Limitations of soil moisture and formation rate on vegetation growth in karst areas

Vegetation changes in karst areas are controlled by the soil formation rate (SFR) and soil moisture (SM). However, little is known about their thresholds and global control patterns. To this end, based on high-precision climate and vegetation data for 2000-2014, using Pearson correlation analysis, the Hurst index, and change-point analysis, the thresholds of the SFR and SM in vegetation growth in karst areas were identified. Furthermore, a spatial map (0.125 degrees x 0.125 degrees) of the global karst ecosystem with a static/dynamic limitation zone was established. We found that the net primary productivity (NPP) in 70% of the global climate zones exhibited a dual restriction relationship with the SM and SIR. The limitations of the SIR and SM in vegetation growth were most obvious in subpolar and semi-arid climates. In addition, their ecological thresholds were 25.2 t km(-2) yr(-1) and 0.28 m(3) m(-3). respectively. The static limitation of the SIR on the NPP in karst areas accounted for 28.37%, and the influence of the SM enhanced this limit (21.79%). The limitation of the SFR on vegetation was mainly concentrated in Boreal forests (17%), and the limitation of the SM was mainly concentrated in tropical savannas (12%). The NPP and the Normalized Difference Vegetation Index (NDVI) were the most sensitive to changes in the SM and SFR. Moreover, the analysis based on 14 ecologically limitation karst areas further revealed that the reduction in these factors may cause the tropical rain forest to experience degradation. It can be seen that the SM enhanced the limiting effect of the SFR on vegetation in karst areas. In short, this interpretation of karst vegetation limitations provides a deeper understanding of and approach to ecosystem evolution and vegetation restoration in these regions. (C) 2021 Elsevier By. All rights reserved.

Automated summary

This study identifies the thresholds of soil formation rate (SFR) and soil moisture (SM) in vegetation growth in karst areas, and establishes a spatial map of static/dynamic limitation zones in global karst ecosystems. The findings show that net primary productivity (NPP) in 70% of global climate zones is dual-restricted by SM and SIR, with the most significant limitations observed in subpolar and semi-arid climates.