Turning over a new leaf: The influence of tree litter on forest pond communities

The influence which leaf litter input exerts upon forested pond communities remains largely unexplored, although decades of stream studies suggest that much relies upon the species and diversity of litter involved.  Our experiment investigated the role that 10 common, yet chemically diverse broadleaf litter types have upon the development of a typical freshwater pond community.  48 outdoor mesocosms were provided with an equal mass of leaves consisting of a single leaf type, a mixture of all leaves, or no leaves.  Each pond was stocked with an equal amount of water and an identical array of representative pond-dwelling organisms at natural densities, including multiple species of algae, zooplankton, detritivorous macroinvertebrates, generalist snails, and tadpoles.  Samples of all organisms and leaf litter were taken monthly over five months using a variety of methods.  Abiotic variables including light attenuation, pH, temperature, and dissolved oxygen were recorded bimonthly.  Litter treatment had a dramatic impact on communities, such as 80% tadpole mortality given rapidly decaying litter, decreased growth with slow decaying litter, and large communities with nutrient rich litter.  Using this data, we may predict the ecosystem changes which could occur subsequent to the addition or disappearance of common tree species alongside increasing anthropogenic disturbance.