E F F E C T S OF RAINFA L L EXCLOSURE ON THE ECTOMYCORRHIZAL FUNGI OF A CANOPY TREE IN A TROPICAL RAINFOREST

Abstract

YAMASHITA S, HIROSE D & NAKASHIZUKA T. 2012. Effects of rainfall exclosure on the ectomycorrhizal
fungi of a canopy tree in a tropical rainforest. We expected ectomycorrhizal (ECM) fungal community
structure on mature tree to be affected by drought. A rainfall exclosure treatment was conducted to study
changes in the ECM community of a single tree at Lambir Hills National Park, Malaysia. A vinyl sheet of conical
shape covered the entire rooting area of a Dryobalanops aromatica from 22 November 2008 until 7 December
2008. Three root samples each were collected from both the tree that was treated with rainfall exclosure
sheet and a control tree nearby before and after the treatment. ECM samples were identified using molecular
technique. The ECM species abundance (mean number of species per sample) on the rainfall exclosure tree
decreased from 8.0 ± 1.0 to 4.7 ± 0.6, whereas species abundance on the control tree was similar. Non-metric
multidimensional scaling (NMDS) showed that the species composition of ectomycorrhizas differed between
samples collected before and after treatment. Changes in species composition before and after treatment
were caused by difference in tolerance to reduction in rainfall among fungal species and by spatiotemporal
variation in species composition of ectomycorrhizas.