Disturbance Type and Plant Successional Communities in Bahamian Dry Forests

Different disturbances in similar habitats can produce unique successional assemblages of plants. We collected plant species composition and cover data to investigate the effects of three common types of disturbancesfire, anthropogenic clearing (cleared), and clearing followed by goat grazing (cleared-and-grazed)on early-successional coppice (dry forest) community structure and development on Eleuthera, Bahamas. For each disturbance type, both the ground layer (<0.5 m height) and shrub layer (>0.5 m height) were sampled in eight patches (>1 ha) of varying age (128 yr) since large-scale mature coppice disturbance. Overall, plant communities differed among disturbance types; several common species had significantly higher cover in the shrub layer of fire patches, and cleared-and-grazed patches exhibited higher woody ground cover. Total percent cover in the shrub layer increased in a similar linear fashion along the investigated chronosequence of each disturbance type; however, cover of the common tree species, Bursera simaruba, increased at a notably slower rate in cleared-and-grazed patches. The pattern of increase and subsequent decrease in cover of Lantana spp. and Zanthoxylum fagara in the shrub layer was characterized by longer persistence and higher covers, respectively, in cleared-and-grazed patches, which also exhibited low peak cover and fast decline of nonwoody ground cover. Our results suggest that goats may accelerate some aspects of succession (e.g., quickly removing nonwoody ground cover) and retard other aspects (e.g., inhibiting growth of tree species and maintaining early-successional shrubs in the shrub layer). These effects may lead to different successional trajectories, and have important conservation implications.