Deer herbivory and old field succession

Succession in old fields is affected by existing seed banks, seed rain, herbivory, and disturbances both natural and man-made. This study examined these factors and their effects over a period of three years at a bottomland long-term study site near Carbondale, IL.; Similarity of species richness of the seed bank was low compared with that present in the field. Six species of tree seeds were collected from the seed traps, four of which were present in the experimental plots. The similarity between the species in the tree line and the plots was low. Tree seed rain composition was most dense closest to the tree line but accounted for bottomland tree species establishing throughout the site. Seasonal seed dispersal differed for each species, with spring and early summer showing greatest amounts of dispersal.; Deer herbivory impacted the field vegetation by reducing biomass and retarding tree establishment. Vegetation change was measured in permanent 5 m2 plots within 15 m2 blocks. Twelve blocks were exclosed from deer herbivory and four were not exclosed. All blocks had treatments of simulated herbivory (mowing) and disturbance (rototilling). Blocks exclosed from deer browsing had higher mean biomass and lower mean species richness and diversity than blocks that were not exclosed. Tree establishment was lower but not prevented in blocks not exclosed.; The effects of fertilizer treatments on vegetation change were measured at the long-term succession site. Of the 9 plots within blocks, 3 received annual fertilizer, 3 were fertilized the first year, and 3 were not fertilized. Mean biomass was higher in annually fertilized plots than in those fertilized the first year or control (no fertilizer). Mean species richness was higher in plots fertilized the first year and control plots as compared to the annually fertilized plots. Species diversity was not affected by any of the fertilizer treatments.; Vegetation patterns along microelevations revealed that the portions of the field with the lowest elevations were dominated by obligate or facultative wetland vegetation, while higher elevations were characterized by facultative and facultative upland species. However, biomass and species richness of the individual plots were not correlated with elevation.