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Past agricultural land use and present-day fire regimes can interact to determine the nature of seed predation

Stuhler, John D., Orrock, John L.
Oecologia 2016 v.181 no.2 pp. 463-473
Tephrosia, Vernonia, agricultural land, arthropods, ecosystems, fire regime, granivores, land use, microhabitats, plant communities, predators, rodents, seed predation, seeds, woodlands
Historical agriculture and present-day fire regimes can have significant effects on contemporary ecosystems. Although past agricultural land use can lead to long-term changes in plant communities, it remains unclear whether these persistent land-use legacies alter plant–consumer interactions, such as seed predation, and whether contemporary disturbance (e.g., fire) alters the effects of historical agriculture on these interactions. We conducted a study at 27 sites distributed across 80,300 ha in post-agricultural and non-agricultural longleaf pine woodlands with different degrees of fire frequency to test the hypothesis that past and present-day disturbances that alter plant communities can subsequently alter seed predation. We quantified seed removal by arthropods and rodents for Tephrosia virginiana and Vernonia angustifolia, species of conservation interest. We found that the effects of land-use history and fire frequency on seed removal were contingent on granivore guild and microhabitat characteristics. Tephrosia virginiana removal was greater in low fire frequency sites, due to greater seed removal by rodents. Although overall removal of V. angustifolia did not differ among habitats, rodents removed more seeds than arthropods at post-agricultural sites and non-agricultural sites with low fire frequencies, but not at non-agricultural sites with high fire frequencies. Land-use history and fire frequency also affected the relationship between microhabitat characteristics and removal of V. angustifolia. Our results suggest that historical agriculture and present-day fire regimes may alter seed predation by shifting the impact of rodent and arthropod seed predators among habitats, with potential consequences for the establishment of rare plant species consumed by one or both predators.