Shrub encroachment and soil respiration (SR) are predicted to increase in the tundra ecosystem under climate warming, but little is known regarding potential causal relationships between shrubs and SR at a local scale. Multiple and complex belowground processes exist between the two phenomena, and consolidation is logistically difficult. Our study aimed to identify and integrate multiple belowground processes to elucidate the impact of shrub coverage on SR, using structural equation modeling (SEM). Results indicated that shrub coverage enhanced SR through root biomass, fungal community composition and soil temperature. SEM also revealed a potential indirect effect via interactions among those soil factors. Soil factors relating heterotrophic respiration affected on SR through more complex interaction among the factors. However, total effect sizes on SR were similar between factors relating autotrophic respiration and that relating heterotrophic respiration, suggesting that SR increases with shrub coverage would be unlikely to result from decreases in soil organic matter.

在气候变暖下，苔原生态系统中灌木入侵和土壤呼吸（SR）预计会增加，但是对于局部尺度上灌木和SR之间的潜在因果关系知之甚少。在这两种现象之间存在着多个复杂的地下过程，从逻辑上来说，整合是困难的。我们的研究旨在使用结构方程模型（SEM）来识别和整合多个地下过程，以阐明灌木覆盖对SR的影响。结果表明，灌木覆盖通过根系生物量，真菌群落组成和土壤温度提高了SR。扫描电镜还揭示了通过这些土壤因素之间相互作用的潜在间接影响。与异养呼吸有关的土壤因素通过各种因素之间更复杂的相互作用而影响SR。然而，