Why do plants of different types not change color of foliage at the same time? Explain and provide examples

Leaf fall is the adaptation of leaves to the elimination of harmful substances. But, in different plants, leaf fall is different. In deciduous plants of a temperate climate, leaf fall is massive, that is, all leaves fall off in autumn. This is due to the fact that if the leaves remain, then they will continue to evaporate water and the plant will die. And in conifers, needle leaves have a small area and are covered with a waxy coating, which reduces evaporation. But it is necessary to remove harmful substances, so old leaves fall off, leaf fall is constant.