Disturbances cause rapid changes to forests, with different disturbance types and severities creating unique ecosystem trajectories that can impact the underlying soil microbiome. Pile burning – the combustion of logging residue on the forest floor – is a common fuel reduction practice that can have impacts on forest soils analogous to those following high severity wildfire. Further, pile burning following clear-cut harvesting can create persistent openings dominated by non-woody plants surrounded by dense regenerating conifer forest. A paired 60-year chronosequence of burn scar openings and surrounding regenerating forest after clear-cut harvesting provides a unique opportunity to assess whether belowground microbial processes mirror aboveground vegetation during disturbance-induced ecosystem shifts. Soil ectomycorrhizal fungal diversity was reduced the first decade after pile burning, which could explain poor tree seedling establishment and subsequent persistence of herbaceous species within the openings. Fine-scale changes in the soil microbiome mirrored aboveground shifts in vegetation, with short-term changes to microbial carbon cycling functions resembling a post-fire microbiome (e.g., enrichment of aromatic degradation genes) and respiration in burn scars decoupled from substrate quantity and quality. Broadly, however, soil microbiome composition and function within burn scar soils converged with that of the surrounding regenerating forest six decades after the disturbances, indicating potential microbial resilience that was disconnected from aboveground vegetation shifts. This work begins to unravel the belowground microbial processes that underlie disturbance-induced ecosystem changes, which are increasing in frequency tied to climate change.

中文翻译：

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干扰驱动的森林生态系统转变过程中的土壤微生物组反馈

干扰会导致森林发生快速变化，不同的干扰类型和严重程度会产生独特的生态系统轨迹，从而影响潜在的土壤微生物组。堆烧——在森林地面上燃烧伐木残渣——是一种常见的燃料减少做法，它对森林土壤的影响类似于严重野火后的影响。此外，砍伐后的堆放燃烧会形成持续的开口，这些开口主要由非木本植物主导，周围环绕着茂密的再生针叶林。烧伤疤痕开口和砍伐后周围再生森林的配对 60 年时间序列提供了一个独特的机会来评估在干扰引起的生态系统转变期间地下微生物过程是否反映了地上植被。土壤外生菌根真菌多样性在堆焚烧后的第一个十年内减少，这可以解释树苗生长不良以及随后草本物种在开口内持续存在的原因。土壤微生物组的精细变化反映了植被的地上变化，微生物碳循环功能的短期变化类似于火灾后微生物组（例如，芳香族降解基因的富集）以及烧伤疤痕中与基质数量和质量脱钩的呼吸作用。然而，总的来说，烧伤疤痕土壤中的土壤微生物组组成和功能在干扰发生六年后与周围再生森林的微生物组组成和功能趋同，表明潜在的微生物恢复能力与地上植被的变化无关。这项工作开始揭示地下微生物过程，这些过程是干扰引起的生态系统变化的基础，这些变化与气候变化相关的频率正在增加。