<P> Tropical and subtropical deciduous forest biomes have developed in response not to seasonal temperature variations but to seasonal rainfall patterns . During prolonged dry periods the foliage is dropped to conserve water and prevent death from drought . Leaf drop is not seasonally dependent as it is in temperate climates, and can occur any time of year and varies by region of the world . Even within a small local area there can be variations in the timing and duration of leaf drop; different sides of the same mountain and areas that have high water tables or areas along streams and rivers can produce a patchwork of leafy and leafless trees . </P> <Ul> <Li> Lesser celandine (Ranunculus ficaria) dominates deciduous woodland in early spring . </Li> <Li> <P> Dry - season deciduous tropical forest </P> </Li> <Li> <P> Mixed deciduous forest in spring, Texas, United States </P> </Li> </Ul> <Li> Lesser celandine (Ranunculus ficaria) dominates deciduous woodland in early spring . </Li> <Li> <P> Dry - season deciduous tropical forest </P> </Li>

When do trees lose their leaves in the fall