A Meta-Analysis on Degraded Alpine Grassland Mediated by Climate Factors: Enlightenment for Ecological Restoration

Abstract

Alpine grassland is the main ecosystem on the Qinghai-Tibet Plateau (QTP). Degradation and restoration of alpine grassland are related to ecosystem function and production, livelihood, and wellbeing of local people. Although a large number of studies research degraded alpine grassland, there are debates about degradation patterns of alpine grassland in different areas and widely applicable ecological restoration schemes due to the huge area of the QTP. In this study, we used the meta-analysis method to synthesize 80 individual published studies which were conducted to examine aboveground and underground characteristics in non-degradation (ND), light degradation (LD), moderate degradation (MD), heavy degradation (HD), and extreme degradation (ED) of alpine grassland on the QTP. Results showed that aboveground biomass (AGB), belowground biomass (BGB), Shannon-Wiener index (H′), soil moisture (SM), soil organic carbon (SOC), soil total nitrogen (TN), and available nitrogen (AN) gradually decreased along the degradation gradient, whereas soil bulk density (BD) and soil pH gradually increased. In spite of a tendency to soil desertification, losses of other soil nutrients and reduction of enzymes, there was no linear relationship between the variations with degradation gradient. Moreover, the decreasing extent of TN was smaller in areas with higher precipitation and temperature, and the decreasing extent of AGB, SOC, and TN was larger in areas with a higher extent of corresponding variables in the stage of ND during alpine grassland degradation. These findings suggest that in areas with higher precipitation and temperature, reseeding and sward cleavage can be used for restoration on degraded alpine grassland. Fencing and fertilization can be used for alpine grassland restoration in areas with lower precipitation and temperature. Microbial enzymes should not be used to restore degraded alpine grassland on a large scale on the QTP without detailed investigation and analysis. Future studies should pay more attention to the effects of climate factors on degradation processes and specific ecological restoration strategies in different regions of the QTP.

Impact of deeper groundwater depth on vegetation and soil in semi-arid region of eastern China

“…These results indicated that the discrepancy of groundwater depth in specific terrains may form a specific microclimate or habitat traits that regulate vegetation growth and comprise a specific microenvironment, with the addition of desorption, dissolution, or the lateral export of groundwater, ultimately acting on the accumulation and distribution of nutrients in different profiles of soils ( Shi and Shao, 2000 ; Wang, 2002 ; Xu et al., 2012 ; Yu et al., 2019 ). Several studies suggested that precipitation was the driving factor of nutrient distribution in soil profiles at global, regional, and site scales ( Zhang et al., 2019 ; Yu et al., 2022 ). However, in arid and semi-arid regions characterized by scarce rainfall and intense evaporation, groundwater serves as a vital and sole source of water, and the variability of soil moisture primarily depends on groundwater depth.…”

Global warming changes biomass and C:N:P stoichiometry of different components in terrestrial ecosystems

“…We used random forest mean predictor IncNodePurity (increase in node purity) to characterize the main predictors (Wang et al., 2021). We used the meta‐regression models to determine the relationship between RR of biomass and C:N:P ratio with warming magnitude and climate factors (van Houwelingen et al., 2002; Yu et al., 2022). Here, only results with more than three comparisons are displayed (Figure 1).…”

Morphology, photosynthetic physiology and biochemistry of nine herbaceous plants under water stress

“…However, approximately 70% of alpine grassland has been degraded in recent decades ( Peng et al., 2019 ). The degradation of grasslands has resulted in soil erosion ( Liu et al., 2018 ; Li et al., 2019 ; Dai et al., 2021 ; Li et al., 2023 ) and biodiversity loss ( Wang et al., 2009 ; Yu et al., 2022 ).…”