Environment and the Distribution of Microfungi in a Hawaiian Mangrove Swampl

EXTENSIVE INVESTIGATIONS of the ecological relationships of soil microfungi with soil types, pH, moisture, horizon, temperature, and macrovegetation have been published (Parkinson and Waid, 1960; Alexander, 1961; and Burges and Raw, 1967). It is a well-established principle that soil fungi are influenced by specific soil environments. Mangroves occupy a littoral habitat, characterized almost invariably by salt or brackish water and coastal silt. The microfungi in the mangrove swamp must be able to tolerate the conditions characteristic of this special ecosystem: Their distribution in particular may be affected by the salinity of the mangrove swamp (Swart, 1958; and Kohlmeyer, 1969). Tolerance to different salinity levels may correlate with temperature levels as demonstrated by Ritchie (1957, 1959) in a series of in vitro experiments. For those microfungi occurring in association with the mangrove roots, it is also necessary to consider the influence of the root itself and the rhizosphere effect. The latter is designated as the region of soil subject to the immediate influence of plant roots (Katznelson, Lochhead, and Timonin, 1948). A series of in vitro tests was undertaken to determine the relationship of environmental conditions to the distribution of fungi in the Heeia mangrove swamp on Oahu, Hawaii. Test fungi were selected from isolates obtained from brackish to marine habitats and included species growing on roots of Rhizophora mangle 1. and in mangrove (R. mangle) swamp soil. Studies were designed to determine levels of salinity tolerance for each species and the combined