PS 28-97 - Re-establishment of legumes in restored prairies may depend more on herbivores than rhizobia.

Background/Question/Methods

Rapid land conversion for urban and agricultural use has resulted in a severe decrease in biodiversity. Restoration seeks to curb the loss of biodiversity by converting degraded land back into functioning ecosystem. Ecosystem function is determined by the interactions between species in their environment thus increasing biodiversity is one of the primary goals of land managers in restoration. Unfortunately, the reintroduction of species into degraded environments requires plants to surpass a myriad of barriers such as herbivores, environmental conditions, or seed dispersal. Legumes are often difficult to establish in restored tallgrass prairies. Legumes form symbiotic relationships with nitrogen-fixing bacteria called rhizobia, in which the plant receives atmospheric fixed nitrogen in exchange for carbon. One barrier to the establishment of legumes may be their inability to find suitable rhizobia symbionts. Over the summer of 2022, we monitored the survival and seed production of 405 individuals of Chamaecrista fasciculata inoculated with different strains of rhizobia and transplanted into a prairie restoration. We used generalized linear models to assess the impact of treatment type on herbivory, pollination, and seed production of C. fasciculata.

Results/Conclusions

We found that herbivory was the most important factor affecting the survival of C. fasciculata. Overall, 63% of plants experienced herbivory over the season with inoculated C. fasciculata more likely to be grazed than uninoculated C. fasciculata. Plants inoculated with rhizobia also tended to produce more flowers, experience greater visitation by pollinators, and produce more seeds, although these patterns were not always statistically significant. Our results indicate that rhizobia could shape Chamaecrista fasciculata interactions with both herbivores and pollinators to influence survival and seed production. Future research should focus on the interaction between rhizobia symbionts and herbivores within tallgrass prairies.