Ecological Asset Assessment and Ecological Compensation Standards for Desert Nature Reserves: Evidence from Three Different Climate Zones in China

Abstract

The ecological environments of nature reserves with desert ecosystems are fragile, and it is necessary to implement scientific and effective ecological compensation strategies. However, the development of an ecological compensation theory for desert ecosystems is relatively immature, and no proprietary, theoretical basis or system has yet been formed. When formulating compensation standards for ecological protection, it is usually necessary to draw on other types of compensation theories to formulate ecological compensation strategies. This study focuses on three nature reserves located in different desert climatic zones as the research object—a hyper-arid desertification area, an arid desertification area, and a semi-arid desertification area—which serve as the main bodies for evaluating ecological assets. Considering the direct costs and opportunity costs of the ecological protection of nature reserves, we can estimate appropriate ecological compensation standards. The study’s results show that the ecological asset value per unit area and the ecological compensation standard are the greatest in the semi-arid desertification climate area. The ecological asset value per unit area of Haba Lake nature reserves is 6.59 × 10⁴ CNY/hm², and the ecological compensation standard is 1.18 × 10⁴ CNY/hm². The cost of ecological protection of Anxi nature reserves is 8204.09 × 10⁴ CNY/hm², and the ecological compensation standard is 0.15 × 10⁴ CNY/hm². The cost of ecological protection is the greatest, and the standard of ecological compensation is the lowest, in the hyper-arid desertification climate area. The ecological compensation coefficients of the hyper-arid, arid, and semi-arid desertified areas were 0.181, 0.183, and 0.180, respectively. The research results could provide a scientific basis for the formulation of differentiated ecological protection compensation standards for nature reserves with desert ecosystems, and they provide an effective theoretical basis and technical support for the construction of other types of ecological protection compensation models.

1. Introduction

At present, the constraints of ecological resources are tightening, and the trend of ecological environmental deterioration has not been fundamentally reversed. It is urgent to protect the ecological environment, and ecological protection compensation is an important means for doing so. The United Nations’ 2030 Agenda for Sustainable Development sets the goal of combating desertification by restraining and reversing land degradation, and it recommends that participants should protect, restore, and promote sustainable land use through ecological compensation. Ecological compensation is of great significance to ecological construction. The economic mechanism of ecological compensation has been implemented and applied in Chinese ecological construction projects, such as the project of returning farmland to forests, as well as the construction of nature reserves. Due to the lack of a compensation system for ecological benefits to ameliorate the actual situation in arid areas, the ecological benefits actually obtained are not very significant. As a result, the desert is constantly invaded, and local residents are reluctant to improve the ecological environment, causing problems for ecological construction in arid areas. If this continues over the long term, it will form a vicious circle, eventually leading to threats against the sustainable and healthy development of the surrounding ecological area. Therefore, it is imperative to establish a unique ecological compensation system in arid areas [1,2,3,4,5,6,7].

The practice of ecological compensation has been implemented in many countries and regions spanning all of the continents. The varying sources and methods of ecological compensation found in different countries and regions demonstrate different characteristics, including regional ones [8,9,10]. At present, the global research on ecological compensation mainly focuses on the construction of ecological compensation models and the measurement of ecological compensation standards [11,12]. In China, all regions and relevant departments have made progress in building ecological protection compensation mechanisms in an orderly manner. However, the practice of ecological compensation in China is not balanced across different fields. The practice of ecological compensation in watershed ecosystems is relatively mature, while that in desert ecosystems is relatively backward. Song C. (2021) [13] explored the ecological compensation mechanism for the windbreak and sand-fixation function of Baijitan National Nature Reserve, but did not conduct a comprehensive ecological compensation study for all ecosystem services. Bao Y.S. et al. (2019) [14] developed a framework for assessing desert ecological assets in China and discussed how to design the desert ecological compensation policy based on the assessment of desert ecological assets, but they did not adopt different ecological compensation standards according to different climatic zones and regions. Li H.T. (2017) [15] discussed ecological compensation for Haba Lake Nature Reserve based on ecosystem services and residents’ willingness to receive compensation, without considering the cost to the reserve. Zhang Y.S. (2015) [16] conducted a study on ecological compensation in the Anxi Extreme Arid Desert Reserve based on the environmental replacement cost method, but the study did not examine different desertification areas. To sum up, the current literature on ecological compensation for desert ecosystems mainly focuses on the research of ecological compensation in a one-size-fits-all manner for the entire desertification area, for a single protection area, or for a single function, but it does not consider differential compensation according to different natural conditions, nor has it yet formed a proprietary theoretical basis and system. It is often necessary to draw on other types of compensation theories. There are many difficulties in improving the geographical conditions, climatic conditions, and natural ecological conditions of desertification areas. In terms of ecological compensation, in order to consider the coordinated and unified development of regions, social equity, and unified management, China lacks a physical compensation system for the actual conditions of desertification areas, and the actual ecological benefits are not very significant, resulting in continuous desert attacks. Local residents are not willing to improve the ecological environment, and ecological construction in desertification areas is in trouble, which affects the sustainable and healthy development of the entire ecosystem [17,18,19,20,21].

Nature reserves are an important part of China’s system of natural protected areas, accounting for about 70.00% of the total area of China’s natural protected areas, and these are high-quality ecological assets [22]. China’s national nature reserves cover an area of about 986,100 km², accounting for 10.00% of the land area. They are key areas for biodiversity and ecosystem functions, and they play an important role in protecting ecological space, improving the ecological environment, practicing environmental responsibility, safeguarding national ecological security, and promoting ecological civilization. Nature reserves in desertification areas are affected by factors such as the expansion of the surrounding population, the increase in various production and management activities, the shortage of water resources, the decrease in precipitation, the industrial structure, the economic layout, the shortage of funds for nature reserves, and the highly unified compensation standard and the contradiction between population, resources, and environment are still prominent. Therefore, the present study selected different types of nature reserves in hyper-arid, arid, and semi-arid areas, quantitatively evaluated their ecological asset values, and explored the ecological compensation standard of desertification areas. It provides a scientific basis for further improving the ecological compensation policy for desert ecosystems and can better improve the regional, nature-based environment.

2. Methods

2.1. Study Area

Desert areas in China can be divided into various types according to the climate zone: hyper-arid (humidity index < 0.05), arid (0.05 ≤ humidity index < 0.20), semi-arid (0.20 ≤ humidity index < 0.50), and subhumid arid areas (0.5 ≤ humidity index ≤ 0.65). Under different climate conditions, production modes, ecosystem services, and economic development vary across different desertification areas. In order to explore the ecological compensation standards and methods in different desertification areas, the present study selected three different types of nature reserves, namely the Anxi Extreme Drought Desert National Nature Reserve in Gansu (hyper-arid zone), Hatengtaohai National Nature Reserve in Inner Mongolia (arid zone), and Haba Lake National Nature Reserve in Ningxia (semi-arid zone), as shown in Figure 1. The three nature reserves meet the following conditions: (1) The three nature reserves belong to different climatic zones, those being hyper-arid, arid, and semi-arid; (2) the three reserves are national nature reserves, have typical significance at home and abroad, have a great international influence in science or special scientific research value as nature reserves; (3) these three nature reserves are all dedicated to protecting desert ecosystems. An overview of the study area is presented in

Table 1. Overview of the study area.

Study Area	Climatic Region	Elevation (m)	Soil Type	Annual Mean
				Precipitation (mm)	Humidity Index	Drought Index	Temperature (°C)	Evaporation (mm)
Gansu Anxi Extreme Drought Desert Reserve (Anxi)	hyper-arid	1800–2334	Brown desert soil, gray brown desert soil, salt soil, meadow soil, aeolian sand soil, etc.	66.75	0.024	41.33	8.9	2758
Hatengtaohai Reserve (Hatengtaohai)	Arid	1030–2046	Gray desert soil, aeolian sand soil	119	0.060	16.69	7.6	2406
Haba Lake Reserve (Haba Lake)	Semi-arid	1300–1622	Calcareous soil, tidal soil, salt soil, new accumulation soil, aeolian sand soil, etc.	270	0.254	9.56	7.7	1064.2

.

2.2. Data Sources and Processing

The Landsat 8 OLI dataset was acquired from the Geospatial Data Cloud site of the Computer Network Information Center of the Chinese Academy of Sciences [23]. Radiometric calibration, atmospheric correction, and other preprocessing of remote sensing data were carried out using ENVI (Environment for Visualizing Images) software. Combining the data from the Second National Land Survey, reserve planning data, and field survey data, according to the “Classification of Land-Use Status” (GB/T 21010-2017), the 2018 land-use status map of the study area was divided.

Temperature, precipitation, wind speed, and other meteorological data from 2018 were downloaded from the Resource and Environment Data Cloud platform [24]. Kriging interpolation of the precipitation data from 68 meteorological and hydrological stations in the study area was conducted using ArcGIS 10.2, and grid maps with a resolution of 30 m were subsequently generated.

Digital Elevation Model (DEM) data were generated in ArcGIS 10.2 by means of interpolation, cutting, and filling digital elevation data from the Global Digital Elevation Model v2 (GDEM v2), with a high resolution of 30 m, which was sourced from the Geospatial Data Cloud [23]. Soil data were obtained from the results of the Second National Soil Survey.

The Land Vegetation Data product for 2018 can be downloaded from the official NASA website, MOD13Q1 (MODIS/Terra Vegetation Indices 16-Day L3 Global 250 m SIN Grid). The accuracy of the data was 250 m, and the data were preprocessed with Mosaic, projection conversion, band arithmetic, and image cropping.

The 2018 lease prices for different land-use types were obtained from the Land Transfer Network [25]. The socio-economic data were obtained from the 2018 National Economic and Social Development Statistical Bulletin and the 2019 Yearbook of Gansu, Inner Mongolia, and Ningxia. Data on infrastructure construction and protection structure construction were extracted from the overall planning documents the three study areas. The operation cost of the nature reserves were obtained from the 2018 revenue and expenditure summaries for the three research areas in the Analysis of Management Personnel and Fund Needs of Nature Reserves. The data standard of the depreciation life of infrastructure and equipment was obtained from the third edition of the Economic Evaluation Methods and Parameters of Construction Projects.

2.3. Assessment of Desert Ecological Assets

Gao et al. (2007) argued that ecological assets should encompass all natural resources and environments that can provide services and benefits to humans. These services and benefits include the tangible supply of physical resources, such as minerals, fruits, woods, and water resources, and ecological services in intangible and non-physical forms, such as air purification, oxygen supply, climate regulation, and landscape recreation [26]. Gao et al. (2016) further described ecological assets as organismal and derivative entities that have material and environmental production capacities and provide services and benefits to humans, including fossil energy and ecosystems [27].

Based on the existing definitions, desert ecological assets are defined as the stock of desert ecological resources and desert ecosystem services that can yield flows of products/services at the present or in the future. They can be divided into two broad categories, i.e., desert ecological resource assets and desert ecological service assets.

The present study utilizes the method of Bao et al. (2016) in evaluating the value of desert ecological assets in nature reserves [14]. We referred to the Assessment criteria of desert ecosystem services in China to evaluate the value of ecosystem services in desert system nature reserves [28].

$$V_{de}=V_{der}+V_{des}$$

(1)

$$V_{der}=V_{Land}+V_{bio}=\sum _{k=1}^K{LA}_k\times {LR}_k+\sum _{i=1}^4{LAR}_i\times {LPR}_i\times {RP}_i$$

(2)

$$V_{des}=V_{wis}+V_{scv}+V_{war}+V_{toc}+V_{bio}$$

(3)

In the formula, $V_{de}$ represents the value of desert ecological assets, $V_{der}$ represents the value of desert ecological resources, $V_{des}$ represents the value of desert ecosystem services, $V_{Land}$ represents the value of land resource assets, $L{A}_k$ represents the area of k land-use types, ${LR}_k$ represents the rent of k land-use types, $V_{bio}$ represents the value of biological resource assets, ${LAR}_i$ represents the area of Class i biological resources in the area, ${LPR}_i$ represents the productivity per unit area of class i biological resources, ${RP}_i$ represents the price of class i biological resource products, $V_{wis}$ represents the total value of windbreak and sand fixation, (CNY/a), $V_{scv}$ represents the total value of soil conservation value (CNY/a), $V_{war}$ represents the value of water resources regulation (CNY/a), $V_{toc}$ represents the total value of carbon sequestration (CNY/a), and $V_{bio}$ is the value of biodiversity conservation (CNY/a).

2.3.1. Assessment of Desert Ecological Resources Assets

(1)

Evaluation of land resources and assets

The value of land resources can be estimated by multiplying the type of land use in the study area by the area of each type of land and the associated rent [14].

(2)

Assessment of biological resources assets

Biological resources in desertification areas can be divided into five categories according to their uses: agriculture, forestry, animal husbandry, biological resources, and medicinal resources. The value of biological resource assets can be estimated on the basis of the acreage, productivity, and product price of each biological resource.

2.3.2. Desert Ecosystem Service Assets Assessment

(1)

Assessment of windbreak and sand fixation

In the present study, the Revised Wind Erosion Equation (RWEQ) was used to calculate the amount of windbreak and sand fixation [29,30,31,32,33,34]. For these calculations, we referred to the research of Gao J.L. (2013) [35].

$$V_{wis}={V_{saf}+V}_{arp}$$

(4)

In the formula, $V_{\mathrm{w}\mathrm{i}\mathrm{s}}$ represents the total value of windbreak and sand fixation (CNY/a), $V_{saf}$ represents the sand-fixation value of a desert ecosystem (CNY/a), and $V_{arp}$ represents the economic loss value reduced by windbreak and sand-fixation area (CNY/a).

(2)

Soil conservation assessment

In desertification areas, 50% of soil is transported through wind erosion to other areas to form new soil with a soil bulk density of 1.30 g/cm³. The total amount of new soil formed in the study area in 2018 was determined, and the fixed amount of soil was taken as the amount of sand fixation. Then, according to the contents of N, P, K, and organic matter at a scale of 1:1,000,000 in the Chinese soil database, the mass of N, P, K, and organic matter retained in the soil of the study area was calculated as follows:

$$V_{scv}=V_{sofr}+V_{sofx}$$

(5)

In the formula, $V_{scv}$ represents the total soil conservation value (CNY/a), $V_{sofr}$ represents the total value of soil formation in desert systems (CNY/a), and $V_{sofx}$ represents the conservation value of soil nutrients in desert systems (CNY/a).

(3)

Assessment of water resource regulation

In this study, the Penman–Monteith equation was used to estimate the amount of condensed water, and the dynamic principles of precipitation distribution, vegetation water consumption, and water balance in desert ecosystems were used to evaluate the quality of water storage in the study area. The value of water resource regulation was calculated according to different land-use types in the study area.

$$V_{war}=V_{cow}+V_{dws}$$

(6)

In the formula, $V_{war}$ represents the value of water resources regulation (CNY/a), $V_{cow}$ represents the value of condensate water (CNY/a), and $V_{dws}$ represents the desert water storage value (CNY/a).

(4)

Carbon sequestration assessment

This study employed remote sensing data and the CASA (Carnegie –Ames –Stanford Approach) model of the light energy utilization to estimate NPP (Net Primary Productivity) [36,37]. The results of remote sensing estimation of vegetation biomass were multiplied by 0.50 to convert the aboveground biomass into biomass carbon [38], and the underground biomass carbon was then calculated according to the results of Jackson et al. (1996) [39] (See

Table 2. Above-ground/below-ground biomass ratio.

Study Area	Above/Below-Ground
Anxi	0.142
Hatengtaohai	0.142
Haba Lake	0.197

). Soil organic carbon storage in the study area was estimated using the parameters obtained from the soil profile information extracted from Soils in China (1998) [40].

$$V_{toc}=V_{vec}+V_{soc}$$

(7)

In the formula, $V_{toc}$ represents the total value of carbon sequestration (CNY/a), $V_{vec}$ represents the value of carbon sequestration by vegetation (CNY/a), and $V_{soc}$ represents the value of soil carbon sequestration (CNY/a).

(5)

Biodiversity assessment

In this study, the equivalent method of ecosystem service value proposed by Xie et al. (2015) was applied to calculate the biodiversity conservation value [41].

$$V_{bio}=A{B}_i{E}_a$$

(8)

In the formula, $V_{bio}$ is the value of biodiversity (CNY/a), $A$ is the area of different land-use types, and $B_i$ is the unit area value equivalent of biodiversity conservation of Class i land-use type (

Table 3. Ecosystem service equivalent values per unit area.

Land-Use Type	Arable Land	Woodland	Grassland	Waters	Residential Land	Unutilized Land
Value equivalent	0.34	8.46	4.01	2.56	0	0.07

).

Based on the treatment method of Xie et al. (2015) [41], the net profit of grain production per unit area of farmland ecosystem is taken as the value of ecosystem services with one standard equivalent factor. The grain yield value of farmland ecosystems is mainly calculated based on the three main products of rice, wheat and maize.

$$E_a=S_r\times F_r+S_w\times F_w+S_c\times F_c$$

(9)

$S_r$, $S_w$ and $S_c$ represent the percentage (%) of the total sown area of rice, wheat and maize in the total sown area of the three crops in 2018. $F_r$, $F_w$ and $F_c$, respectively, represent the national average net profit per unit area of rice, wheat and corn in 2018 (CNY/hm²) [41].

$E_a$ is the ecosystem service value equivalent of 1 standard equivalent factor, and the economic value of the standard ecosystem service value equivalent factor is 0.21 × 10⁴ (CNY/hm²). The data were obtained from the China Statistical Yearbook 2019 and China Agricultural Product Cost and Income Data Compilation 2019 (http://www.stats.gov.cn/).

2.4. Ecological Protection Cost Accounting

2.4.1. Direct Cost of Ecological Protection

The cost of restoring, maintaining, and protecting the ecological environment is the direct cost of environmental protection and the cost and expenditure generated in reality. Based on the studies of Liu et al. (2015) and Yang et al. (2019), the present study calculated the direct cost of ecological protection in the study area according to China’s national conditions [42,43].

$$C_D=C_c+C_p{+C}_o$$

(10)

In the formula, $C_D$ is the direct cost of ecological protection, $C_c$ is the input of nature reserve construction, $C_p$ is the input of specific protection measures, and $C_o$ is the operation cost of the conservation area.

2.4.2. Opportunity Cost Accounting Method

In the ecological compensation mechanism, “opportunity cost” refers to the economic income given up and the development rights lost in order to protect the ecological environment [42]. To establish a more scientific and accurate amount of compensation for nature reserves, the characteristics of the ecosystem and regional differences should also be considered. As a reference, adjacent non-nature reserves with similar resource, environmental, and population conditions were selected for this study. The reference areas are shown in

Table 4. List of reference areas.

Nature Reserve or Reference Area	Per Capita Net Income of Rural Residents (CNY/Person)	Population of the Reserve (Persons)
Anxi	16,550	6295
Subei Mongol Autonomous County	24,951	/
Hatengtaohai	17,692	860
Hangjin Houqi	18,160	/
Haba Lake	10,685	8269
Lingwu City	14,848	/

.

$$P=(F_0-F)\times N_f$$

(11)

where $P$ is the opportunity cost, $F_0$ is the per capita net income of farmers in the reference area, $F$ is the per capita net income of farmers in the reserve, and $N_f$ is the number of agricultural populations in the reserve (Table 4).

2.5. Calculation of Ecological Compensation Coefficient and Standard

In this study, the ecological compensation coefficient (Equation (11)) was determined by referring to the method combining the Engel coefficient and the Peel growth curve model proposed by Li F. et al. (2010) [44]. Then, according to the economic development status of different climate zones, the correlation between the compensation coefficient and the level of the indicators of economic development was determined. To this end, the per capita GDP ($x_1$), total sales of consumer goods ($x_2$), resident population ($x_3$), fixed asset investment ($x_4$), per capita disposable income ($x_5$), per capita gross output value of primary industry ($x_6$), per capita gross output value of secondary industry ($x_7$), and per capita gross output value of tertiary industry ($x_8$) were selected [45,46].

The multivariate linear stepwise regression method in SPSS (Statistical Product and Service Solutions) was used to construct the measurement model of the compensation coefficient and the above indexes.

$$y=\frac{1}{1+{4.65}^{e^{-0.052\left(\frac{1}{En}-3\right)}}}$$

(12)

where y is the ecological compensation coefficient and En is the Engel coefficient.

In order to effectively improve the efficiency of ecological compensation, the highest standard of ecological compensation for desert areas should not exceed the social benefits they provide to human beings, and the minimum should not be lower than the minimum cost to maintain their sustainability. The calculation formula of the ecological compensation standard used in the present study is as follows:

$$R=y\times \left(M-C_D-P\right)$$

(13)

where $R$ is the ecological compensation standard (CNY/hm²), $M$ is the value of the ecological assets (CNY/hm²), $C_D$ is the direct cost of ecological protection, $P$ is the opportunity cost, and $y$ is the ecological compensation coefficient.

2.6. Multiple Stepwise Regression Analysis

The present study only utilized the method of stepwise regression method and used SPSS v20 to create a multiple linear regression equation of the ecological compensation coefficient and the economic development level index [47,48].

$$Y={\beta }_0+{\beta }_1{X}_1+\dots +{\beta }_p{X}_p+\epsilon$$

(14)

In this study, the dependent variable is the ecological compensation coefficient $Y$, the independent variable $X$ comprises 8 indicators of per capita GDP (10⁸ CNY), total sales of social consumer goods (10⁴ CNY), resident population (10⁸ people), total investment in fixed assets (10⁸ CNY), per capita disposable income (10⁴ CNY), per capita gross output value of the primary industry (10⁴ CNY), per capita gross output value of the secondary industry (10⁴ CNY), per capita gross output value of the tertiary industry (10⁴ CNY), and ${\beta }_0$, which is the constant. ${\beta }_1$, …,${\beta }_p$ is the partial regression coefficient, $p$ is the number of independent variables, and $\epsilon$ is the residual.

3. Results

3.1. Ecological Assets Assessment

3.1.1. Land-Use Classification

Based on remote sensing image data, combined with statistical data and field survey data, maps of the land-use status of the nature reserves in 2018 were drawn, as shown in Figure 2.

In Anxi Nature Reserve, unutilized land accounted for the greatest proportion (99.60%), followed by grassland (0.25%), and residential land accounted for the lowest proportion (0.15%). It did not include arable land, forest land, or water. In Hatengtaohai Nature Reserve, unutilized land accounted for the greatest proportion (66.04%), followed by grassland (21.76%). In Haba Lake Nature Reserve, grassland accounted for the greatest proportion (70.38%), and water accounted for the lowest proportion (0.76%).

3.1.2. Value of Desert Ecological Resource Assets

The total values of ecological resource assets in the Anxi, Hatengtaohai, and Haba Lake Reserves in 2018 were found to be 44.65 × 10⁸ CNY, 5.70 × 10⁸ CNY, and 5.56 × 10⁸ CNY, respectively (

Table 5. Values of ecological resource assets.

Nature Reserve	Land Resource (108 CNY)	Biological Resources (108 CNY)	Ecological Resources (108 CNY)	Total Area (hm2)	Value of Ecological Resource Assets per Unit Area (104 CNY/hm2)
Anxi	44.53	0.12	44.65	583,863.86	0.76
Hatengtaohai	3.69	2.02	5.70	123,103.68	0.46
Haba Lake	5.02	0.54	5.56	85,753.81	0.65

). The values of ecological resource assets per unit area followed the order: Anxi Reserve (0.76 × 10⁴ CNY/hm²) > Haba Lake (0.65 × 10⁴ CNY/hm²) > Hatengtaohai (0.46 × 10⁴ CNY/hm²). In terms of different climatic zones, the ecological resource asset values per unit area followed the order: hyper-arid desertification area > semi-arid desertification area > arid desertification area. The value of ecological resource assets in the study area was primarily derived from the value of land assets. The value of land assets in Anxi, Haba Lake, and Hatengtaohai accounted for 99.7%, 64.7%, and 90.2% of the value of ecological resource assets, respectively.

3.1.3. Assessment of Desert Ecosystem Service Assets

The value of ecological service assets varied among different reserves. According to the proportional maps of different ecosystem service values (Figure 3), ecosystem service values in Anxi followed the order soil conservation (59.00%) > biodiversity conservation (17.12%) > carbon storage (16.56%) > windbreak and sand fixation (6.10%) > water resources regulation (1.22%). In Hatengtaohai, the order was water resource regulation (44.41%) > soil conservation (29.46%) > biodiversity conservation (20.74%) > carbon storage (4.98%) > windbreak and sand fixation (0.41%). In Haba Lake, the order was water resource regulation (83.35%) > biodiversity conservation (15.40%) > carbon storage (1.13%) > soil conservation (0.12%) > windbreak and sand fixation (0.001%).

The values of ecosystem services in nature reserves are shown in

Table 6. Values of ecosystem services in nature reserves per unit area.

Ecosystem Services	Haba Lake		Hatengtaohai		Anxi
	Values of Ecosystem Services (108 CNY)	Ecosystem Service Value per Unit Area (104 CNY/hm2)	Values of Ecosystem Services (108 CNY)	Ecosystem Service Value per Unit Area (104 CNY/hm2)	Values of Ecosystem Services (108 CNY)	Ecosystem Service Value per Unit Area (104 CNY/hm2)
Windbreak and sand fixation	0.00	0.000056	0.06	0.0049	0.35	0.006
Soil conservation	0.06	0.0071	4.31	0.35	3.37	0.058
Water resources regulation	42.50	4.96	6.50	0.53	0.07	0.0012
Carbon storage	0.57	0.067	0.73	0.06	0.95	0.016
Biodiversity conservation	7.85	0.92	3.04	0.25	0.98	0.017
Total	50.99	5.95	14.64	1.19	5.72	0.098

. The total value of ecosystem services followed the order Haba Lake (50.99 × 10⁸ CNY) > Hatengtaohai (14.64 × 10⁸ CNY) > Anxi (5.72 × 10⁸ CNY). The ecosystem service value per unit area followed the order Haba Lake (5.95 × 10⁴ CNY/hm²) > Hatengtaohai (1.19 × 10⁴ CNY/hm²) > Anxi (0.098 × 10⁴ CNY/hm²). In terms of different climatic zones, the ecosystem service value per unit area followed the order semi-arid desertification area > arid desertification area > hyper-arid desertification area.

3.1.4. Value of Desert Ecological Assets

Haba Lake was found to have the greatest value of ecological assets (56.54 × 10⁸ CNY), followed by Anxi (50.37 × 10⁸ CNY), and Hatengtaohai had the lowest value (20.34 × 10⁴ CNY) (

Table 7. Value of ecological assets in the study area and ecological asset value per unit area of the study area.

Value	Haba Lake		Anxi		Hatengtaohai
	Total Value (108 CNY)	Value of per Unit Area (104 CNY/hm2)	Total Value (108 CNY)	Value of per Unit Area (104 CNY/hm2)	Total Value (108 CNY)	Value of per Unit Area (104 CNY/hm2)
Ecological resource assets	5.56	0.65	44.65	0.76	5.70	0.46
Ecosystem service	50.99	5.95	5.72	0.098	14.64	1.19
Ecological asset	56.54	6.59	50.37	0.86	20.34	1.65

). The value of ecological assets per unit area in the study area was as follows: Haba Lake (6.59 × 10⁴ CNY/hm²) > Hatengtaohai (1.65 × 10⁴ CNY/hm²) > Anxi (0.86 × 10⁴ CNY/hm²). In nature reserves, the main source of the ecological asset value is ecosystem services; the value of ecosystem services accounted for 71.98% in Hatengtaohai and 90.17% in Haba Lake. However, in Anxi, the main source was ecological resource assets, accounting for 88.64%.

3.2. Ecological Protection Costs

Ecological protection costs include direct costs and opportunity costs (

Table 8. Cost of ecological protection.

Nature Reserve	Direct Cost	Opportunity Cost	Total
Anxi	2915.66	5288.43	8204.09
Haba Lake	1509.84	3442.38	4952.22
Hatengtaohai	752.68	40.25	792.93

Unit: 10⁴ CNY.

). The cost of ecological protection in Anxi was the greatest (8204.09 × 10⁴ CNY), followed by Haba Lake (4952.22 × 10⁴ CNY), and Hatengtaohai Reserve, which had the lowest cost (792.93 × 10⁴ CNY). The ecological protection cost per unit area of the three reserves followed the order: Haba Lake (0.059 × 10⁴ CNY/hm²) > Anxi (0.010 × 10⁴ CNY/hm²) > Hatengtaohai (0.0064 × 10⁴ CNY/hm²). From the perspective of different climatic zones, the protection cost followed the order semi-arid desertification area > hyper-arid desertification area > arid desertification area.

The proportion of ecological protection cost differed among the nature reserves (Figure 4). The proportion of direct costs for ecological protection costs followed the order Hatengtaohai (94.92%) > Anxi (35.54%) > Haba Lake (30.49%). The proportion of opportunity costs followed the order Haba Lake 69.51% > Anxi (64.46%) > Hatengtaohai (5.08%).

The direct cost includes three aspects: the infrastructure construction input cost, the daily management and operation cost, and the protection measure input. According to the overall plan of the reserves and the annual statements, the investment costs for infrastructure construction in Anxi, Hatengtaohai, and Haba Lake were 2173.75 × 10⁴ CNY, 222.364 × 10⁴ CNY, and 319.27 × 10⁴ CNY, respectively. The input costs of protection measures were 151.5 × 10⁴ CNY, 121.27 × 10⁴ CNY, and 213.24 × 10⁴ CNY, respectively, and the daily management and operation costs were 590.41 × 10⁴ CNY, 409.05 × 10⁴ CNY, and 977.33 × 10⁴ CNY, respectively. The three costs were combined to determine the direct cost of the nature reserve. Among them, the direct cost of ecological protection in Anxi was the greatest at 2915.66 × 10⁴ CNY, followed by Haba Lake (1509.84 × 10⁴ CNY), and that of Hatengtaohai was the lowest (752.68 × 10⁴ CNY). In terms of the direct cost per unit area of ecological protection (

Table 9. Costs of ecological protection in nature reserves.

Nature Reserve	Direct Cost			Opportunity Cost	Total
	Infrastructure Construction	Protective Measure	Daily Management Operation
Haba Lake	0.0038	0.0025	0.012	0.041	0.06
Anxi	0.0027	0.0002	0.0007	0.0066	0.01
Hatengtaohai	0.0018	0.0010	0.0033	0.0003	0.006

(10⁴ CNY/hm²).

), the direct cost of Haba Lake was the greatest at 0.018 × 10⁴ CNY/hm², followed by Hatengtaohai (0.006 × 10⁴ CNY/hm²), and that of Anxi was the lowest (0.0036 × 10⁴ CNY/hm²). In terms of different climatic zones, the ecological protection cost per unit area of nature reserves followed the order hyper-arid desertification areas > semi-arid desertification area > arid desertification area.

The total opportunity cost of Anxi was the greatest at 5288.43 × 10⁴ CNY, followed by Haba Lake Reserve (3442.39 × 10⁴ CNY), and that of Hatengtaohai was the lowest (40.25 × 10⁴ CNY).

Owing to the large differences in their areas, the opportunity costs per unit area of the three nature reserves varied widely (Table 9). Haba Lake Reserve is located in a semi-arid climatic zone, and it had the greatest opportunity cost per unit area at 0.041 × 10⁴ CNY/hm². The opportunity cost per unit area of Anxi was lower than 0.0066 × 10⁴ CNY/hm², and that of Hatengtaohai was only 0.0003 × 10⁴ CNY/hm².

3.3. Measurement of Ecological Compensation Standards

By determining the correlation between the compensation coefficient and the indicators representing the level of economic development (

Table 10. Correlation between the compensation coefficient and the indicators representing the level of economic development.

Desertification Area	Representative Research Area	Regression Function	R2	p	The Ecological Compensation Coefficients
Hyper-arid desertification area	Anxi	$y_1=-0.002x_8+3.445x_1+0.183$	0.652	p < 0.05	0.181
Arid desertification area	Hatengtaohai	$y_2=13.122x_1-0.004x_5-0.001x_7+4.651\times {10}^{-6}{x}_4-0.127x_3+0.188$	0.908	p < 0.05	0.183
Semi-arid desertification area	Haba Lake	$y_3=13.254x_1-0.006x_5+0.223x_3+0.186$	0.712	p < 0.05	0.180

), the constituent indicators of the compensation coefficient were found to vary among the different climate zones. The calculation model of the compensation coefficient in the hyper-arid desertification area was $y_1=-0.002x_8+3.445x_1+0.183$, and the main indicators affecting the compensation coefficient included per capita tertiary industry income and per capita GDP. The model for the arid desertification area was $y_2=13.122x_1-0.004x_5-0.001x_7+4.651\times {10}^{-6}{x}_4-0.127x_3+0.188$, and the main indicators affecting the compensation coefficient included per capita GDP, per capita disposable income, per capita secondary industry income, and total investment in fixed assets. The model for the semi-arid desertification area was $y_3=13.254x_1-0.006x_5+0.223x_3+0.186$, and the main indicators affecting the compensation coefficient included per capita GDP, per capita disposable income, and population. The ecological compensation coefficients of the hyper-arid, arid, and semi-arid desertification areas were 0.181, 0.183, and 0.180, respectively.

The net income of the ecological asset price was corrected using the ecological compensation coefficient. Subsequently, the ecological compensation quota for nature reserves were calculated (

Table 11. Ecological compensation quota for nature reserves.

Representative Research Area	The Value of Ecological Assets per Unit Area (104 CNY/hm2)	The Cost per Unit Area of Ecological Protection (104 CNY/hm2)	The Ecological Compensation Limits (104 CNY/hm2)
Anxi	0.86	0.01	0.15
Hatengtaohai	1.65	0.006	0.30
Haba Lake	6.59	0.06	1.18

). The ecological compensation quotas of Haba Lake, Hatengtaohai, and Anxi were 1.18 × 10⁴ CNY/hm², 0.30 × 10⁴ CNY/hm², and 0.15 × 10⁴ CNY/hm², respectively.

4. Discussion

4.1. Comparison with Ecological Compensation Standards in Different Regions

At present, the ecological compensation standard based on ecosystem service value in China ranges from 0.0935 × 10⁴ to 1.62 × 10⁴ CNY/hm² [19,49,50,51,52]. This is mainly due to the fact that the difference in geographical factor endowment is an important factor affecting the ecological compensation standard. The study area is located in the arid desertification region of Northwest China, where precipitation is scarce, and the evaporation intensity is high. This region has very fragile ecosystems that are sensitive to human activities. Moreover, the ecosystem capacity is weak, and the ecological restoration cost is high. At the same time, the protection area is large and the pipeline scope is wide, thus increasing the protection expenditure [53]. Therefore, the ecological compensation values determined in the present study are essentially consistent with the range of ecological compensation standards obtained by other scholars, but the overall amount is higher. The ecological compensation standards of the three study areas are also very different, mainly because they are located in different desert climatic zones and the types of nature reserves are different. The ecological asset value per unit area and ecological protection cost per unit area are the greatest for the Haba Lake Reserve in the semi-arid region. The ecological asset value per unit area of the Hatengtaohai Reserve in the arid area is higher than that of Anxi in the hyper-arid area, but its ecological protection cost is lower than that of Anxi. Therefore, the ecological compensation amount varies widely among the three study areas. The ecological compensation standard should be calculated according to the actual situation of the compensation area.

4.2. Uncertainty in Ecological Compensation

In the process of assessing ecological assets, this study calculated only the annual value provided by desert ecosystems, underestimating the actual value of desert ecological assets. Furthermore, only ecological assets and ecological compensation for nature reserves in desertification areas were calculated. Future research should investigate ecological compensation beyond nature reserves. More comprehensive and scientific estimations of ecological compensation standards in desertification areas can be achieved only through complete consideration. The method of calculating ecological compensation according to the direct input and opportunity cost of ecological conservationists has been recognized in a large number of studies [54,55]. However, this method ignores the sustainable development of local industries and the restoration of the ecological environment; thus, using such a method cannot give full play to the role of ecological compensation, and it cannot guarantee the sustainable health of ecological environments in the long term [50]. As local residents strongly depend on ecological compensation, they will lose their basic sources of income when the subsidies stop, which will undoubtedly weaken the effect of the implementation of ecological compensation policies significantly [56,57]. Therefore, China should take the national nature reserves as the entry point, absorb ecological compensation methods from all over the world, integrate China’s national conditions to carry out experiments and attempts, and formulate ecological compensation standards scientifically and reasonably [19,58]. This is a significant step toward improving the protection and management of nature reserves in China, gradually easing conflicts and achieving sustainable development.

4.3. Future Ecological Compensation

Ecological compensation is an important measure to solve land degradation. China has carried out trials of compensation for desert ecological protection in six provinces, including Inner Mongolia, Tibet and Xinjiang et al. The government provided funds to nature reserves, mainly for the construction of fencing facilities, the erection of sand barriers, the construction and maintenance of supporting facilities, and the construction of warning signs. The Haba Lake Nature Reserve has implemented the compensation system of forest ecological benefit and wetland ecological benefit, the Anxi Nature Reserve has only carried out ecological compensation for grassland vegetation restoration, however, the Hatengtaohai Nature Reserve has not implemented the ecological compensation system at present, and more efforts should be made to strive for ecological compensation policies in the future. In the research of desert ecological compensation, we can refer to the horizontal compensation method of river basins, and share the ecological protection cost of nature reserves according to the ecosystem service benefits enjoyed by the administrative regions within the ecological benefit radiation range, and determine the ecological protection compensation amount payable by each administrative region.

5. Conclusions

Desert ecosystems are sparsely populated and ecologically fragile. The innovation in this study is the selection of nature reserves in different climate zones of desert ecosystems, enabling us to build ecological compensation standards for nature reserves in different desert climate zones based on the concepts of near-nature ecological restoration, ecological asset value, and ecological protection costs. The following conclusions can be drawn:

(1)

As the study areas are located in different desert climatic zones and different types of nature reserves, the ecological asset value per unit area and ecological protection cost per unit area show wide variations, with the greatest values in the Haba Lake Reserve in the semi-arid region. The ecological asset value per unit area of the Hatengtaohai Reserve in the arid area is higher than that of Anxi in the hyper-arid area, but its ecological protection cost is lower than that of Anxi.

(2)

The ecological compensation coefficients determined using the stepwise linear regression method were 0.181, 0.183, and 0.180 for the hyper-arid, arid, and semi-arid desertification areas, respectively.

(3)

The amount of appropriate ecological compensation varies among the three desertification areas owing to their different climatic zones, types of nature reserves, and social and economic development levels. Specifically, semi-arid desertification areas have the greatest ecological compensation value, followed by arid desertification areas and hyper-arid desertification areas. The corresponding ecological compensation quotas of the Anxi Reserve, Hatengtaohai Reserve, and Haba Lake Reserve are 1.18 × 10⁴ CNY/hm², 0.30 × 10⁴ CNY/hm², and 0.15 × 10⁴ CNY/hm², respectively. The enthusiasm of farmers and herdsmen regarding the protection of the ecological environment can be mobilized only by giving them full ecological compensation.

6. Shortcomings and Outlook

This study explores ecological compensation standards for nature reserves in different desertification climate areas based on the value of their ecological assets, the direct input of ecological conservators, and the opportunity costs. This method has been recognized in a large number of recent studies in the literature. However, the shortcoming of this method is that compensation is based on current ecological conditions. It does not consider the sustainable management and operation modes after local industrial development and ecological environment restoration have occurred, which will cause the ecological compensation to be merely a temporary effect, and it is necessary to explore a dynamic ecological compensation standard based on the trend changes in desert ecosystems to ensure the sustainable development of desert ecosystems and residents’ production and lives.

Due to the fragile ecological environment of desertification nature reserves, establishing nature reserves is an effective way to protect desert ecosystems. However, after the establishment of nature reserves, the production and lives of local residents are greatly affected, and ecological compensation achieved solely through funding cannot fundamentally solve the livelihood problems of residents in the reserves. It is necessary to consider the impact on local residents after the establishment of nature reserves. Therefore, in addition to basic financial compensation, ecological compensation should also focus on increasing the infrastructure construction in poor areas and on increasing capital investments in healthcare, education, and other livelihood projects. In addition, it is necessary to actively expand employment channels, increase the number of re-employment possibilities, and promote the people’s production and income. Under the premise of ecological protection in the reserve, it is important to support the development of characteristic agriculture and promote the sustainable and efficient development of the social economy in the reserve. For young people and school-aged children, the problems of difficult schooling and employment can be alleviated through tuition subsidies, employment training, and other programs designed to lessen the impact of ecological construction on the livelihoods of ecological protected families so as to achieve the goal of compensation.