Impacts of climate change and human activities on different degraded grassland based on NDVI

Abstract

Grassland degradation has emerged as a serious socio-economic and ecological problem, endangering both long-term usage and the regional biogeochemical cycle. Climate change and human activities are the two leading factors leading to grassland degradation. However, it is unclear what the degradation level caused by these two factors is. Using the normalized difference vegetation index (NDVI) and coefficient of variation of NDVI (CVNDVI), the spatial distribution features of grassland degradation or restoration were analyzed in Qilian County in the northeast of the Qinghai–Tibet Plateau. The dominant climate variables affecting NDVI variation were selected through the combination of random forest model and stepwise regression method to improve the residual trend analysis, and on this basis, twelve possible scenarios were established to evaluate the driving factors of different degraded grasslands. Finally, used the Hurst index to forecast the trend of grassland degradation or restoration. The results showed that approximately 55.0% of the grassland had been degraded between 2000 and 2019, and the area of slight degradation (NDVIslope > 0; CVNDVI (slope) > 0; NDVIvalue > 0.2) accounted for 48.6%. These regions were centered in the northwest of Qilian County. Climate and human activities had a joint impact on grassland restoration or degradation. Human activities played a leading role in grassland restoration, while climate change was primarily a driver of grassland degradation. The regions with slight degradation or re-growing (NDVIslope > 0; CVNDVI (slope) > 0), moderate degradation (NDVIslope < 0; CVNDVI (slope) > 0), and severe degradation or desertification (NDVIslope < 0; CVNDVI (slope) < 0) were dominated by the joint effects of climate and anthropogenic activity accounted for 34.3%, 3.3%, and 1.3%, respectively, of the total grassland area. Grasslands in most areas of Qilian County are forecasted to continue to degrade, including the previously degraded areas, with continuous degradation areas accounting for 54.78%. Accurately identifying the driving factors of different degraded grassland and predicting the dynamic change trend of grassland in the future is the key to understand the mechanism of grassland degradation and prevent grassland degradation. The findings offer a reference for accurately identifying the driving forces in grassland degradation, as well as providing a scientific basis for the policy-making of grassland ecological management.

Strong Agricultural Resilience to 2022 Southern China Drought

“…On the other hand, for rice, irrigation is the primary driver of rice growth (Li et al., 2015). Against the backdrop of large‐scale climate change, human activities such as irrigation, vegetation conservation and restoration, land development, and grazing can influence vegetation growth within relatively small spatial scales (Feng & Fu, 2013; Hou et al., 2022; Hussain et al., 2020; Wang et al., 2021).…”

“…Presently, while the primary focus of ecosystem resilience research centers on natural vegetation ecosystems (Chen et al., 2020; Dubovyk et al., 2016; Liu et al., 2023; Qu et al., 2020), specific analyses of resilience within ecosystems such as grasslands (Hou et al., 2022; Kath et al., 2019; Liu et al., 2021; Zheng et al., 2019) and forests (Jiménez‐Muñoz et al., 2016) are well‐documented. In contrast, research on the resilience of farmland ecosystems remains relatively understudied, with inadequate consideration of the interplay between anthropogenic and climatic factors influencing farmland vegetation (Qu et al., 2020).…”

“…Notably, the Southern Drought of 2022 is considered the worst drought in the Yangtze River Basin (YRB) since 1961 (Zhang, 2022). Amidst these changing conditions, the rising influence of human interventions, especially advancements in irrigation technology, has substantially shaped agroecosystems, with both natural factors and human activities now playing pivotal roles (Hou et al, 2022;Kath et al, 2019). This convergence has led to a complex interplay of factors influencing the resilience of agroecosystems (Li et al, 2023).…”

“…Hence, there is a compelling need to bolster research on agricultural resilience, deepening our understanding of the impacts of climate and anthropogenic factors on agriculture, especially in the context of severe droughts (Qu et al., 2020). With the wealth of advanced remote sensing data, remote‐sensing vegetation products have gained prominence in extensive research concerning agriculture’s response to climate (Allen et al., 2006; Habib‐ur‐Rahman et al., 2022; Hou et al., 2022; Liu et al., 2023; Wei et al., 2013). These products encompass the Leaf Area Index (LAI), Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index, and more.…”

Assessing the win–win situation of forage production and soil organic carbon through a short-term active restoration strategy in alpine grasslands

“…Previous research claims that nearly 39.06% of grasslands globally have some form of degradation ( Liu et al., 2019 ). Although the overall trend in grassland degradation has been curbed in the last 10 years, grassland degradation in some areas has become more serious, and the productive capacity of some grasslands has been lost completely ( Hou et al., 2022 ). The world’s largest alpine grassland ecosystem is found on the Qinghai–Tibet Plateau, which is significant to the development of local animal husbandry, water conservation, and environmental security ( Liu et al., 2021 ).…”