State of the Forests

To understand the state of Maine’s forests it is useful to first consider the section “Managing for Biodiversity.”

The forests of the Maine Mountains are on the edge of the boreal forests, the largest single biome on earth, accounting for 30% of all forests. There are symptoms that this forest ecosystem is rapidly shrinking and breaking apart. Climate zones are moving north ten times faster than forests can migrate.

With the steep decline and die off the boreal forest you lose not simply spruce but everything that lives in the spruce region including moose, lynx and snowshoe hares.

Much of the above material comes from the Yale Environment 360 report “The Rapid and Startling Decline of World’s Vast Boreal Forests,” linked below.

In the following text we discuss the problem of fragmentation of the forest, which negatively impacts biodiversity. There is also the problem of the lack of old growth forest and late successional forests which limits biodiversity of all species, and thereby reduces the level of ecosystem services provided. We also provide information below on the loss of habitats and threats to them and their associated species.

Sources:

1) The Rapid and Startling Decline of World’s Vast Boreal Forests, Yale Environment 360
2) Higher Levels of Multiple Ecosystem Services are Found in Forests With More Tree Species, Nature Communications

Fragmentation of Forests

Our society continues the fragmentation of natural habitats. As land is fragmented, it results in a loss of species that were in the original unfragmented areas, it destroys habitats, and it lowers biodiversity.

Fragmentation of forests results an increase of the edge effect. As natural areas become smaller, the length of edges becomes larger. Fragmentation in increasing the forest edges, opens up the areas used by predators such as cowbirds, certain raptors such as goshawk, foxes, blue jays, etc. The edge effects include increased predation, isolation from mates, invasive seed and insect spread along edges, wind and sun effects leading to desiccation, and a whole array of physical, physiological, behavioral, and population effects.

“Raptors were found to be more abundant in the proximity of infrastructure whereas other bird taxa tended to avoid it.” (Benitez-Lopez et. al., Biological Conservation)

“The cumulative effect of loss of habitat security, soil erosion, vegetation loss, introduction of non-native invasive species, and forest fragmentation results in the loss of functional wildlife habitat that supports healthy individuals and populations of wildlife. Animals may be impacted directly and/or indirectly. A direct impact may be an ORV that collapses a small mammal burrow or runs an animal over.” (Walters, Wild Earth Guardians)

On local extirpation due to fragmentation from the National Audubon:

“We have plenty of evidence that demonstrates the stresses potentially leading to local extirpation that come from uniformly young forest stands, fragmentation, and overall reduction of habitat.” (in email to The Mountain Conservancy, December 2014)

Sources:

1) The Impacts of Roads and Other Infrastructure on Mammal and Bird Populations: A Meta-Analysis, Biological Conservation
2) Off-Road Vehicle Impacts on Wildlife, Wild Earth Guardians
3) Habitat Fragmentation and its Lasting Impact on Earth’s Ecosystems, Science
4) Review of Ecological Effects of Roads on Terrestrial and Aquatic Communities, Conservation Biology

Threats

Emerald Ash Borer:

Emerald Ash Borer (EAB), aka “You Can Kiss your Ash Goodbye” beetle. The Agrilus planipennis from northern Asia.

As it moves into Maine it will decimate the White Ash trees. They will go to the happy hunting ground where the chestnuts and elms trees have gone. For more information see the Maine Department of Agriculture’s EAB Resource Page.

In Maine, if you suspect you may have EAB in your ash trees, report it online, or call (207) 287-3891.

Insecticides can control the EAB, but it will have an impact on birds and pollinators, which has not been fully studied.

Sources:

1) Maine EAB Resource Page, Maine Department of Agriculture

2) Insecticide Options for Protecting Ash Trees from Emerald Ash Borer, USDA-NIFA North Central Integrated Pest Management Center

Hemlock Woolly Adelgid

The hemlock woolly adelgid (Adelges tsugae), native to Asia is a small, aphid-like insect that threatens the health and sustainability of eastern hemlock (Tsuga canadensis). For more information and what you can do to control the woolly adelgid see the Maine Department of Agriculture’s Overview of the Woolly Adelgid.

For additional information see the pest alert from the USDA.

Sources:

1) Maine Hemlock Woolly Adelgid Overview, Maine Department of Agriculture
2) Pest Alert Hemlock Woolly Adelgid, United States Department of Agriculture

Spruce Bud Worm:

Spruce budworms and relatives are a group of closely related insects in the genus Choristoneura. Most are serious pests of conifers.

Budworm populations are usually regulated naturally by combinations of several factors such as insect parasites, vertebrate and invertebrate predators, and adverse weather conditions. During prolonged outbreaks when conifer stands become heavily defoliated, starvation can be an important mortality factor in regulating populations.

This species is a favored food of the Cape May Warbler, which is therefore closely associated with its host plant, Balsam Fir. This bird, and the Tennessee and Bay-breasted Warblers, which also have a preference for budworm, lay more eggs and are more numerous in years of budworm abundance.

Natural enemies are probably responsible for considerable mortality when budworm populations are low, but seldom have a regulating influence when populations are in epidemic proportions. (Notes from Wikipedia)

Sources:

1) Maine Spruce Budworm, Maine Forest Service
2) Assumptions and Recommendations for the Next Spruce Budworm Outbreak, Keeping Maine’s Forests

Threatened Habitats

The Maine forests provide critical habitat to a variety of endangered and threatened species. Each habitat type faces different threats, which are categorized and covered in the following resources from the Maine 2015 Wildlife Action Plan.

Sources:

1) Alpine Habitat Threats and Species
2) Boreal Upland Forest Habitat Threats and Species
3) Northern Floodplain Forest Habitat Threats and Species
4) Northern Hardwood Conifer Habitat Threats and Species