Soil fungi fundamental to diversity of forests

"Certain groups of fungi have critical roles in the establishment of tree seedlings: pathogenic fungi which are detrimental to survival, while mycorrhizal fungi are beneficial to the seedlings. This latter group are essential for the survival and growth of the trees"

Different groups of soil fungi control the interactions between seedlings and established trees and can play a key role in the development or restoration of forests, new research by James Hutton Institute scientists has found.

Northern forests are typically composed of only a few tree species, but in other parts of the world, especially in subtropical and tropical rain forests, the number of tree species can be extraordinarily high. The factors supporting this incredible diversity of trees are still poorly understood, but such knowledge is critical for the conservation of these amazing ecosystems.

In a new study published in Nature Communications, Hutton ecologists working with other UK and Chinese researchers investigate the links between tree species and groups of soil fungi in maintaining both the high diversity of the trees and as a factor in supporting the formation of areas within the forests that are dominated by only a few tree species.

Dr Andy Taylor, co-author of the study and a fungal ecologist within the Institute’s Ecological Sciences department, said: “Certain groups of fungi have critical roles in the establishment of tree seedlings: pathogenic fungi which are detrimental to survival, while mycorrhizal fungi are beneficial to the seedlings. This latter group are essential for the survival and growth of the trees, and indeed nearly all land plants.

“Tree species form one of two types of beneficial association and it is this divergence in association that we have found to be critical for explaining tree diversity patterns. In one type, the ectomycorrhizal association, the fungi spread out from established trees and colonise and support germinating seedlings that can form the same type of association. Thus, these seedlings had greater survival and grew faster under the same type of trees.

“The other type, the arbuscular mycorrhizal association, did not support seedlings that form similar associations to the same extent. In addition, seedlings forming arbuscular mycorrhizal associations had greater numbers of pathogenic fungi on their roots compared to ectomycorrhizal seedlings, which could further lead to lower survival.”

Findings of the research shed light into the mechanisms of regulation of tree species diversity and community structure in species-rich forests and can prove valuable for the development of strategies to conserve or restore forests.

Paper: Minxia Liang, David Johnson, David F. R. P. Burslem, Shixiao Yu, Miao Fang, Joe D. Taylor, Andy F. S. Taylor, Thorunn Helgason & Xubing Liu, Soil fungal networks maintain local dominance of ectomycorrhizal trees. Nature Communications (26^th May 2020).