Soil Microbial Responses to Increased Moisture and Organic Resources along a Salinity Gradient in a Polar Desert

Abstract

dMicrobial communities in extreme environments often have low diversity and specialized physiologies suggesting a limited resistance to change. The McMurdo Dry Valleys (MDV) are a microbially dominated, extreme ecosystem currently undergoing climate change-induced disturbances, including the melting of massive buried ice, cutting through of permafrost by streams, and warming events. These processes are increasing moisture across the landscape, altering conditions for soil communities by mobilizing nutrients and salts and stimulating autotrophic carbon inputs to soils. The goal of this study was to determine the effects of resource addition (water/organic matter) on the composition and function of microbial communities in the MDV along a natural salinity gradient representing an additional gradient of stress in an already extreme environment. Soil respiration and the activity of carbon-acquiring extracellular enzymes increased significantly (P < 0.05) with the addition of resources at the low-and moderate-salinity sites but not the high-salinity site. The bacterial community composition was altered, with an increase in Proteobacteria and Firmicutes with water and organic matter additions at the low-and moderate-salinity sites and a near dominance of Firmicutes at the high-salinity site. Principal coordinate analyses of all samples using a phylogenetically informed distance matrix (UniFrac) demonstrated discrete clustering among sites (analysis of similarity [ANOSIM], P < 0.05 and R > 0.40) and among most treatments within sites. The results from this experimental work suggest that microbial communities in this environment will undergo rapid change in response to the altered resources resulting from climate change impacts occurring in this region.

Association of Shifting Populations in the Root Zone Microbiome of Millet with Enhanced Crop Productivity in the Sahel Region (Africa)

“…A pattern of both increased soil organic C and microbial diversity in plots treated with residue was observed at both field sites. Soil organic matter has been shown to have an impact on arbuscular mycorrhizal diversity in other semiarid soils (22) and on bacterial communities in polar desert soil (23). There was no detected response by the Glomeromycota in this study, but there were large increases in fungal diversity with intercropping and residue amendment.…”

Microbial Diversity of Browning Peninsula, Eastern Antarctica Revealed Using Molecular and Cultivation Methods

“…The variability in diversity structures in each of these sites may be due to variable organic matter content (Takebayashi et al, 2007; Bell et al, 2013; Ji et al, 2015). Previously, the dominance of Proteobacteria was linked with areas rich in higher organic matter (Bell et al, 2013) and moisture content (Horn et al, 2014; Niederberger et al, 2015), while dominance of Actinobacteria has been documented in arid soils (Niederberger et al, 2015), and linked to low moisture and nutrients (Takebayashi et al, 2007). Further biotic and abiotic factors, such as plants, penguins, birds, seal carcasses, and human activity are also reported to affect microbial community distributions across Antarctica (Cowan et al, 2014; Wang et al, 2015).…”

Efeito da aplicação de biofertilizante líquido no desenvolvimento do sorgo irrigado com água salobra

“…Várias alternativas para minorar os efeitos da água salina, tanto no solo quanto nas plantas, vêm sendo testadas, dentre elas a aplicação de biofertilizantes (Oliveira et al, 2015) aparece como forma de reativar a atividade microbiológica do solo, prejudicada pelo conteúdo elevado de sais da água de irrigação (Van Horn et al, 2014).…”