Shiny, brown buds began to open on a neighbor’s quaking aspen trees today! Each open bud held what looked like a tiny, soft, gray cat’s paw, similar to a pussy willow bud. Aspens are members of the willow family, so it’s no coincidence that they bear soft, fuzzy catkins. The buds will develop into long catkins, which are the aspen’s flowers. They are wind-pollinated and the male catkins will release large amounts of yellow pollen into the air later in the spring. (According to pollen.com, poplars and junipers already are releasing low levels of pollen in the Twin Cities.) The seeds will develop and be dispersed with tufts of soft, white “cotton” before the leaves open.
Seasonal changes happen quickly in Minnesota during October and it’s interesting to watch the progression into autumn. For example, swamp milkweed seed pods break open, male goldfinch feathers transform from bright yellow to olive green, chipmunks and other rodents stash nuts and seeds for the winter, and bees and most other insects have either died or are hibernating until spring.
Naturalists use the term phenology to refer to these changes. Phenology is the study of the changes that occur in plants and animals from year to year — such as flowering, ripening of fruit and nuts, emergence or disappearance of insects, and migration of birds — especially the timing and relationship of these events with weather and climate. It also can include other observations, such as the occurrence of the first frost, the date on which a body of water freezes, and when specific constellations are visible in the sky. Here are a few examples of current autumn phenology that I photographed along the Snake River in Pine County, MN:
Everyone who observes nature and records their observations contributes to the science of phenology. If you’re interested in contributing your own observations, there are several organizations online, including: “Nature’s Notebook” at the USA Phenology Network, the University of Minnesota’s Minnesota Phenology Network and the National Science Foundation’s “Project Budburst”.