Research on the Territorial Ecological Restoration of Counties for the Increase of Carbon Sinks—A Case Study of Wensu County, Xinjiang Uygur Autonomous Region, China

Abstract

As global climate continues to change, it is pressing to integrate the carbon peaking and carbon neutrality goals into territorial spatial planning. While little existing ecological restoration research focuses on counties in western China, particularly arid areas of northwest China, this research took Wensu County of the Xinjiang Uygur Autonomous Region in China as the study case, evaluated the carbon sequestration capacity and carbon storage of the current carbon sinks, identified the spatial pattern of carbon sinks, and proposed the territorial ecological restoration approaches to increasing carbon sinks. The evaluation results show that the importance level of carbon sinks varies significantly across geographical environments of the county, where one primary carbon sink, two secondary carbon sinks, and potential carbon sinks with a total area of 2259.81 km² were identified. This research extracted eight typical land use patterns based on current land use and proposed ecological restoration strategies accordingly. This research shows a way to integrate carbon peaking and carbon neutrality goals in territorial spatial planning, which is instrumental for carbon sink management in the arid areas of northwest China and provides a referable paradigm for regions with similar geographical conditions.

● Focuses on ecological restoration in a county in the arid areas of northwest China, aiming for carbon sink increase

● Evaluates the carbon sequestration and storage patterns of current carbon sinks in the study area and identifies the spatial pattern of carbon sink importance level

● Extracts typical land use patterns based on current land use and proposes ecological restoration strategies accordingly

Graphical abstract

Keywords

Carbon Sink Increase / Carbon Sequestration / Carbon Storage / County Region / Arid Areas of Northwest China / Ecological Restoration / Territorial Spatial Planning

1 Introduction

Climate change threatens natural ecosystems and socioeconomic systems, with carbon dioxide viewed as the main driving force^[1]. To promote ecological civilization construction and cope with global climate change, China first proposed the carbon peaking and carbon neutrality goals ("dual carbon" goals hereafter) in 2020^[2] and addressed to integrate it into the overall plan of ecological civilization construction in 2021^[3].

The achievement of "dual carbon" goals depends on both controlling carbon emissions and increasing carbon storage in ecosystems, and ecological restoration has been proven effective in enhancing ecosystem carbon sequestration^[4]~[6]. To increase carbon sinks via ecological restoration, it is essential to evaluate the current ones with scientific methods. At present, it is common to analyze the spatial pattern or conduct spatio-temporal evolution of carbon sinks based on remote sensing data^[7]. The measuring and calculating methods include the calculation of net ecosystem production (NEP)^[8], simulation with the InVEST Carbon model^[9], and evaluation with carbon sink coefficients^[10]. Based on their evaluation results, some scholars proposed strategies for zoning and managing ecological spaces^[11]. However, most existing research focuses on larger scales of national, regional, or provincial^[8][10][12], some focuses on cities or counties in developed regions^[11][13], while little studies counties in western China, particularly the arid areas of northwest China.

As for ecological restoration, existing research reviewed the impact factors of ecosystem carbon sequestration and the mechanism of carbon sink increase^[14]; analyzed the current situation of utilizing ecological restoration strategies to promote carbon sequestration and carbon sink^[15]; and explored approaches to restoring forest^[16], grassland^[17], cultivated land^[18], wetland^[19], desert^[20], and marine^[21] ecosystems based on field measurement, literature review, case study, and policy interpretation. Yet few studies proposed restoration strategies incorporating ecological spatial patterns.

Focusing on Wensu County in the Xinjiang Uygur Autonomous Region of China, this research evaluated current carbon sinks in the study area, identified spatial pattern of these carbon sinks, and developed ecological restoration strategies according to different land use spatial patterns. Unlike those in the developed Beijing–Tianjin–Hebei region and coastal southeast China, most counties in the arid areas of northwest China cover relatively larger areas with less development land and more ecologically vulnerable non-development land^[22][23], where ecological restoration becomes a pressing task. This research aims to put forward ecological restoration approaches to increasing carbon sinks in the counties in the arid areas of northwest China, promoting the integration of "dual carbon" goals in territorial spatial planning and providing a referable paradigm for areas with similar geographical conditions. This paper discusses the following questions.

1) What is the spatial pattern of carbon sinks in Wensu County?

2) What are the territorial ecological restoration approaches to increasing carbon sinks?

And 3) how do the findings of this research contribute to carbon sink management in the arid areas of northwest China and similar regions?

2 Overview of Study Area and Data

2.1 Study Area

Administered by Aksu Prefecture in the Xinjiang Uygur Autonomous Region, Wensu County (40°52'–42°21'N, 79°28'–81°28'E) is located at the south foot of the Tomur Peak in the middle of Tianshan Mountain and borders the north edge of the Tarim Basin. Covering a total area of 14,600 km², Wensu County stretches 153 km from east to west and 167 km from north to south (Fig.1)^①. With elevations ranging from 800 m to 8,000 m, this county is higher in the northern mountains and lower in the southern plains and hills. Wensu County has a temperate continental arid climate with little rainfall, high evaporation, abundant sunshine, an annual mean temperature of 10.10℃, annual mean precipitation of 65.4 mm, and annual mean frost-free period of 185 days.^② The county has extensive natural areas indicating high carbon sink potential, with the major soil types being gypsisols, petrified gypsisols, and luvic calcisols; the primary vegetation types being desert and meadow; and the most common land use types being unused land, grassland, and farmland (Fig.1)^③.

① Part of Aral City is surrounded by Wensu County. Although not administered by Wensu County, this exclave was included in the study area for ecological integrity. Limited by availability of the data, the raster data of this research covers about 14,200 km².

② Information about Wensu County was sourced from the official website of the Wensu Government.

③ This research adopted the land use classification system proposed in China's Multi-Period Land Use and Land Cover Remote Sensing Monitoring Dataset (CNLUCC) and related data sources from the Resource and Environment Science and Data Center, Chinese Academy of Sciences.

2.2 Data Sources and Preprocessing

The research evaluated the current carbon sinks in Wensu County and identified their spatial pattern based on multiple data sources. Considering the update frequency, availability, spatio-temporal synchronization, and data quality in recent years, the research team utilized the multi-source data of Wensu County from 2015 (Tab.1). All data were projected into the Xi'an Geodetic Coordinate System 1980 and transformed into raster layers (1-km resolution).

3 Research Methods

3.1 Research Framework

The research followed the framework of "current carbon sink evaluation–spatial pattern identification–restoration strategy development." The research team first evaluated the carbon sequestration, carbon storage, and importance level of the current carbon sinks in Wensu County, then identified the spatial patterns of these carbon sinks. Lastly, based on the above analyses and approaches to increasing carbon sequestration and carbon sinks in existing studies, the research team proposed ecological restoration strategies for local land use spatial patterns (Fig.2).

3.2 Current Carbon Sink Evaluation

Ecological restoration can disturb the land, affecting vegetation carbon sequestration and storage. Therefore, it is necessary to comprehensively assess the carbon sequestration capacity ("flow") and storage ("stock") patterns of current carbon sinks in Wensu County, thereby analyzing the spatial pattern of the carbon sink importance level. The evaluation tool adopted is ArcGIS 10.3.

3.2.1 Carbon Sequestration Capacity Evaluation

Carbon sequestration capacity was measured with NEP, which is the difference between the net primary production (NPP) and the soil heterotrophic respiration (R_H)^[24][25], i.e.,

(1)\mathrm{N}\mathrm{E}\mathrm{P}=\mathrm{N}\mathrm{P}\mathrm{P}-R_{\mathrm{H}},

(2)R_{\mathrm{H}}=0.22\times [\exp (0.0913T)+\ln (0.3145A+1)]\times 30\times 46.5\mathrm{\%}\text{,}

where T is the monthly mean temperature (℃) and A is the monthly total precipitation (mm).

3.2.2 Carbon Storage Evaluation

Wensu County has a high soil carbonate content. The research team evaluated both soil and vegetation carbon storage. The soil carbon storage is composed of topsoil inorganic carbon (P_ic), topsoil organic carbon (P_oc), subsoil inorganic carbon (S_ic), and subsoil organic carbon (S_oc). Topsoil and subsoil are the soil within 30 cm depth and 30 ~ 100 cm depth, respectively. The total carbon storage of the soil within 100 cm depth (C_soil) can be calculated with Eq. (3):

(3)C_{\text{soil}}=\left(P_{\text{ic}}+P_{\text{oc}}\right)\times 0.3+\left(S_{\text{ic}}+S_{\text{oc}}\right)\times 0.7\text{.}

As vegetation carbon density largely depends on vegetation types^[26], of which carbon densities were determined based on existing research and site conditions including location, elevation, and climatic characteristics^[27]~[29] (Tab.2, Fig.3).

3.2.3 Carbon Sink Importance Level Evaluation

Addressing equal importance on carbon sequestration capacity and carbon storage, the researchers gave equal weight to those indicators. First, normalize NEP, vegetation carbon density, and soil carbon density according to Eq. (4). Second, overlay the obtained results to score the carbon sink importance level (I) with Eq. (5). Then, rate the results as "very high, " "high, " "moderate, " "low, " and "very low" with natural breaks classification method.

(4)X^{\mathrm{\prime }}=\frac{X-X_{min}}{X_{max}-X_{min}},

(5)I=0.5\times X_{\text{NEP}}^{\mathrm{\prime }}+0.25\times X^{\mathrm{\prime }}{}_{\text{veg}}+0.25\times X_{\text{soil}}^{\mathrm{\prime }},

where X' is the normalization result; X_NEP^', X_veg^', and X_soil^' are the normalization results of NEP, vegetation carbon density, and soil carbon density, respectively.

3.3 Spatial Pattern of Carbon Sinks

Referring to the relevant concepts of spatial pattern in landscape ecology, this research recognized the carbon sinks in Wensu County in three spatial categories based on their importance level, namely primary, secondary, and potential carbon sinks (Tab.3).

Based on the importance level evaluation results of carbon sinks, areas rated as "very high" and "high" were identified as the primary and secondary carbon sinks that should be managed according to land use boundaries.

As natural land with higher connectivity can better perform ecological functions^[30][31], the research team proposed to identify the potential carbon sinks to connect the primary and secondary carbon sinks, which have high feasibility of restoring ecosystem and increasing carbon sinks at low cost and are prone to generate carbon emissions that need to be sequestered locally. Accordingly, the research team selected relevant resistance factors and calculated with the minimum cumulative resistance (MCR) model. Areas with low resistance level were identified as potential carbon sinks. Areas featuring higher elevation, steeper slopes, lower annual accumulated temperature, or less annual precipitation are less suitable for plant growth^[32]~[34] and more vulnerable to human intervention^[35], making ecological restoration more challenging^[36]. In this sense, slope, elevation, land use, annual accumulated temperature, annual precipitation, and population density were chosen as the resistance factors and then graded based on site conditions. Weights of these resistance factors were drawn with the entropy weight method^[37][38] in Stata (Tab.4). The resistance level of each factor (Tab.5) was assigned a value before a weighted superposition was applied in ArcGIS (Fig.4, Fig.5). By setting the primary and secondary carbon sinks as source patches, the potential carbon sinks were identified with Eq. (6),

(6)MCR=f_{min}{\sum }_{j=n}^{i=m}\left(D_{ij}\times R_i\right),

where D_ij is the physical distance between the ecological source patch j and the landscape unit i, R_i is the resistance coefficient, and f is the positive correlation between minimum cumulative resistance and ecological processes^[35][39].

3.4 Ecological Restoration Strategy Development

After analyzing the current land use in the primary, secondary, and potential carbon sinks, this research extracted typical spatial patterns of land use. Referring to existing research^[40]~[46], varied ecological restoration strategies, as well as management approaches were proposed specifically for different land use spatial patterns (Tab.6) to maintain carbon sinks in unused land, moderately increase those in forests, and significantly boost those in grasslands and farmlands.

4 Results and Analyses

4.1 Current Carbon Sinks in Wensu County

4.1.1 Current Carbon Sequestration Capacity

According to the results, the NEP of Wensu County ranges between –229.125 ~ 293.020 gC·m^{– 2}·a^{– 1} and varies significantly across different areas, indicating a staggering pattern of carbon sequestration capacity. Gobi deserts and bare rock or gravel areas in southern Wensu County show low NEP with the weakest carbon sequestration capacity. The high northern areas of Tianshan Mountain exhibit poor NEP and carbon sequestration capacity due to year-round snow cover and scarce vegetation. The belt of the southern foothills of Tianshan Mountain with an elevation of 2,000 ~ 3,000 m, where the natural forest and grassland flourish, has a high NEP, suggesting the best carbon sequestration capacity in the county. In addition, the cultivated vegetation area (mainly farmland) in the southern Wensu County is characterized by a higher NEP with a great carbon sequestration capacity (Fig.6).

4.1.2 Current Carbon Storage

The central area of Wensu County has the highest soil carbon storage, followed by the southern area, and the northern area has the least (Fig.7). Higher inorganic carbon content are found in both topsoil and subsoil in the central and some southern areas of the county, and in the southeastern alluvial plain (Fig.8, Fig.9). Topsoil in the southern foothills of Tianshan Mountain with an elevation of 2,000 ~ 3,000 m is richer in organic carbon (Fig.10). Overall, Wensu County subsoil contains little organic carbon, with higher content found only in the central (1,500 ~ 2,000 m in elevation) and a few southern plain patches in the county (Fig.11).

Total vegetation carbon storage in Wensu County is 361.013 × 10⁴ t (Tab.2). The temperate grass and forb halophytic meadows contribute the most (89.059 × 10⁴ t), followed by cultivated vegetation, featuring two-year triple cropping or one-year double cropping dry farming and deciduous orchard (65.322 × 10⁴ t). The cool temperate and temperate montane coniferous forest covers a small area but boasts the highest carbon density and high carbon storage (57.007 × 10⁴ t). The carbon storage of the temperate steppe shrub desert is the lowest (0.8 × 10⁴ t) due to the small area and low carbon density.

Combining vegetation and soil carbon storage, the plain in the southern county and the southern foothills of Tianshan Mountain have the largest total carbon storage. These areas are currently dominated by forest land, grassland, and farmland. Future ecological restoration should focus more on land development and transfer, and ensure that the carbon storage remains largely undisturbed.

4.1.3 Spatial Pattern of Carbon Sink Importance Level

According to the evaluation results, the importance level of carbon sinks in different geographical environments of Wensu County varies significantly. Carbon sinks in the southern foothills of Tianshan Mountain areas (2,000 ~ 3,000 m elevation) are of "very high" and "high" importance level; those continuous in the southern and southeastern plains are of "high" and "moderate" importance level; and those in the northern Tianshan Mountain areas elevated above 3,000 m and Gobi desert and bare rock and gravel areas in the central and southeastern county are of "low" and occasionally "very low" importance level (Fig.12).

4.2 Spatial Pattern Identification of Carbon Sinks

One primary, two secondary, and one potential carbon sinks are identified in Wensu County. The primary carbon sink (1,083.87 km²) lies in the southern foothills of Tianshan Mountain, with an elevation of 2,000 ~ 4,000 m. Two secondary carbon sinks (1,899.69 km² in total) are located in the southern and southwestern plains of the county. The potential carbon sinks (2,259.81 km²) are found in the central part of the county. The land uses in the primary carbon sink are mainly high-, medium-, and low-coverage grasslands, occupying 48.60%, 11.48%, and 31.76% of the total area, respectively (Tab.7). The secondary carbon sinks are mainly dry land, which account for 86.63% of the total area (Tab.8). The potential carbon sinks feature the low-coverage grassland and bare rock and gravel, covering 51.28% and 24.81% of the total area, respectively (Tab.9, Fig.13).

4.3 Ecological Restoration Strategies

Based on the land use patterns in Wensu County, this research extracted eight typical spatial patterns of land use—one in the primary, two in the secondary, and five in the potential carbon sinks. To boost carbon sinks, the research proposed ecological restoration strategies for each typical land use spatial pattern, namely high-carbon reinforcement; carbon conservation, low-carbon development; carbon conservation expansion, replanting for carbon sequestration, restoring for carbon sequestration, maintaining high carbon storage, and carbon sequestration monitoring. Approaches to promoting ecological restoration and carbon sink benefits were proposed based on local conditions (Tab.10, Fig.14).

5 Conclusions and Discussion

5.1 Conclusions

This research evaluated current carbon sinks in Wensu County based on data from multiple sources, identified the pattern of carbon sinks in the county, and proposed ecological restoration strategies to increase carbon sinks. According to the findings, carbon sequestration capacity varies across the county. The southern foothills of Tianshan Mountain, with an elevation of 2,000~3,000 m, have the best carbon sequestration capacity. The plain in the southern county and southern foothills of Tianshan Mountain have the largest carbon storage. Carbon sink importance level varies significantly across geographical environments of the county. That in the southern foothills of Tianshan Mountain and in the southern and southeastern plains of the county are grated higher than the others. Based on the carbon sink importance level evaluation, one primary, two secondary, and potential carbon sinks with a total area of 2,259.81 km² are identified. Eight ecological restoration strategies are proposed based on local conditions to achieve the main goal of boosting carbon sinks.

5.2 Inspirations for Carbon Sink Management in the Arid Areas of Northwest China

The findings suggest that grassland and farmland are the key land use types when aiming at carbon sequestration and carbon sink enhancement in the arid areas of northwest China (Tab.7 ~ Tab.9). Although the carbon sink capacity of forests is higher than that of grasslands^[47], in Wensu County, where forests cover a small area due to the arid climate, their carbon sink benefits are therefore insignificant. Meanwhile, grassland and dry land are of higher carbon sink importance level and function as the main carbon sinks in the county. Existing research evaluating the vegetation carbon sink capacities in the arid areas of northwest China also concludes that temperate grasslands and high-quality farmlands function better as carbon sinks^[24], which further supports the carbon sink potential of grasslands and farmlands. In this sense, ecological restoration in the arid areas of northwest China should take characteristics of local vegetation into consideration to avoid changing vegetation types or maintaining non-local vegetation, which causes material and energy consumption that leads to carbon emissions. Also, it is important to avoid large disturbances in grasslands, optimize management measures, and increase organic matter in the soil to boost carbon storage^[48]. On farmlands, while photosynthesis helps carbon sequestration, respiration and production activities emit carbon^[49]. Agricultural activities such as cropping system adjustment and agricultural investment control that minimize soil disturbance, as well as management upgrade^[50][51], can further increase carbon sequestration and carbon sinks.

The identified spatial pattern of carbon sinks in Wensu County could be instrumental to carbon sink management in the arid areas of northwest China. Compared with more developed regions where most carbon sinks are found in the natural areas distant from downtown^[9][52], in Wensu County, apart from the southern foothills of Tianshan Mountain, the rural settlements and farmlands featuring intensive human activities in the southern county have shown significant carbon sink benefits. In other words, landscapes under human intervention play an essential role in increasing carbon sequestration and carbon sinks in arid areas. More research is expected to further evaluate carbon sink potentials of cultivated vegetation in arid areas, thereby guiding the efforts for increasing carbon sequestration and carbon sinks.

5.3 Values to the Territorial Ecological Restoration

China has launched a number of ecological restoration projects since the 1950s. Many forest, grassland, wetland, and farmland ecosystems have been restored, with their carbon sequestration capacity improved remarkably^[15]. Focusing on more than any singular factor, territorial ecological restoration aims to enhance the stability and security of the whole regional ecosystem^[53]. The proposal of "dual carbon" goals makes carbon sequestration and carbon sink increase an integral component of ecological restoration, boosting the number of related research^[17][18]. Yet, most research focuses on a single ecosystem and provides specific ecological restoration approaches, or makes theoretical discussions on carbon sequestration approaches only^[14]. With a spatial perspective, this research took Wensu County as the study area, and proposed ecological restoration strategies that increase carbon sequestration and carbon sinks by current carbon sink evaluation, spatial pattern analyses, and feasible restoration strategies development. The MCR employed to identify the spatial pattern of carbon sinks can also be applied in territorial ecological restoration focused on biodiversity protection^[54] and mountain disaster prevention^[55]. The framework of this research integrates carbon sink increase with other ecological restoration goals, and the findings contribute to the holistic preservation, restoration, and governance of mountains, rivers, forests, farmlands, lakes, grasslands, and deserts.

5.4 Prospects

The application of MCR, basing the resistance of developing potential carbon sinks on restoration difficulties and demand for local absorption of carbon emission, is still in the early development stage. Further post-implementation validation is required. In addition, more measured data with better precision over a longer period are expected in future research, so as to make the carbon sink evaluation more comprehensive and accurate. Moreover, carbon sink increase should be integrated with other ecological problems to emphasize the carbon problems in territorial ecological restoration and holistic maintenance.

References

[1] China Meteorological News. (2021, August 10). Report Made by the Working Group Ⅰ from IPCC AR6. China Meteorological Administration.

[2] Xinhua News Agency. (2020, September 22). President Xi Jinping's Remarks at the General Debate of the 75th Session of the United Nations General Assembly. Chinese Government Website.

[3] Xinhua News Agency. (2021, March 15). President Xi Jinping's Remarks at the ninth meeting of the Central Committee for Financial and Economic Affair. Chinese Government Website.

[4] Lao, B. , Zhuo, W. , & Zhu, R. (2020) The rebirth of tropical rainforest—Ecological restoration planning for Sanda Mountain of Xishuangbanna, China. Landscape Architecture Frontiers, 8 (31), 108– 125.

[5] Lu, F. , Hu, H. , Sun, W. , Zhu, J. , Liu, G. , Zhou, W. , Zhang, Q. , Shi, P. , Liu, X. , Wu, X. , Zhang, L. , Wei, X. , Dai, L. , Zhang, K. , Sun, Y. , Xue, S. , Zhang, W. , Xiong, D. , Deng, L. , Liu, B. , Zhou, L. , Zhang, C. , Zheng, X. , Cao, J. , Huang, Y. , He, N. , Zhou, G. , Bai, Y. , Xie, Z. , Tang, Z. , Wu, B. , Fang, J. , Liu, G. , & Yu, G. (2018) Effects of national ecological restoration projects on carbon sequestration in China from 2001 to 2010. PNAS, 115 (316), 4039– 4044.

[6] Hou, R. , Xia, C. , Chen, J. , Zheng, Q. , Li, H. , Huang, J. , Huang, X. , Deng, J. , Han, X. , An, T. , Hao, Y. , & Gou, L. (2022) Carbon storage and carbon sink of forest land and other biomass in the Yangtze River Economic Belt. Acta Ecologica Sinica, 42 (323), 9483– 9498.

[7] Xie, L. , Bai, Z. , Yang, B. , Chen, M. , Fu, S. , & Mao, Y. (2023) Carbon sequestration assessment methods at home and abroad for terrestrial ecosystems: Research progress in achieving carbon neutrality. Earth Science Frontiers, 30 (32), 447– 462.

[8] Lin, Z. , Wang, P. , Liu, Q. , & Yang, Y. (2022) Spatio-temporal evolution characteristics of cultivated land carbon storage and identification of carbon sink areas in Huaihai Economic Zone from 2005 to 2020. Transactions of the Chinese Society of Agricultural Engineering, 38 (319), 259– 268.

[9] Han, Y. , Zhang, S. , & Yin, L. (2019) Quantifying the carbon storage capacity and its spatial distribution patterns of green spaces in a metropolitan area: A case study of Seoul, South Korea. Landscape Architecture Frontiers, 7 (32), 55– 65.

[10] Zhang, H. , Peng, Q. , Wang, R. , Qiang, W. , & Zhang, J. (2020) Spatiotemporal patterns and factors influencing county carbon sinks in China. Acta Ecologica Sinica, 40 (324), 8988– 8998.

[11] Zhang, H. , He, J. , Yang, X. , & Peng, Q. (2022) Zoning and governance of county ecological space for the increase of carbon sinks: A case study of the Beijing-Tianjin-Hebei region. Planners, 38 (31), 32– 40.

[12] Jiang, J. , Xu, J. , Wu, W. , Zhou, L. , & Sun, D. (2014) Patterns and dynamics of China's human-nature carbon source-sink system. Journal of Natural Resources, 29 (35), 757– 768.

[13] Fan, Y. , & Wei, F. (2022) Contributions of natural carbon sink capacity and carbon neutrality in the context of net-zero carbon cities: A case study of Hangzhou. Sustainability, 14 (35), 2680.

[14] Kong, F. , Ying, L. , Wen, W. , & Liang, M. (2021) Exploring carbon sequestration and sink enhancement based on ecological restoration of territorial space. Natural Resource Economics of China, 34 (312), 70– 76.

[15] Li, M. , & Wu, C. (2022) Application of NbS in terrestrial ecological restoration project to promote carbon sequestration and sink in China. Natural Protected Areas, 2 (34), 25– 31.

[16] Piao, S. , Yue, C. , Ding, J. , & Guo, Z. (2022) Perspectives on the role of terrestrial ecosystems in the 'carbon neutrality' strategy. Science China Earth Sciences, 65 (36), 1178– 1186.

[17] Zhao, J. , Liu, Y. , & Han, F. (2023) Thoughts on the path of increasing carbon sink in grassland under carbon peak and carbon neutrality targets. Acta Agrestia Sinica.

[18] Zhou, Q. , Wang, Q. , Zheng, Z. , & Liu, W. (2023) Carbon neutrality and ecological remediation in agricultural grain production. Journal of Agro-Environment Science, 42 (31), 1– 10.

[19] Li, W. , Li, J. , Zhang, Y. , Li, P. , & Han, J. (2022) Ecological restoration technologies for lake wetlands for carbon peaking and neutrality. Journal of Nanjing Forestry University (Natural Sciences Edition), 46 (36), 157– 166.

[20] Yang, L. (2016). Evaluations of carbon sink benefit under the ecological restoration model of Karst rocky desertification [Master's thesis]. Guizhou Normal University.

[21] Kang, B. , Li, M. , & Li, H. (2021) A case study of Nature-based Solutions in coastal zone blue carbon ecosystems restoration. Landscape Design, (34), 10– 15.

[22] Zhang, X. , Wei, W. , Zhou, L. , Guo, Z. , Li, Z. , Zhang, J. , & Jie, B. (2021) Analysis on spatio-temporal evolution of ecological vulnerability in arid areas of northwest China. Acta Ecologica Sinica, 41 (312), 4707– 4719.

[23] Lu, Y. , Zhao, Y. , & Dong, J. (2022) Ecological security evaluation and driving force analysis of three-dimensional ecological footprint in northwestern China. Acta Ecologica Sinica, 42 (34), 1354– 1367.

[24] Pan, J. , & Wen, Y. (2015) Estimation and spatial-temporal characteristics of carbon sink in the arid region of northwest China. Acta Ecologica Sinica, 35 (323), 7718– 7728.

[25] Pei, Z. , Zhou, C. , Ouyang, H. , & Yang, W. (2010) A carbon budget of alpine steppe area in the Tibetan Plateau. Geographical Research, 29 (31), 102– 110.

[26] Wang, Y. , Luo, G. , Wang, Y. , Han, Q. , Fan, B. , & Chen, Y. (2014) Vegetation and soil carbon density in arid region of Central Asia. Arid Land Geography, 37 (32), 239– 249.

[27] Lai, L. (2010). Carbon emission effect of land use in China[Master's thesis]. Nanjing University.

[28] Yang, M. , Yang, X. , Zhao, Y. , Huang, Q. , Li, C. , Cao, W. , Chen, A. , Gu, Q. , Li, Z. , & Wang, S. (2023) Estimated carbon storage and influencing factors of alpine grassland in the source region of the Yellow River. Acta Ecologica Sinica, 43 (39), 3546– 3557.

[29] Wang, S. , Zhou, C. , & Luo, C. (1999) Studying carbon storage spatial distribution of terrestrial natural vegetation in China. Progress in Geography, 18 (33), 238– 244.

[30] Sun, X. , & Liu, H. (2010) Effects of land use change on wetland landscape connectivity and optimization assessment of connectivity—A case study of wetlands in the coastal zone of Yancheng, Jiangsu. Journal of Natural Resources, 25 (36), 892– 903.

[31] Fu, F. , Liu, Z. , & Liu, H. (2021) Identifying key areas of ecosystem restoration for territorial space based on ecological security pattern: A case study in Hezhou City. Acta Ecologica Sinica, 41 (39), 3406– 3414.

[32] He, B. , Ding, J. , Li, H. , Liu, B. , & Chen, W. (2018) Spatiotemporal variation of vegetation phenology in Xinjiang from 2001 to 2016. Acta Ecologica Sinica, 38 (36), 2139– 2155.

[33] Xiong, Q. , He, Y. , Li, T. , & Yu, L. (2019) Spatiotemporal patterns of vegetation coverage and response to climatic and topographic factors in growth season in southwest China. Research of Soil and Water Conservation, 26 (36), 259– 266.

[34] He, Y. , Kong, Z. , Hu, X. , Zhang, J. , Wang, M. , Peng, C. , & Zhu, Q. (2022) Water and heat conditions separately controlled inter-annual variation and growth trend of NDVI in the temperate grasslands in China. Acta Ecologica Sinica, 42 (32), 766– 777.

[35] Jiao, S. , Liu, Y. , Han, Z. , Zhou, K. , Hu, L. , & Liu, T. (2021) Determining priority areas for land ecological restoration based on ecological network-human disturbance: A case study of Changsha-Zhuzhou-Xiangtan Urban Agglomeration. Journal of Natural Resources, 36 (39), 2294– 2307.

[36] Shao, R. , Wang, W. , Shi, K. , & Liu, Y. (2014) Research for restoration of soil and vegetation in human disturbance zone of road in high-cold grassland area. Research of Soil and Water Conservation, 21 (36), 181.

[37] Wang, J. , & Zhang, J. (2001) Comparing several methods of assuring weight vector in synthetical evaluation. Journal of Hebei University of Technology, 30 (32), 52– 57.

[38] Tao, X. , Zhang, R. , Xu, H. , & Zhu, J. (2006) Assessment of City's sustainable development based on improved entropy method. Journal of Arid Land Resources and Environment, 20 (35), 38– 41.

[39] & Yu, K. (1999) Landscape ecological security patterns in biological conservation. Acta Ecologica Sinica, 19 (31), 8– 15.

[40] Yu, G. , Zhu, J. , Xu, L. , & He, N. (2022) Technological approaches to enhance ecosystem carbon sink in China: Nature-based Solutions. Bulletin of the Chinese Academy of Sciences, 37 (34), 490– 501.

[41] Qin, G. , & Tian, M. (2022) The development opportunities and implementation path of forestry carbon sequestration under the target of carbon peak and carbon neutrality. Administrative Reform, (31), 45– 54.

[42] Wang, C. , Wang, R. , & Lin, Z. (2010) Carbon sequestration estimation by different tree species and reforestation types in forest ecosystem. Ecology and Environmental Sciences, 19 (310), 2501– 2505.

[43] Zhang, Y. , Yang, G. , Liu, N. , Chang, S. , & Wang, X. (2013) Review of grassland management practices for carbon sequestration. Acta Prataculturae Sinica, 22 (32), 290– 299.

[44] Xue, C. , Li, Y. , Hu, C. , & Yao, S. (2022) Study on spatio-temporal pattern of conservation tillage on net carbon sink in China. Journal of Natural Resources, 37 (35), 1164– 1182.

[45] Zheng, J. , Cheng, K. , Pan, G. , Smith, P. , Li, L. , Zhang, X. , Zheng, J. , Han, X. , & Du, Y. (2011) Perspectives on studies on soil carbon stocks and the carbon sequestration potential of China. Chinese Science Bulletin, 56 (326), 2162– 2173.

[46] Huo, H. , Zhang, J. , Ma, A. , & Huo, J. (2018) Progress and prospects of soil carbon cycle in arid deserts. Journal of Northwest Forestry University, 33 (31), 98– 104.

[47] Li, Z. , Shan, N. , Wang, Q. , Li, W. , Wang, Z. , Bao, S. , Dou, H. , Ao, W. , Pang, B. , & Wang, W. (2022) Estimation of vegetation carbon source/sink and analysis of its influencing factors in Hulun Lake Basin from 2013 to 2020. Journal of Ecology and Rural Environment, 38 (311), 1437– 1446.

[48] Qu, F. , Lu, N. , & Feng, S. (2022) Effects of land use change on carbon emissions. China Population, Resources and Environment, 21 (310), 76– 83.

[49] Li, Y. , Hao, X. , Zhang, J. , Fan, X. , & Zhao, Z. (2022) Spatial and temporal variation of net carbon sink function of farmland in Aksu oasis in the past 17 years. Arid Zone Research, 39 (34), 1303– 1311.

[50] Li, M. , Liu, S. , Sun, Y. , & Liu, Y. (2021) Agriculture and animal husbandry increased carbon footprint on the Qinghai-Tibet Plateau during past three decades. Journal of Cleaner Production, (3278), 123963.

[51] Wu, Y. , Zhang, M. , Yang, M. , & Jun, Y. (2022) Exploration of the implementation of carbon neutralization in the field of natural resources under the background of sustainable development—An overview. International Journal of Environmental Research and Public Health, 19 (321), 14109.

[52] Xu, Q. , Dong, Y. , & Yang, R. (2018) Influence of the geographic proximity of city features on the spatial variation of urban carbon sinks: A case study on the Pearl River Delta. Environmental Pollution, 243 (3A), 354– 363.

[53] Cao, Y. , Wang, J. , & Li, G. (2019) Ecological restoration for territorial space: Basic concepts and foundations. China Land Science, 33 (37), 1– 10.

[54] Han, Y. , Zhang, Q. , Zhang, S. , & Yin, L. (2021) Optimizing the habitat quality of the East Lake Scenic Area in Wuhan. Chinese Landscape Architecture, 37 (39), 95– 100.

[55] Xu, S. , Wang, H. , & Kong, W. (2021) Study on mountainous optimization of ecological security pattern based on MCR model from the perspective of disaster prevention: A case study of Beijing-Tianjin-Hebei mountainous area. Journal of Catastrophology, 36 (32), 118– 123.

RIGHTS & PERMISSIONS

© Higher Education Press 2024