Abstract
Upward shifts of alpine treelines and shrub expansion are occurring under climate change, and Abies faxoniana (AF) and Rhododendron lapponicum (RL) may become distributed at higher altitudes. How do abiotic factors and litter quality modulate the effects of soil fauna on carbon release in this context? A field decomposition experiment involving the foliar litter of AF and RL was conducted along an elevation gradient encompassing coniferous forest, alpine shrubland and alpine meadow by using litterbags with different mesh sizes (3 and 0.04 mm). The objective was to determine the influences of soil fauna, litter quality and abiotic factors on species-specific carbon release and their contributions during litter decomposition. Our findings demonstrated that higher soil fauna abundance and diversity facilitated litter carbon release. The contribution rates of soil fauna to carbon release (Cfau) decreased with elevation increasing and decomposition time. Cfau are influenced by soil faunal diversity, dominant fauna groups (Collembola, Oribatida, Mesostigmata), and abiotic factors (temperature). Soil fauna significantly and directly regulated carbon release, abiotic factors indirectly regulated carbon release via altering soil fauna community composition and litter quality. This study improve our understanding in the mechanisms of decomposer contributions to carbon cycling in the context of global climate change.
Highlights
Plant litter decomposition is a fundamental ecological process, linking nutrient cycling and energy flows in food webs and the structure and dynamics of ecosystems[1,2]
This ecotone typically appears as a patchy transition that consists of several intermediate vegetation zones and components, such as dark coniferous forest (CF), alpine shrubland (AS) and alpine meadow (AM)[18]
We suggest that the magnitude of Home-field advantage (HFA) effect on litter mass loss may be underestimated, since litterbags restrict the removal of litter from litterbags by soil fauna, and that HFA may increase with greater differences in litter quality between two litter types
Summary
Plant litter decomposition is a fundamental ecological process, linking nutrient cycling and energy flows in food webs and the structure and dynamics of ecosystems[1,2]. Climate, litter quality and decomposers are considered the most important factors controlling litter decomposition[3]. The soil fauna is an important component of ecosystems due to their functional roles in biogeochemical cycles in accelerating the rates of litter decomposition and nutrient transformation[5,6]. The interactions between litter and decomposer communities in response to climate change appear to be uncertain It is well understood how climate and substrate quality influence litter decomposition, the functional roles of decomposers in biogeochemical cycles remain unclear. We studied the litter decomposition rates of representative plants (0.16–1.70) g/yr[19] and the release of carbon and nutrients during litter decomposition[20,21], mainly focusing on abiotic factors, such as freeze-thaw cycles, during the long snow-cover season. How soil fauna affect litter C release remains unclear
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