Department of Botany and Plant Sciences, University of California Riverside, Riverside, California.
Department of Microbiology and Plant Pathology, University of California Riverside, Riverside, California.
Mol Ecol. 2018 May;27(10):2461-2476. doi: 10.1111/mec.14694. Epub 2018 May 10.
Global climate and land use change are altering plant and soil microbial communities worldwide, particularly in arctic and alpine biomes where warming is accelerated. The widespread expansion of woody shrubs into historically herbaceous alpine plant zones is likely to interact with climate to affect soil microbial community structure and function; however, our understanding of alpine soil ecology remains limited. This study aimed to (i) determine whether the diversity and community composition of soil fungi vary across elevation gradients and to (ii) assess the impact of woody shrub expansion on these patterns. In the White Mountains of California, sagebrush (Artemisia rothrockii) shrubs have been expanding upwards into alpine areas since 1960. In this study, we combined observational field data with a manipulative shrub removal experiment along an elevation transect of alpine shrub expansion. We utilized next-generation sequencing of the ITS1 region for fungi and joint distribution modelling to tease apart effects of the environment and intracommunity interactions on soil fungi. We found that soil fungal diversity declines and community composition changes with increasing elevation. Both abiotic factors (primarily soil moisture and soil organic C) and woody sagebrush range expansion had significant effects on these patterns. However, fungal diversity and relative abundance had high spatial variation, overwhelming the predictive power of vegetation type, elevation and abiotic soil conditions at the landscape scale. Finally, we observed positive and negative associations among fungal taxa which may be important in structuring community responses to global change.
全球气候和土地利用变化正在改变世界各地的植物和土壤微生物群落，特别是在北极和高山生态系统中，那里的变暖速度正在加快。木本灌木的广泛扩张进入历史上草本的高山植物带，很可能与气候相互作用，影响土壤微生物群落结构和功能；然而，我们对高山土壤生态学的理解仍然有限。本研究旨在：（i）确定土壤真菌的多样性和群落组成是否随海拔梯度而变化；（ii）评估木本灌木扩张对这些模式的影响。在加利福尼亚州的白山地区，自 1960 年以来，山艾树（Artemisia rothrockii）灌木已经向上扩张到高山地区。在这项研究中，我们结合了观测性野外数据和沿高山灌木扩张海拔梯度的操纵性灌木去除实验。我们利用真菌的 ITS1 区域的下一代测序和联合分布建模来梳理环境和群落内相互作用对土壤真菌的影响。我们发现，土壤真菌多样性随着海拔的升高而下降，群落组成也发生了变化。非生物因素（主要是土壤水分和土壤有机碳）和木本山艾树的扩张范围对这些模式都有显著影响。然而，真菌多样性和相对丰度具有很高的空间变异性，在景观尺度上超过了植被类型、海拔和非生物土壤条件的预测能力。最后，我们观察到真菌分类群之间存在正相关和负相关，这可能对群落对全球变化的反应结构很重要。
