Autumn is a beautiful time of year in most regions of Earth, especially in Europe and North America. Before nature settling down into winter’s monochcrome quiet, autumnal leaf color change transforms the entire landscape into a colorful mosaic. This vivid color palette of autumn foliage is produced by three types of pigments. Chlorophyll, which gives leaves their basic green color, Carotenoids, which produce yellow and orange colors and Anthocyanins, which deliver red and purple colors. The chlorophyll and the carotenoids are present all year round in the leaves, however, yellow color of carotenoids are masked in the leaves by the green of chlorophyll. In autumn, carotenoids become visible because of the breakdown of chlorophyll. Traditional explanation of the autumn colors was that they are only the side effect of leaf senescence. Anthocyanins, however, are newly generated in autumn, thus, red color is produced actively in autumn and is not simply the by-product of leaf senescence, therefore fall colors may have adaptive value. One hypothesis is that autumn colors protect leaves against the harmful effects of light at low temperature, allowing a more efficient resorption of nutrients before the leaves fall. Another explanation of fall colors is the coevolution hypothesis. According to the coevolution hypothesis, autumn coloration is a signal that warns insects not to lay eggs on these trees. Bright colors reveal that the tree is healthy and has better chemical defenses or worst nutritional capacity. There are many more hypotheses that try to explain the adaptive advantage of autumn leaf coloration and some of them have evidences, so fall colors probably have multiple roles.

Source:

Archetti, M. (2009). Classification of hypotheses on the evolution of autumn colours. Oikos, 118: 328–333.

Whatever the reason of fall colors, nature is simply beautiful in this season, so I set up a small gallery from some of my favorite fall color images I’ve taken in Hungary and Upstate New York, USA. The gear I used for these images: Canon EOS 30D, Canon EOS 7D, Canon 17-40mm F/4, Canon 70-200mm F/4 and Canon 60mm F/2.8 macro lenses.