## 3 Results  
### At the Plot Level: Visible Land Fragmentation and Dispersion  
Figure 2 shows that the cultivated land in Shanghai is mainly distributed in the periphery of the central city and towns, and Chongming District. It consists of dry land and paddy fields, of which paddy fields account for the majority. Dry land is scattered at the edge of the city and part of the coastal leisure and rotation land. According to the variation in land spatial morphology, the characteristics of farmland fragmentation and sparsity in the suburbs of Shanghai are visible. According to the GIS spatial overlay analysis of the reclassified cultivated land data of Shanghai, the cultivated land area of Shanghai was 4793.40 km\({}^{2}\) in 1990, 4384.55 km\({}^{2}\) in 2000, 3567.91 km\({}^{2}\) in 2010, 3383.81 km\({}^{2}\) in 2015, and only 3337.38 km\({}^{2}\) in 2018, which represented a decrease of nearly 30% in 28 years. Among these changes, cultivated land decreased at the fastest rate from 2000 to 2010, and the rate of decline has dropped significantly since 2010 (Figure 2). The results of landscape spatial analysis show that, from 1995 to 2018, the cultivated land NP in Shanghai increased from 103 to 613, the PD increased from 0.02/100 ha to 0.18/100 ha, and the MPS decreased from 4330.01 ha to 501.02 ha year by year. The doubling of the NP and PD value and the shrinkage of the MPS value directly reflected the trend of the fragmentation of cultivated land in the suburbs of Shanghai. From 1990 to 2018, the LPI, which measures the dominance of land types, decreased from 23.16% to 21.85%, which means that the advantage of cultivated land among various land types in Shanghai declined. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**R** & **R\({}^{2}\)** & **Adjusted R\({}^{2}\)** & **Errors in Standard Estimates** \\ \hline
0.969 & 0.939 & 0.909 & 0.114 \\ \hline  & F-test & \multicolumn{2}{c}{_t_-Test} \\ \hline F & Statistical Significance (sig) & t & sig \\
30.870 & 0.004 & \(-\)7.715 & 0.002 \\  & & \(-\)1.489 & 0.004 \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Goodness of fit, F-test and _t_-test of the regression model. The cultivated land LSI increased from 43.89/100 ha to 52.28/100 ha, indicating that the irregularity of the cultivated land patch shape increased; the cultivated land form changed from simple to complex; and the overall degree of dispersion increased (Table 11). In summary, from the perspective of the most intuitive spatial distribution maps of cultivated land in Shanghai and landscape metrics, cultivated land in Shanghai showed an overall morphological evolution process of shrinkage, dispersion, fragmentation, and complexity from 1995 to 2018. Similarly, from 1990 to 2018, the AI of cultivated land in Shanghai decreased from 98.14% to 97.20%, indicating that cultivated land in Shanghai gradually became fragmented. The DIVISION of cultivated land increased from 0.89 to 0.99, indicating that the separation degree of cultivated land landscape increased. The overall change trend of the cultivated land metric COHESION is not significant, and the MNN of cultivated land shows an overall upward trend in fluctuations. The cultivated land metric CONNECT decreased from 3.41% to 3.41%, indicating that the total variation of the cultivated land is 1.05%, indicating that the total variation of the cultivated land is 1.  
in 1995 to 0.49% in 2018, which means that the connectivity of cultivated land in Shanghai shows a downward trend. The SPLIT index continued to increase from 1.6812 in 1990 to 3.8821 in 2018, which means that the fragmentation of cultivated land in Shanghai is more serious (Table 12). By region, the aggregation index (AI) of cultivated land in Shanghai suburban districts tends to decline on the whole, among which Minhang, Baoshan, and Jiading have the largest decline, while Chongming, Jinshan, and Fengxian have the smallest decline (Table 13).