Dominant plant functional groups regulate soil respiration response to warming in three types of alpine grassland on the Qinghai-Tibet Plateau

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Abstract Background Soil respiration (Rs) is critical for maintaining the terrestrial carbon (C) cycling, and considerable research has focused on its response to climate warming. However, our knowledge of the mechanistic basis of the plant functional composition on Rs is limited. We conducted a 2-year field warming experiment to explore Rs responses to different warming levels across three types of alpine grasslands: alpine steppe (AS) dominated by grasses, alpine meadow (AM) and alpine swamp meadow (ASM), both of the latter two dominated by sedges. Results Our findings revealed contrasting effects of warming on Rs across three alpine grassland types: minimal change in the AS, a significant 24% increase in the AM, and a 20% decrease in the ASM. Dominant plant functional groups in each grassland type play an important role in regulating the response of Rs to warming. Moreover, we found a negative correlation between plant height and Rs in the grass-dominated AS and sedge-dominated AM. However, there was no correlation between plant height and Rs in ASM. Furthermore, Rs was regulated by both soil moisture and soil temperature, while in ASM it was constrained by soil moisture levels. Conclusions Our results underscore the importance of incorporating plant functional composition mechanisms when assessing ecosystem C balance under climate warming. Future studies should consider the ecosystem‐specific characteristics when investigating the connections between plant community structure, traits, and ecosystem function.

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