Phenology and Seasonal Resource Partitioning in Forest Floor Collembola

The phenologies of eight surface dwelling entomobryid Collembola species, occurring in a mixed woodland in the Netherlands were mutually compared. Most species had two generations per year, except Tomocerus longicornis, which is univoltine. The presence of timing mechanisms such as a diapausing egg stage or a reproductive oligopause in wintering adults suggests that selective pressures to adjust phenology to seasonally varying resources are important. A detailed analysis of seasonal resource partitioning was performed on resource utilization by the hatchlings of each species, which are considered to be the most sensitive for exploitation competition. In spite of clear niche differences, no relation could be demonstrated between the degree of seasonal niche overlap of one species with other species and its numerical dominance. It is argued that a versatile reproductive strategy, which allows for a large seasonal niche breadth, and a close tracking of variations in resource supply are the main determinants of success in this community. Because the seasonal temperature regime has a highly synchronizing effect on phenology, neither species can completely monopolize all seasonal resources. Resources left by one can be consumed by another species if it has a different life history configuration, which allows the coexistence of several species, on qualitatively similar food resources.