Mass and nutrient dynamics of decaying litter from Passiflora mollissima and selected native species in a Hawaiian montane rain forest

Abstract

The structure and functioning of Acacia koa-Metrosideros polymorpha forests between 1200 and 1800 m elevation on the island of Hawaii are being threatened by Passiflora mollissima, an aggressive introduced liana from South America. This study was done to evaluate the short-term decomposition dynamics of Passiflora and selected native leaf and twig litter. The nutrient-rich, non-sclerophyllous Passiflora leaves completely disappeared in less than 5 mo. The estimated time for native leaf litter to lose 95% of initial dry weight ranged from 1.65 y for N-rich Acacia phyllodes to 6.67 y for Cibotium glaucum; for woody litter, the time ranged from 4.5 y for Acacia twigs to 23 y for Acacia bark. Except for Cibotium frond litter, decay rates were significantly correlated with initial lignin-ash ratios. Passiflora litter did not accelerate decomposition of Acacia and Metrosideros leaf litter. Passiflora, Acacia, and Metrosideros leaf litter showed net mineralization of N, P, Ca, K, and Mg during the study. Cibotium frond litter showed significant accumulation of N, Ca, and Mg; P levels stayed constant and K was rapidly lost. In general, twigs experienced a net loss of most nutrients, while bark experienced either no change or a significant net gain of nutrients. Nutrient cycling has increased in P. mollissima infested forests.

Citation

Scowcroft, Paul G. 1997. Mass and nutrient dynamics of decaying litter from Passiflora mollissima and selected native species in a Hawaiian montane rain forest. Journal of Tropical Ecology 13(3): 407-426