This article was written by Eva Mitchell, Minneapolis Parks and Recreation Board Naturalist at North Mississippi Regional Park
This month’s column is inspired by questions from Quinn (age 4) and Izzy (age 10). Thanks for your contagious curiosity!
Though it may be hard to believe with snow on the ground, freezing temperatures and the lingering threat of a winter storm, the month of March signals the coming of spring to Minnesota. The change of season can vary incredibly from year to year, but even in those winters that feel endless there are many exciting signs of spring to notice!
The increased sounds of chirping may mark the return of migrating birds, the sight of a chipmunk may show that hibernators are coming out of their wintertime naps, and tiny buds emerging remind us that the greenery will return to plants again soon. Trees are a great place to look to see signs of the changing seasons, as they show off some of the behaviors that make them unique to other types of plants.
While there are important differences among tree types, we will take a closer look at the trees most abundant in Minneapolis and North Mississippi Regional Park. These are the trees that grow leaves rather than needles, called “deciduous.” After losing their leaves in fall to prepare for a cold and dark winter, deciduous trees no longer make energy for themselves through the process of photosynthesis and instead depend on energy that has been stored inside of them. In order to use their stores more sparingly in the winter, deciduous trees slow down their metabolism and stop processes that consume energy, such as growth and reproduction. For several months, trees remain in this dormant mode and bear witness to the often harsh conditions as winter comes and goes.
During the shift from winter to spring, triggered by warmer days and longer periods of sunlight, trees go through a series of subtle changes as they essentially “wake up” from their wintertime rest. One of the first changes gradually occurs as snow melts and the ground thaws, which allows more water and nutrients to flow to a tree’s roots. To notice this process happening, pay attention to the base of a tree as winter transitions to spring. The dark bark absorbs heat from the increased sunlight, which causes snow to melt around its base, resulting in a ring of exposed ground around it.
As the snowmelt is absorbed by the tree’s roots, the water will move through the tree and mix with starches and sugars that have been stored since the previous summer and fall. This process happening under the bark causes movement of sap through the tree, while water, sugars and nutrients are delivered throughout. The tree sap flowing this time of year is why some people will tap maple trees in their yard to capture sap and use it to make maple syrup.
The movement of sap will continue in the tree through the early spring, as long as temperatures fluctuate above and below freezing. Within the tree, sap provides the nutrients needed for a new season of leaf creation. After leaves have begun to emerge, the spring awakening continues with trees opening flowers so that they can reproduce, spreading pollen and seeds that may create new trees. Once trees and other plants have fully leafed out, they will once again create energy through the process of photosynthesis, using sunlight to synthesize sugars from carbon dioxide and water. As spring and summer go on and trees flourish with full leaves and favorable weather, trees will gradually grow in both height and width. Though we may not be able to witness the growth as it happens, trees record their annual growth in rings that we can see when a tree is cut down.
Although they remain bare for now, keep your eye out for the exciting changes happening in trees this time of year. Stop by the Kroening Interpretive Center to count the rings inside an old tree, check out a free nature pack and explore the park to find evidence of the coming spring. Come celebrate spring with us on March 22 from 1-3 p.m. for our Family Funday focused on Spring Art and animals! Don’t forget to sign kids up for day camp over spring break, Monday-Friday 8 a.m.-4 p.m., so they can be active outside and keep learning.
Public programs in March – Free for all ages unless noted otherwise
Saturday, 3/7 – Bird Watching: Beginner Basics, 8:30-10 a.m.
Sunday, 3/8 – Nature Tots: Bird is the Word, 11:30 a.m.-12:30 p.m.
Sunday, 3/8 and 22 – Nature Book Club, 4:30-6 p.m. $2, ages 18+
Tuesday, 3/10 and 24 – Phenology Hike Club, 4-5 p.m. Ages 16+
Wednesdays, 3/12 to 3/18 – Nature Nuts: Nature Play Group, 10:15-11:15 a.m. $24, ages 2-6
Thursday, 3/12 – Homeschool Day: Things with Wings, 1-3 p.m. $5, ages 3-13
Saturday, 3/14 – Hike: Eagles of the Mississippi, 11:30 a.m.-1 p.m.
Thursday, 3/19 – Campfire Mingle, 6-8 p.m. $5, ages 18+
Sunday, 3/22 – Family Funday: Spring Arts & Animals, 1-3 p.m.
Saturday, 3/28 – Nature Art: Earthen Art, 2-3 p.m.
Sunday, 3/29 – Nature Tots: Weather Wonders, 11:30 a.m.-12:30 p.m.
Find registration/info for these programs at minneapolisparks.org/nature or 612-370-4844. Do you have a question about nature in your own backyard? Then send it our way by emailing northmississippi@minneapolisparks.org and it could appear in a future article. Like us on Facebook to stay in the loop about what is happening at your park.