Leaf litter species identity alters the structure of pond communities

Abstract

The input of leaf litter resources is a major driver of ecosystem processes in terrestrial and freshwater habitats. Although variation exists in the quantity and composition of litter inputs due to natural and anthropogenic causes, few studies have examined how such variation influences the structure and composition of aquatic food webs. Using outdoor mesocosms, we examined the bottom–up effects of 10 chemically distinct tree litter species on microbial, algal, invertebrate and vertebrate fauna found in temperate ponds. We hypothesized that individual litter species, which differ in their traits, would differentially and predictably affect abiotic and biotic elements of pond communities. We further hypothesized that the presence of leaf litter, regardless of species, would elevate resource supply and increase the biomass of community members. Finally, we hypothesized that a mixture of litter species would have non‐additive effects on community responses. We followed the system for > 4 months and measured > 30 abiotic and biotic responses related to primary and secondary production. The different species of leaf litter had major effects on abiotic and biotic responses, including phytoplankton, periphyton, zooplankton, snails, amphipods and tadpoles. Most biological responses were negatively associated with soluble carbon content of litter, or litter decay rate. Other litter traits, including phenolic concentrations and litter C:N were of secondary importance but did exhibit both positive and negative associations with several responses. The absence of litter had pervasive effects on abiotic attributes, but did not promote substantial changes in organism biomass. Most responses to the litter mixture were additive. Our results suggest that changes in temperate forest composition can strongly affect pond communities.

Litter chemistry and chemical diversity drive ecosystem processes in forest ponds

“…Several studies note that the performance of tadpoles and other consumers is positively correlated with litter nutrient content (Moran andHodson 1989, Cohen et al 2012). Thus, our study finds partial support for the notion that litter nutrient concentration is an important determinant of consumer biomass (Moran and Hodson 1989), yet we find support for the overriding effect of leached litter components in forest wetlands (Stephens et al 2013, Stoler andRelyea 2016). However, the effects of litter nutrients in their study were relatively weak compared to factors such as dissolved oxygen and phenolics, which parallels the findings of Stoler and Relyea (2016).…”

“…Biomass of wood frogs, survival of spring peepers, and mass at metamorphosis of spring peepers all increased with nutrient content. However, the effects of litter nutrients in their study were relatively weak compared to factors such as dissolved oxygen and phenolics, which parallels the findings of Stoler and Relyea (2016). For example, Kupferberg (1997) demonstrated that tadpole growth rate increases with algal protein content.…”

“…Mechanistically, the negative effects of phenolics are likely direct, due to the ability of these compounds to bind with active proteins (Maerz et al 2005). decreases primary production, pH, and dissolved oxygen (Stoler and Relyea 2016). 4.…”

Specialist and generalist amphibians respond to wetland restoration treatments

“…Because specialist relative species richness was highest under low canopy closure and low leaf litter accumulation, we conclude that many longleaf pine specialist amphibians require autotrophic wetlands driven by primary productivity (i.e., periphyton and phytoplankton) as opposed to heterotrophic wetlands driven by detrital input. Although detritus can be an important food source for amphibians (Altig et al , Stoler and Relyea ), or prey of amphibians (Earl and Semlitsch ), in the system we studied the negative effects of leaf litter on periphyton or phytoplankton growth (Kominoski et al , Stoler and Relyea ) likely outweigh potential benefits of leaf litter as a resource for most longleaf pine specialists. This is what one would expect if specialist species evolved in a pyric system.…”

Combined effects of road salt and an insecticide on wetland communities

“…On 13 July, we added 5 g of rabbit chow (Blue Bunny 16; Kent Nutrition Group) to each mesocosm to provide an initial source of organic nutrients that would normally be present in a natural wetland [24]. We placed a 60% shade cloth cover on each pool to simulate moderate canopy cover and to prevent oviposition of insects and frogs.…”