PS 42-148 - Fungal communities in the changing vegetation of the Chihuahuan Desert

Abstract: Ecosystems around the globe are experiencing alterations to species distribution and abundance due to global climate change. The northern region of the Chihuahuan Desert—the largest warm desert in North America—is experiencing a shift from a grassland-dominated ecosystem into a shrub-dominated state (i.e., shrub encroachment) due to increased drought and overgrazing by livestock. Such alterations to the plant community affect soil fungi. Attempts to restore the degraded dryland ecosystems have proven challenging as attempts to remove the shrubs and restore the native grasses have been largely unsuccessful. A crucial piece of missing information within dryland communities is how the fungal communities are responding to shrub encroachment. To address this knowledge gap, a yearlong study analyzing the fungal communities associated with Honey Mesquite (Prosopis glandulosa) dominated shrublands, Black Grama (Bouteloua eriopoda) dominated grasslands, and shrubland-grassland transition zones is being conducted in the Chihuahuan Desert. The goal of this analysis is to assess the fungal community composition associated with grassland and shrubland states to increase understanding of microbial community changes associated with shrub encroachment. We hypothesize that there will be significant differences in the dominant ecological role (i.e., pathogen, decomposer, symbiotic species) of fungal communities in each vegetation type (i.e., grassland, shrubland, transition zone). We also hypothesize that seasonality drives variation in fungal communities and this differs in grass-dominated versus shrub-dominated plots. To address these hypotheses, we are conducting metabarcoding of the ITS2 region and measuring microbial biomass and soil respiration to understand microbial activity within the soil. Additionally, the seasonal variation of these analyses is being assessed across five distinct sampling periods. Preliminary ANOVA analysis of soil respiration demonstrates significant differences in soil activity between plots with and without shrubs. We expect to find additional variation between shrub-dominated states and grass-dominated states as research and analysis continues. By understanding changes in the fungal community associated with shrub encroachment, we can improve our understanding of the level of degradation in these grassland ecosystems and work to improve restoration efforts.