Seasonal Variation in Soil and Herbage CO2 Efflux for a Sheep-Grazed Alpine Meadow on the North-East Qinghai-Tibetan Plateau and Estimated Net Annual CO2 Exchange

Abstract

The Qinghai-Tibetan Plateau is a vast geographic area currently subject to climate warming. Improved knowledge of the CO2 respiration dynamics of the Plateau alpine meadows and of the impact of grazing on CO2 fluxes is highly desirable. Such information will assist land use planning. We measured soil and vegetation CO2 efflux of alpine meadows using a closed chamber technique over diurnal cycles in winter, spring and summer. The annual, combined soil and plant respiration on ungrazed plots was 28.0 t CO2 ha−1 a−1, of which 3.7 t ha−1 a−1occurred in winter, when plant respiration was undetectable. This suggests winter respiration was driven mainly by microbial oxidation of soil organic matter. The winter respiration observed in this study was sufficient to offset the growing season CO2 sink reported for similar alpine meadows in other studies. Grazing increased herbage respiration in summer, presumably through stimulation of gross photosynthesis. From limited herbage production data, we estimate the sustainable yield of these meadows for grazing purposes to be about 500 kg herbage dry matter ha−1 a−1. Addition of photosynthesis data and understanding of factors affecting soil carbon sequestration to more precisely determine the CO2 balance of these grasslands is recommended.

Development of long‐term spatiotemporal continuous NDVI products for alpine grassland from 1982 to 2020 in the Qinghai–Tibet Plateau, China

“…As an alpine climate zone, grassland vegetation predominates in this region, with main grassland types including alpine meadow, alpine steppe, and alpine desert steppe (Wu et al, 2007) (Figure 1b). It makes the plateau one of the most significant pastoral areas in China (Wu et al, 2007; Yuan et al, 2022). Therefore, generating a long‐term, high‐resolution NDVI data set is of great importance for monitoring the long‐term vegetation changes in this region.…”

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

“…In alpine steppe, N and P application led to an increase in aboveground biomass ( Li et al., 2021b ), and increased intensity of bacteria and fungi ( Li et al., 2021c ), also affected the plant functional traits ( Li et al., 2022d ). Meanwhile, grazing increased herbage respiration in summer, presumably through stimulation of gross photosynthesis ( Yuan et al., 2022 ), and changed plant community composition and reduced stochasticity of soil microbial community assembly of alpine grasslands ( Li et al., 2022a ). Restoration of degraded grassland significantly improves shoot and root biomass ( Zhang et al., 2022 ), plant interspecific associations ( Wu et al., 2022 ), soil enzymatic activities ( Wang et al., 2022b ), and water storage ( Guo et al., 2021 ).…”