Hourly fluctuations in labile soil phosphorus in response to climate variability in a wet tropical forest, La Selva, Costa Rica

Tropical rain forests are one of the most productive ecosystems in the world and play a significant role in the global carbon budget.  Changes in phosphorus cycling dynamics as a result of on-going climate change have the potential to limit productivity in this ecosystem.  Our objective was to determine hourly patterns in labile soil phosphorus throughout the day and explore possible mechanisms driving these patterns.  We conducted an in situ experiment on soils from a wet tropical forest at La Selva Biological Station located in N.E. Costa Rica.  A variety of climatic and biotic variables including temperature, precipitation, PAR, soil temperature, soil moisture and soil respiration were measured in order to determine their effect on labile phosphorus.  Our results indicate that labile phosphorus does vary significantly throughout the day in response to a combination of climatic variables.  An understanding of the mechanisms driving phosphorus availability at fine temporal scales can provide a valuable indicator of long term trends in phosphorus cycling dynamics.