Niche partitioning of bacterial communities in biological crusts and soils under grasses, shrubs and trees in the Kalahari

Abstract

Elliott, D. R., Thomas, A. D., Hoon, S. R., Sen, R. (2014). Niche partitioning of bacterial communities in biological crusts and soils under grasses, shrubs and trees in the Kalahari. Biodiversity & Conservation, 23 (7), 1709-1733The Kalahari of southern Africa is characterised by sparse vegetation interspersed with microbe-dominated biological soil crusts (BSC) which deliver a range of ecosystem services including soil stabilisation and carbon fixation. We characterised the bacterial communities of BSCs (0?1 cm depth) and the subsurface soil (1?2 cm depth) in an area typical of lightly grazed Kalahari rangelands, composed of grasses, shrubs, and trees. Our data add substantially to the limited amount of existing knowledge concerning BSC microbial community structure, by providing the first bacterial community analyses of both BSCs and subsurface soils of the Kalahari region based on a high throughput 16S ribosomal RNA gene sequencing approach. BSC bacterial communities were distinct with respect to vegetation type and soil depth, and varied in relation to soil carbon, nitrogen, and surface temperature. Cyanobacteria were predominant in the grass interspaces at the soil surface (0?1 cm) but rare in subsurface soils (1?2 cm depth) and under the shrubs and trees. Bacteroidetes were significantly more abundant in surface soils of all areas even in the absence of a consolidated crust, whilst subsurface soils yielded more sequences affiliated to Acidobacteria, Actinobacteria, Chloroflexi, and Firmicutes. The common detection of vertical stratification, even in disturbed sites, suggests a strong potential for BSC recovery after physical disruption, however severe depletion of Cyanobacteria near trees and shrubs may limit the potential for natural BSC regeneration in heavily shrub-encroached areas.authorsversionPeer reviewe

Development of bacterial communities in biological soil crusts along a revegetation chronosequence in the Tengger Desert, northwest China

“…The main function of these dominant bacteria involves the cycling and storage of C and N in desert ecosystems, which is vital to the functioning of arid land (Weber et al, 2016). Firmicutes are more frequently detected in below-biocrust soils (1-2 cm depth) (Elliott et al, 2014) and dominated in MS and 5YR, with the vast majority of abundant species being in Firmicutes in the Tengger Desert. Cyanobacteria are the main contributors to C and N fixation in soils during successional processes of BSCs (Belnap and Gardner, 1993).…”

Metabolic profiles of household Pseudomonas species groups.

“…These results are consistent with previous studies that microbes exhibit some form of biogeographic patterns in different environments (Belottle et al 2003;Dumbrell et al 2010;Remold et al 2011;Lennon et al 2012;Larouche et al 2012;Elliot et al 2014;Purdy-Gibson et al 2014;Remold et al 2015). This study utilized different resources to test for effects of environment and species groups on the biogeographic patterns of household Pseudomonas strains.…”

“…Lennon et al, (2012) showed that soil moisture availability influenced the activity and distribution of microbes, suggesting that some microbes may be able to coexist by partitioning their moisture niche axis using contrasting ecological strategies such as dry-adapted generalists or wet-adapted specialists. Elliot et al, (2014) also showed that biological crust bacterial communities were determined by vegetation type and soil depth and that bacterial communities differed with soil carbon, nitrogen and surface temperature.…”

“…This is consistent with niche differentiation (Cunningham and Cunningham, 2015). Niche differentiation by microbes has been documented by (Dumbrell et al 2010;Remold et al 2011;Lennon et al 2012;Elliot et al 2014). The resources that our strains utilized (Fig 3.1) are similar to the resources that were utilized by the Pseudomonas strain used by Paixoa et al, (2003), and the Pseudomonas strains in the Aagot et al, (2001) studies.…”

Biological soil crusts in a changing world: introduction to the special issue

“…Two articles of this special issue deal with this topic. Elliot et al (2014) characterized the bacterial communities of biocrusts (0-1 cm depth) and the subsurface soil (1-2 cm depth) in the Kalahari Desert (southwest Botswana) using a high throughput 16S ribosomal RNA gene sequencing approach. They found that biocrust bacterial communities were distinct with respect to vegetation type and soil depth, and varied in relation to soil carbon, nitrogen, and surface temperature.…”