The factors that influence the leaf colors in the autumn season are :length of night, weather. The Increasing length of night will effect on the leaf color change. The other environmental parameters like temperature, rainfall, food supply will gradually change as the length of night increases during autumn. As night time increases, the day time grow shorter and conditions will become cooler. It effects on the biochemical processes of the leaf and thus it effects on the leaves to change their color.
Where do autumn colors come from?
There are three types of color pigments that are involved in autumn color.
- Chlorophyll: gives green color to the leaves. It is useful for photosynthesis.Trees that are grown in the temperate zones store sugars for the dormant period in the winter.
- Carotenoids: helps in getting yellow, orange, and brown colors to the leaves in such things as corn, carrots etc.
- Anthocyanins: These are the water soluble pigments and appear in the watery liquid of leaf cells.
Throughout the growing season, the leaves contain chlorophyll and carotenoids in the chloroplast and anthocyanin are produced in the autumn season in response to bright light and more amount of sugars within the leaves
During normal growth of the leaf,chlorophyll is continuously produces and utilized for photosynthesis and hence leaves appear green in color. But in the autumn season, as the night length increases,chlorophyll production will be gradually decreased and finally the production is stopped. But the carotenoids and anthocyanins are kept unchanged. So that leaves show other than green color.
Certain colors are characteristic of particular species. Oaks turn red, brown, or russet; hickories, golden bronze; aspen and yellow-poplar, golden yellow; dogwood, purplish red; beech, light tan; and sourwood and black tupelo, crimson. Maples differ species by species-red maple turns brilliant scarlet; sugar maple, orange-red; and black maple, glowing yellow. Striped maple becomes almost colorless. Leaves of some species such as the elms simply shrivel up and fall, exhibiting little color other than drab brown.
The timing of the color change also varies by species. Oaks put on their colors long after other species have already shed their leaves.The differences in these timings is because of genetic inheritance ,weather conditions like temperature and moisture and the latitude at which the plant species is growing.
How does weather affect autumn color? The environment condition like warm, sunny and cool day and not freezing nights gives bright colors to the plants. In such a conditions, lots of sugars are produced in the leaf. But because of cool nights and gradual closing of veins causes obstruction to the sugar flow of the leaves. These conditions make some favour for the production of anthocyanin pigments which gives red, purple and crimson colors. These clogged veins trap sugars in the leaf and promote production of anthocyanins. Once this separation layer is complete and the connecting tissues are sealed off, the leaf is ready to fall.
The autumn colors are also influenced by the moisture in the soil. The moisture content in the soil will change according to the change in the climatic conditions.The warm period is also effect on the autumn colors. A warm wet spring and favourable summer weather and the warm sunny days with cool days will effect on the change in the color of the plant leaves.
What does all this do for the tree?
Perennial plants, including trees, must have some sort of protection to survive freezing temperatures and other harsh wintertime influences. Stems, twigs, and buds are equipped to survive extreme cold so that they can reawaken when spring heralds the start of another growing season. Tender leaf tissues, however, would freeze in winter, so plants must either toughen up and protect their leaves or dispose of them.
The evergreens-pines, spruces, cedars, firs, and so on-are able to survive winter because they have toughened up. Their needle-like or scale-like foliage is covered with a heavy wax coating and the fluid inside their cells contains substances that resist freezing. Thus the foliage of evergreens can safely withstand all but the severest winter conditions, such as those in the Arctic. Evergreen needles survive for some years but eventually fall because of old age.
The leaves of broadleaved plants, on the other hand, are tender and vulnerable to damage. These leaves are typically broad and thin and are not protected by any thick coverings. The fluid in cells of these leaves is usually a thin, watery sap that freezes readily. This means that the cells could not survive winter where temperatures fall below freezing. Tissues unable to overwinter must be sealed off and shed to ensure the plant's continued survival. Thus leaf fall precedes each winter in the temperate zones.
Use of the fallen leaves
The fallen leaves are not wasted at all. They are degraded in the soil by the decomposers and restock the soil with nutrients and forms spongy humus layer of the floor in the forest. This soil has a great hygroscopic capacity and holds rain water. In the forest ecosystem the fallen leaves are used as a food for some micro organisms which are a part of it.
Tags:Fallen leaves, colour changes, leaves changes colour,Perennial plants, Perennial, Carotenoids, chlorophyll, Anthocyanins, colors pigments in autumn, leaves change color in autumn, plants change color in autumn.