Advances and Prospects in Research of Land Ecosystem Service Value

Kai XU, Zisheng YANG

Institute of Land & Resources and Sustainable Development, Yunnan University of Finance and Economics, Kunming 650221, China

Abstract Ecosystem provides supply, regulation, support and cultural services. The value assessment of ecosystem service functions is helpful for people to understand the importance of natural ecosystems to production and life. Through analyzing domestic and foreign research on ecosystem service value, this paper sorted out the research process of value assessment. Based on the assessment process, the existing assessment methods and the introduced model methods were summarized, and the methods and models used by the latest research were classified. According to the weakness of the existing studies, it discussed prospects of future research. It is expected to promote multi-scale and multi-directional research exploration and enrich the theory and method of value assessment.

Key words Land ecosystem service value, Research advances, Prospects

1 Introduction

An ecosystem has extremely high or even immeasurable value and is extremely closely related to human well-being[1]. Although domestic and foreign scholars have carried out extensive research activities on ecosystem service value (ESV), there is still no mature ESV pricing method. From an ecological point of view, the land itself is an ecosystem, and it can be called a land ecosystem[2]. The natural landscape of an area with rapid urbanization development will change greatly, which will lead to the decline of the ecological function of the area, and then a series of studies have been carried out successively. For the research on regional ESV, foreign countries started earlier, and the research content is also relatively rich and comprehensive. In comparison, domestic research started basically after 1997, and the research has also shifted from value research to driving force research. After a series of studies, the research content is very rich in both time and space scales. According to the research findings of domestic and foreign scholars, we divided the accounting methods into two categories: ecological service product price method and value equivalent factor method. We summarized the technical means and model system introduced by the research, and explored the future research direction.

2 Research advances

2.1 Advances in foreign researchIn 1997, Daily stated that ecosystem services refer to the natural environment conditions and functions that are formed in the ecosystem and ecological process to maintain the survival of human beings[3]. In 1997, Costanzaetal.[4]assessed the value of global ecosystem services for the first time. Johannaetal.[5], Turneretal.[6]estimated the ESV of agricultural land. Through research, Firbanketal.[7]and Kragtetal.[8]found that biodiversity and soil organic matter would affect the ecosystem service value. Capitanietal.[9]and Kubiszewskietal.[10]set up a variety of development scenarios to simulate land use patterns and assess ecosystem service values. In recent years, many foreign scholars have evaluated the ecosystem service value of a certain area or a certain land use type. Paudyaletal.[11], Gashawetal.[12], Davidsonetal.[13], and Sotoetal.[14]used analytical models to assess the ecosystem service value of rivers and lakes, wetlands and forests. Some scholars have explored the destruction of the ecological environment in the process of developing production in some regions and countries. Arowolo assessed the ecosystem service value in Nigeria from 2000 to 2010 based on the value transfer method. The total ESV in the study area decreased by 4.83%, and about 70% of Nigeria’s ecosystem services were degraded[15].

2.2 Advances in domestic researchBasically, after the publication of the research results of Costanzaetal.in 1997, domestic scholars carried out extensive studies. In addition to conducting research on ESV based on land use and land cover change (LUCC), domestic scholars have carried out research on driving forces, ecological risks and ecological compensation, and some scholars have introduced prediction models to start simulation research. Xiao Hanetal.[16]and Zong Yueguangetal.[17]used engineering method and alternative cost method to estimate forest ESV. Xie Gaodietal.revised the equivalent factor of Costanzaetal.and constructed an equivalent factor system in line with national conditions[18-19]. Liu Yongqiangetal.[20], Xue Minggaoetal.[21], Li Yuanyuanetal.[22]analyzed the response relationship between ecosystem service value and land use change. Chen Wanxuetal.[23]and Yan Yanetal.[24]assessed the ecosystem service value of river basins by introducing ecological change degree and regression analysis. Using the GWR model, Geng Tianweietal.[25]analyzed the strength of the dominant factors causing ESV changes. Ouyang Xiaoetal.[26], Wang Peijunetal.[27], Chu Zhietal.[28], and Chen Bingfeietal.[29]used the FLUS model to simulate the impact of land use change on ESV under different situations. Yu Miaoetal.[30]and Zhang Mufengetal.[31]used the CLUE-S model to estimate the ESV. Zhang Xiaoyaoetal.[32]and Wang Jinfengetal.[33]used the Markov-CA model to predict the ecosystem service value. Li Huietal.[34]analyzed the correlation between ESV and ecological risk index in the Three Gorges Reservoir area. In recent years, many domestic scholars have studied the future ecosystem service value with the help of geographic prediction models, which have enriched and improved the value assessment theory.

3 Estimation methods and technical means

Based on the different value units, the methods can be divided into the ecological service product price method and the value equivalent factor method. In recent years, in the research of ESV calculation, domestic and foreign scholars have introduced some new technical means and model methods into different assessment methods, and successfully combined these models with ecosystem service value assessment, and have made significant achievements.

3.1 Ecological service product price methodThe ecological service product price method is based on statistics and market value theory. The ecological service product price method usually adopts the direct market method, the alternative market method and the simulated market method, and the various services provided by the region are reflected in the form of monetary value. The assessment of ecosystem service value based on this method requires a large amount of data and has many assessment calculation steps, but the result of the land value assessment is highly accurate, which is suitable for the research on the ecosystem service value of townships and towns with high precision. If an inappropriate calculation method is selected and some basic data are missing, the assessment results will be not representative. Different methods will be used in the assessment, mainly market method, cost method, shadow price method, substitution method,etc.With the development of 3S technology, based on ecological data, the value calculation method is optimized, and the model is constructed based on GIS to reflect the spatial distribution and changes of the assessed value in the region. The InVEST[35]model is relatively mature, and is widely used in ecosystem service value assessment (Table 1).

Table 1 Technical means introduced by the ecological service product price method and its representative achievements

3.2 Value equivalent factor methodThe value equivalent factor method fully considers the characteristics of regional ecosystems and then modifies the equivalent factor, so it is suitable for assessing the value of ecosystem services in larger spatial scales such as provinces, cities and counties. This method is simple to operate, can be widely used, and is easier to combine with statistical prediction models on the basis of ecosystem service value research. At present, in the research of value assessment, some scholars have introduced the methods of geography, ecology and mathematics. The methods can be summed up as follows: index analysis method, statistical and quantitative analysis model, geographic prediction model,etc.(Table 2). With the continuous development of science and technology, the remote sensing (RS), geography information system (GIS), and global positioning system (GPS), collectively called 3S technology, is gradually applied in the field of ecological research. with the aid of 3S technology, it is able to obtain accurate and detailed geographic location and land use data in the process of estimating the value of ecosystem services, and provide support for spatial analysis of the data.

Table 2 Technical means introduced by value equivalent factor method and its representative achievements

4 Research prospects

In recent years, scholars at home and abroad have carried out various researches on the ecosystem service value, but they are still in the exploratory stage. There is no unified standard and indicator system for value assessment, dynamic value assessment is weak, less in-depth research on the value of a single service, lack of monthly and quarterly value assessment research, and lack of an assessment model that conforms to China’s national conditions. Therefore, the future research should focus on the following aspects.

4.1 Research on the spatio-temporal dynamic assessment model of innovation ecosystem service valueIn order to accurately assess the value, it is necessary to strengthen the research on the calculation of the value per unit area by the equivalent factor method. The two mainstream methods of cellular automata CA and multi-agent ABM model for land use simulation have made significant achievements in both theoretical research and practical application. It is necessary to eEstablish a set of value coefficients in line with national conditions, and dynamically simulate the spatial pattern of ESV changes with the help of prediction models. Besides, it is recommended to enrich model research on dynamic value assessment, focusing on changes in land ecosystems under different situations.

4.2 Strengthening the research on the ecosystem service value of an individual ecosystemAt present, many scholars have conducted value assessments for individual ecosystems such as wetlands, forests and grasslands. On this basis, it is necessary to comprehensively use a variety of assessment methods to innovate value assessment, and use GIS to explore the spatial pattern of ESV. The existing land resource classification system in China has some problems such as few classification levels, confusing classification standards and unclear classification standards, resulting in a lack of scientificity and logical rigor in the study of ecosystem service value[36]. These problems will lead to disagreements in how ecosystems are divided and the value of services assessed.

4.3 Cross-validation of ecosystem service value assessment methodsAt present, there are various value assessment methods and combined models, and the results obtained by different methods for value assessment are also different. Comparing the value results obtained under different assessment methods can improve the scientificity and accuracy of value estimation, and at the same time compare the advantages and disadvantages of assessment model methods, and explore suitable assessment methods for different regions. Using different assessment methods to assess the value of ecosystem services in multiple regions can also explore whether the results obtained by different assessment methods are quantitatively related, and the final assessment results can reflect the ecosystem service value of the region more comprehensively and accurately.

4.4 Research of quarterly and monthly changes of ecosystem service valueOn the time scale, most studies of ecosystem service value are on the scale of years. Most of the analysis of value change is based on five-year or ten-year intervals, and there are few studies on the monthly and quarterly changes of ESV within the same year. Studying the changes in ESV over a year in an area can find the months with the highest and lowest service value. Exploring the influence of seasonal changes on ecosystem service value can obtain the fitting curve of ESV monthly changes, and find the relationship between ESV and temperature and precipitation. In addition, according to the research, it can be seen that the changes of various land ecosystems in different months, and the service value provided for different land types is ranked according to the sensitivity of the seasons.

5 Conclusions

At the end of the 20thcentury, the value of ecosystem services attracted extensive attention from scholars both at home and abroad. With the deepening of research, the value assessment system and the standard of equivalent factor coefficient become more scientific and perfect. On the basis of a deep understanding of ecosystem service value assessment theory, exploratory experiments are carried out in the complex reality of China to seek verification methods for value assessment results. It is recommended to establish a national ESV assessment database to compare the value assessment results of different scholars in the same region and the same period, and establish a value assessment system in line with national conditions of China Besides, it is necessary to strengthen the research on the value of individual ecological services, explore the connotation of each service, and enhance the ecological value of the region. In addition, it is necessary to simulate the spatial pattern of the land ecosystem under different situations as needed to deal with the negative impact of rapid urbanization on the ecological environment, optimize the layout of land use, and enhance the service value of the land ecosystem.