Latorre, B. E. 2024. The effect of seed mix design on plant reproductive output in an experimental prairie system. Thesis, Michigan State University, East Lansing, MI.

Ecological restoration reverses habitat loss and destruction by promoting the establishment of native communities. Despite this, most restoration outcomes are notoriously unpredictable. Restoration practitioners need to make important decisions while restoring ecological communities and these decisions can have lasting impacts on the outcome of the restoration. In particular, managerial decisions regarding the richness and location sourcing of a seed mix are especially important in seed based restoration, such as prairie ecosystems. These decisions can influence reproductive output. For example, seeds sourced from a distant location might produce individual plants that are maladapted to the local environment and produce fewer seeds. Additionally, higher initial seed mix richness may correlate with a decrease in seeding density, resulting in a plant population that is too small, sparse, or clumped for optimal reproduction to occur. In this study, I sought to answer the following question: How does initial seed mix richness and location sourcing affect plant reproductive output across different biological scales? To answer this question, the Brudvig Lab restored twelve experimental prairies in the Kellogg Biological Station, where we manipulated initial seed mix richness and the number of sources. We collected total plant and floral abundance data by counting the number of plants and flowers across various transects. I estimated reproductive output by counting the total number of seeds of nearly 400 individuals of two dominant prairie forbs, Ratibida pinnata and Echinacea purpurea. I derived values that allowed the scaling of our data, such as the number of inflorescences per plant, plant count per area, developed seed count per seed head, and more. Our results suggest that initial seed mix design is important for the reproductive output of target plant populations in restoration. Namely, I found that restorations sown with three sources and 71 species at lower seeding rates decrease reproductive output for Echinacea across all biological scales, from individual infructescences to the entire population, but only for Ratibida at the population scale. There are predictable lasting impacts of seed mix design on reproductive output. Our study suggests prioritizing seeding rate per species in seed mixes, ideally with a high species richness from fewer sources.

Associated Treatment Areas:

• KBS Landscape

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