In the temperate regions, when autumn comes, the tree changes the color of its leaves from green to yellow, finally shedding this shirt, naked to welcome the coming winter. If you pay close attention, you will see the leaves on the main branch change color first, then gradually spread to the top of the tree, the top of the branch. Deciduous is the same, falling at the bottom first, the higher the top, the slower the leaves fall.
You might say, it’s a natural phenomenon of the living world, aging first and dying first. The lower leaves come out before the top leaves, so they fall earlier. This is also an explanation, but there is a deeper understanding.
When the top of the tree grows to a certain extent, growth slows down.
In the process of growth, every plant reaches its fullest development, so it always puts more food to the top to accelerate growth . The tops of branches are provided with many nutrients. When the top of the tree grows to a certain extent, growth slows down. At this time, the tree loses its leaves due to two conditions: Inside, the supply of nutrients is limited and outside, the weather conditions change in an unfavorable direction , the function of food synthesis of the leaves gradually decreases, Leaves no longer exist, scattered.
But even so, the top part of the tree is still prioritized for care, the most food is provided, so even though the tree stops bringing food to the top, thanks to the reserves it still survives for a while. At the same time, the chlorophyll in the leaves has not been destroyed, still synthesizing some nutrients. Thus, the leaves on the top of the tree will fall later than in other parts of the tree.