Short-Term Thinning Influences the Rhizosphere Fungal Community Assembly of Pinus massoniana by Altering the Understory Vegetation Diversity

Abstract

Thinning can significantly promote forest productivity and ecological function. Rhizosphere fungi play an indispensable role in regulating nutrient cycling between plants and the environment, and their community composition can positively respond to anthropogenic disturbance. However, the initial effects of thinning on rhizosphere fungal community assembly have seldom been reported. In this research, we studied the alterations in the rhizosphere fungal communities of 29-year-old Pinus massoniana in East Sichuan 2 years after three different thinning intensity treatments. In addition, the responses of fungal community and functional group composition to alterations in understory vegetation and soil physiochemical properties were analyzed. Three thinning intensities were set, which were 0 (CK), 25% (LIT), and 50% (HIT), respectively. The results suggested that the richness index and Shannon index of understory vegetation increased significantly with increasing thinning intensity. The alpha diversity indices of rhizosphere fungal community and soil physiochemical properties did not show significant differences among the three treatments. The relative abundances of 17 fungal indicator species varied regularly with increasing thinning intensity, and most of them belong to Hypocreales and Eurotiales, indicating that these two orders were potential indicators for different thinning treatments. Rhizosphere fungal community assembly was determined by deterministic process, and it was driven by the diversity of understory vegetation in the initial stage of thinning. The Simpson index and Pielou index of herbs were useful measures of the main environmental factors driving the differentiation of fungal functional group composition. Based on network analysis, thinning resulted in distinct co-occurrence patterns of rhizosphere fungal functional groups. This research elucidates the initial role of thinning in rhizosphere fungal community assembly of P. massoniana and has practical significance for the functional restoration and protection of local forest ecosystem.

The Bacterial and Fungal Compositions in the Rhizosphere of Asarum heterotropoides Fr. Schmidt var. mandshuricum (Maxim.) Kitag. in a Typical Planting Region

“…The air-dried and sieved (<2 mm) soil samples were used to determine the soil's physicochemical properties, including pH, available phosphorus (AP), and alkaline nitrogen (AN). Soil pH was measured using a pH meter in a soil/water suspension (1:2.5 w/v) after shaking for 30 min [23,24]. The AN was determined using alkali diffusion methods.…”

Understory vegetation diversity, soil properties and microbial community response to different thinning intensities in Cryptomeria japonica var. sinensis plantations

“…Soil microorganisms play a crucial role in nutrient decomposition, absorption, and transformation in terrestrial ecosystems (Soong et al, 2019;Tian et al, 2019;Averill et al, 2021). The diversity and abundance of soil bacteria and fungi not only affect nutrient mineralization and cycling but are also sensitive to ecological environmental conditions, such as soil properties (Stark et al, 2012;Shen et al, 2013;Urbanová et al, 2015;Lladó et al, 2018), vegetation diversity (Liu et al, 2021;Shang et al, 2021), and climatic conditions (Bona et al, 2021). Soil properties are considered crucial factors influencing soil microbial activity and community structure, which have become a research hotspot in the field of the soil microbiome.…”

Thinning can increase shrub diversity and decrease herb diversity by regulating light and soil environments

“…However, due to the asymmetric consumption of space, light, water, and soil nutrients by the overstory, understory vegetation often exists in a limited resource environment (Su et al, 2019). Previous studies have confirmed that light and soil conditions are generally considered to be the main limiting resources affecting the establishment and growth of understory vegetation (Nicotra et al, 1999;Stein et al, 2014;Zhou et al, 2016;Su et al, 2019;Liu et al, 2021). The reasons for these inconsistent results may be related to stand types, and for the mixed broadleaf-conifer forest, the response of vegetation diversity to light and soil environments was still unclear.…”