Do all trees defoliate at the same rates? If they don't, why do they defoliate at different rates? Do the same oak tree species and the same maple tree species dofliate at the same rate?
Accepting that trees of different species (& genus) will defoliate at different times and at different rates (this should be obvious to you in Milwaukee), trees of the same species also show some variation. The variation within a species growing in the same region can be caused by: - minor genetic differences - wind & rain - sheltered or exposed microclimates - soil moisture - soil fertility (soil conditions in general) - vigor of the tree - age of the tree All of these things play into how stressed a tree is when it's growing outside it's 'window' of ideal conditions. Dropping leaves earlier or later are a response to the conditions the tree is experiencing in order to preserve itself or gain a competitive advantage. Simon
