Spatiotemporal Dynamics of the Carbon Budget and the Response to Grazing in Qinghai Grasslands

Abstract

Estimating the grassland carbon budget is critically important for ensuring that grassland resources are used sustainably. However, the spatiotemporal dynamics of the carbon budget and the response to grazing have not yet been characterized in Qinghai grasslands. Here, we estimated the gross primary productivity (GPP) and net ecosystem exchange (NEE) in Qinghai grasslands using the improved Biome-BGCMuSo model to characterize the spatiotemporal dynamics of the carbon budget and the response to grazing in this region from 1979 to 2018. The GPP of Qinghai grasslands fluctuated during the study period, with an average annual value of 118.78 gC/m2. The NEE of Qinghai grasslands fluctuated from 1979 to 2018, with an average value of −5.16 gC/m2. After 2,000, GPP increased, and NEE decreased in a fluctuating manner. There were clear regional differences in GPP and NEE. GPP was low in most areas of Qinghai, and GPP was high in eastern and southern Qinghai. The southern, southeastern, and northeastern parts of Qinghai were mainly carbon sinks, and the northwestern part of Qinghai and the region between the southeastern and northeastern parts of Qinghai were mainly carbon sources. Grazing generally decreased GPP and increased NEE in Qinghai grasslands from 1979 to 2018. There was spatial heterogeneity in the effect of grazing on GPP and NEE. Under grazing, GPP and NEE were significantly decreased mainly in eastern Qinghai, and GPP and NEE were significantly increased mainly in southern and eastern Qinghai. NEE was most affected by grazing in eastern Qinghai. The results of this study aid our understanding of the mechanism driving variation in the grassland carbon budget and provide new data that could be used to support local grassland management.

The Three Rivers Source Region Alpine Grassland Ecosystem Was a Weak Carbon Sink Based on BEPS Model Analysis

“…These results enrich the knowledge and comprehension of the dynamics of the carbon budget in the alpine ecosystem of the TRSR in recent decades. The average carbon sequestration rate of the TRSR alpine grassland during the study period was 3.74 Tg C, ranging from −3.30 to 11.51 Tg C/year, which was in concordance with previously published literature on carbon sequestration in alpine grassland ecosystems on the Tibetan Plateau [68][69][70][71][72].…”

“…We compared the results of the BEPS-NEP with those of other models. The NEP of alpine steppe and alpine meadow matched the simulation results of other models [68,69,71]; however, the simulation results of all these models were lower than the values at the flux tower observation [30], and this was because carbon fluxes measured by eddy correlation observations generally do not include the effects of disturbances such as grazing and fire and therefore may overestimate carbon sinks at the regional scale. For instance, based on the carbon fluxes from global eddy correlation observations, the global NEP was estimated by scaling to be 23 Pg C/yr, which is approximately eight times greater than the global terrestrial carbon sink [91].…”

“…Apart from temperature, precipitation, and solar radiation, there were other external factors that had vital effects on carbon fluxes, such as grazing intensity, indiscriminate mining, and human activities [69]. This was particularly true for the restoration of previously destroyed vegetation through anthropogenic measures such as the establishment of protected areas, the implementation of fencing, the return of farmland to grassland, the ecological migration pioneered by the Chinese government in the TRSR via ecological compensation in 2005, and the official establishment of the TRSNP in 2020 [21,93].…”

Spatio-temporal patterns of oasis dynamics in China’s drylands between 1987 and 2017

“…Grasslands and croplands restoration co-dominate the oasis dynamics in Xinjiang Gansu and Ningxia provinces, while in Inner Mongolia and Qinghai provinces it is mainly dominated by grasslands. This is because Inner Mongolia and Qinghai provinces are famous pastoral locations in China, and grassland restoration and desertification reversal are the goals of ecologically high-quality development rather than food production in these two provinces (Robinson et al 2017, Huang et al 2022.…”

Editorial: Patterns, functions, and processes of alpine grassland ecosystems under global change

“…(2021) carried out a 5,000 km belt transect investigation to distinguish stoichiometric homeostasis of soil microbial biomass in alpine grassland ecosystems. Huang et al. (2022) estimated the net ecosystem exchange (NEE) using the improved Biome-BGCMuSo model to characterize the spatiotemporal dynamics of the carbon budget.…”