In the Negev Desert, phosphate mining has been practiced for over 60 years, destroying local habitats and fragmenting the landscape. Since the biological soil crust (BSC) layer is a pivotal contributor to desert ecosystem function, it is imperative to evaluate its health following severe disturbances. We have monitored BSCs in four phosphate mining sites and investigated the bacterial communities over spatial (between rehabilitated and undisturbed plots) and temporal (various restoration years between 2007-2015) scales. We hypothesized that BSC communities vary in community attributes on both scales, according to a successional sequence. Forty-eight composited BSC samples were collected and their physicochemical properties and bacterial community composition evaluated using qPCR and deep sequencing of the 16S rDNA. Our results suggest that bacterial total abundance, richness, and diversity in undisturbed plots are significantly higher than in rehabilitated plots across all sampling sites, regardless of their time of restoration. Community composition also varies between undisturbed and rehabilitated plots; whereas the dominant phyla in undisturbed BSC are Cyanobacteria and Chloroflexi, rehabilitated plots are dominated by Actinobacteria and Proteobacteria. We also found a consistent pattern of significantly higher total and relative abundances of Cyanobacteria in undisturbed plots. Along the temporal gradient, we found no significant differences in richness, diversity, or community composition; BSC communities differ significantly from undisturbed areas even 12 years following restoration. These results indicate that BSC communities are altered following the mining disturbance and have slow recovery times with possible ramifications to entire ecosystem health and a need for active BSC restoration measures.
Audio/Video, Conference Presentation, SER2019
Society for Ecological Restoration