The Effects of Shrub Removal on Soil Microbial Communities in Primary Forest, Secondary Forest and Plantation Forest on Changbai Mountain

Niches, interspecific associations, and community stability of main understory regeneration species after understory removal in temperate forests

Introduction

Understory removal is frequently used to relieve the renewal pressure on trees and promote the growth capability of trees for maintaining community stability, while the lack of previous study on temperate forests limits our assessment of the effectiveness of this essential management measurement.

Methods

In this study, we calculated the niche characteristics and interspecific association of main understory species and community stability in temperate forests [original broad-leaved Korean pine forest (BKF), Betula platyphylla secondary forest (BF), and Larix gmelinii plantation (LF)] after understory removal for characterizing the resource utilization capacity of the regeneration trees.

Results

During the restoration stage, the niche breadth of understory plants with similar habits varied across stands and layers; regeneration tree species with heliophile and semishade occupied a larger niche in BKF and LF, while it was the opposite in LF. Niche overlap among heliophile regeneration trees increased in both BKF and BF, but not in LF. The interspecific association among main species revealed that the distribution of each species was independent and the interspecific association was loose and it varied in different forests and different light-demanding species with regeneration trees. The stability of shrub communities in BF and LF improved whereas that of BKF declined, while that of the herb communities of corresponding forests showed the opposite state.

Discussion

Our study demonstrated that the effectiveness of understory removal depends on species' ecological habits, which enhances the renewal and resource utilization capacity of regeneration tree species in temperate forests and shrub community stability in BF and LF.

Effect of elevation on composition and diversity of fungi in the rhizosphere of a population of Deyeuxia angustifolia on Changbai Mountain, northeastern China

Soil fungi are a key component of terrestrial ecosystems and play a major role in soil biogeochemical cycling. Although the diversity and composition of fungal communities are regulated by many abiotic and biotic factors, the effect of elevation on soil fungal community diversity and composition remains largely unknown. In this study, the soil fungal composition and diversity in Deyeuxia angustifolia populations along an elevational gradient (1,690 m to 2020 m a.s.l.) were assessed, using Illumina MiSeq sequencing, on the north-facing slope of the Changbai Mountain, northeastern China. Our results showed that soil physicochemical parameters changed significantly along with the elevational gradients. The Ascomycota and Basidiomycota were the most dominant phyla along with the gradient. Alpha diversity of soil fungi decreased significantly with elevation. Soil nitrate nitrogen (NO₃^--N) was positively correlated with fungal richness and phylogenetic diversity (PD), indicating that soil nitrate nitrogen (NO₃^--N) is a key soil property determining fungal community diversity. In addition to soil nitrate content, soil pH and soil moisture were the most important environmental properties determining the soil fungal diversity. Our results suggest that the elevational changes in soil physicochemical properties play a key role in shaping the community composition and diversity of soil fungi. This study will allow us to better understand the biodiversity distribution patterns of soil microorganisms in mountain ecosystems.

Forest understory vegetation study: current status and future trends

Understory vegetation accounts for a large proportion of floral diversity. It provides various ecosystem functions and services, such as productivity, nutrient cycling, organic matter decomposition and ecosystem self-regeneration. This review summarizes the available literature on the current status and progress of the ten most studied branches of understory vegetation on both its structural and functional aspects based on global climate change and forest management practices. Future research directions and priorities for each branch is suggested, where understory vegetation in response to the interplay of multiple environmental factors and its long-term monitoring using ground-based surveys combined with more efficient modern techniques is highlighted, although the critical role of understory vegetation in ecosystem processes individually verified in the context of management practices or climate changes have been extensively investigated. In summary, this review provides insights into the effective management of the regeneration and restoration of forest ecosystems, as well as the maintenance of ecosystem multilevel structures, spatial patterns, and ecological functions.