Interspecific variation in leaf litter production, decomposition, and nitrogen and phosphorus loss from decomposing leaves in a humid subtropical forest ecosystem of northeastern India

Studies providing direct experimental evidence of species impact on litter dynamics in forest ecosystems are limited. The decomposition processes in subtropical forests are also poorly understood. We studied variation in quality and quantity of leaf litter production, decomposition, and N and P loss from decomposing foliar litter in three tree species as well as a mixed-species plot in a subtropical broad-leaved forest of northeastern India. The annual leaf litter production was highest in Rhododendron arboreum Sm. (7293 kg*[ha.sup.-1]*[year.sup.-1]) followed by Myrica esculenta Buch.-Ham. ex D. Don (6902 kg*[ha.sup.-1]*[year.sup.-1]), mixed plots (6808 kg*[ha.sup.-1]*[year.sup.-1]), and Neolitsea cassia (L.) Kosterm (6299 kg*[ha.sup.-1]*[year.sup.-1]). The annual N and P inputs through litter were highest in the mixed plot (N, 111.0 kg*[ha.sup.-1]*[year.sup.-1]; P, 4.8 kg*[ha.sup.-1]*[year.sup.-1]) and lowest in the Rhododendron plot (N, 65.6 kg*[ha.sup.-1]*[year.sup.-1]; P, 2.9 kg*[ha.sup.-1]*[year.sup.-1]). The highest decay rate was recorded for Neolitsea (k = 0.89) and lowest for Myrica (k = 0.53) litter. The rate of N loss was highest for Neolitsea ([k.sub.N] = 1.39) and lowest for Myrica ([k.sub.N] = 0.68) species, and P loss was in the order of mixed ([k.sub.P] = 1.02) > Neolitsea ([k.sub.P] = 0.88) > Rhododendron ([k.sub.P] = 0.84) > Myrica ([k.sub.P] = 0.62). Acid-insoluble residue, which indicates lignin content and P-related litter chemistry, were correlated with the differential decomposition rates and nutrient loss pattern among the species. Les etudes qui fournissent des preuves experimentales directes de l'impact dune espece sur la dynamique de la litiere dans les ecosystemes forestiers sont peu nombreuses. Les processes de decomposition dans les forets subtropicales sont egalement mal compris. Nous aeons etudee la variation qualitative et quantitative de la production de litiere, sa decomposition et les pertes de N et P dans la litiere en decomposition de trois especes arborescentes ainsi que dans une parcelle d'especes mixtes dans une foret feuillue subtropicale du nord-est de l'Inde. La production annuelle de litiere de feuilles etait la plus elevee pour Rhododendron arboreum Sm. (7293 kg*[ha.sup.-1]*[an.sup.-1]) suivi de Myrica esculenta Buch.-Ham. ex D.Don. (6902 kg*[ha.sup.-1]*[an.sup.-1]), de la parcelle mixee (6808 kg*[ha.sup.-1]*[an.sup.-1]) et de Neolitsea cassia (L.) Kosterm. (6299 kg*[ha.sup.-1]*[an.sup.-1]). Les apports annuels de N et P (kg*[ha.sup.-1]*[an.sup.-1]) dans la litiere etaient les plus eleves dans la parcelle mixee (N : 111,0 kg*[ha.sup.-1]*[an.sup.-1]; P : 4,8 kg*[ha.sup.-1]*[an.sup.-1]) et les plus faibles dans la litiere de Rhododendron (N : 65,6 kg*[ha.sup.-1]*[an.sup.-1]; P : 2,9 kg*[ha.sup.-1]*[an.sup.-1]). Le taux de decomposition le plus eleve a ete observe dans la litiere de Neolitsea (k = 0,89) et le plus faible dans celle de Myrica (k = 0,53). Le taux de perte de N etait le plus eleve dans la litiere de Neolitsea ([k.sub.N] = 1,39) et le plus faible dans celle de Myrica ([k.sub.N] = 0,68) tandis que la perte de P suivait l'ordre suivant : especes mixtes ([k.sub.P] = 1,02) > Neolitsea (0,88) > Rhododendron (0,84) > Myrica (0,62). Les residus insolubles dans l'acide, un indice du contenu en lignine et des caracteristiques chimiques de la litiere en lien avec P, etaient correles avec les differents taux de decomposition et les patrons de perte de nutriments des differentes especes. [Traduit par la Redaction]
Introduction Litterfall, which is a major biological pathway for element transfer from vegetation to soil, and the two related processes of decomposition and mineralization are critical to the functioning of [...]