Transcript Signs of Forest Succession in Maine

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…