# Monitoring Land Cover Change on a Rapidly Urbanizing Island Using Google Earth Engine
## 3 Results
### The Spatial Patterns of Land Cover Change  
Figure 5 shows the transition of each land cover type during different intervals. In the periods between 1990-2000 and 2000-2007, the greatest transition was other land to forest land. Between 2007 and 2019, some of the forest land was transformed into other land, and most of them remained unchanged. For the whole period, the predominant land cover transitions were other land and cultivated land areas to forest land area.  
Figure 4: The change in the area of land cover classes in different time intervals: 1990–2000, 2000–2007, 2007–2019, and 1990–2019. SL = sandy land, BL = built-up land, CL = cultivated land, FL = forest land, OL = other land, \(W\) = water.  
Figure 5: Conversion matrix of land use: (**a**) 1990–2000, (**b**) 2000–2007, (**c**) 2007–2019, and (**d**) 1990–2019. SL = sandy land, BL = built-up land, CL = cultivated land, FL = forest land, OL = other land, \(W\) = water.  
Over the past 30 years, forest, cultivated land, and built-up land were the major changed land cover types. The spatial patterns of these land cover changes are shown in Figure 6a-f, which progressed as follows: Reforestation, cultivated land shrink, and built-up land expansion.  
The results of forest change analysis show 106.48 km\({}^{2}\) of forest gain and 14.11 km\({}^{2}\) of forest loss between 1990 and 2019 (Figure 6d). Forest gain area was transferred from cultivated land (28.88 km\({}^{2}\)), built-up land (1.59 km\({}^{2}\)), and other land cover types (76.01 km\({}^{2}\)), respectively. The area of forest gain is larger on the western than the eastern area of the Island. Forest loss area was transferred to cultivated land (2.82 km\({}^{2}\)), built-up land (7.71 km\({}^{2}\)), and other land cover types (3.58 km\({}^{2}\)), respectively. Cultivated land loss amounted to 48.87 km\({}^{2}\) on Haitan Island, with 41.64% (28.88 km\({}^{2}\)), 23.03% (15.97 km\({}^{2}\)), and 5.80% (4.02 km\({}^{2}\)) converted to forest, built-up land, and other land cover types, respectively. The most apparent reduction occurred in the middle of Haitan Island. A total of 51.66 km\({}^{2}\) of built-up land expanded from other land cover types (27.98 km\({}^{2}\)), cultivated land (15.97 km\({}^{2}\)), and forest land (7.71 km\({}^{2}\)). The most obvious built-up land expansion occurred in the middle of Haitan Island (e.g., Tancheng town). Meanwhile, in order to evaluate the influence of LULC changes, the maximum NDVI in the years of 1990, 2000, 2007, and 2019 was calculated (Figure 7). Comparing the maximum NDVI in a given year, more greenery and fragmentation of Haitan Island can be seen in 2019, which indicated that the vegetation increased and was accompanied by built-up land expansion.  
Figure 6: The main land cover types: (**a**) forest change, (**b**) cultivated land change, and (**c**) built-up land change loss and gain between 1990 and 2019 and their conversion. Transfer to/from (**d**) forest land, (**e**) cultivate land, and (**f**) built-up land. Other = sandy land, water, and other land; BL = built-up land, CL = cultivated land, FL = forest land.