Plateau pika offsets the positive effects of warming on soil organic carbon in an alpine swamp meadow on the Tibetan Plateau

• Published in: Catena (Giessen) 2021-09, Vol.204, p.105417, Article 105417
• Main Authors: Yuan, Xia, Qin, Wenkuan, Chen, Ying, Xu, Tianle, Chen, Kelong, Zhu, Biao
• Format: Article
• Language: English
• Subjects: Climate warming; Microbial biomass; Microbial functional genes; Plateau pika; SOC fractionation; Soil enzyme activities
• ISSN: 0341-8162; 1872-6887
• DOI: 10.1016/j.catena.2021.105417

•Warming and plateau pika have interactive effects on SOC in an alpine swamp meadow.•Without pika, warming increases SOC by 22% because inputs outweigh decomposition.•With pika, warming does not alter SOC because decomposition counteracts inputs.•Microbial community structure is sensitive to pika disturbance but not warming.•Pika offsets the positive effect of warming on soil carbon in the swamp meadow. Both climate warming and plateau pika (Ochotona curzoniae) exert considerable impacts on carbon cycling in alpine ecosystems on the Tibetan Plateau. However, the interaction of warming and pika disturbance on soil organic carbon (SOC) dynamics in alpine ecosystems remains largely unknown. Here, we measured plant, soil and microbial properties after four-year warming in a swamp meadow (with or without pika disturbance) on the Tibetan Plateau. Our results showed that in non-pika plots, warming not only increased plant belowground biomass (48%), but also enhanced microbial biomass, hydrolytic enzyme activities, and bacterial functional genes (41–46%). More plant inputs likely outweighed faster microbial decomposition, leading to the accumulation of fast-cycling particulate organic carbon (POC, 49%) and bulk SOC (22%), but not slow-cycling mineral-associated organic carbon (MAOC). In pika-disturbed plots, however, warming did not significantly change plant belowground biomass (which dominates total plant biomass), microbial biomass and hydrolytic enzyme activities. Although bacterial functional genes were suppressed (−40%) and plant aboveground biomass was increased (118%), oxidative enzymes were significantly stimulated (17%), which likely counteracted the higher aboveground plant inputs and led to minor changes in soil carbon pools (SOC, POC and MAOC) with warming. Moreover, bacterial and fungal community structure were significantly altered by pika disturbance, but not warming. Overall, these findings demonstrated that pika disturbance could offset the short-term positive effect of warming on soil organic carbon in the alpine swamp meadow ecosystem.