Spatial distribution of arbuscular mycorrhizas along an elevation and edaphic gradient in the forest dynamics plot at Sinharaja, Sri Lanka

To study how the endomycorrhizal spore density and diversity varies with soild parameters and elevation in the 25 ha forest dynamics plot in the sinharaja forest, soil samples were collected from three transects, along the elevational gradient. Soil micorrhizal spores were isolated using the wet - sieving and decanting method (Brundrett et al., 1996). They were observed and counted under stereo zooming microscope with an external light source. Different morphotypes of spores were identified using external spores were identified using external spore characteristics to find spore diversity. Soil chemical and physical properties such as water potential, pH, total soil organic carbon and plant available phosphate were analyzed using standard methods.
There is a decreasing trend in spore density and spore diversity with increasing elevation (R2=21.6%, 40.6% respectively) but spore density does not vary with four main habitat types in the 25 ha FDP plot. The number of small spores of 45-125 ?m contributed more to the total spore counts in all smaples examined. Soil parameters except water potential, do not correlate with endomycorrhizal spore density and diversity. Spore diversity showed a significant positive correlation with soil water potential (P=0.041), but not spore density.