Document: SEA-3-75-2

Plant-soil interactions and redox processes in a Micronesian mangrove forest.

GLEASON, S.M.* ¹, K.C.EWEL ² and N.V.HUE ¹

University of Hawaii, Honolulu, HI 96822 USA ¹
USDA Forest Service, Institute of Pacific Islands Forestry, Honolulu, HI 96813 USA ²

Abstract:
We examined characteristics of the soil environment related to redox in the rhizospheres of three mangrove species that commonly grow near one another. The aim of the study was to evaluate the implications of anthropogenic and natural species composition shifts that may be occurring. Porewater soluble reactive phosphate was analyzed in conjunction with soil pyrite, organic carbon, Eh, and root mass in the rhizospheres of three species with aboveground root structures: Rhizophora apiculata (prop roots), Bruguiera gymnorrhiza (knee-like structures), and Sonneratia alba (pneumatophores). A series of Eh measurements over the course of a tidal cycle indicated that a significant (P=0.013) species-specific effect exists for two to three hours after aboveground root structures are exposed to the atmosphere. No other porewater or soil variables were significantly species-specific. Pyrite accumulation was positively correlated with total dead root mass (P=0.0031; r=0.71), and soluble reactive phosphate was positively correlated with organic carbon (P=0.0004; r=0.79). The soil redox environment may be predominantly influenced by long-term nutrient turnover processes related to decomposition and not by species-specific characteristics of the mangroves. Species shifts are therefore not likely to have a significant effect on the soil characteristics examined in this study.

Keywords: Mangrove Redox Nutrient-Turnover Species-Specific

This abstract is being presented at: 10:30 AM in session:
MANGROVES