PS 42-147 - Drought legacy impacts plant and plant-soil interactions to improve Bouteloua gracilis biomass recovery post-drought in a desert grassland ecosystem

Abstract: Climate projections across many regions predict a future with increased frequency of drought, aridity, and precipitation variability. The consequences of these increases may be more acute in dryland areas where predictions have a high certainty of developing by the end of the century. There is evidence that plant-soil-feedbacks (PSF) may be utilized to promote ecosystem recovery from drought. Plants cultivate unique soil microbial communities, and the feedback from these microbes can alter host plant fitness and the fitness of the host plant’s competitors. However, altered precipitation regimes can be a strong selective filter of plant allele frequencies, complicating our current understanding of field-based PSF. Thus, accounting for plant-genotype specific PSF interactions is necessary to fully account for contemporary evolutionary change which may recast historic PSF. Here we explored the question: Does drought disrupt PSF to alter the pace of ecological recovery? We built from a previous 7-year extreme drought manipulation (EDGE) that occurred at two dominant grasslands, each with its own foundational grass Bouteloua gracilis (blue grama) or B. eriopoda (black grama), at the Sevilleta Long Term Ecological Research station (SEV) in south-central New Mexico. We designed a classic greenhouse PSF experiment with two novel variations: 1) Soil inoculum was collected from field plots that had experienced the 7-year drought manipulation and their paired control plots that did not experience drought conditions. 2) We added a novel plant genotype treatment for a full-factorial manipulation of plant genotype (drought/control), soil microbial inoculum origin (blue/black grama rhizosphere), drought history (drought/control plots), and microbe manipulation (live/sterile).



Our preliminary results indicate that blue grama control genotypes shoot biomass significantly increased by ~20% with the addition of live soil microbial inoculum from black grama that did not have a drought legacy ( P= 0.0140). Additionally, blue grama from drought genotypes experienced significant increases in root biomass (~15%) with the addition of live soil microbial inoculum from black grama that did not have a drought legacy (P = 0.0222). Our work suggests that plant genotype interacts with the drought history of the soil microbial communities and confirms the consistency of negative PSF interactions with blue grama and positive interactions with its competitor, black grama. Our work emphasizes the importance of considering localized plant genotype-specific soil interactions and how climate legacies may disrupt these interactions. Further, we provide evidence of strategies that can aid drought recovery across a desert grassland ecosystem.