Effect of plateau pika disturbance and patchiness on ecosystem carbon emissions in alpine meadow in the northeastern part of Qinghai-Tibetan Plateau

Abstract

Plateau pika (Ochotona curzoniae) disturbance and patchiness intensify the spatial heterogeneous distribution of vegetation productivity and soil physicochemical properties, which may alter the ecosystem carbon emission process. Nevertheless, previous research has mostly focused on the homogeneous vegetation patches rather than heterogeneous land surface. Thus, this study aims to improve our understanding of the difference in ecosystem respiration (Re) over heterogeneous land surface in an alpine meadow grassland. Six different land surface types, namely large bald patches, medium bald patches, small bald patches, intact grassland, above pika tunnel and pika pile, were selected to analyze the response of Re to pika disturbance and patchiness and the key controlling factors. The results showed that (1) Re in intact grassland was 0.22-1.07 times higher than pika pile and bald patches, (2) soil moisture (SM) of intact grassland was 2%-11% higher than that of pika pile and bald patches, despite the fact that pika disturbance increased the water infiltration rate while soil temperature (ST) in intact grassland was 1-3 ° less than pika pile and bald patches, (3) soil organic carbon (SOC) and total nitrogen (TN) in intact grassland were approximately 50% and 60% less than above pika tunnel, whereas they were 10%-30% and 22%-110% higher than pika pile and bald patches, and (4) Re was significantly correlated with SM, TN and vegetation biomass (P<0.05). Our results suggested that pika disturbance and patchiness altered the ecosystem carbon emission pattern, which was mainly attributed to the reduction in soil water and supply of substrates. Given the wide distribution of pikas and the large area of bald patches, the varied Re in heterogeneous land surfaces should not be neglected in the estimation of ecosystem carbon emissions at the plot or regional scale.