Tree leaves tend to die shortly after changing color in the fall due to the process of senescence, as indicated by declining chlorophyll levels and nutrient reabsorption, as shown in the graph.
The phenomenon of tree leaves dying shortly after changing color in the fall is attributed to a natural process known as senescence, as evident in the information provided by the graph. Senescence is the programmed aging and death of plant tissues, a crucial part of the annual life cycle of deciduous trees.
As autumn arrives, the days become shorter, and temperatures drop, triggering physiological changes in trees. One of the notable changes is the decline in chlorophyll levels, the green pigment responsible for photosynthesis. The reduction in chlorophyll reveals other pigments, such as anthocyanins and carotenoids, leading to the vibrant hues of red, orange, and yellow characteristic of fall foliage.
Simultaneously, the tree initiates the process of nutrient reabsorption. Before shedding leaves, the tree withdraws valuable nutrients, particularly nitrogen, from the leaves and transports them back to the branches and trunk for storage. This nutrient reabsorption is an adaptive strategy to conserve resources for the upcoming winter when photosynthesis is limited.
As the leaves undergo senescence, their cells break down, and eventually, the connection between the leaves and the tree weakens, leading to leaf fall. The dead leaves contribute to the nutrient cycling and organic matter in the soil, enriching the ecosystem.
Complete ques:
Why do tree leaves tend to die shortly after changing color in the fall, based on the information in the graph?