Non-random tree species loss shifts soil fungal communities

Ongoing global changes speed up forest diversity loss, typically in a non-random manner, with potential consequences for soil fungal communities. However, it remains elusive how non-random tree species loss, based on distribution ranges or specific traits, impacts soil fungal communities. Here we employed a large-scale field experiment where random and non-random tree species losses were experimentally manipulated, to estimate soil fungal responses using high-throughput sequencing. Two non-random scenarios were studied: non-random loss of either rarer species (measured by regional frequency) or more acquisitive species (measured by specific leaf area, SLA). We found that soil fungal communities were more profoundly affected by the non-random rather than the random tree species loss. Preferential loss of higher-SLA species resulted in significant decreases in soil fungal diversity, shifts in community composition and simplifications in fungal co-occurrence network. Moreover, both the diversity and relative abundance of saprotrophic fungi decreased, whereas those of ectomycorrhizal (EcM) fungi increased with SLA-oriented tree species loss. With biased loss of rarer species, plant pathogenic fungi showed decreases in diversity and shifts in community composition. Compared with the random scenario, the significant effects of non-random tree species loss are closely related to the covaried trait dominance of plant communities, notably to the changes concerning community life-history traits and mycorrhizal associations. Our study provided novel evidence that the non-random, trait-oriented tree species loss exerted far-reaching effects on soil fungal community structures compared with the random species loss, highlighting the potential of trait-based predictions for understanding the dynamics of soil fungal communities. Modified ecosystem functioning under disturbances causing non-random tree species loss in the real-world can, therefore, be expected owing to the trait-based plant-soil fungal interactions.<br>

持续发生的全球环境变化正加速森林多样性丧失，且该过程通常呈非随机模式，将对土壤真菌群落产生潜在影响。然而，基于分布范围或特定功能性状的非随机树木物种丧失，如何影响土壤真菌群落，目前仍未明确。本研究依托一项大型野外控制实验，通过人为操控随机与非随机树木物种丧失的处理组，利用高通量测序（high-throughput sequencing）技术评估土壤真菌的响应特征。本研究设置两类非随机丧失场景：一类为以区域性频度衡量的稀有种非随机丧失，另一类为以比叶面积（specific leaf area, SLA）衡量的资源获取型物种非随机丧失。研究结果表明，相较于随机树木物种丧失，非随机丧失对土壤真菌群落的影响更为显著。优先丧失高SLA物种会导致土壤真菌多样性显著下降、群落组成发生偏移，同时简化真菌共现网络结构。此外，随着以SLA为导向的树木物种丧失，腐生真菌（saprotrophic fungi）的多样性与相对丰度均出现下降，而外生菌根（ectomycorrhizal fungi, EcM）真菌的相应指标则有所上升。当发生稀有种的偏倚性丧失时，植物病原真菌的多样性会下降且群落组成发生偏移。相较于随机丧失场景，非随机树木物种丧失所产生的显著影响，与植物群落的协变性状优势度密切相关，尤其是与群落生活史性状及菌根共生关系的变化紧密关联。本研究提供了新的实证证据：相较于随机物种丧失，以功能性状为导向的非随机树木物种丧失，会对土壤真菌群落结构产生更为深远的影响，这凸显了基于功能性状的预测方法在解析土壤真菌群落动态方面的应用潜力。因此，鉴于基于功能性状的植物-土壤真菌互作机制，现实世界中由非随机树木物种丧失引发的干扰，将可能改变生态系统的功能状态。