October EcoQuest: Leaf Peeping for Science

October has arrived and with it the leaves are beginning to change their colors in the Front Range. But have you every wondered why this happens and what determines the colors we see?

The green in leaves is a result of chlorophyll, a pigment which allows plants to make their own energy by converting sunlight into sugars through photosynthesis. Deciduous trees prefer to make the bulk of their sugars in the warmer seasons and store it for the winter, so they drop their leaves to prevent damage from snowfall and freezing temperatures. The shorter fall days reduce direct sunlight, causing chlorophyll to break down, unveiling hidden yellow and orange pigments in the leaves. Rich red hues in trees such as red maples or sumac arise from a different process. In order to drop leaves, a layer of cells is formed between the leaf and branch. When this happens, sugars become trapped in the leaves and produce anthocyanins, the source of deep auburn shades.

Here in Colorado, when we think of fall colors we typically think of the iconic quaking aspen. The scientific name, Populus tremuloides, reflects the ‘trembling’ characteristic of the leaves in the wind. Aspen is in the Salicaceae family, which was named after the chemical salicin found in the bark of aspen and its relatives. Salicin is converted by the body into salicylic acid—a major ingredient of aspirin. Many species in this family, such as willows, have been cherished for their medicinal properties for millennia.

In addition to their medicinal significance, aspen are also ecologically important. They serve as keystone species which support biodiverse forest habitats. They are also considered an indicator species for environmental health and can be sensitive to changes in soil conditions and climate. Unfortunately, aspen have been declining in North America for several decades. Consequently, monitoring their locations and health offers valuable insights into the effects of climate change and land management practices.

This October, let's turn our leaf peeping into a scientific adventure. As you marvel at the changing colors of our local aspen trees, consider making iNaturalist observations of your sightings. By documenting these moments, you're not only capturing the beauty of nature but also contributing to valuable research on environmental health and climate change effects.

@nmwmson

Posted on October 2, 2023 03:12 PM by alissa_iverson