Responses of landscape structure to the ecological restoration programs in the farming-pastoral ecotone of Northern China

Driving model of land use change on the evolution of carbon stock: a case study of Chongqing, China

Terrestrialecosystems are significant carbon sinks and are crucial for understanding the regional and global carbon cycles, energy flow, and climate change. As land use change is a significant process affecting ecosystem carbon stocks and striving for land degradation neutrality (LDN), studying it is essential for comprehending the evolution of regional carbon sink functions and achieving sustainable development goals. The drastically diverse land use patterns in each of the study area's regions resulted in significant differences in carbon stock. This study explores the evolution traits of carbon stocks based on land use data and their driving mechanisms in Chongqing during the past 30 years by using spatial analysis, the InVEST model, and geographic probes. The results demonstrate that from 1990 to 2020, land degradation in Chongqing was made worse by the demand for land for construction land, but the strategy of converting cropland back to forests raised the carbon stock of forest land. The overall result is a decrease in total carbon stocks of 5.1078 Tg or 1.5%. The main pathway for carbon loss pathway in the evolution of carbon stock is the conversion of cropland to construction land, and the primary carbon compensation pathway is the conversion of grassland and cropland to forest land, with a spatial distribution characterized by "higher in the whole area and obvious local differences." The land use intensity index has the most significant influence on the evolution of carbon stock. Moreover, the interaction of pairwise factors played a more important role in affecting the evolution of carbon stocks than did each factor individually. The case study in this paper shows that land use change is a significant driving mechanism for the evolution of carbon stock, and the development of a driving model theory is appropriate for deciphering the trajectory of carbon stock evolution and offering research suggestions for other regions.

Impacts of climate change and human activities on vegetation coverage variation in mountainous and hilly areas in Central South of Shandong Province based on tree-ring

Introduction

It is of great significance to understand the characteristics and influencing factors of vegetation coverage variation in the warm temperate zone. As a typical region of the warm temperate zone in eastern China, the mountainous and hilly region in central-south Shandong Province has fragile ecological environment and soil erosion problem. Studying on vegetation dynamics and its influencing factors in this region will help to better understand the relationship between climate change and vegetation cover change in the warm temperate zone of eastern China, and the influence of human activities on vegetation cover dynamics.

Methods

Based on dendrochronology, a standard tree-ring width chronology was established in the mountainous and hilly region of central-south Shandong Province, and the vegetation coverage from 1905 to 2020 was reconstructed to reveal the dynamic change characteristics of vegetation cover in this region. Secondly, the influence of climate factors and human activities on the dynamic change of vegetation cover was discussed through correlation analysis and residual analysis.

Results and discussion

In the reconstructed sequence, 23 years had high vegetation coverage and 15 years had low vegetation coverage. After low-pass filtering, the vegetation coverage of 1911-1913, 1945-1951, 1958-1962, 1994-1996, and 2007-2011 was relatively high, while the vegetation coverage of 1925-1927, 1936-1942, 2001-2003, and 2019-2020 was relatively low. Although precipitation determined the variation of vegetation coverage in this study area, the impacts of human activities on the change of vegetation coverage in the past decades cannot be ignored. With the development of social economy and the acceleration of urbanization, the vegetation coverage declined. Since the beginning of the 21st century, ecological projects such as Grain-for-Green have increased the vegetation coverage.

Can China's ecological civilization strike a balance between economic benefits and green efficiency? A preliminary province-based quasi-natural experiment

To encourage the building of a development route for ecological civilization construction which commensurates with China's unique national conditions, early demonstration and pilot ecological civilization zones should be built. This study aims to investigate the effects of ecological civilization construction policies on regional total factor productivity, green total factor productivity, and the methods of action by using panel data from 30 provinces in Mainland China from 2005 to 2020. Our findings indicate that the pilot eco-civilization policies have a more significant effect on the promotion of green total factor production, while the effect on total factor productivity is average. Furthermore, the main purpose of the ecological civilization construction pilot is to improve the level of green innovation, optimise the industrial structure and promote the allocation of factors to achieve a win-win situation for regional economic development and green benefits. Moreover, under different levels of economic growth, the pilot eco-civilization policies have a more significant effect on the promotion of green total factor at various stages of economic growth and industrialization. There are also clear discrepancies in how well ecological civilization construction programmes are implemented. Thus, in order to support high-quality regional economic development, it is crucial to continue to advance and promote the pilot eco-civilization initiatives.

Quantifying Vegetation Vulnerability to Climate Variability in China

Climate variability has profound effects on vegetation. Spatial distributions of vegetation vulnerability that comprehensively consider vegetation sensitivity and resilience are not well understood in China. Furthermore, the combination of cumulative climate effects and a one-month-lagged autoregressive model represents an advance in the technical approach for calculating vegetation sensitivity. In this study, the spatiotemporal characteristics of vegetation sensitivity to climate variability and vegetation resilience were investigated at seasonal scales. Further analysis explored the spatial distributions of vegetation vulnerability for different regions. The results showed that the spatial distribution pattern of vegetation vulnerability exhibited spatial heterogeneity in China. In spring, vegetation vulnerability values of approximately 0.9 were mainly distributed in northern Xinjiang and northern Inner Mongolia, while low values were scattered in Yunnan Province and the central region of East China. The highest proportion of severe vegetation vulnerability to climate variability was observed in the subhumid zone (28.94%), followed by the arid zone (26.27%). In summer and autumn, the proportions of severe vegetation vulnerability in the arid and humid zones were higher than those in the other climate zones. Regarding different vegetation types, the highest proportions of severe vegetation vulnerability were found in sparse vegetation in different seasons, while the highest proportions of slight vegetation vulnerability were found in croplands in different seasons. In addition, vegetation with high vulnerability is prone to change in Northeast and Southwest China. Although ecological restoration projects have been implemented to increase vegetation cover in northern China, low vegetation resilience and high vulnerability were observed in this region. Most grasslands, which were mainly concentrated on the Qinghai–Tibet Plateau, had high vulnerability. Vegetation areas with low resilience were likely to be degraded in this region. The areas with highly vulnerable vegetation on the Qinghai–Tibet Plateau could function as warning signals of vegetation degradation. Knowledge of spatial patterns of vegetation resilience and vegetation vulnerability will help provide scientific guidance for regional environmental protection.

Evaluating Ecosystem Services and Trade-Offs Based on Land-Use Simulation: A Case Study in the Farming–Pastoral Ecotone of Northern China

Evaluating the impacts of land-use change (LUC) on ecosystem services (ESs) is necessary for regional sustainable development, especially for the farming–pastoral ecotone of northern China (FPENC), an ecologically sensitive and fragile region. This study aimed to assess the impacts of LUC on the ESs and provide valuable information for regional planning and management in the FPENC. To accomplish this, we assessed LUC in the FPENC from 2010 to 2020 and simulated land-use patterns in 2030 under three plausible scenarios: the business as usual scenario (BAUS), economic development scenario (EDS), and ecological protection scenario (EPS). Then, we quantified five ESs (including crop production, water yield, soil retention, water purification, and carbon storage) for 2020–2030 and analyzed the trade-offs and synergies among ESs in all scenarios. The results show that FPENC experienced expanding farming land and built-up land throughout 2010–2020. Under the BAUS and EDS from 2000 to 2030, especially EDS, the increase in farming land and built-up land will continue. As a result, crop production and water yield will increase, while soil retention, water purification, and carbon storage will decrease. In contrast, EPS will increase soil retention, water purification, and carbon storage at the cost of a decline in crop production and water yield. These results can provide effective reference information for future regional planning and management in the farming–pastoral ecotone.

The spatiotemporal change of cropland and its impact on vegetation dynamics in the farming-pastoral ecotone of northern China

Due to the unfavorable soil conditions and water resources, the cropland use pattern in the farming-pastoral ecotone in northern China is complex. The program named "Grain for Green" has accelerated the cropland change. However, the complex cropland and retired cropland are challenging to monitor with remote sensing due to their spatially dispersed and easily confused with spectrally similar land use classes such as nature grasslands and non-cropped fields. Taking farming-pastoral ecotone in the northern foot of the Yinshan Mountains as a case study, we explored a classification approach for complex cropland and retired cropland, which was introduced as a specific land use class by using multi-temporal Landsat TM and OLI images with Google Earth Engine. During 1990-2000, cropland increased with a sharper growth and increased with a slower growth from 2001 to 2010, and then decreased significantly from 2011 to 2019, to lead the cropland area in 2019 was smaller than an area in 1990. We analyzed the spatiotemporal trajectories of retired cropland in 2019 using the Land Use Change Trajectory method to evaluate its source. In our finding, approximately 77% of retired cropland was labelled as cropland before 2019; albeit, not all retired cropland was converted from cropland. Moreover, we qualitatively assessed the vegetation dynamics in the study area by utilizing the long-term NDVI-mean value to reveal that vegetation coverage has shown a continuously increasing trend. It is related to the decline of cropland and the increase of retired cropland at the same rate. Our results highlighted that the "Grain for Green" program had led the vegetation restoration in the farming-pastoral ecotone. Our approach for monitoring cropland and retired cropland can improve the understanding of the driving factors and consequences of these critical land use change trajectories.

Impacts of ecological restoration on public perceptions of cultural ecosystem services

Although ecological restoration has increased the stability and diversity of regional ecosystem services, its effects on public perceptions of cultural ecosystem services (CESs) remain unclear. Therefore, this study conducted a questionnaire survey of 455 interviewees in Ansai County on the Loess Plateau and combined the structural equation model (SEM) to explore the characteristics and influencing factors of public perceptions of CESs. Moreover, we also calculated landscape importance to quantify the impact of landscape features on CESs. The results showed that ecological restoration increased the overall public perceptions of CESs. Regarding the different types of CESs, the public most strongly perceived esthetic services but had the lowest perception of cultural heritage after ecological restoration. Regarding demographic characteristics, gender and age were the most important factors affecting public perceptions. Men were more likely to perceive CESs than women, while older interviewees had higher perceptions of the value of physical and mental health services, education and science than young interviewees. In addition, forestlands were perceived as playing more important roles than other landscape types in providing CESs. This study demonstrates that ecological restoration will improve public perceptions of CESs. Managers should incorporate public perceptions of CESs into the formulation of ecological management policies.

Projecting Future Vegetation Change for Northeast China Using CMIP6 Model

Northeast China lies in the transition zone from the humid monsoonal to the arid continental climate, with diverse ecosystems and agricultural land highly susceptible to climate change. This region has experienced significant greening in the past three decades, but future trends remain uncertain. In this study, we provide a quantitative assessment of how vegetation, indicated by the leaf area index (LAI), will change in this region in response to future climate change. Based on the output of eleven CMIP6 global climates, Northeast China is likely to get warmer and wetter in the future, corresponding to an increase in regional LAI. Under the medium emissions scenario (SSP245), the average LAI is expected to increase by 0.27 for the mid-century (2041–2070) and 0.39 for the late century (2071–2100). Under the high emissions scenario (SSP585), the increase is 0.40 for the mid-century and 0.70 for the late century, respectively. Despite the increase in the regional mean, the LAI trend shows significant spatial heterogeneity, with likely decreases for the arid northwest and some sandy fields in this region. Therefore, climate change could pose additional challenges for long-term ecological and economic sustainability. Our findings could provide useful information to local decision makers for developing effective sustainable land management strategies in Northeast China.

Greater increases in China's dryland ecosystem vulnerability in drier conditions than in wetter conditions

Dryland ecosystems are experiencing dramatic climate change, either drier or wetter. However, the differences in response amplitudes of dryland ecosystems to drier and wetter climates have not been frequently discussed, especially when using composite indicators at large scales. This study explores the changing patterns of ecosystem vulnerability in China's drylands by comprehensively considering exposure, sensitivity and resilience indicators using leaf area index (LAI) datasets and meteorological data within two periods from 1982 to 1999 (P1) and from 2000 to 2016 (P2). The results show that nearly 57% of China's drylands have experienced drier conditions in 2000-2016 based on the average aridity index (AI) values compared with the conditions in 1982-1999. Compared with the conditions in 1982-1999, ecosystem vulnerability has increased in 78% of dryland, and ecosystem resilience has decreased in 46% of the area in 2000-2016. The amplitudes of vulnerability increase are higher in drier conditions than in wetter conditions. Ecosystem resilience has obviously increased in wetter conditions but has decreased in drier conditions, especially in farming-pastoral ecotones with an obvious land use change. Consequently, vegetation-climate composite indicators provide a holistic pattern of China's dryland ecosystem response to climate change, and the decreased ecosystem resilience in drier conditions in northeast China should be a warning signal under the national vegetation greening background. This research highlights that the impact of drying on ecosystem resilience leads the response of ecosystems to drier environment.