Effects of Lime Application and Understory Removal on Soil Microbial Communities in Subtropical Eucalyptus L’Hér. Plantations

Abstract

Soil microorganisms play key roles in ecosystems and respond quickly to environmental changes. Liming and/or understory removal are important forest management practices and have been widely applied to planted forests in humid subtropical and tropical regions of the world. However, few studies have explored the impacts of lime application, understory removal, and their interactive effects on soil microbial communities. We conducted a lime application experiment combined with understory removal in a subtropical Eucalyptus L’Hér. plantation. Responses of soil microbial communities (indicated by phospholipid fatty acids, PLFAs), soil physico-chemical properties, and litter decomposition rate to lime and/or understory removal were measured. Lime application significantly decreased both fungal and bacterial PLFAs, causing declines in total PLFAs. Understory removal reduced the fungal PLFAs but had no effect on the bacterial PLFAs, leading to decreases in the total PLFAs and in the ratio of fungal to bacterial PLFAs. No interaction between lime application and understory removal on soil microbial community compositions was observed. Changes in soil microbial communities caused by lime application were mainly attributed to increases in soil pH and NO3–-N contents, while changes caused by understory removal were mainly due to the indirect effects on soil microclimate and the decreased soil dissolved carbon contents. Furthermore, both lime application and understory removal significantly reduced the litter decomposition rates, which indicates the lime application and understory removal may impact the microbe-mediated soil ecological process. Our results suggest that lime application may not be suitable for the management of subtropical Eucalyptus plantations. Likewise, understory vegetation helps to maintain soil microbial communities and litter decomposition rate; it should not be removed from Eucalyptus plantations.

Understory removal accelerates nucleic phosphorus release but retards residual phosphorus release in decomposing litter of Phyllostachys edulis in subtropical China

“…This result is in line with most previous studies conducted in temperate and subtropical plantations (e.g., Wan et al, 2019;Winsome et al, 2017), confirming the strong controls of understory plants on soil microbial communities (Yin et al, 2016). In general, most fungi are moderately acidophilic; therefore, fungal activities would be facilitated and the microbial communities would typically shift from bacterial to fungal as soil pH decreases (Wan et al, 2019;Zhao et al, 2015). The negative relationship between 18:2ω6,9c and soil pH in this study implied that the altered soil microbial community would be partly resulted from the decreased soil pH (Figures 2 and 4).…”

“…In most forest plantations, understory removal (UR) is a common management practice to reduce competition for resources and increase stand productivity (Giuggiola et al, 2018;Qiao, Miao, Silva, & Horwath, 2014;Zhao et al, 2013). Previous studies have observed that UR caused substantial changes in soil microclimate, nutrient availability, and microbial composition and structure (Wan et al, 2014(Wan et al, , 2019. Accordingly, UR could potentially influence litter decomposition and P release through its effects on microclimate, soil microorganisms, and soil nutrient availability.…”

“…However, the effects of understory removal on litter decomposition and P release are highly ecosystem-dependent. For example, previous studies have observed that litter decomposition and P release were retarded by UR in a subtropical Eucalyptus plantation (Wan et al, 2019) but accelerated in a postfire boreal forest (De Long et al, 2016). Moreover, few studies have assessed the effect of UR on the dynamics of P fractions in decomposing litter.…”

Bacillus pumilus Group Comparative Genomics: Toward Pangenome Features, Diversity, and Marine Environmental Adaptation

“…The land group was enriched in signal transduction mechanisms (T), cell cycle control, cell division, chromosome partitioning (D) among the COG categories (Figure 5B). It has been suggested that land bacteria might respond quickly to environmental variation (Wan et al, 2019). At the same time, it has also been suggested that having dispensable genes involved in cell wall biogenesis, transport and metabolism of amino acids, carbohydrates, inorganic ions, and secondary metabolites, could be how certain members of Azospirillum adapt to terrestrial niches (Wisniewski-Dyé et al, 2011).…”

Research in Forest Biology in the Era of Climate Change and Rapid Urbanization

“…Furthermore, both lime application and understory removal significantly reduce the litter decomposition rates, which may impact the microbe-mediated soil ecological process. They suggest that lime applications may not be suitable for the management of subtropical Eucalyptus plantations [24]. Wu, Li, Chen et al examine the effects of two native phosphate solubilizing bacteria (PSB), and a mixture of both strains on the growth of seedlings of Camellia oleifera (Theaceae).…”