing. Overall, the rural residential land in the study area is mainly characterized by the largest amount of land and broken map spots, which is consistent with the surface features of a broken karst mountainous area. In terms of map spots, in 2020, the number of map spots for urban use was 8155, while the number for rural residential land was up to 75,178. The medium-high-density and high-density areas of urban–rural construction land are mainly distributed in non-central urban areas and towns, indicating that rural residential land in the study area has the characteristics of large land occupation, scattered layout, and low land use efficiency. During the monitoring period, the area of urban land continued to increase, and its proportion reached a maximum of 28.86% in 2017.

As shown in Figure 2, the central urban area has always been in a low-density area, while the conclusions of previous works were mostly related to urban expansion and showed higher exponential growth than other regions [50]. A previous study suggested that high-density construction land areas, such as industry and transportation, should be mainly distributed in relatively good township areas, which disagrees with our study. There are two possible reasons for this: (1) The present study area is located in a karst mountain area, where the ecological environment is relatively fragile, the location is relatively remote, there is insufficient motivation for urban development motivation, economic and social development are seriously lagging behind, the planned urban expansion area is limited, and the administrative division of several streets in the central urban area is small. (2) The flow of farmers to more developed cities to work and the return of funds will increase the rural residential land area or improve the residential functions, resulting in a spreading of rural space, which will continue to increase the rural residential land use.


**Table 2.** Quantity of change in urban–rural construction land in Qixingguan District (2009–2020) (hm2, %).

Note: In land use classification, proportion refers to the proportion of each land use type in urban–rural construction land.

**Figure 2.** Spatial distribution of urban–rural construction land characteristics in Qixingguan District from 2009 to 2020.

It is worth noting that, during the study period, the quantity and scale of transportation land changed the most significantly; its area increased by 5460.00 hm2, and the average annual growth rate in each monitoring period was higher than that of other land types, with an average annual increase of 546 hm<sup>2</sup> (Table 2). During the study period, the average annual growth rate was 82.01%. The reason for this is that, during the research period, Guizhou Province achieved high-speed access between counties, highways to villages, and hardened roads between groups, establishing a main transportation network extending all over the study area. At the same time, with the development of urbanization, road facilities also continuously increased. The quantity and scale of urban industrial and mining land, scenic spots, and special land had little variation during the study period.

#### 3.1.2. Sources and Trends of Urban–Rural Construction Land
