Short-Term Impacts of Frangula alnus Litter on Forest Soil Properties

Abstract

Effects of invasive plants on soil properties and microbial communities have been observed, but the mechanisms driving change are less obvious. The objective of this study was to determine the short-term impacts of litter from the invasive shrub Frangula alnus on soil properties and soil microorganims. In situ soil rings (6-cm diameter by 7-cm deep) received the following aqueous treatments: deionized water, dextrose, cellulose, Quercus alba leaf extract, and F. alnus leaf extract (n = 7) and were sampled 1, 2, and 4 weeks after additions were made. Microbial biomass carbon did not respond differently to treatments containing carbon (C) sources at any sampling period, suggesting that C quality had little impact on microbial abundance at this site. However, in weeks 1 and 2, soil treated with F. alnus had significantly higher total extractable nitrogen (N) than the control, dextrose, cellulose, and Q. alba extract (all comparisons for both weeks p < 0.001). We suspect that the increase in extractable N in the F. alnus-treated soil was due to enhanced N mineralization. In addition, changes to the microbial biomass C-to-N ratio in the F. alnus-treated soil indicated that microbial function had been altered. Overall, results from this study suggest that F. alnus leaf litter has the capacity to alter soil properties and microbial function by stimulating N mineralization.