Forest managers must do much more than plan. We must be protectors and stewards of the land. To achieve this goal, many of us use an approach to management that is sometimes referred to as ecosystem-based forest management.
What are ecosystems?
Generally speaking, an ecosystem is a community of interacting organisms. Ecosystems generally have similar site conditions (i.e., soil, climate, moisture), and the species in a particular ecosystem are all adapted to these shared environmental conditions. Ecosystems vary from one place to another because of differences in physical characteristics (geology, soils, landforms, topography, and surface materials) and biological characteristics (vegetation, animals, and microbes).
Ecosystems can be found on land (terrestrial) or in the water (aquatic) and can be very large (for example the Earth) or relatively small (a local forest). Ecosystems usually overlap and are interconnected or are dependent on one another through various processes—for instance the water cycle.
The Acadian Forest, where we live, is an ecosystem that contains many different ecosystems. The mix of tree species and other vegetation within each Acadian Forest ecosystem depends on various factors:
- site and soil conditions (aka moisture and nutrient regimes. For instance, wet to very dry sites and nutrient poor to rich fertile sites);
- climate or microclimate (a microclimate is an area where the climate is different from the climate in surrounding areas);
- the way humans have used the land (aka land-use patterns or human disturbances),
- the frequency with which the ecosystem experiences naturally occurring events such as high winds, fires, lightning, and insect outbreaks (aka natural disturbance regimes); and
- the forest’s current stage of development—that is, whether it is just beginning to grow back, is mature, is somewhere in between, or is a mixture of stages. This process of development from early stages to later stages, which all ecosystems go through, is referred to as natural or ecological succession.
How can we identify ecosystems in Nova Scotia?
In Nova Scotia we have two newly available tools that provide a good basis for identifying ecosystems across our landscape.
The Ecological Land Classification (ELC) for Nova Scotia uses information on climate, geology, soils, and so on to create maps of ecological groupings within the province at three levels: ecoregion, ecodistrict, and ecosection. The Acadian Forest Ecozone is divided first into 9 main ecoregions. These ecoregions are differentiated primarily by elevation and proximity to the ocean. For example, the Valley and Central Lowlands Ecoregion essentially extends from Digby to Truro surrounding the Minas Basin. The distinguishing feature of this ecoregion, as outlined in the ELC manual is that the ecoregion is “sheltered from coastal climatic influences with warmer summer temperatures and milder winters than elsewhere in the province”. These conditions bring forth a unique combination of soil and vegetation types.
The ecoregions are further subdivided into ecodistricts as classified by distinct combinations of geology, landforms, soils and vegetation. There are a total of 40 ecodistricts in Nova Scotia. The Valley and Central Lowlands Ecoregion, for example, contains 3 ecodistricts: the Annapolis Valley Ecodistrict (extending from Digby to Canning), the Central Lowlands Ecodistrict (includes much of Hants County), and the Minas Lowlands (extending from east of Truro to Bass River).
A more detailed, localized way of classifying a forest or forest stand is by ecotype. Ecotypes are broad ecological groupings with similar moisture and nutrient regimes that are reflected in similar growth (productivity) capabilities. Forest Ecosystem Classification (FEC) manuals for the central, west, and eastern regions of Nova Scotia define forest ecotypes according to their dominant soil and vegetation types. (The manuals for the west and east are interim versions. The NSDNR provincial manual is scheduled for publication in 2011.) They contain vegetation and soil identification keys, descriptions, photographs, and corresponding management interpretations for the various vegetation and soil types found in Nova Scotia.
Soil types are classified by moisture (wet, moist, fresh or dry), texture (coarse, medium, fine) and sometimes fertility (poor, medium, rich). Soil types can be easily identified in the field by digging a small soil pit and using the keys provided in the FEC manual to determine texture and type.
The photo above shows a clear, large American beech in a hardwood old growth forest near Mabou. It is estimated that these trees are about 200 years old, raising questions about why this tree was not affected by the beech canker disease that was introduced into Nova Scotia in the early 1900s.
Vegetation types are described in terms of dominant overstory tree species cover and understory vegetation species. Vegetation communities and particular species can be used as indicators of site productivity. For instance, a ground vegetation mix of Red baneberry, Rose twisted stalk, Oak fern and Beaked hazelnut is an indicator of soil richness and a site that will support a shade-tolerant hardwood mix forest of Sugar maple, Yellow birch, White ash, and American beech. On the other hand, a ground vegetation mix of Cinnamon fern, Dwarf raspberry, Starflower, Sphagnum moss, False holly and Lambkill is suited to wet and poor-to-medium fertility sites, thus serves as an indicator of a site that will support a mainly coniferous forest of Red spruce, Black spruce, and Balsam fir with a mix of Red maple, White birch, Yellow birch, and White pine.
The photo above shows a Yellow birch in the same old growth forest pictured in the previous photo. This forest was actually close to being entirely harvested until, at the last minute, it was purchased by the neighbouring forest owner. The trees stretch 22 meters into the sky. This forest is truly breathtaking to walk through, particularly when the leaves are off the trees.
Using the vegetation and soil type keys provided in the manual, ecosystems are classified into 10 ecotypes. These range from dry-poor conifer (i.e., rock barren) to very rich deciduous (i.e., floodplains). Once the ecotype of a site has been identified, the FEC manual provides management interpretations that address potential and operational hazards, including hazards associated with the particular soil type. Using the manual, the forest manager can develop appropriate prescriptions to ensure that activities on the ground are a success and not detrimental to the ecosystem.
For instance, an ecosystem with Soil type 12 as classified in the FEC manual (“Rich moist, fine—medium textured”) is prone to rutting, compaction, and erosion. Thus management recommendations made using an ecosystem-base approach will include measures to minimize this risk. Protecting the soil will, in turn, ensure that the site remains productive for many years to come.
In ecosystem-based forest management, tools such as these are very valuable. They are used to identify and apply management interpretations that reflect opportunities and address hazards and operational limitations associated with a site’s specific ecosystem (ecotype) . Incorporating such information into recommendations and operational planning will limit possible damage from harvesting and help to maintain both overall ecosystem health and site productivity for the long term. Together, the ELC and the FEC provide a valuable perspective on a woodlot at the landscape and forest stand level, allowing the forest manager to fully understand ecological processes at play.
What is ecosystem-based forest management?
In ecosystem-based forest management, forest managers try to determine the natural ecological process that should be occurring on a particular site. We then try to protect these processes while also achieving landowner’s goals, which may include not only timber production but also conservation, recreation, aesthetics, and other resource values and benefits. The key principles of EBFM are:
- Manage the natural forest
- Mimic natural processes, including natural disturbances
- Maintain multiple forest values, benefits and uses
- Prescribe site-specific treatments
- Focus efforts where they will yield the best returns
- Improve the quality and value of individual trees over time
- Avoid predictable hazards
- Maintain and protect long-term site productivity
- Maintain and protect ecosystem functions and health
This approach to forest management respects the dynamic, changing character of the forest community and forest landscape. It takes a more holistic view of the forest and is especially appropriate for landowners whose goals and objectives are based on multiple values and use.
This item is drawn from two columns I wrote for the Nova Scotia Woodlot Owners and Operators' "Update" newsletter and from a presentation Sandy Hyde made to the NSWOOA Annual General Meeting in April 2009.