## 4 Discussion  
### Constructing Ecological Security Pattern Based on Ecosystem Service Value  
Based on the interaction between landscape patterns and ecological processes, the ESP theory maximizes the utility of ESs by establishing landscape patterns and optimizing the process of ESs to achieve an effective and rational allocation of natural resources and green infrastructure, allowing ecological security to finally be realized. As a result, research on ESs has become a key element of the construction of the ESP. For a long time, the academic circle has failed to reach a consensus on the identification and construction of different kinds of landscape elements. Taking ecological sources as an example, at present, the mainstream method is to carry out quantitative identification by integrating ecological function and ecological sensitivity [87]. Starting from structural connectivity, some scholars use methods such as morphological spatial pattern analysis (MSPA) to identify ecological sources. By calculating the ESV, ESs can be converted to the same unit, thus solving the problem of comparison. In this study, the original value is adjusted according to the spatial distribution of the ESs, which eliminates the mean distribution of the ESV under a single land use type so that it can accurately reflect the quality of the ESs in the study area. In the construction of resistance surface, the resistance value calculated by the ESV fully takes into account ecological functions so that the calculated results can reflect the difficulty of organisms passing through the landscape unit and then obtain a more precise ecological corridor distribution. Compared to ecological processes, ESV pays less attention to landscape connectivity. To compensate for the deficiency in landscape connectivity in the process of ecological source identification, in this study, the contribution of ecological corridors to landscape functional connectivity was added to the evaluation content in the extraction of ecological corridors. The ESP of Sichuan Province in 2018 was constructed by comprehensively considering the importance of ESs and landscape connectivity. The results show that the central part of Sichuan Province can provide high-quality and diversified ESs. This area is located at the junction of the first and second steps of the three steps of Chinese topography, which deserve more attention in the formulation of environmental protection strategies. It should be noted that the area is close to Chengdu, the capital of Sichuan Province, and is extremely vulnerable to interference from human activities. Therefore, in the formulation of urban policies, it is necessary to restrict urban development activities in this area through the introduction of an eco-environmental access list to prevent the quality and stability of ecological corridors from being destroyed. Eastern Sichuan presents fragile ecological security due to intensive human activities, and ecological corridors with a longer average length are prone to breaking up due to factors such as reclamation and urban expansion; thus, so special attention is needed to ensure the protection of these ecological corridors. Approaches such as returning farmland to woodland and strictly restricting human activities around corridors are effective methods that can be put into use. For more isolated mountains, such as the Longquan Mountains in eastern Chengdu, urban sprawl should be strictly restricted in order to protect biodiversity; ecological conservation measures are also needed to protect the mountains as \"stepping stones\" for species migration [3]. As an important part of ecosystems, low-intensity arable land provides important ESs such as gas regulation, grain production, and pollination. It is necessary to maintain its role in ecological protection based on following the national ecological red line strategy [88]. For high-quality farmland, strict protection measures