With the recent snow and cold weather, last summer’s dry heat seems like a distant memory. Yet, it was only this past week that the National Weather Service officially changed its “moderate drought” designation to “abnormally dry” for most of Lake County, Illinois (although, a small northwest portion of the county is still considered to be in a “moderate drought”). While every drop of rain and flake of snow is helping to slowly ease our way out of the past eight months of drought, the damage already done will decide the sweetness of this spring.
Each spring for the past three decades, the naturalists at Ryerson Conservation Area have tapped sugar maple trees to harvest the sap and turn it into pure maple syrup.
Even though Illinois recently received a break from this summer’s heat and drought, the precipitation deficit that remains statewide has kicked off autumn with atypical natural events. Thus far, the year 2012 has been the fourth driest on Illinois record. However, it has been raining acorns and fall colors have been peeking through the greenery since late August—three weeks earlier than usual. This fast-forward to fall is a tree’s way of protecting itself when water is in short supply. The vibrant color displays of autumn, which seem so lively, are actually a sign that a tree is entering dormancy.
These flashes of fall colors are a result of changes in pigments. The dominant green pigment in leaves is chlorophyll. The leaves in a tree are like little factories, mixing together a recipe of specific ingredients (sunlight, carbon dioxide and water) to make food for the tree’s growth. Chlorophyll acts as the “chef” in this process, called photosynthesis; its presence is necessary in bringing everything together.
Typically, autumn’s cool nights and shortening days trigger photosynthesis to slow down. The scarcity of one key ingredient, water, is triggering this earlier-than-average dormancy. As the work of the leaves comes to an end for the year, chlorophyll breaks down and reveals yellow and orange pigments that have hidden behind its green cloak all summer. Leaves that contain the pigments xanthophyll and carotene—as do hickories, cottonwoods, elms and some maples—will change to vivid shades of yellow and orange as the green fades. Continue reading →