Microbial Compositions and Enzymes of a Forest Ecosystem in Alabama: Initial Response to Thinning and Burning Management Selections

Abstract

Prescribed burning and tree thinning are commonly used restoration practices for US forests management to increase forest productivity and enhance plant and animal diversity. The impact of these practices in Alabama's Bankhead National Forest (BNF) to soil microbial components and overall forest soil health are unknown. We hypothesized that microbial assemblages and enzyme activities are continuously changing in forest ecosystems especially due to management selections. Therefore, the objective of this study was to assess changes in microbial community compositions (fungal vs bacterial populations) via fatty acid methyl ester (FAME) profiling and several enzyme activities (β-glucosaminidase, acid phosphatase, arylsulfatase, β-glucosidase, xylanase, laccase, and manganese peroxidase) critical to soil organic matter (SOM) dynamics and biogeochemical cycling. In this forest, heavily-thinned plots without burning or less frequent burning treatments seemed to provide more favorable conditions (higher pH and lower C:N ratios) for C and N mineralization. This may explain a slight increase (by 12%) detected in fungi:bacteria (F:B) ratio in the heavily-thinned plots relative to the control. Thinned (lightly and heavily) plots showed greater ligninolytic (laccase and MnP) activities and lower β-glucosidase and β-glucosaminidase activities compared to the no-thinned plots probably due to increase depositions of woody recalcitrant C materials. We observed significant but negative correla

Temporal effects of thinning on soil organic carbon pools, basal respiration and enzyme activities in a Mediterranean Holm oak forest

“…In the same way, Kim et al (2018) reported that thinning did not alter enzyme activities in the soil of Pinus densiflora forests after 7 years. Conversely, Ntoko et al (2018) reported lower acid phosphatase activity in heavily-thinned plots compared to control and explained that it could be attributed to the lower plant available P in those plots. In our case, the enzyme activity was consistent with the lack of increase in the levels of microbial biomass under the thinning treatment.…”

Forest floor manipulation effects on the relationship between aggregate stability and ectomycorrhizal fungi

“…Our study supports the notion of soil recovery from forest floor manipulation and 34 reveals a potential relationship between aggregate stability and ECM abundance in Coastal Plain loblolly pine forests. (Ntoko et al, 2018).…”

“…Samples were assayed in duplicate and included a control for each assay, where the substrate was added after the reaction was terminated following incubation. The amount of p-nitrophenol released was calculated by reference to a calibration curve developed with standards containing 0, 100, 200, 300, 400, and 500 nmol of p-nitrophenol (Ntoko et al, 2018).…”

“…Enzyme activities were measured to determine the functioning and dynamics of soil microbes related to nutrient cycling in the soil (Table 2.4). The acid phosphatase enzyme is used here as an indicator of ECM activities (Ntoko et al, 2018). There appeared to be a trend in the acid-phosphatase data pointing to increasing activities with increasing forest floor retention as well as in the mixing treatment.…”

Impact of Forest Fires on Wood Anatomy, Soil Composition, and Soil Microorganisms of Acacia origena Asfaw (Leguminosae) in Al Souda Mountain, Southwestern Saudi Arabia

“…Microbial cells' lysing and altered reproductive capacity under the influence of soil heating are direct consequences of fire on soil microflora (Guénon et al, 2013). Moreover, the relative abundance of bacteria over fungi tends to increase after moderate-intensity fires due to their greater resilience to heat (Ntoko et al, 2018). So, the aim of this study was to investigate the impact of forest fires on Acacia origena Asfaw in Al Souda Mountain, Southwestern Saudi Arabia, with a focus on understanding changes in wood anatomy,soil composition, and soil microorganisms.…”