Changing colour: The science of autumn

lecture 8

leaf senescence

• how deciduous trees prepare for winter

• process in which leaves lose their functions, recover valuable nutrients and eventually die

why do leaves fall in autumn

• leaves of deciduous trees cannot survive freezing temperatures

• soil water is often unavailable when it is cold so the canopy reduces environmental stress

• freezing temperatures result in ice crystals that can damage or destroy leaf cells

Leaf senescence in deciduous plants

• aptosis

• coordinated loss of function and deterioration in leaves

• triggered by critical photoperiod

apoptosis

programmed cell death

do trees detect night or day length

night length