Changes in Soil Microbial Biomass, Community Composition, and Enzyme Activities After Half-Century Forest Restoration in Degraded Tropical Lands

Abstract

Soil carbon (C) sequestration and stabilization are determined by not only the C input to the soil but also the decomposition rate of soil organic matter (SOM), which is mainly mediated by soil microbes. Afforestation, an effective practice to restore forests from degraded or bare lands, may alter soil microbial properties, and thus soil C and nitrogen (N) dynamics. The aim of this study was to investigate the impacts of different afforestation strategies on soil microbial compositions and activities after afforestation for half a century. Soil samples were collected from two afforested sites (i.e., a restored secondary forest (RSF) and a managed Eucalyptus forest (MEP)) and two reference sites (i.e., a nearby undisturbed forest (UF), representing the climax vegetation and a bare land (BL), representing the original state before restoration) in south China. We quantified the soil microbial biomass, microbial community compositions, and activities of nine extracellular enzymes at different soil depths and in different seasons. Results showed that the soil microbial biomass, all the main soil microbial groups, and the activities of all extracellular enzymes were significantly increased after afforestation compared to the BL sites, while the ratios of fungi/bacteria (F/B), specific enzyme activities, and the ecoenzymatic stoichiometry were significantly decreased regardless of the season and soil depth. Between the two afforested sites, these microbial properties were generally higher in the RSF than MEP. However, the microbial properties in the RSF were still lower than those in the UF, although the differences varied with different seasons, soil depths, and microbial groups or enzymes. Our findings demonstrated that afforestation might significantly improve microbial properties. Afforestation is more effective in mixed-species plantation than in the monoculture Eucalyptus plantation but needs a much longer time to approach an equivalent level to the primary forests.

Covariation between plant biodiversity and soil systems in a European beech forest and a black pine plantation: the case of Mount Faito, (Campania, Southern Italy)

“…When also considering the higher activity of peroxidase, a lignin decomposing enzyme produce by specialized fungi (Datta et al 2017), it may be inferred that the microbial community in the beech stand reflects the stability and maturity of the vegetation as well. Such trends towards more specialized microbial communities and higher C stocks in the soil, along with the maturity of the vegetation, has been also shown during afforestation (Zhang et al 2019) and within natural forests (Trap et al 2013). The same trend also occurred when considering the plant community on an ecological and functional aspect, considering Ellenberg's indicator value.…”

“…In general, decreases in organic matter with depth closely mirror changes in the total microbial and fungal biomass (Chen et al 2005). Several studies have reported a decrease in soil enzyme activities with depth in forest soils (Aon and Colaneri 2001;Lindner et al 2010;Fioretto et al 2018;Zhang et al 2019). Moreover, a strong correlation between the decrease in organic carbon and its readily utilizable forms with depth, and the vertical gradient of lignocellulosedegrading enzymes (Andersson et al 2004;Wittmann et al 2004) has been reported at an even finer scale (Šnajdr et al 2008).…”

Evaluating the impact of land-use change on Arbuscular Mycorrhizal Fungi (AMF) diversity and function

“…In the study by Zhang et al, the authors aimed to examine the impact of reforestation on soil microorganism characteristics. Following reforestation, the scientists uncovered a noteworthy surge in soil microorganism biomass, all major microorganism groups, and extracellular enzyme activities compared to bare-land sites [29]. These findings provide valuable insights into the potential benefits of afforestation in improving microbial properties.…”

Mixed-Species Plantation Effects on Soil Biological and Chemical Quality and Tree Growth of A Former Agricultural Land

“…All enzymatic activities had lower values in AL compared with tree stands, except the acid phosphomooesterase in PJC (Figures 2 and 3). The enhanced enzymatic activities could be attributed to the increase in soil TOC and TN stocks due to plant residue inputs with afforestation [60], as this provides more substrate for microbial assimilation [61].…”