[Impact of Climate Change and Human Activities on Net Primary Productivity of Vegetation in the Yunnan-Guizhou Plateau].

Abstract

Vegetation net primary productivity （NPP） is a key indicator for assessing the carbon budget of terrestrial ecosystems. Studying the impact of climate change and human activities on vegetation NPP is critical for a deeper understanding of carbon cycling mechanisms and promoting sustainable economic development. Based on MOD17A3 NPP data, meteorological data, and land use data, this study explores the spatiotemporal variation characteristics of NPP across different geological backgrounds and vegetation types in the Yunnan-Guizhou Plateau from 2001 to 2020, using the Theil-Sen Median slope estimator and Mann-Kendall significance test. An improved residual analysis method is employed to investigate the relative contributions of climate change and human activities to vegetation NPP in the Yunnan-Guizhou Plateau. The results indicated the following： From 2001 to 2020, the NPP of vegetation in the Yunnan-Guizhou Plateau showed an increasing trend at a rate of 3.39 g·（m²·a）^-1. The multi-year average NPP of vegetation in non-karst areas was 901.42 g·（m²·a）^-1, which was higher than the 837.83 g·（m²·a）^-1 in karst areas. However, the growth rate of vegetation NPP in non-karst areas was 2.56 g·（m²·a）^-1, which was lower than the 3.69 g·（m²·a）^-1 in karst areas. Among different types of vegetation, herbaceous vegetation had the highest multi-year average NPP at 900.26 g·（m²·a）^-1, with a relatively high growth rate of 3.6 g·（m²·a）^-1. Arbor vegetation had a higher multi-year average NPP of 864.54 g·（m²·a）^-1 but the lowest growth rate at only 2.69 g·（m²·a）^-1. Economic vegetation had a lower multi-year average NPP of 809.24 g·（m²·a）^-1 but a higher growth rate of 3.96 g·（m²·a）^-1. Precipitation contributed positively to vegetation NPP in the Yunnan-Guizhou Plateau, with a positive contribution rate of 68.16%, while temperature had a positive contribution rate of 74.5%. Precipitation significantly promoted vegetation growth in the central and eastern regions of the Yunnan-Guizhou Plateau but had a suppressive effect on vegetation in the western regions. From 2001 to 2020, climate change contributed 77.09% to the changes in vegetation NPP in the Yunnan-Guizhou Plateau, which was higher than the 22.91% contribution from human activities. Human activities had a positive contribution rate of 70.76% to vegetation NPP in karst areas, higher than the 60.96% in non-karst areas. Human activities had a larger positive contribution rate to herbaceous vegetation NPP at 73.02% and to shrub vegetation at 71.92%. The findings provide a theoretical basis for formulating tailored ecological restoration and management strategies for the Yunnan-Guizhou Plateau.