Abstract
Glomalin-related soil protein (GRSP) is a recalcitrant glycoprotein
mainly produced by arbuscular mycorrhizal fungi and contributes to soil
carbon sequestration. Human activities (grazing, fertilization, etc.)
can change plant productivity, soil carbon pool, and microbial community
in an alpine grassland ecosystem. However, no study has reported on the
effect of human activities on GRSP. Besides, the effect of the
interaction between environmental factors and human activities on GRSP
is unknown. This study assessed GRSP response to grazing intensity
gradients and fertilization in an alpine grassland (Qinghai-Tibet
Plateau). The result showed that livestock grazing changed GRSP
stability in alpine grassland. Moreover, the content of total GRSP and
easily extractable GRSP were gradually decreased with increasing grazing
intensities in both surface and subsurface soils. GRSP was highly
positively correlated with soil organic carbon (SOC), total nitrogen
(TN), and available phosphorus (AP) but negatively correlated with the
soil inorganic carbon (SIC) and PH (P<0.001). GRSP promoted
SOC by 3.7-14.18%. In contrast, N and P addition for five years did not
affect SOC and GRSP contents. Therefore, GRSP is a stable organic carbon
essential for SOC fixation. Short-term distractions cannot affect GRSP
stability, while long-term overgrazing can gradually reduce GRSP
stability. This study provides new insights into soil carbon pool and
ecological stoichiometry in the grassland succession process on the
Qinghai-Tibet plateau.