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A land manager's guide to conserving habitat for forest birds in ...

A land manager's guide to conserving habitat for forest birds in ...

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Photo: Lucas Foerster Rehabilitating Degraded Woodlands Many woodlot owners have purchased or inherited a woodlot that is degraded and has been mismanaged recently or repeatedly through diameter-limit harvests or high grading. In many cases the landowners are interested in cost efficient methods to repair damage, improve tree growth, quality and re-establish healthy ecological functions. While these are commendable goals, the pathway to recovery will differ depending on the quality of the site and state of degradation. These two factors will determine how long it will take and what effort is required to restore your forest. As with any forest management project, you should consult experts at the planning and inventory stage. An assessment is required to determine the site quality and the level of soil damage the site has sustained. Harvests using diameter-limit cuts (with landowners uninterested in controlling logging practices), often lead to excessive skidding, soil compaction, and rutting, reducing future growth rates and the health of residual trees. Injuries to the remaining trees like bark scrapes, broken tops, and severed roots provide entry points for fungi inducing rot, hampering growth potential and future value. An initial inventory will evaluate the number and distribution of healthy trees that remain. Land managers attempting to rehabilitate stands that have undergone repeated diameter-limit or other heavy cutting are likely to face numerous challenges: • Mature or semi-mature trees are absent from many areas of the woodlot. This is known as under stocked. • There are very few trees of good vigour and quality left—severely limiting volume and growth potential. • The trees that remain are poorly distributed across the woodlot. They can be left in periodic clumps or completely isolated, limiting growth and control over the species that develops in the understorey. • Very limited commercial value remains on the site. This makes operations in the next cutting cycle marginal or even at a cost. • If there is limited existing tree regeneration, the low number of high quality seed trees left on site will compromise seed production and the establishment of new seedlings. • As trees that remain are often poor quality or small, the genetics of new seedlings will be comprised of low quality, inferior parent trees. • The establishment and growth of new tree seedlings will be challenged by the dense response of competing shrubs and other interfering plants (like raspberry) that will flourish in the very open canopy, where full sunlight exists. Recovery from this list of problems may seem overwhelming and clearly indicates the importance of using good silviculture and avoiding diameter-limit cutting right from the start. However, land managers can work to bring a woodlot back to a more sustainable condition. Depending on the severity of degradation, this may take many years if not decades and will, in many cases, require financial investments. Rehabilitation will be most effective when it targets the limitations in stand structure and focuses on improvements in the remaining elements with the best potential, including: 1. Desirable trees Identify all trees with no defects or damage and those with minimal damage without infectious diseases (conks, cankers) across all sizes of residual trees. Watch for representatives of all species that are suited to the site and wildlife trees (cavity trees, snags, mast trees, etc.) These desirable trees will be responsible for seed supply, wildlife habitat, and commercial potential for future harvests. 2. Improve spacing and quality Where necessary improve spacing for desirable residual trees by removing the poorest neighbouring trees through targeted thinning. This will improve seed production and growth on trees with the best genetics, health, and quality. 3. Advanced regeneration Identify and protect areas of established tree seedlings and saplings (advanced regeneration). These patches of seedlings should not be trampled or driven over by logging equipment or any other vehicles. It is these areas that will largely determine the future forest composition. 4. Maintain growth of advanced regeneration Overhead shade provided by single undesirable trees in or adjacent to patches of advanced regeneration should be carefully removed to allow for maximum growth of desirable seedlings. Regeneration patches should be monitored for competition from undesirable shrubs and trees. Where competition is severe, tending operations should remove the competitors as early and often as possibly (for up to 10 years) until desirable trees are clearly above the height of the competition. 5. Establish trees in open spaces Within a few years of the last harvest operation monitoring activities should identify patches where there is limited tree regeneration. Target these areas for regeneration by considering: site preparation, seeding, planting, monitoring, and tending. The goal is to establish regenerating trees of local seed sources across all areas of the stand where trees would normally occur as quickly and efficiently as possible. In some cases, especially on poor sites or under severe cases of abuse, time and money can only do so much and you will need to be realistic in your expectations. Often high-grading or diameter-limit activities remove all the old age classes and push stands towards a more even-aged condition. In the most severe cases, all the mature and semimature trees have either been removed or damaged and have no 80 Where to Begin

potential. In these cases, the manager is really striving to do the best thing possible with the next generation: targeting the advanced regeneration and new trees that become established. The overstorey is still needed to provide protection, proper light conditions, and wildlife habitat. Activities in the overstorey will primarily be directed to providing the best conditions for growing the new forest while maintaining structure and food resources for birds and other wildlife. In summary, you should retain as many of the best trees as the situation will permit. Land managers should strive for uniform spacing between trees, and work toward establishing a new age-class of trees between and beneath residual trees. This takes a careful evaluation of the current conditions, and consideration of the costs and potential future benefits. Using these rehabilitation measures will improve health and vigour and decrease the time it takes for your woodlot to return to a sustainable state. Following good silviculture initially is really the best tool for maintaining continuous and consistent benefits including a steady supply of valuable wood products. Benefits of Birds in Forests Clearly, forests provide food and habitat for many bird species, but it may not be obvious that the presence of birds is essential to maintaining the health and productivity of the forest. This mutually beneficial relationship (symbiosis) is just one of several reasons forest managers must aim not only to grow healthy trees but also to meet other goals, including protecting and maintaining healthy forest bird populations. Birds provide a variety of services, particularly as predators, pollinators, and seed dispersers that are beneficial to forests. As predators, birds play an important role in insect control, reducing destructive insect numbers in forests by as much as 80–90 percent. Birds can help prevent outbreaks by congregating in areas of greater insect populations (i.e., woodpeckers are important predators of emerald ash borer). They are particularly effective at low to moderate insect densities. Almost all forest birds eat insects, primarily larvae of butterflies, moths, and beetles. As predators of leaf-chewing insects, birds can reduce defoliation rates, maintain a fuller leaf canopy, and thereby improve tree growth and health. Much of their prey includes insects that not controlled by natural means, particularly insects that are not vulnerable to parasites. Many wasps and some flies are parasites that live on or within their host insects, and ultimately kill them. These parasites are valuable as natural pest control agents. Birds spread insect parasites, further aiding in natural insect control. Woodpeckers help parasites by creating openings under bark through which the parasites can enter. Because most woodpeckers are non-migratory, they provide year-round insect control for particular areas. As natural insect control agents, forest management practices that benefit diverse insectivorous bird populations are important to the maintenance of forest productivity. Hummingbirds play colourful and functionally important roles as pollinations of wildflowers and tree flowers throughout the world. In eastern North America, there is only one species, the Rubythroated Hummingbird. Hummingbirds have very good eyes and are extremely attracted to brightly coloured red, orange, or yellow (also visit white) flowers. They thrust their long slender bills deep into the tube shaped flowers, withdrawing faces dusted in pollen. To meet their high energy needs, hummingbirds visit numerous flowers regularly, which not only assists pollination, but increases gene flow among plants (genetic diversity). Another big role for birds is seed dispersal. It is well known that seeds, in particular oak acorns are an important food source for many birds. In fact, trees like oak depend on seed or acorn consuming wildlife to disperse their seeds. Blue Jays play a critical role in oak dispersal and oak succession as they have a thick bill to pound and break acorns into smaller pieces and an elastic oesophagus that allows them to carry several acorns at a time. By carrying the acorns to new areas and burying them, Blue Jays can improve germination and the spread of oak at a local scale. They are particularly effective at dispersing acorns from oak forests to open or semi-open environments such as old fields and forest edges, which are favourable for acorn germination and seedling growth. Oak populations, like some bird populations, are declining in eastern North America. This is not only a concern for people who love trees, but for the variety of birds and other wildlife that rely on them. As the proportion of oak declines in forests, they are most often replaced by shade-tolerant maples. A regional change from oak to maple dominated forests, can strongly affect avian community structure and populations of some common bird species. Managers should strive to maintain oak as an important component of woodlands where it already exists, to avoid any cascading loss of biodiversity. Blue Jay with acorn — Photo: Marie Read Where to Begin 81

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