*5.2. Driving Mechanisms of Land Use Change in Typical Rural Settlement Types*

Considering the characteristics of typical settlement types in karst trough valleys, the analysis of land use changes around settlements revealed that land use changes around rural settlements in karst trough valleys are driven by multiple factors and are the result of the interaction between the natural environment and human activities. Natural, human, socio-economic, and environmental factors influence land use changes around different settlement types. Among them, topography, climate, hydrology, geology, soil, and other physical, geographic, and environmental factors directly influence regional differences in rural settlements, especially in the driving mechanism of land use change in rural settlements.

In this study, the influence of regional geological composition and soil texture on the land type change around rural settlements was relatively weak, so the mechanism driving factors were not explored here. In the unique environment of regional karst geomorphology,

in addition to geological features partially influencing factors, the changes in cultivation conditions and radius caused by the dual factors of elevation and slope become the main limiting drivers of land use changes around rural settlements. Therefore, land use changes in rural settlements in the LangXi karst trough valley are driven by natural geographic and environmental factors (Figure 9). The land use change in the settlement is driven by the positive double feedback mechanism of topography and slope, with the dynamic change pattern of "low-low expansion." The average slope of the typical settlements in SanCun, Chuangyan, and ZengJia is 5–15◦, the average elevation is 580 to 795 m, and the land use around the settlements is forest land and arable land expansion (Figure 9). The driving pattern of land use change in and around a shrinking slotted slope settlement showed "low-low shrinkage" dynamics. The average slope of typical settlements in Ganlong and Xinchu is 15–20◦, and the elevation is between 920 and 1170 m. Balanced rural settlements form "medium-medium average" and "high-high extinction" dynamic change driving patterns, respectively, with the medium-high slopes and land use changes showing dynamic equilibrium and extinction.

**Figure 9.** Driving mechanisms of land use change around typical settlements.

In summary, the ES showed a trend of spatial expansion to lower elevations and elevation zones over time. The AS showed the trend of atrophy of high elevation and high-altitude settlement centers over time, while the BS showed the trend of balanced rural development in the middle elevation of troughs and valleys. The DS showed the development trend of high altitude and high elevation to restrict the land use of clusters.

The change of land use in and around rural settlements is a process of selective regional development under the combined influence of natural resource conditions and human and socio-economic infrastructure conditions; it can be seen as the result of competition between rural settlement land and other types of surrounding land. Natural factors determine the basic structure of rural settlements and their surrounding land pattern and constitute the substrate for the growth and development of rural settlements. Moreover, they have a significant influence on the origin, change, and extinction of rural settlements in karst troughs; human and socio-economic factors directly or indirectly cause the activity state of rural settlements in the trough and constitute the main drivers of dynamic changes in land use in and around rural settlements on short and medium time scales. The land use changes around the rural settlements in typical karst trough valleys are mainly driven by policy orientation, population change orientation, farmer willingness orientation, farmer livelihood orientation, and economic development regarding human and socio-economic factors, specifically including returning farmland to forest policy (S-RFF), farmers' behavior and willingness (S-FBW), policy (S-POL), economy(S-ECO), Stone Desertification Management (S-SDM), farmers' livelihood (S-FL), population loss (S-PL), Precise Poverty Alleviation and Land Policy Innovation (S-PPAL), and Land Remediation (S-LR) (Figure 9). Under the policy-driven guidance, land use changes around typical rural settlements in the trough valley are influenced by the policy of returning farmland to forest, stone desertification control projects, ecological restoration project construction, and sloping land improvement policy. Precise poverty alleviation and the policy of stone desertification management are significant. Driven by population orientation, the population's age structure in the trough area is dominated by young children and older adults, and the labor capacity of rural settlements is weak. The labor capacity determines their labor distance and intensity, and the labor distance and intensity affect the planting and tending of rural settlement land, thus affecting the land use pattern of rural settlements in the karst trough area. For example, the population loss of TaiYangPing in the trough valley slope of DS gradually increased from 2000 to 2020 (Table 3), and the loss rate reached 50%, and a large number of young people in the settlement went out or moved out, and the land use pattern around the settlement changed from comprehensive mixed-use land type to single abandoned land type, and the settlement gradually showed the extinction trend. The labor force of Ganlong and XinCao has left, and middle-aged and young people have been lost, among which the loss of people in Ganlong increased from 21% in 2000 to 46% in 2020. There was dynamic stability in the rate of human flow loss in the trough dam settlements of HeXi and GaoZhai from 2000 to 2020, and the land use changes around the settlements showed a balanced state. The population of the expanding settlement is returning to the land, and the settlement and land use are expanding. Driven by the livelihood orientation of farmers, typical settlements in karst trough valleys diversify with agrochemical livelihoods and show diversity in surrounding land use changes. In general, the evolution of rural settlements at the top and slopes of trough valleys with higher elevation is dominated by more decisive geographical factors; rural settlements in trough dam areas show a stronger correlation with socio-economic factors and are more strongly influenced by population, policies, and economic development levels; rural settlements and their surrounding land use changes have obvious clustering effects toward transportation, rivers, and cultural centers.
