Chlorophyll Breaking Down
It’s as if a magic brush painted the northern New England landscape with every conceivable shade of vibrant red, orange and yellow this past week. The major player in this phenomenon is chlorophyll, the pigment that gives leaves their green coloration during spring and summer. Chlorophyll is able to absorb from sunlight the energy that is used in transforming carbon dioxide and water to carbohydrates, such as sugars and starch, inside cell-like structures called chloroplasts, a process referred to as photosynthesis. But in the fall, because of changes in the length of daylight and changes in temperature, the leaves stop their food-making process. Chlorophyll breaks down and the green color of leaves disappears, revealing colors that have been masked by the chlorophyll all summer (as well as reds manufactured in the fall). Imagine a world without chlorophyll, where the bright golds, purples, yellows, oranges and reds of autumn leaves would be the natural colors seen in spring, summer and fall.
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Mouse Meals
Deer and White-footed Mice are viewed negatively due to their association with Deer, or Black-legged, Ticks, carriers of Lyme Disease. However, these mice are also beneficial, not only as a staple prey food for many predators, but as a vital contributor to the health of our forests.
Mice help spread various kinds of fungi by eating the fruiting bodies (which contain spores) and eventually excreting the spores. Certain fungi colonize the root system of trees, creating a symbiotic relationship called mycorrhizae. The fungus provides increased water and nutrient absorption capabilities to the tree while the tree provides the fungus with carbohydrates formed from photosynthesis. For many temperate forest trees, these fungi have been shown to be an essential element in order for them to prosper. By consuming fungi and dispersing their spores, these small rodents are inadvertently contributing to the vitality of our forests. (Note: look for the tiny incisor marks of mice in the devoured fungus.)
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Abscission Layers Forming
As the days grow shorter and the nights longer, cells near where a leaf’s stem joins a tree’s branch start to divide rapidly. This is the start of the creation of the corky layer of cells known as the abcission layer.
The annual growth of a tree ends with the formation of the abcission layer. This layer prevents the transport of materials such as carbohydrates from the leaf to the branch and it blocks the flow of minerals from the roots into the leaves. Chlorophyll, critical to the process of photosynthesis, breaks down with exposure to light and is replaced continually by the leaves during the summer. When the abcission layer forms, this is no longer possible. The chlorophyll slowly breaks down and disappears, revealing the underlying xanthophylls (yellow pigments) and carotenoids (orange pigments) that the chlorophyll was masking. These pigments, in addition to the red pigments (anthocyanins) that are manufactured from sugars trapped in the leaf, provide us with our brilliant foliage.
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