It is the question who decides if removing a current feature is improving or enhancing the common property the feature may have different impact on different lots a tree may not give a privacy or sound blocking of passing cars for all lots and some owners may even think a tree is an unwanted maintenance cost.
Clearly any action other than maintenance must be under an owner’s resolution.
In our council area trees over a given size requires council approval for all actions and maybe it is neglect in the first instance of the owner’s corporation in allowing the tree to grow to that size?