The effects of lichens and mosses on vascular plants, soil microbial activity and nutrient cycling of the New Jersey pinelands

The purpose of this research was to examine the effects of lichens and mosses on vascular plants, soil microbial activity and nutrient cycling of the NJ Pinelands. We hypothesized that lichens have an overall negative effect on vascular plants, soil microbial activities and nutrient cycling due to allelopathic and antibiotic properties, low litter inputs and poor litter quality. Mosses were expected to have positive effects on all of these parameters because of their lack of allelopathic compounds, higher rates of nutrient input and higher C:N ratio. Light and moisture levels were expected to affect relative distribution of lichens and mosses. We conducted a series of field-based and laboratory studies, investigating relative distribution of lichens, mosses and vascular plants, microbial activities and nutrient availability under different vegetation types. It appears that lichens inhibit vascular plant germination, mycorrhizal infection in the field and OM formation. The decomposition rates under lichens are slower than under mosses, and enzyme activities indicate lower nutrient availability. Nitrification rates are high under lichens and bare soils, while mosses have very low levels of nitrification and high levels of ammonification. Soils under grasses have high rates of both ammonification and nitrification. Overall, soils under lichens are more similar to bare soils than any other groundcover type. Transplant experiment demonstrated that while both mosses and lichens show an increase in ammonium and soil organic matter content, mosses show a greater increase in both of these parameters. Nitrate concentrations were similar in lichen and bare patches, while nitrate concentration under mosses decreased. These experiments provided support for our original hypothesis.