## 4 Discussion  
The current study employed extended periods of Landsat images and the up-to-date CCDC algorithm to monitor the LUCC of the DTLR continuously from 1990 to 2019. Then the corresponding landscape patterns and ecosystem services were evaluated. We further analyzed the impacts of LUCC and landscape pattern changes on ecosystem services. This is the first study that reveals the driving mechanisms of ecosystem services impacted by the long-time LUCC and landscape patterns changes in the Dongting Lake region, which is informative for regional landscape optimization and sustainable development. The results showed that drastic LUCC occurred in the DTLR in the past 30 years (Figures 2 and 3), which was attributed to local socio-economic development and ecological protection policies. During the period of the 12 th Five-Year Plan (2011-2015), the central government authorized the Dongting Lake region as the key area of the Yangtze River Basin for one of the \"Ten ecological barriers.\" In 2012, cycle economy and sustainable development strategies in Pan-Dongting Lake Economic Circle were included in the national development strategy, and its eco-environmental sustainability has been of increasing concern [58]. For example, the rapid increase of impervious surface areas mainly occurred around urban areas and in the plain areas of the lake region, which could be attributed to the fact that this region is the core of the Yangtze River Economic Belt and has undergone rapid urbanization [31; 38]. Meanwhile, the area of cropland declined obviously throughout the period mainly in the plain areas around the lake region, while the area of forest and waterbody increased simultaneously. This trade-off link could be explained by the strict land use and ecological protection policy implemented in the area [59; 60]. Regarding waterbody and wetlands, the dam and reservoir constructions, land reclamation, and ecological restoration could change the cycle of surface water and wetland cover [61]. In the DTLR, the area of waterbody has decreased gradually since 2003, resulting from the impoundment of the Three Gorges Dam [62; 63]. The land reclamation or waterbody into other land covers resulted in the loss or shrinking of the waterbody and the rapid increases in cropland between 2000 and 2010. These processes together brought about the decline of wetlands and the shrinkage of the waterbody. In addition, the continued development of urbanization, industrialization, and population in the DTLR rapidly increased, leading to waterbody shrinkage. However, after the catastrophic flood in 1998, the government implemented the \"Returning Farmland to Lake\" program to prevent floods  
Figure 10: Variations of the relationships between landscape patterns and ecosystem services. The relationship between forest landscape patterns and carbon storage (**a**) and water conservation capacity (**b**). The relationship between wetland landscape patterns and carbon storage (**c**) and water conservation capacity (**d**). The relationship between cropland landscape patterns and carbon storage (**e**) and crop yield (**f**). by promoting the conversion of farmland to natural lakes in the Yangtze River basin [60]. In Hunan, a project in Dongting Lake called \"4350\" (i.e., restoring the lake to its original size of 4350 km\({}^{2}\) in 1949) was implemented after 1998 to prevent floods and restore the wetland [59]. This program systematically returned parts of cropland to wetlands, forests and grasslands, which increased the waterbody to some extent. The land reclamation was reversed in some areas to restore wetlands and other aquatic systems. This study confirmed that the evolution of composition (e.g., PLAND), agglomeration degree (e.g., COHESION), and fragmentation degree (e.g., FRAC) showed obvious spatial heterogeneity.