Response of grassland productivity to climate change and anthropogenic activities in arid regions of Central Asia

Abstract

Background Quantitative evaluations of the relative impacts of climate change and anthropogenic activity on grasslands are significant for understanding grassland degradation mechanisms and controlling degraded grasslands. However, our knowledge about the effects of anthropogenic activities and climate change on the grassland in a mountain basin system in arid regions of Central Asia is still subject to great uncertainties. Methods In this research, we have chosen the net primary productivity (NPP) as an index for revealing grassland dynamics processes. Moreover, the human appropriation of net primary production (NPPH), which was calculated as the potential NPP (NPPP) minus the actual NPP (NPPA), was applied to distinguish the relative influences of climate change and human activities on the grassland NPP variations in a mountain basin system of Central Asia from 2001–2015. Results The results indicated that the grassland NPPA showed an increasing trend (35.88%) that was smaller than the decreasing trend (64.12%). The respective contributions of human activity, climate change and the two together to the increase in the NPPA were 6.19%, 81.30% and 12.51%, respectively. Human activity was largely responsible for the decrease in the grassland NPPA, with the area experiencing human-induced decreases accounting for 98.21% of the total decreased area, which mainly occurred during spring/autumn pasture and winter pasture. Furthermore, the average grazing pressure index (GPI) values of summer pastures, spring/autumn pasture and winter pastures were 1.04, 3.03 and 1.83, respectively, from 2001–2015. In addition, negative correlations between the NPP and GPI occupied most of the research area (92.41%). Discussion Our results indicate that: (i) anthropogenic activities were the primary cause of the reduction in the grassland NPP, especially grazing activities. (ii) For areas where the grassland NPP has increased, precipitation was the dominant climatic factor over temperature in controlling the grassland NPP changes in the study area. (iii) The findings of the current research indicate that some measures should be taken to reduce livestock pressure, and artificial grasslands can be built along the Irtysh River and the Ulungur River to relieve grazing pressure on spring/autumn pastures and winter pastures. Our results could provide reliable information for grassland management and the prevention of grassland degradation in arid regions of Central Asia.

Assessment of Spatio-Temporal Variation and Driving Mechanism of Ecological Environment Quality in the Arid Regions of Central Asia, Xinjiang

“…If > 1, the grassland has been overgrazed; if < 1, it indicates that the grassland still has carrying capacity. The calculation methods of and are specified by Bi et al [ 35 ].…”

“…The results showed that the decreased MODEI of summer pastures was mainly concentrated in the high-altitude mountainous area with abundant precipitation in the northernmost summer pastures (Figure 6b). However, when the precipitation exceeds the water level required for vegetation growth, the photosynthesis of vegetation will be inhibited due to the limited solar radiation and the increased relative humidity [35,64]. Previous studies have shown that most vegetation in arid regions of Central Asia was more sensitive to changes in precipitation than to changes in temperature [33,65].…”

“…In recent years, grassland desertification, biodiversity reduction, carbon sink loss, and other phenomena have appeared in this region [ 33 ], which not only endangered the production, life, and development of local farmers and herders, but also threatened regional ecological security [ 34 ]. Currently, studies on the MBS in the arid region of NW China mainly focus on grassland productivity change [ 35 ], land use change [ 36 ], ecosystem services [ 37 ], and household livelihood change [ 38 ]. However, few studies have focused on monitoring and evaluating the ecological quality of the MBS in the arid region.…”

Examining long-term natural vegetation dynamics in the Aral Sea Basin applying the linear spectral mixture model

“…Sen trend analysis can calculate the trend degree, and the Mann–Kendall trend test can test the significance of the change trend ( Drápela & Drápelová, 2011 ). The combination of the two methods has formed a new long time series trend analysis method, which can reduce the impact of data noise ( Bi et al, 2020 ). The Sen trend analysis combined with the Mann–Kendall test can be utilized to determine the variation trend of long-term series data ( Jiang et al, 2015 ).…”

Effect of Nutrient Addition on the Productivity and Species Richness of Grassland Along With an Elevational Gradient in Tajikistan

“…Grasslands are important terrestrial ecosystems, accounting for almost 30% of the land area of earth (Bi et al, 2020). They are important providers of various ecosystem services including the production of livestock forage and biodiversity conservation.…”