Attribution of vegetation coverage change to climate change and human activities based on the geographic detectors in the Yellow River Basin, China

Unveiling spatiotemporal patterns and key drivers of soil conservation from a "historical-future-intervention" perspective: A case study of the Danjiangkou Reservoir Area, China

The soil conservation of ecosystems in water source areas is crucial for ensuring water quality and supply. It is primarily shaped by natural factors like rainfall intensity, soil characteristics, and topography, alongside the impact of human activities. As the starting point and core water source area of the South-to-North Water Diversion Middle Route Project, the Danjiangkou Reservoir has experienced increasing risks of soil erosion under the combined effects of extreme climate events and land cover changes. Effectively assessing these changes and formulating policies to address future challenges is of great significance for the stable operation of the reservoir and the long-term, sustainable transfer of clean water. This study incorporates human intervention factors to generate three future development scenarios for the DRA, including protection priority, natural development, and economic priority, corresponding to SSP1-2.6, SSP2-4.5, and SSP5-8.5 stem from the future climate, social, and economic scenarios (CMIP6-SSP-RCP), respectively. Additionally, we uses land use/land cover (LULC) data from 2000 to 2020 as historical input and applies the LULC simulation model model (PLUS) to predict land use types for the 2025-2035 period under the current land use continuation scenario, and employ the InVEST model to quantify SC (soil conservation) services for both the 2000-2020 period and the different future scenarios (2025-2035). The findings indicate that the land use structure in the reservoir area has undergone changes over the past two decades, with a reduction in forest and grassland, leading to a gradual weakening of soil conservation capacity. Among the future scenarios, the protection-priority scenario, which involves human intervention, offers the highest soil conservation. LULC is identified as a major variable influencing these changes. The findings offer scientific evidence and support for future land use and soil conservation management in the DRA.

Multidimensional landscape changes contribute significantly to vegetation distribution: The evidences from the Luo River Watershed in the eastern part of the Qinling Mountains, China

Assessment of vegetation characteristics plays an important role in monitoring ecosystem health and restoration status, and it is necessary to consider the response characteristics of vegetation assessment indicator (VAI) to multidimensional landscape structure. Therefore, this research constructed a framework for analyzing landscape structure from two dimensions of landscape element and landscape pattern, selected fractional vegetation cover (FVC) and net primary productivity (NPP) as VAI, determined the response degree and spatial correlation of VAI to landscape structure by using geographical detector and bivariate Moran's index, and finally obtained the change threshold of VAI based on the constraints of landscape pattern by building a cubic polynomial. FVC and NPP were significantly higher from 2001 to 2021, with the expansion of the high-value areas. Cropland and woodland were the dominant landscape elements. The spatial explanatory power of landscape element for VAI was better than that of landscape pattern characteristics, while the combined factors in landscape structure all explained VAI better than univariate. The response of FVC to landscape structure was more significant compared to NPP. The high value areas of FVC tended to occur in natural landscape elements. FVC showed spatial correlation and clustering characteristics with both PD and LPI. One or more thresholds existed in the response of FVC to changes in landscape pattern. The research results have important reference value in the optimization of landscape structure and vegetation restoration, and can provide practical guidance for the sustainable development of the ecosystem.

Exploring the evolution of ecosystem health and sustainable zoning: A perspective based on the contributions of climate change and human activities

Maintaining ecosystem health (EH) in watersheds is crucial for building a national pattern of ecological security. However, a comprehensive diagnosis of watershed EH and an exploration of its driving mechanisms are still lacking. This study proposed an EH assessment model from a vitality-organization-resilience-service-environment (VORSE) perspective. Taking the Yellow River Basin of Shaanxi Province (YRBS), China, as a research object, the spatiotemporal evolution trend of EH from 2000 to 2020 was quantified. At the same time, we also quantified the respective contributions of climate change (CC) and human activities (HA) to the EH dynamics based on residual analysis. The results showed that EH in the YRBS increased by 11.80 % from 2000 to 2020, and the spatial distribution of the EH was higher in the southern region than in the northern part. At the pixel scale, areas with improving trends accounted for 90.57 % of the YRBS, while 9.43 % deteriorated, with the improving areas mainly in northern Shaanxi and the deteriorating areas in the Guanzhong region. The correlation between the EH and precipitation was primarily positive, while the correlation between the EH and temperature was mainly negative. The residual analysis showed that the contribution rate of CC to EH changes was 78.54 %, while that of HA was 21.46 %, indicating that CC was the dominant driver of EH changes in the YRBS. Specifically, 82.64 % of the improvement in EH was attributed to CC and 17.36 % to HA. Conversely, 65.30 % of the deterioration in EH was attributed to CC and 34.70 % to HA. Furthermore, CC, HA, and CC&HA dominated EH changes in 26.85 %, 3.77 %, and 69.38 % of the YRBS area, respectively. In addition, the Hurst exponent analysis identified six types of future EH development scenarios, each requiring different restoration strategies. This study provides valuable insights for future EH diagnosis, EH restoration efforts, and the formulation of sustainable development goals in other watersheds.

Estimating the Amount of the Wild Artemisia annua in China Based on the MaxEnt Model and Spatio-Temporal Kriging Interpolation

In order to determine the distribution area and amount of Artemisia annua Linn. (A. annua) in China, this study estimated the current amount of A. annua specimens based on the field survey sample data obtained from the Fourth National Census of Chinese Medicinal Resources. The amount was calculated using the maximum entropy model (MaxEnt model) and spatio-temporal kriging interpolation. The influencing factors affecting spatial variations in the amount were studied using geographic probes. The results indicated that the amount of A. annua in China was about 700 billion in 2019. A. annua was mainly distributed in the circular coastal belt of Shandong Peninsula, central Hebei, Tianjin, western Liaoning, and along the Yangtze River and in the middle and lower reaches of Jiangsu, Anhui, and the northern Chongqing provinces. The main factors affecting the amount are the precipitation in the wettest and the warmest seasons, the average annual precipitation, and the average temperature in the coldest and the driest seasons. The results show that the amount of A. annua is strongly influenced by precipitation and temperature.

Spatiotemporal changes of ecological environment quality and climate drivers in Zoige Plateau

Ecological environment is the essential material basis of human survival and connects regional economy with socially sustainable development. However, climate changes characterized by global climate warming have caused a series of ecological environmental problems in recent years. Few studies have discussed various climate factors affecting the ecological environment, and the spatial non-stationary effects of different climate factors on the ecological environment are still unclear. Dynamically monitoring ecological environment changes in fragile areas and identifying its climate-driving mechanism are essential for ecological protection and environmental repair. Taking Zoige Plateau as a case, this paper simulated the eco-environmental quality during 1987-2020 using remote sensing data, utilized Geodetector method to identify the contributions of various climate drivers to ecological environment quality, and then adopted the Geographically Weighted Regression model to explore the spatial non-stationary impacts of climate factors on ecological environment quality. The results showed that the ecological quality in the middle regions of the Zoige Plateau was slightly better than in the surrounding marginal areas. For the whole area of Zoige Plateau, the average ecological environment quality index was 54.92, 53.99, 56.17, 57.88, 63.44, 56.93, 59.43, and 59.76 in 1987, 1992, 1997, 2001, 2006, 2013, 2016 and 2020, respectively, which indicated that eco-environmental quality witnessed several fluctuations during the study period but showed a generally increasing trend. Among five climate factors, the temperature was the dominant climate factor affecting the ecological environment quality (q value: 0.11-0.19), sunshine duration (0.03-0.17), wind speed (0.03-0.11), and precipitation (0.03-0.08) were the main climate drivers, while the explanatory power of relative humidity to ecological environment quality was relatively small. Such various climate factors impacting the ecological environment quality demonstrated distinct spatial non-stationary and the range of driving impact varied with time. Temperature, sunshine duration, wind speed, and relative humidity promoted ecological environment quality in most regions (regression coefficients > 0), while precipitation mainly had a negative inhibitory impact (regression coefficients < 0). Meanwhile, the greater impacts of these five climate factors were concentrated in high-elevation regions of the south and west or the northern areas. The appropriate enhancement of climate warming and air humidity was beneficial to the improvement of the ecological environment, but the excessive precipitation would result in landslides and exhibit inhibition of vegetation growth. Therefore, selecting cold-tolerant herbs and shrubs, and strengthening climate monitoring and early warning systems (such as drought and excessive precipitation) are essential for ecological restoration.

Evaluation for the spatiotemporal patterns of ecological vulnerability and habitat quality: implications for supporting habitat conservation and healthy sustainable development

Currently, the rapid socioeconomic development and urbanization around the world have caused the ecological environment on the earth surface to become extremely fragile and destroyed. In addition, the increasing demand of human beings for material also leads to the unsustainable development of resources and environment. However, how to achieve the win-win goal between socioeconomic development and ecological protection in the context of these impacts? It is becoming a major problem for governments and policy makers. To further reveal the contradiction between man and land, taking Wuhan metropolitan area as the study area, this study mainly proposed a framework for the comprehensive optimization of landscape pattern and ecological environment and constructed the ecological vulnerability mixed evaluation model. Then, the integrated valuation of ecosystem services and trade-offs (InVEST) model was employed to evaluate the changes in habitat quality, focusing on the analysis of the impact mechanism of the evolution of ecological environment. This study found that the hybrid model of landscape vulnerability can successfully explore the landscape ecological vulnerability of Wuhan metropolitan area from 2000 to 2020, and its spatiotemporal differentiation pattern was obvious. The InVEST model showed that the habitat quality had obvious spatial differentiation. On the whole, the overall quality of the habitat was low and the degradation degree was high. Furthermore, our study also showed that the change of landscape ecological environment was influenced by the common potential of local nature and social economy, rather than a single factor. Finally, the main purpose of this study is to help scientifically formulate habitat protection and landscape planning strategies through in-depth study of landscape ecological environment, so as to alleviate man-land contradiction and support regional sustainable development.

Exploring the spatiotemporal variations in regional rainwater harvesting potential resilience and actual available rainwater using a proposed method framework

Rainwater harvesting potential provides a basis for alleviating regional drought and water shortages. The resilience of rainwater harvesting potential is directly related to the sustainable level of actual available rainwater. Thus, SWAT model was combined with the proposed rainwater harvesting potential evaluation model to quantify rainwater harvesting potential, its resilience and actual available rainwater in the study area. The results showed that: (1) restoration of forest and grass increased the rainwater resource potential in the study area by 12.41 %, especially in the northeast, central and southwest of the study area. Although the surface runoff increased slightly in the past 20 years, it remained stable at 28.62 % of rainwater harvesting potential, which was benefited from the rainwater harvesting potential resilience to maintain the component stability; (2) rainwater harvesting potential resilience in the study area increased from class II to class III, which was closely related to the 17.93 % increase in the resilience intensity of the study area to resist external interference; and (3) surface runoff and net soil moisture content were the main components affecting the spatiotemporal variation of actual available rainwater, and lateral flow was also the main component affecting the spatial variation of actual available rainwater. In the past 20 years, the actual available rainwater has been increasing, and its conversion rate exceeded 89 %. The high level of actual available rainwater has been expanding to the western region with dense grassland coverage. This study provides a scientific basis for clarifying the sustainable utilization level of rainwater.