Local Geomorphological Gradients and Land Use Patterns Play Key Role on the Soil Bacterial Community Diversity and Dynamics in the Highly Endemic Indigenous Afrotemperate Coastal Scarp Forest Biome

Abstract

Southern Afrotemperate forests are small multi-layered and highly fragmented biodiversity rich biomes that support unique flora and fauna endemism. However, little is known about the microbial community and their contribution to these ecosystems. In this study, high throughput sequencing analysis was used to investigate the soil bacterial community structure and function, and understand the effect of local topography/geomorphological formations and land use patterns on a coastal scarp forest. Soil samples were collected from three forest topography sites: upper (steeper gradients, 30–55°; open canopy cover, <30%), mid (less steep, 15–30°; continuous forest canopy, >80%), and lower (flatter gradient, <15°; open canopy cover, 20–65%), and from the adjacent sugarcane farms. Results indicated that forest soils were dominated by members of phyla Proteobacteria (mainly members of α-proteobacteria), Actinobacteria, Acidobacteria, Firmicutes, and Planctomycetes, while Actinobacteria and to a lesser extent β-proteobacteria and γ-proteobacteria dominated SC soils. The core bacterial community clustered by habitat (forest vs. sugarcane farm) and differed significantly between the forest topography sites. The Rhizobiales (genera Variibacter, Bradyrhizobium, and unclassified Rhizobiales) and Rhodospirallales (unclassified Rhodospirillum DA111) were more abundant in forest mid and lower topographies. Steeper forest topography (forest_upper) characterized by the highly leached sandy/stony acidic soils, low in organic nutrients (C and N) and plant densities correlated to significant reduction of bacterial diversity and richness, associating significantly with members of order Burkholderiales (Burkholderia-Paraburkholderia, Delftia, and Massilia) as the key indicator taxa. In contrast, changes in the total nitrogen (TN), soil organic matter (SOM), and high acidity (low pH) significantly influenced bacterial community structure in sugarcane farm soils, with genus Acidothermus (Frankiales) and uncultured Solirubrobacterales YNFP111 were the most abundant indicator taxa. Availability of soil nutrients (TN and SOM) was the strongest driver of metabolic functions related to C fixation and metabolism, N and S cycling; these processes being significantly abundant in forest than sugarcane farm soils. Overall, these results revealed that the local topographical/geomorphological gradients and sugarcane farming affect both soil characteristics and forest vegetation (canopy coverage), that indirectly drives the structure and composition of bacterial communities in scarp forest soils.

The Damage Caused by Decline Disease in Bayberry Plants through Changes in Soil Properties, Rhizosphere Microbial Community Structure and Metabolites

“…As we know, bacteria of the Acidothermus genus were able to grow under acidic conditions and degrade plant tissues [25,34], which normally cause increases in organic matter and magnesium content, as well as available nitrogen and calcium. Interestingly, most of these soil parameters are associated with soil pH [35].…”

A UAS and Machine Learning Classification Approach to Suitability Prediction of Expanding Natural Habitats for Endangered Flora Species

“…To potentially extend their habitat to neighboring areas, we proposed a habitat suitability prediction method based on noninvasive field observations from remote sensing imaginh using a UAS multispectral camera system and machine learning classification. Since the evaluated environmental conditions, including vegetation, soil, and topography criteria, impact the ecological gradient of both flora and fauna species [50][51][52], the proposed approach should be applicable to a wide variety of endangered species. Moreover, the application of the UAS mounted multispectral camera system ensured that flora and fauna species would be minimally disturbed in their natural habitat during the field observations and non-invasive population count [53].…”

Termite diet rather than geographical origin determines the microbiome composition and functional genetic structure of nests from South American and African representatives, as revealed by a multiomics approach

“…Our results are in agreement with those described by Enagbonma et al (2020), where they report this group at termite mounds from Coptotermes species. Uncultured representatives of Solirubrobacterales have been associated to the degradation of lignin in soils (Wilhelm et al, 2018;Silva et al, 2021), previously reported as well in sugarcane farm soils (Ogola et al, 2021). Spirochaetales are Gram-negative that can comprise both anaerobic and strict aerobic bacteria (Smibert and Johnson, 1973).…”