In the winter trees do not get enough water to survive.
When winter approaches, our part of Earth receives less sunlight, and the air grows colder. When these changes happen, trees prepare for winter. Trees that drop their leaves seal the spots where the leaves are attached. Then fluids cannot flow in and out of the leaves, which change color and fall off.
The falling of the leaves does more than mark the season. It also helps the tree survive the cold, dry air of winter. In the warm seasons, leaves use sunlight, water, and air to make the tree’s food. In that process, the tree loses a lot of water through tiny holes in the leaves. In winter, the tree does not get enough water to replace what it would lose through the leaves. If the tree did not seal the spots where the leaves grow, it would die. When spring brings warm air and fresh water, the tree will sprout new leaves and start growing again.
Deciduous trees drop their leaves in autumn, so this is a good time to gather up leaves for starting a leaf mould pile. Reception yr1 and 2 started by raking and sweeping the leaves from the playground on to a parachute where lots of fun was had.
Reception spent the afternoon filling the leaf mould bin and digging their raised bed ready for sowing green manure to over winter. Jumping on the leaves in the bin to squash them down seemed to be a highlight.