Vascular arbuscular mycorrhizae - tree association of Varirata National Park and the influence of vegetation types.

Abstract

A study to investigate the occurrence of Vasicular Arbuscular mycorrhizae among tree species of Varirata National Park was conducted at the University of Papua New Guinea. The study also investigated the influence of vegetation types, i.e., savanna, savanna-rain forest ecotone and rain forest on the VA mycorrhizae infection levels among the tree species. The infection levels were investigated using roots sampled from representative tree species. The roots were decolourized, stained and observed under the microscope to assess the levels of infections. The results of the study indicated that generally, all the tree species sampled were infected with the VA mycorrhizae. However, there was a high infection variation among the different tree species. A comparison of infection between the primary and secondary tree species indicated higher infection levels among the secondary tree species. With the highest infection observed among two secondary species, i. e., Leea indica and Rhus taitensis, while the lowest were observed among the Breynia cernua samples. However, there was no significant difference within the same species across the three vegetation types. All the studied sites within the three vegetation types comprised of heavy clay acidic soils, with high organic carbon content ranging from 7.23% in the savanna to 11.91% in the savanna-rain forest. However, there was no correlation between the organic carbon levels and the infection levels. Overall, these results indicate that VA mycorrhizae infection levels vary with species and not vegetation types, and secondary tree species have a higher infection level in comparison to primary species.