Ecosystem plays a key role in the maintenance and balance of life and environmental systems, among which the watershed ecosystem is the most important. It is the origin of human society and is rich, including social, economic, cultural, natural and other elements.A watershed is a major natural area where people and nature coexist, analogous to a major artery connecting a region (Blanchard et al., 2015). It also has a close relationship with regional social and economic growth. Watersheds exhibit considerable spatial heterogeneity and great integrity as a whole ecological unit (Zhao et al., 2018; Straton, 2006 ). Around the world,countries are placing a greater focus on ecological civilization, the concept of watershed ecosystem management and sustainable development has been widely recognized by governments and international scholars (Alcolea et al., 2019).
As a result of rampant development and exploitation of natural resources, the state of the world's ecosystems is deteriorating, which is leading to a number of ecological problems like forest loss and desertification (Hou et al., 2021). Human activities have exacerbated global ecological destruction and ecosystem degradation. In the trend of global environmental change, unreasonable land development caused by human activities poses a serious threat to the development and well-being of human society (Bai et al., 2019). The environmental Kuznets curve states that low-income nations acquire arable land through the early years of nature devastation (Brain and Anderson, 2020). China also experienced this. China entered a phase of rapid economic expansion in 1995 with the introduction of a socialist market economic system and the deepening of reform. According to figures provided by the World Bank, the economic size of China increased from 2.37% of the global economy in 1995 to 18.45% in 2021. People started to show solicitude for the phenomena of ecological damage brought on by earlier economic expansion as a result of the economy's rapid growth.
For improving the management of preservation initiatives, the Chinese government has implemented a range of ecological restoration programs (ERPs). These ERPs include the Program of Returning Farmland to Forest/Grassland (Bennett,2008), the Natural Forest Protection Program (Xu et al.,2006), and the Sloping Land Conversion Program (Yin and Yin,2010). Numerous researches have demonstrated that the implementation of ERPs can successfully enhance damaged ecosystems. Ecological restoration project is an effective way to slow down ecological degradation, solve environmental problems and restore ecosystem function.
The assessment of ecosystem services value (ESv) is an important tool for assessing the level of ecological restoration, which can quantitatively assess the various changes that occur in ecosystems (Ouyang et al., 2020). Ecosystem services (ES) are the benefits peolple receive from the structures, processes, and functions of the natural environment and are essential for human survival and progress (Aschonitis et al., 2016. Costanza et al., 1997). Assessing the value of ecosystem services (ESV) is crucial for safeguarding the ecological environment, understanding the role of ecosystems in specific regions, building sustainable societies, managing environmental economic resources, and making informed decisions on ecological compensation (Daily et al.,2000. Ouyang et al.,1999. Xie et al.,2015). Watershed ecosystems offer us essential products for our survival,as well as important ecosystem services on a large scale like climate regulation,water preservation,carbon dioxide absorption,water and air purification,soil and water conservation,and biodiversity (Daily, 1997; Qin et al., 2020).
The Liaohe River (LHB) is one of the seven major rivers in China with important industrial and agricultural production base. Home to a population of 34.04 million in the LHB. It is also an important base for steel, machinery, building materials, chemical industry, grain production, and animal husbandry in China. The middle and lower reaches of the LHB are one of the most developed industrial and economic regions in China. Since the 1960s, with the acceleration of economic development, industrialization, and urbanization, numerous human activities have caused interference, especially the large discharge of industrial, agricultural, and domestic sewage. A series of problems such as poor water environment quality, river interruption, serious soil erosion, and continuous reduction of biodiversity have made ecological restoration in the LHB urgent. In 2006, the Liaohe River was listed as one of the key rivers for national governance. In 2010, the Liaoning Provincial Party Committee The provincial government has designated the Liaohe River Reserve and established the Liaohe River Reserve Management Bureau to protect and manage the LHB through comprehensive planning, centralized management, and comprehensive protection Between 2000 and 2019, the government invested a total of 18.249 billion yuan in water volume regulation, water quality restoration, and watershed ecological restoration (Fig. 1).
However, due to the lack of reasonable and effective evaluation methods, the effectiveness of ecological restoration is difficult to grasp in a timely manner, resulting in some unreasonable ecological restoration measures being difficult to correct in a timely manner. Not only does this result in a significant waste of human resources and materials,but it also hinders the advancement of ecological restoration and worsens the degradation of the environment. The correct evaluation of the restoration effect of river basin ecosystems has important practical significance in alleviating ecological degradation and promoting sustainable development of regional ecological environment. At the same time, in the context of Global change and human interference, the land use mode of the basin has changed frequently, which has caused noticeable damage to its ecological environment. The urgent problem in achieving sustainable development of the basin ecology is to find solutions to effectively manage the relationship between ecological protection and regional development which includes improving the land distribution and ensuring the continued functionality of the ecosystem service.
To address the above issues, the main objectives of this study are as follows: (1) To test the effectiveness of ecological restoration policies of LHB, we evaluated the changes in ecosystem service value in the LHB from 2000 to 2020 using the equivalent factor method; (2) Based on the method of cold and hot spot analysis, the spatial heterogeneity characteristics of ecosystem service value in river basins were systematically analyzed, revealing the coupling driving mechanism of natural and human factors on the spatial distribution pattern of ecosystem service value; (3) Predicted the ecosystem service value of the LHB under different development scenarios, providing a basis for decision-makers to formulate corresponding land management policies and sustainable development in the LHB.