An all-consuming conundrum : drivers of seed predation in tallgrass prairies

Abstract

Post-dispersal seed predation is a determinant of seed availability for species establishment, and ultimately, community structure. For example, species with high intrinsic fitness and competitive ability may not remain on a landscape if their seeds are preferentially consumed after dispersal. To determine how seed predation structures seed availability in tallgrass prairies, we used seed cafeterias to quantify seed consumption patterns of small mammals and insects -- two common groups of seeds predators in these systems. We investigated how seasonality, plant species rarity, and plant functional group (legume, grass, or non-legume forb) influenced rates of seed predation. For our study, we offered seeds of nine summer-dispersing species during the summer, and seeds of nine fall-dispersing species during the fall to the seed predators. Within a season, we selected 3 species of legumes, grasses, and forbs that are classified as common, uncommon, or rare in local tallgrass prairie ecosystems. Our findings indicate that small mammals were primarily responsible for seed predation at our sites. Also, seasonality was a major indicator of seed predator activity, with fall seeds being consumed at a higher rate than summer seeds. For the fall species, legumes and forbs were preferred over grasses, and species that were locally uncommon and common were preferred over rare species. The preferential predation of uncommon forb and legume seeds and avoidance of common dominant grass seeds has the potential to reduce overall biodiversity at our sites. This reinforces the need for management strategies that maximize the likelihood of uncommon plant species survival.

Quantifying seed rain patterns in a remnant and a chronosequence of restored tallgrass prairies in north central Missouri

“…Because our trapping design did not exclude animals, animal behavior may have influenced species representation in our estimates. For example, species favored by animal predators (e.g., prairie dropseed Sporobolus heterolepis) or reliant on animal dispersers (e.g., wild strawberry Fragaria virginica) were likely underrepresented in our traps as evidence by their high presence in the aboveground flora and low to no presence in our seed rain samples (Figure S4) (Parker-Smith, 2022). Regardless, we captured over 20 times the amount of seed biomass, including unassisted, wind, and animal-dispersed species, in the remnant in 2019 (22.92 g m -2 ) compared to typical restoration seeding rates (Rowe, 2010).…”