Yeasts from soils under forest and under pasture

Abstract

Summary Two kinds of change were seen in the soil yeast flora when native broadleaf forest was replaced by introduced ryegrass — white-clover pasture. A yellow-brown loam under forest contained small numbers of Candida curvata; under pasture yeast numbers were greater and the population dominated by Cryptococcus terreus. In a recent gley soil under forest C. curvata was dominant but Hansenula spp. were also present in considerable numbers. In this soil under pasture yeast numbers were less than under forest; Hansenula spp. were absent and C. curvata was the sole dominant. In a second yellow-brown loam, under pasture and subject to drought, C. curvata, Cryptococcus albidus and Cr. terreus occurred in low numbers and approximately equal proportions together with many contaminant yeasts from pasture plant leaves. A yellow-grey earth under pure perennial ryegrass pasture supported a yeast flora similar to that in the recent gley soil under pasture but in greater numbers.