In my last article I mentioned the four foundations (or precepts) of ecologically-based forest management: 1) context—the importance of planning and management over larger areas of land (landscapes); 2) continuity—the maintenance of forest structure, function, and biota between pre- and post-harvest forest ecosystems; 3) complexity— the need to create complexity and maintain biological diversity; and 4) timing— the importance of applying forest management activities at ecologically appropriate time intervals. In this article, I’ll expand on the concept of the landscape and the importance of landscape considerations in forest planning and management. What then is a landscape, how can landscapes be classified, and how does this information inform forest management? Landscapes are very large land units. According to the International Association for Landscape Ecology, landscapes are often measured in 1,000s of square miles (hundreds of thousands of acres or more). As such, landscapes are best viewed and analyzed using aerial imagery and software such as Google Earth. In northern Michigan, the forests in our landscapes include publicly-owned lands managed by federal, state, and county employees as well as privately-owned lands owned by corporate and non-industrial private landowners. Landscapes dominated by publicly-owned forests tend to be less fragmented by other lands uses compared to landscapes dominated by privately-owned forests. Rarely does any single land owner manage all forests within a given landscape. In Michigan, the landscape classification scheme of Dennis Albert (1995, US Forest Service) classified landscapes based on their climate, geology (including soils), water (hydrology), and past and present vegetation. These landscape characteristics can impact the types of forests found in landscapes (think: “different shades of green”) and the types of treatments used to meet ownership goals and objectives. For instance, some landscapes are dominated by very wet (hydric) soils while other landscapes are dominated by very dry (xeric) soils. These soil characteristics can drive the ecology of forests and how they might be managed. Landscapes dominated by wet soils usually have swamp forests of northern white-cedar, tamarack, and black spruce. Conversely, landscapes characterized by very dry soils are often dominated by a suite of very different (but still coniferous) tree species: white pine, red pine, and jack pine. Differences in landscape soil characteristics can also dictate when forest management might occur. On wet soils, forest management is generally confined to the coldest times of the year when frozen conditions allow heavy machinery to gain access to sites without being bogged down. On very dry sites, some foresters like to work during the growing season. Logging machinery can remove the very top litter layer on the forest floor and allow tree seeds to find their way to the top layer of the soil where they can germinate. Landscape ecologists often use the term “patch” to describe any relatively uniform feature or land use that can be observed and measured on a landscape. These patches are what we see when we see different shapes and colors on aerial imagery. A farm field may be termed a patch as might a forest stand. For a visual here, think of a landscape as a quilt, with the individual blocks on a quilt a patch of land. Similar to the diversity of quilts that can be made by moving different colored blocks around, the arrangement of patches on a landscape can influence how a landscape not only looks, but how it functions. Because some wildlife species with large home ranges may use different patches in difference ways at different times of the year, how patches are arranged on a landscape can be important from a biodiversity perspective. In northern Michigan, white-tailed deer may move to different patches on the landscape during the fawning season and to different patches during the overwintering season. The spatial arrangement of these patches can therefore influence deer movement. Moreover, because browsing by white-tailed deer can impact the regeneration of trees and other plants in our forests, activities that promote a larger deer herd on one patch can impact surrounding patches because deer move within and between the seasons of the year. And because many Neotropical migrant bird species nest either on the forest floor or in the sapling layer of regenerating trees, deer browse can impact biodiversity in many ways. Therefore, one might say that management of the northern Michigan deer herd and many other wildlife species relies on landscape ecology principles. In summary, landscapes are large units of land comprised of individual patches representing a range of land owners and land uses in northern Michigan. The range of land uses found in landscapes is often a result of differences in soils and other landscape characteristics. These difference within and between landscapes can also make wide-spread application of some forest treatments difficult as timber markets, social acceptance of forest practices, as well flora and fauna differ between landscapes. Next: the concept of continuity in ecologically-based forest management. Dr. Greg Corace is the forester for the Alpena-Montmorency Conservation District. Greg has spent the last 25 years publishing forest and wildlife research and conducting forest planning, management, inventory, and monitoring on public and private lands across northern Michigan. For more information, including sources used in this article, Greg can be contacted via email (firstname.lastname@example.org) or via phone (989.356.3596 x102).
Forests provide numerous benefits to society. Some benefits are financial and revolve around the economic goals and objectives of landowners as well as local and state economies. Other benefits fall within the realm of aesthetics. Forests, especially this time of year, offer spectacular scenery that spurs many to visit northern Michigan. But, at their core, forests are essential for many ecosystem functions. Some of these ecosystem functions include regulating hydrology (water movement), stabilizing soils, and storing carbon. Forests are also critical for maintaining biodiversity. Some of the species found in our local forests are well known wildlife game species pursued by landowners and visitors, while the vast majority of the species found in our forests (both flora and fauna) are virtually unknown. Regardless, each and every species has a role within its ecosystem and most forests encapsulate many different habitats for a range of wildlife species. Active forest management is necessary for the conservation of many forest-dependent wildlife species (game and non-game). Many wildlife species benefit from disturbances to the forest that remove only a small proportion of biomass and allow succession to move forward to a more mature and older forest condition. From an ecological perspective, a forest is never “over mature” but simply changing. These older forests provide needs for innumerable wildlife species that benefit from older trees, some of which may be dying or dead already. Conversely, other wildlife species benefit from forest treatments that remove a majority of the living material and initiate a young forest. Regardless, habitat for any single forest wildlife species is nested within a broader forest ecosystem; therefore, habitat management for a given wildlife species or forest product (e.g., sawtimber, pulpwood) can affect other landscape and stand-level biodiversity elements. Forest management can have lasting impacts well beyond the goals and objectives that drive a given treatment. Because forests develop more slowly than other terrestrial ecosystem types and may have conditions arising from forest treatments that can last for decades or longer, those interested in biodiversity are reminded that short-term successes based on optimizing objectives may yield long-term limitations. For instance, forest management that maximizes the short-term financial return may do so to the detriment of long-term economic potentials; cutting all the good timber in one treatment may derail the ability to put into action future treatments. Or forest management that maximizes the production of any single wildlife species may limit the range of habitats available to other species. And since nearly every tree species that comprise our forests has a lifespan greater than any of us (many individuals of most tree species are able to live many centuries), the time frame that forests work within often puzzles us. Too often we force our human expectations on our forests based on our time frames and not those in which the forest operates. Traditional approaches to forest management and wildlife habitat management were developed by Gifford Pinchot, Aldo Leopold and others when the global human population was a third of what it is today and stressors due to invasive species, other land uses, and climate change were not as pervasive. Now, in the 21st century, forest biodiversity challenges require a new working model; that working model is termed ecological forestry. For those managing forests, contemporary biodiversity challenges require us to think more broadly about the past, consider what actions or processes produced the forests we now have, and evaluate post-treatment conditions of forest structure, composition, and function. The need to evaluate the potential biodiversity effects of forest management has led to the development of forest certification programs and related biodiversity metrics. Forest management approaches within a biodiversity context (i.e., ecological forestry) have likewise been developed based on our growing understanding of how landscapes and forests function. Originally developed alongside efforts to maintain forest complexity and conserve the northern spotted owl in the Pacific Northwest of the United States, many advances in ecological forestry are associated with the growing appreciation and understanding of natural models of disturbances to which silvicultural practices can be compared. Ecological forestry has developed the following precepts: 1) context—the importance of planning and management at larger (landscape) spatial scales; 2) continuity—the maintenance of forest structure, function, and biota between pre- and postharvest ecosystems; 3) complexity— the need to create and maintain structural and compositional complexity and biological diversity, including spatial heterogeneity at multiple spatial scales; and 4) timing— the importance of applying silvicultural treatments at ecologically appropriate time intervals. Future articles will review these four precepts and provide examples relevant to those working and enjoying forests of northern Michigan. Dr. Greg Corace is the forester for the Alpena-Montmorency Conservation District. Greg has spent the last 25 years publishing forest and wildlife research and conducting forest planning, management, inventory, and monitoring on public and private lands across northern Michigan. For more information, including sources used in this article, Greg can be contacted via email (email@example.com) or via phone (989.356.3596 x102).
Dr. Greg Corace
Want to hear about what is new in the science world? Maybe get more information on the birds around us? Or maybe you want to keep up to date on what is happening in our current environment and with the natural resources we love. Check out some interesting articles shared by our Forester, Dr. Greg Corace.