Table_1_Low- to Moderate-Level Forest Disturbance Effects on Plant Functional Traits and Associated Soil Microbial Diversity in Western Himalaya.xlsx

This study quantifies the effect of low- to moderate-intensity anthropogenic activities and natural activities affecting less than 40% of the canopy cover on major plant functional traits and associated soil microbial diversity in western Himalayan temperate forests. Plots of 0.1 ha were placed in the temperate forests along disturbance gradient and were categorized based on lopping intensity, deadwood counts, grazing, and litter removal. Plots were classified into three classes, i.e., low disturbance intensity (LDI) and moderate disturbance intensities (MDI1 and MDI2) based on lopping activities and canopy cover. The study was conducted on functional traits related to growth and survival strategies of a species in a complex forest ecosystem. Furthermore, DNA was extracted and metagenome of soil samples was performed using Illumina MiSeq platform from three disturbance classes to study the effect of disturbance and plant traits on microbial diversity. Tree basal area was found to be most significantly affected by disturbance intensity. Total density was found to be greater for the LDI site. Specific leaf area (SLA) and crown cover (CC) were the most affected traits in the moderately disturbed sites, whereas maximum plant height (HT) and seed mass (SM) were least affected by disturbance. Soil microbial diversity was found to be negatively associated with disturbance index. Microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) were found to be significantly higher in LDI sites. Disturbance level elicited variation in microbial community composition. Proteobacteria was the most abundant phylum and Phenylobacterium, DA101, and Candidatus solibacter were mainly abundant at the genus level. A decreasing level of disturbance due to the absence of human residences in the LDI site led to the dominance of Phenylobacterium (27%) which reduced to 18% in MDI1 site. Shannon alpha bacterial diversity and plant species diversity (H′) were found to be greatest for MDI2 site. In forests with varying levels of management, treefall gaps due to low levels of logging intensity might have a similar effect to those of reduced lopping intensities and deadwood count (due to natural disturbances) in the study sites. The study concludes that moderate disturbance is important for promoting species diversity and species richness (SR), but species having conservative ecological strategies would be more prone to continued disturbance intensity. Therefore, low- to moderate-level disturbance in such forests can be used as a model for natural treefall gaps, and moderate-level disturbance intensity plays a powerful role in buffering ecosystem processes.

本研究聚焦喜马拉雅西部温带森林，针对林冠覆盖度低于40%、受低至中强度人为活动与自然活动干扰的区域，量化了此类干扰对核心植物功能性状及相关土壤微生物多样性的影响。研究沿干扰梯度在温带森林中设置0.1公顷的样地，并依据修枝强度、枯木数量、放牧强度及枯落物移除情况对样地进行分类；基于修枝活动与林冠覆盖度，将样地划分为三类：低干扰强度（Low Disturbance Intensity, LDI）、中干扰强度1（Moderate Disturbance Intensity 1, MDI1）及中干扰强度2（Moderate Disturbance Intensity 2, MDI2）。本研究选取与复杂森林生态系统中物种生长及生存策略相关的功能性状开展分析。此外，研究针对三类干扰样地的土壤样品，采用Illumina MiSeq平台进行DNA提取与宏基因组测序，以解析干扰与植物性状对微生物多样性的影响。研究发现，树木胸高断面积受干扰强度的影响最为显著；低干扰强度样地的总种群密度更高。在中度干扰样地中，比叶面积（Specific Leaf Area, SLA）与冠层覆盖度（Crown Cover, CC）为受干扰影响最显著的功能性状；而植株最大高度（Maximum Plant Height, HT）与种子质量（Seed Mass, SM）受干扰的影响最弱。土壤微生物多样性与干扰指数呈显著负相关关系。低干扰强度样地的微生物生物量碳（Microbial Biomass Carbon, MBC）与微生物生物量氮（Microbial Biomass Nitrogen, MBN）含量显著更高。干扰水平会引发微生物群落组成的差异：在门水平上，变形菌门（Proteobacteria）为优势类群；在属水平上，苯基杆菌属（Phenylobacterium）、DA101属与候选索氏杆菌属（Candidatus Solibacter）为主要优势类群。由于低干扰强度样地无人类居住，干扰水平较低，使得苯基杆菌属成为优势类群（占比27%）；而在中干扰强度样地1中，该属占比降至18%。研究发现，中干扰强度样地2的香农细菌α多样性与植物物种多样性指数（H′）均为最高。在不同管理强度的森林中，低强度伐木造成的林隙效应，可能与研究样地中因自然干扰导致的修枝强度降低、枯木数量减少所带来的效应相似。研究得出结论：适度干扰对提升物种多样性与物种丰富度（Species Richness, SR）具有重要意义，但具备保守型生态策略的物种更易受持续干扰强度的负面影响。因此，此类森林中实施的低至中度干扰措施，可作为自然林隙的模拟方案；而中度干扰强度在维持生态系统过程稳定性方面具有显著的缓冲作用。