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Studies on the dynamic properties of terrestrial ecosystems based on a simulation model II. Tropical rainforest dynamics and stability as influenced by stem mortality
Author(s) -
Oikawa Takehisa
Publication year - 1989
Publication title -
ecological research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.628
H-Index - 68
eISSN - 1440-1703
pISSN - 0912-3814
DOI - 10.1007/bf02346947
Subject(s) - rainforest , tropical rainforest , ecosystem , biomass (ecology) , forest ecology , environmental science , ecology , atmospheric sciences , shade tolerance , primary production , forest dynamics , biology , canopy , physics
Further analysis of tropical rainforest dynamics and stability in relation to stem mortality has been conducted using a microcomputer model developed in a previous study (Oikawa, 1985). By simulation experiments covering a period of 100 years, the effects of changing stem mortality (δc) upon a tropical rainforest were investigated. Increasing stem mortality ranging from a standard value (3%yr −1 ) to a 4‐fold value (12%yr −1 ) brings about decreases in stem biomass and thus total living biomass, and a contrasting increase of stem litterfall flux at the steady state of the forest ecosystem. At the same time, the decreased stem biomass at the steady state is predicted to result in increases of gross production ( P g ) and net production ( P n ), and an improvement in production efficiency of the model rainforest expressed as the P n /P g ratio. similar simulation experiments predict that the improved production efficiency in the forest with a 4‐fold stem mortality is able to enhance tolerance to less productive environments such as a prolonged dry season or a reduced incident light flux density. On the other hand, the standard stem mortality (δ c =3%yr −1 ), which was estimated as a probable value for the Pasoh forest, West Malaysia, is considered to approximate the lower threshold necessary for attaining forest stability. Based on the results obtained, the significance of δ c for the dynamics and stability of a tropical rainforest ecosystem is discussed in relation to the competition and tolerance of trees. In addition, the effectiveness of the simulation approach adopted here is emphasized.