Assistant Professor University of Texas at El Paso El Paso, United States
Abstract: In the Chihuahuan Desert, the conversion of historical perennial grasslands to woody shrublands due to dryland degradation can lead to soil erosion, loss of biodiversity, and depletion of soil nutrients and carbon. Climate change-induced droughts have facilitated shrub growth and caused more frequent state transitions. While state transitions can be reversed, restoring grasses remains challenging. To enhance restoration efforts in dryland systems, it is necessary to determine whether microbial community changes with the changes in the state transition and microbial taxa interacting with specific dryland plant species found in the observed state transition in dryland.
To address this need, I choose the Duneland Restoration Project (DuRP) which was established in 2017 to monitor three alternative states at the Jornada Basin Long-Term Ecological Research (JRN LTER) site: black gramma-dominated sites (the reference historical perennial grassland state), shrub-invaded grasslands (recovering state), and dune lands (mesquite shrub-dominated, unrecovered state), for my study on microbial community changes across state transition. For the research, in each plot, I collected soil samples, four replicates from two regions: bulk soil from each state and rhizosphere. Plant cover, biomass, litter, infiltration rate was calculated in each site. DNA was extracted from each sample to assess microbial diversity and community.
Our study showed some differences among different state transitions that were being studied. First, the black gramma sites produce more litter than the other vegetation states. Revealing that black gramma sites had higher plant cover, followed by mesquite-invaded sites and then dune sites. Second, infiltration rate was significantly higher between mesquite and dune sites, due to grass and bare cover. Dune sites showed a significant increase in aggregate stability compared to mesquite-invaded and black gramma sites. In bacterial and fungal diversity, structure did not correlate with plant cover or biomass, but overall soil properties were a better predictor of microbial structure. While microbial diversity was higher in soil samples from grass plots, rhizosphere diversity did not significantly differ between the plots. Our research suggests that microbial rhizosphere hotspots may exist even in dune sites, which could be important for grass establishment and ecological restoration efforts.
