UNDERSTANDING SYMBIOTIC NITROGEN FIXATION IN LONGLEAF PINE SAVANNAS TO ENHANCE PRODUCTION

The once expansive and biodiverse longleaf pine (LLP) savanna ecosystem is of high conservation value and is in need of restoration practices that increase soil fertility, and thus productivity and long-term sustainability, of LLP savannas. To use the legume-rhizobia symbiosis as a restoration tool, we must better understand what factors drive this symbiosis, including information on both abiotic environmental drivers and biotic drivers, such as the specific microbial species within nodules. As such, my study aims to (1) further our understanding of symbiotic nitrogen fixation (SNF), (2) put practical tools in the hands of restoration practitioners, and (3) bring back valuable productivity and diversity lost with the destruction of the once widespread LLP savanna ecosystem. To address these aims, I have two objectives that will be accomplished through a field and a greenhouse study, respectively. Objective 1: Determine which abiotic (i.e., environmental) and biotic (i.e., plant traits, plant community characteristics, nodule traits, and rhizobia symbiont) factors are driving SNF rates using a field study. Objective 2: In a controlled greenhouse experiment, assess how rhizobia inoculations influence nodulation and SNF rates, plant productivity, and leaf tissue N content.