Chinese privet (Ligustrum sinense Lour.) alters the timing of litterfall and nutrient quality of leaf litter inputs in invaded riparian forests

Abstract

The invasive non-native shrub Chinese privet occupies riparian forests throughout the southeastern US however little is known regarding its ability to impact ecosystem processes. This study aimed to characterize phenological patterns of privet litterfall, litter chemistry, and changes in availability of mobile soil nutrients within riparian zones invaded by privet. Comparisons of native and invaded sites showed that privet invasion alters the timing but not quantity of litter deposition. In contrast to native species, total privet litterfall displayed little seasonal variation however invaded sites had similar total litter mass compared to native sites. Within invaded sites privet litter was 26% of total litterfall in spring. Privet leaf litter was seasonally enriched in nitrogen during winter as compared to fall and spring. Compared to native sites, invaded sites had significantly increased soil nitrate availability and decreased soil carbon:nitrogen ratios. In contrast, dissolved organic matter and dissolved nitrogen in soil solution was lower in invaded compared to native sites. Results suggest that privet enhances litter and inorganic nitrogen availability in ways that have potential to impact decomposer and detritovore communities in the riparian zone and adjacent aquatic systems.