Dominant Tree Species Shape Soil Microbial Community via Regulating Assembly Processes in Planted Subtropical Forests

Abstract

Understanding the ecological processes that regulate microbial community assembly in different habitats is critical to predict microbial responses to anthropogenic disturbances and environmental changes. Rubber (Hevea brasiliensis) and Eucalypt (Eucalyptus urophylla) plantations (thereafter RP and EP) are rapidly established at the expense of forests in tropical China, greatly affecting tropical soils and their processes. However, the assembly processes of soil microbial communities after forest conversions remain unclear. We investigated soil microbial communities’ attributes and quantified the portion of deterministic assembly variation in two RP (a 3- and a 5-year-old) and two EP (a 2- and a 4-year-old) in Southern China. Shannon and Faith’s Phylogenetic α-diversity of both bacterial and fungal communities were higher in RP than in EP, regardless of plantation age or soil depth (0–50 cm). Bacterial and fungal community structure was significantly different among the four plantations. The dominant microbial taxa in RP closely tracked the availability of nitrogen, phosphorus and potassium (K) while those in EP were closely related to the high total K content. Microbial co-occurrence networks in RP were more modular than those in EP, as governed by more keystone taxa that were strongly dependent on soil available nutrients. Environmental filtering imposed by soil nutrients heterogeneity contributed a considerable portion (33–47%) of bacterial assembly variation in RP, but much less (8–14%) in EP. The relative contribution of environmental selection on fungal assembly was also greater in RP than in EP. Our findings suggest that in RP clear microbial community patterns exist with respect to soil nutrients, whereas in EP microbial community assembly patterns are more stochastic and variable. The large variation in soil microbial community assembly patterns in EP could lead to fragile and unstable microbial-soil relationships, which may be one factor driving soil degradation in EP.

Soil Bacterial Community Shifts Are Driven by Soil Nutrient Availability along a Teak Plantation Chronosequence in Tropical Forests in China

“…The present study also shows that SOC has a significant impact on the bacterial community structure in bulk soils. Our results show that AK and TK have a significant impact on bacterial community structure, especially in bulk soils, which is consistent with the results reported by Ma et al [ 24 ], who reported a statistical correlation between microbial structure and soil TK in Eucalyptus urophylla plantations. Leaching of K from the soil may explain this phenomenon [ 9 ].…”

“…Therefore, the lack of K not only directly affects the microbial communities but also indirectly limits the absorption and utilization of other nutrients by plants. In this sense, teak trees may facilitate the shift of bacterial communities towards a community with an increased ability to mobilize soil K [ 24 ]. Moreover, AP and TP were significantly correlated with bacterial community structure in this study.…”

“…In the natural environment, microbes usually live within complex ecological networks that interact with each other [ 24 , 25 ] and include positive interactions, such as competition and predation, and negative interactions, such as commensalism and mutualism. [ 26 ].…”

Multiscale ecological niche modeling exhibits varying climate change impacts on habitat suitability of Madrean Pine-Oak trees

“…Dominant trees provide various functions that guide overall forest community function and structure (Power et al, 1996). Observations suggest that dominant tree species direct the ecological processes that regulate microbial soil community assembly, which play a critical role in maintaining forest functional and structural stability (Ma et al, 2019). Dominant tree species are also driving factors in shaping spatial patterns of plant biodiversity, locally and regionally (Hao et al, 2007;Draper et al, 2019).…”

Network complexity of rubber plantations is lower than tropical forests for soil bacteria but not for fungi

“…Compared with primary forests, agricultural systems tend to have higher bacterial richness but lower fungal richness (Lan et al, 2017a;Cai et al, 2018;Tripathi et al, 2012;Kerfahi et al, 2016). Compared with Eucalyptus plantations, rubber plantations have been found to possess a higher diversity of both bacteria and fungi (Ma et al, 2019). Song et al (2019) reported that tropical forest conversion to rubber plantation results in reduced fungal microbial community network complexity.…”