Fungus Communities Associated with Leaf Surfaces of Endemic Vascular Plants in Hawaii

Abstract

SUMMARYThree vascular plants endemic in native forests of the Hawaiian Islands were assessed for their phylloplane fungal communities. The taxa comprising the populations of the three communities are primarily cosmopolitan species but they are host related. The total Metrosideros collina var. polymorpha community (transients and residents) was three times greater than that of Acacia koa. The Cheirodendron trigynum var. trigynum community was not comparably significant because of fewer samples. Community overlap, an indirect measure of host dependence, was less than 15% for Metrosideros and Acacia. Resident populations, those recovered only by maceration, represented 63% of the Metrosideros and 50% of the Acacia communities. Differences among the communities and their resident populations can be equated to leaf anatomy. Metrosideros with hairy surfaces is a successful trapping and retaining host substrate compared to the smooth phyllodes of Acacia. Distribution of populations by elevation was sporadic but by ordination Metrosideros and Acacia communities segregated into two groups which reflect climatic control. One group occurred at 1,600 and 1,650 m, regions of high moisture. The remainder ordinated together. Of the resident fungi few can be considered to have endemic status.