Signs of Fall Approaching

by Laura Duncan

Photo by Sherrin Perrouault

Fall is one of those transitional times of the year when we can notice changes in the plants and animals around us. On Sunday, Aug. 25, eight people joined Laura and Sherrin in looking for some of the changes to be seen in the vegetation, starting from the Higgins St. entrance.

Two of the most notable changes to be seen in plants are the changing colours of the leaves and the leaves falling from deciduous trees and shrubs. Colours in the leaves change because of chemical changes within the leaf caused by shorter days and cooler temperatures. Chlorophyll creates the green colour we usually see in leaves. Less chlorophyll is produced by the leaf as days shorten and cool, meaning that the red and yellow colours that are usually covered by the green chlorophyll can show through, giving us the colourful red, yellow, orange and purple display before the leaves fall off. 

Photo by Sherrin Perrouault

Cooler temperatures and shorter days also cause a ridge or callous to form at the junction of the branch and leaf stalk. This pushes the leaf off the branch, resulting in the annual dropping of deciduous leaves. Trees and shrubs cannot uptake water through the frozen winter and since leaves lose a lot of water through transpiration, dropping the leaves conserves the tree/shrub’s water supply, therefore giving the plant a much better chance of survival.

Another thing that plants do as fall approaches is to form the seeds and berries that will ensure the future longevity of the species. Some plants form seeds directly that will be distributed by air, water, mammals, birds or insects. Other plants form berries that are attractive to be eaten and the seeds within the berries are then distributed by the critters that eat them. We noted 26 varieties of seeds and berries along our walk, which included a look at the sphagnum bog at Eimer’s Lake. Along the way we also noted if a species’ berry was either edible, toxic or medicinal.

Photo by Beth Cannon