Signs of Forest Succession in Maine Prepared for Maine EcoScienceWorks, August 2006 Use “normal” view to see detailed notes All images by Robert Bryan except as noted. All images except those by others may be reproduced for educational purposes with the following credit: Photo by Robert Bryan, Maine Audubon Note to teachers: This slide show is designed to introduce some of the concepts of “Field to Forest” and “Forest to Forest” succession that commonly occurs in Maine. This presentation is designed to be reviewed before conducting the EcoScienceWorks succession field exercise. It would be a good general introduction to succession and could be reviewed with students before doing the EcoBeaker Beaver Pond Succession lab. This presentation could be used as a self study module for students, or it can be presented to the entire class. In the latter case, depending on your teaching style, you might want to delete some of the text boxes, since they say much of what you might say in class. Note to students and teachers: First, view the presentation in “slide show” view because some of the slides have layered effects that are only available in that view. If you come to a question, look at the slide and try to answer the question before clicking for the answer. Then view the presentation in “normal” view to see the notes at the bottom. These notes have more detail than the brief text boxes on the slides. Have you seen something like this? What happened here? This was once a pasture with no trees. 4 million acres in Maine like this have undergone “field to forest” succession. This slide show will help you become a forest detective by teaching you common “signs of succession” that you can find in most woodlots. 1855 1830 1910 2000 Farm to Forest Succession – Harvard Forest Dioramas (source: http://harvardforest.fas.harvard.edu/museum/landscape.html) Bowdoin, ME (undated) Source: http://www.link75.org/bcs/grade4/BowdoinHist/bbicenjpg/Small.jpeg Old Farmhouse Foundation, Acton, Maine, 2005. Young Forest Shrub Field 3 Stages of Succession, Falmouth, ME White Pine Seed Source White Pine Common Juniper Red Oak Early succession, old field 10 years after last mowing Yellow Birch “Wolf Tree.” Wide spreading branches show that this tree grew in the open before the small trees were growing. Nobleboro, ME. 2006. Early succession, aspen (popple) and birch after heavy logging disturbance, Bangor, ME Different species of wildlife prefer different stages of succession. Moose thrive in young forests, which have broad-leaved plants within easy reach. The dense canopy of young forests shades out most understory plants. A single canopy layer of small to medium-sized trees is also characteristic of young forests. Aspen (“popple”) forest, Colorado. Early succession stages have sun loving plants like these aspens and birches, but these trees usually have short life span for a tree (about 100 years). Trees and other plants that can tolerate shade grow in the understory and eventually dominate the site when the other trees die. Note the understory conifers that will eventually reach the overstory through succession. Here is a similar site a later stage in succession. Hemlock, a long-lived shadetolerant conifer is replacing the sun-loving aspen, birch, and red maple. White pine is a common “old field” tree species in New England. Recall the earlier slide with white pine seedlings in a field. Note forest structure. What stage does this suggest? Island spruce, Muscongus Bay, ME. Although more than 80 years old this forest still has a “young” structure. Late succession stages have plenty of dead trees like this old growth spruce-fir forest in Colorado. Some times the oldest stage of succession is called a “climax forest” because it can last a long time and regenerate itself after disturbances. Dead and dying trees and logs have many ecological values. Many species of insects, fungi, birds, and mammals live only in dead and dying trees and many depend of them to find food. Porcupine den tree, Hinckley, ME, 2006. Hemlock forest, Pleasant River State Park, Beddington, ME. What signs of succession do you see? Hermit thrushes prefer to nest in older forests with dense ground cover. Hermit thrushes are related to robins, which also have Late Succession Early Succession Sun-loving plants 0 years Mown Field 0-10 Old Field Disturbance 10-30 Saplingshrub Shade-tolerant plants 30-80 Young, simple forest 125+ years Old, complex forest Forest disturbance allows light to reach the forest floor and new plants to grow. “Pillow and cradle” topography created by fallen trees is characteristic of areas that were never plowed. Can you see what happened here? This is an area with older pillows and cradles, created when trees fell in a hurricane about 50 years ago. Hog Island, Muscongus Bay, Maine, 2006. What killed these trees? This wet meadow in Orono, ME was once a forest that was flooded by beavers. What Happened here? Wind blew down the trees in middle. The older, sun-loving white spruce in the canopy only lives for 100 years. It is being replaced by shade-tolerant red spruce that can live for more than 300 years. Hog Island, Muscongus Bay, ME, 2006. Insects are another form of disturbance that will set back the clock of succession. Here, the mature forest canopy is being replaced by younger trees. Lodgepole pine, Colorado. Name other types of forest disturbance. Much of this area at South Branch Pond in Baxter State Park was heavily logged and burned before it became a park. Succession and Disturbance: forests: are always changing…