Yankee Division
Forest Health and Management
There are many threats to our forests that can drastically change the structure and overall health of forest ecosystems. These include, but are not limited to:
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the introduction and spread of invasive species of insects, diseases, and plants
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over-browsing vegetation (one result of the overpopulation of deer)
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climate change
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forest fragmentation and conversion to other land uses
Forests become stressed when their defenses are weakened. In a weakened state they become more susceptible and less resilient to these disturbances. A healthy forest is one that is resilient to change. It has the capacity to respond to disturbances by resisting damage or stress while maintaining its ecological functions.
Several major pests and pathogens have already altered the composition of our forests, such as the chestnut blight, red pine scale, hemlock woolly adelgid, and more recently the emerald ash borer. It is impossible to know when potential threats will reach an area, but early detection will help to control the spread of an outbreak.
In our increasingly mobile society, the introduction and spread of non-native invasive species is a constant and growing threat. Invasive species are plants, animals, or other organisms that are introduced to a given area outside their original range and cause harm in their new home. Many invasive species are superior competitors, have fewer predators, form monoculture stands, and spread at the expense of native species. Native species have not evolved alongside the invaders and lack appropriate defenses.
Invasive species are recognized as one of the leading threats to biodiversity and impose enormous costs to agriculture, forestry, fisheries, and other human enterprises, as well as to human health.
Managing for diverse species, age classes, and structures make a healthy forest.
Diversity makes a forest resilient to disturbances and the impacts of climate change.
Climate change is a major factor influencing the health of our forests. (include link to the climate section of website) Climate change can alter the frequency and intensity of forest disturbances such as insect outbreaks, invasive species, wildfires, and storms. These disturbances can reduce forest productivity and change the distribution of tree species. In some cases, forests can recover from a disturbance. In other cases, existing species may have to shift their range or die out.
Warmer temperatures alter the growing season and the natural ranges of certain species. While some plants may benefit from longer growing seasons, others may not be able to compete and may disappear from the landscape. Changes in temperature may also alter the moisture regime of the region, causing prolonged periods of drought or more erratic weather patterns.
Forest fragmentation and land use conversion
Loss of forest land resulting in fragmented parcels or in total conversion of forests to other land uses, are important factors influencing the health and integrity of our forests.
Forest fragmentation is the breaking of large, contiguous forested areas into smaller pieces of forest. Typically, these pieces are separated by roads, agriculture, utility corridors, subdivisions, or other human development. Over time, those non-forest patches tend to multiply and expand until eventually the forest is reduced to scattered, disconnected forest islands. The surrounding non-forest lands and land uses seriously threaten the health, function, and value of the remaining forest.
Fragmentation and conversion of forest lands to other uses affects biodiversity by decreasing forest habitat and disrupting the movement and dispersal patterns of native wildlife. By reducing forest health and degrading habitat, this leads to loss of biodiversity, increases in invasive plants, pests, and pathogens, and reductions in water quality.
Improving Forest Health Through Management
Forest management improves the condition of forests, allowing new trees to establish and existing trees to grow more vigorously.
Forest management practices can be tailored to improve forest health, resilience, and adaptability, and they can also mitigate the negative impacts of climate change on society. An effective strategy for reducing the impact of disturbances is to diversify forest types, structures, and age classes through active management.
Healthy, diverse forests have the greatest capacity to adapt to changing conditions, and as long as they remain healthy, they will continue to deliver social and ecological services.
Forestry can make it possible for landowners to keep their forests as forests while improving forest health and function. In fact, without management, southern New England would have fewer tree species, fewer animal species and pollinators, a weaker economy, and fewer sustainable resources.
Forest management practices are often tailored to achieve forest health goals such as improved biodiversity, resilience, and adaptability alongside other management goals. Managing forests for structural complexity in mixed northern hardwood forests has been found to increase elements of late-successional biodiversity (Dove and Keeton 2015; Gottesman and Keeton 2017; McKenny et al. 2006) and carbon storage (Ford and Keeton 2017) while, at the same time, providing wood products from timber harvests (Nunery and Keeton 2010). Reducing harvest frequency and favoring high levels of structural retention can sequester up to 57% more carbon in northern hardwood-conifer forests (Nunery and Keeton 2010).
Additional Resources
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Click here for links to more informative forest health resources
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For a detailed review of academic resources concerning management and forest health in a time of climate change see the YSAF position statement.
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DEER BROWSE prevents regeneration and is a major health issue for southern New England forests. Read this USDA publication to better understand the impacts.
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For an easy-to-understand guide to forest health, complete with an assessment form to use on your own land: Forest Health - an introductory guide for conservation volunteers of eastern Massachusetts.
Deer are voracious animals. Their grazing (or "browsing") of seedlings often causes regeneration of a forest to fail unexpectedly, or changes the types of trees that regenerate from a foresters intentions. Learn more about how deer impact forests and how to improve regeneration in spite of them:
White Tailed Deer in northeastern Forests: Understanding and Assessing Impacts - a USDA Publication
A Deer fence in the first year of regeneration of the forest (picture credit : Carol Youell)
A Deer fence several years into forest regeneration - there is much more vegetation on the inside of the fence (picture credit : Carol Youell)