Question

Eucalyptus trees are a dominant species in some forests. These trees can be effected by a root rotting disease caused by a fungal like protist called Phytophthora. Where this disease is present individual trees in the forest die over a period of several years. Often the majority of surrounding trees are not affected. It is observed that in such forests there are a greater number of plant species that grow in the clearings created by the dead trees and more animal species as well. What role is the Phytophthora pathogen playing in this situation and what is your hypothesis for explaining the greater species diversity in this instance?

Answer 1

Answer to above question

Phytophthora is a fungal disease which affects a huge number of woody plants, including eucalyptus.Phytophthora can attack all parts of the tree and is often evidenced by following symbols like wilted, yellowing foliage, stunted growth, and reddish, orange or brown cankers on the trunk and stems or under the bark. Same situation occurs wit eucalyptus too.But sometimes as it is mentioned in above situation surrounding trees are not affected ,this may happen when there is no presence of moist soil which will be not good for growth of oocytes of phytophthora hence growth of trees will not be affected and instead it will support in growth of trees.In this case if no moist soil is present, phytophtora will maintain proper nature of soil and thus no transmission of disease and hence no disease spread and hence no disease infection.If there are fruits tress present then also this disease isexpressed as fruit rot rather than destruction of tress.There are certain trees that grow on clearings created by dead trees and animal species because it will provide nitogen in soil which will make soil suitable for growth of trees.In this case with destruction of eucalyptus,their decomposition will add on nitrogen to soil thus increasing fertility of soil which will be good for growth of various trees and thus maintaining density of trees in forest.