Disentangling the determinants of litter decomposition among invaded and uninvaded habitats: A field experiment from the Kashmir Himalaya

Abstract

Litter decomposition, a key biogeochemical cycling process regulating carbon and other nutrient balances, is driven by several factors including vegetation composition, litter quality and local environmental conditions. However, the relative role of these drivers on decomposition process in the context of plant invasions has been little investigated, particularly in the Himalaya. In this study, we investigated the effect of plant invasion, litter quality and altitude on decomposition rate at multiple sites along an elevational gradient in Kashmir Himalaya. We used the standard litterbag incubation experiment to compare decomposition rates among the plots with- and without global plant invader Leucanthemum vulgare, using both standard (cellulosic filter papers) and local (pine needles) litter types. Our results show that invasion had a significant effect on decomposition rates of both the litter types with relatively higher decomposability in case of invaded plots than the uninvaded ones. Litter quality was the predominant factor in controlling the decomposition rate as evidenced from much higher decomposability (about eight times) of filter papers as compared to pine needles. Also, altitude had a significantly negative effect on decomposition rate of both the litter types, possibly through the influence on abiotic conditions (temperature and precipitation in particular). Our results highlight that, although multiple factors are affecting the litter decomposition at the regional scale, the litter quality exerted the stronger influence. Our study suggests that invasive L. vulgare by altering the litter decomposition rates could greatly influence the cycling of nutrients in the invaded landscapes.