Leaf Litter Inputs And Breakdown Rates In Tropical Riparian Zones

Leaf litter input and decomposition in the riparian zones of temperate forests are important sources of organic carbon for instream food webs.  However, little is known about the factors that influence these rates in tropical forest ecosystems.  Previous studies of tropical forests have found litter input and decomposition rates do not differ between these areas. 

This study was conducted to assess differences in litter input rates and types in tropical habitats with different levels of anthropogenic disturbance in the Las Cruces Biological Station in Costa Rica.  Litter baskets were placed in these habitats and were allowed to collect leaf litter over a period of 18 days.  At the end of that period, the average daily input rates and types were compared between the three habitat sites.  To study the decomposition rates in these same areas, litter bags containing 7-10 g of Miconia leaves were divided between the three areas and allowed to decompose for 20 days on the forest floor. The samples were then analyzed to see if there was a significant difference in decomposition between these areas.  Preliminary estimates of leaf litter decomposition suggest that rates were highest in the abandoned pasture site, primarily through the activity of leaf cutter ants. Leaf litter input types were also found to be significantly different between the three sites, showing leaves to be the dominate type of input.  These results provide important insight into the role of anthropogenic disturbance on the availability of coarse particulate organic matter in tropical riparian systems