Research - Leaf fall

To understand leaf senescence we need to focus on the key role of the leaves in trees, which is to make photosynthesis and provide the trees with ‘fuel’ to function. When trees cannot grow anymore in autumn because of the harsh environmental conditions (for example, low light and colder temperature), leaves are less crucial for the trees that can have more advantages by degrading their pigments and recycle their essential nutrients. Therefore, the key hypothesis of LEAF-FALL is that leaf senescence is triggered by the cessation of tree growth in autumn. However, we expect that light also plays a role as, thanks to the seasonal changes in day length, trees sense if cessation of tree growth occurs in autumn (so they allow the onset of leaf senescence) or, because of some temporary stress, in spring – summer (without allowing the onset of leaf senescence). To understand leaf senescence we need to focus on the key role of the leaves in trees, which is to make photosynthesis and provide the trees with ‘fuel’ to function. When trees cannot grow anymore in autumn because of the harsh environmental conditions (for example, low light and colder temperature), leaves are less crucial for the trees that can have more advantages by degrading their pigments and recycle their essential nutrients. Therefore, the key hypothesis of LEAF-FALL is that leaf senescence is triggered by the cessation of tree growth in autumn. However, we expect that light also plays a role as, thanks to the seasonal changes in day length, trees sense if cessation of tree growth occurs in autumn (so they allow the onset of leaf senescence) or, because of some temporary stress, in spring – summer (without allowing the onset of leaf senescence).