*3.3. Driving Forces behind the Multifunctional Coupling Coordination Degree of Cultivated Land* 3.3.1. Single Factor Detection

To reveal the driving forces behind the spatial-temporal evolution of the multifunctional coupling coordination degree of cultivated land in different years in the study areas, the differentiation and factor detection module of Geodetector was used for analysis. The differences in the driving forces and the results of factor detection for each year are shown in Table 5.

**Table 5.** Results of single factor detection of the spatial-temporal evolution of the multifunctional coupling coordination degree of cultivated land in the study areas in 2005, 2010, 2015, and 2020.


Note: \* and \*\* represent statistically significance at 10% and 5%, respectively.

Generally speaking, the factors that have a significant impact on the spatial-temporal evolution of the multifunctional coupling coordination degree of cultivated land in the study areas include the slope of cultivated land (X1), the contribution of primary industry to GDP (X4), the rural per capita disposable income level (X6), the effective irrigation rate of cultivated land (X7), and the urbanization level (X10).

From 2005 to 2020, the *q*-value ranking of the rural per capita disposable income and the effective irrigation rate of cultivated land increased, indicating that the construction of modern irrigation and water conservancy facilities and the improvement of the agricultural income level are conducive to promoting the orderly development of the multifunctional coupling coordination degree of cultivated land. The *q*-value ranking of the primary industry's contribution to GDP remained basically unchanged and only passed the significance test in 2005 and 2010, indicating that the pulling effect of the primary industry on economic development had a limited effect on the multifunctional coupling coordination degree of cultivated land. The *q*-value ranking of the slope and urbanization level declined, illustrating that with the development of science and technology, the influence of the natural local conditions of cultivated land and the number of agricultural populations on cultivated land utilization declined. In 2020, both of these failed to pass the significance test and their *q*-value was small, indicating that these factors have basically no influence on the ordered development of cultivated land used for multiple functions.

#### 3.3.2. Dual-Factor Detection

The factor interaction detection module of Geographical Detector was used in our analysis to explore the effect of the factor interaction on the spatial-temporal evolution of the coupling coordination degree of cultivated land in the study areas. The results obtained

for the dual-factor interaction of the spatial-temporal evolution of the multifunctional coupling coordination degree of cultivated land in the study areas are shown in Figure 6.

**Figure 6.** The detection results for the dual-factor interaction of the spatial-temporal evolution of the multifunctional coupling coordination degree of cultivated land in the study areas in 2005, 2010, 2015, and 2020.

According to the results obtained for the factor interaction, the interaction among factors has shown dual-factor enhancement and nonlinear reinforcement, indicating that the multifunctional coupling coordination degree of cultivated land in the study areas is influenced by multiple factors. Figure 6 shows that the interaction between slope factor (X1) and other factors is strong, with the strong interaction between the four factors representing the level of agricultural development. It is worth noting that there is an interaction between the altitude factor (X2) and the other factors, but it can be seen that this interaction tends to weaken over time. The interaction between the rural per capita disposable income level (X6), the effective irrigation rate of cultivated land (X7), and other factors relating to the agricultural development level is strong, and it can be seen that this interaction tends to increase over time. The interaction between the average salary level (X5) of those working in agriculture, stockbreeding, forestry, and fishery and other factors is also strong, but the influence of a single factor is not significant. The results obtained for the interaction among factors further verify that the agricultural development and cultivated land resource endowment are the key driving factors that influence the spatial-temporal evolution of the multifunctional coupling coordination degree of cultivated land in the study areas, demonstrating the complexity of the spatial-temporal evolution of the multifunctional coupling coordination degree of cultivated land.

#### 3.3.3. Influence Mechanism

Among the natural resource endowments, the slope is the only key factor that influences the evolution of the spatial-temporal pattern of the multifunctional coupling coordination degree of cultivated land in the study areas. The slope of cultivated land reflects the topographic conditions of the surface units to which the cultivated land belongs and is an important indicator for grading the quality of cultivated land. Under the appropriate slope conditions, cultivated land resources can be fully and effectively utilized, ensuring the grain yield and agricultural income, enriching the crop variety, and attracting agricultural labor to engage in agricultural production, thus improving the production, social, and ecological functions of cultivated land and promoting the multifunctional coupling

coordination degree of cultivated land. However, the *q*-value ranking of the influence of altitude, average annual precipitation, and other indicators on the multifunctional coupling coordination degree of cultivated land each year is in the middle level and has not passed the significance test, indicating those two indicators have limited effects on the coordinated development of cultivated land utilization and multifunctional coupling. If one wants to improve the multifunctional coupling coordination degree of cultivated land, one should start by upgrading the natural conditions of cultivated land, improving its quality, and ensuring the suitability of cultivated land.

The agricultural development level strongly explains the spatial-temporal pattern of the multifunctional coupling coordination degree of cultivated land in the study areas. Over time, the effect of the rural per capita disposable income level and effective irrigation rate of cultivated land on the spatial-temporal pattern of the multifunctional coupling coordination degree of cultivated land gradually strengthens. The increase in farmers' disposable income can effectively improve agricultural production factors and can lead to the allocation of more funds for agricultural production, land transfer, the employment of labor force, the use of modern agricultural machinery, etc. The improvement of agricultural development is conducive to realizing the large-scale and intensive utilization of cultivated land, thus enhancing the production function of cultivated land. The construction of farmland water conservancy facilities can further improve the mechanization level of agricultural production, increasing farmland biodiversity and thus promoting the orderly development of the production, social, and ecological functions of farmland, moving towards coupling and a coordinated direction.

The influence of social factors on the spatial-temporal evolution of the multifunctional coupling coordination degree of cultivated land in the study areas is generally weak. Among the three factors, only urbanization had a significant influence on the multifunctional coupling coordination degree of cultivated land in 2005 and 2015, indicating that with the improvement of the urbanization level, the rural population gradually declined, resulting in a reduction in agricultural labor force input to a certain extent, which was not conducive to the development of the production function and social function of cultivated land or to its coupling and coordinated development. Therefore, in 2020, this factor only had a very weak effect on the multifunctional coupling coordination development of cultivated land.

#### **4. Discussion**
