Recommendations for Ecologically Sustainable Forestry in the UP (Full Text)
By Greg Kudray and the Upper Peninsula Environmental Coalition Forestry Committee
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Maintaining a sustainable ecosystem in the UP is a goal we all share. Yet most forestland in the UP is managed for timber production, sometimes as the only goal but often with some acknowledgment of other values. The Forest Service calls it Ecosystem Management, it's multiple-use to the State of Michigan and even most forest industries support the principles of the Sustainable Forestry Initiative of the American Forest and Paper Association; see guiding principles at: http://www.afandpa.org/
Timber harvesting can have extremely negative impacts on nearly all ecosystem components.
Since timber production will go on in most areas, we need to find ways to shape timber management to maintain ecosystem sustainability over time. The following recommendations address only smaller scale stand-level management, without involving other larger scale issues in ecosystem management, such as migratory bird habitat or global warming. The objective is to provide guidelines for UPEC comments on public and private timber management activities and to promote understanding of what land managers can do to protect ecosystem sustainability.
HARVESTING METHODS
SILVICULTURAL PRACTICES SHOULD MIMIC NATURAL PATTERNS TO SUSTAIN BIODIVERSITY.
Ecosystems will best provide overall natural habitat and biodiversity values if they are left alone with no timber management. However, if harvesting occurs, conservation biologists generally agree that, management should mimic natural disturbance processes. This philosophy will help ensure sustainability for ecosystem function, structure and composition, the three important components of biodiversity. Each ecosystem type will have a unique disturbance regime that creates openings for new tree growth, whether it is fire for jack pine or treefalls for gaps in northern hardwood forests. Timber harvesting can remove only a few trees, selection, or the entire stand, clearcutting. These two general types can provide a framework for discussion, although there is an entire range of intermediate methods possible.
SELECTION
This is a partial removal of trees in the stand, typically every 10 to 20 years. The trees to be removed can either be marked for removal by a forester or chosen by another method, like only cutting the best trees, high-grading, or cutting everything above a certain size, diameter-limit (e.g., cut everything > 14 inches in diameter). High-grading and diameter-limit cuts degrade the quality of the timber stand over time and should be avoided. Partial cutting is the dominant harvesting method in northern hardwood stands and is similar to natural stand replacement processes with the following exceptions.
SOME AMOUNT OF HABITAT TREES SHOULD BE LEFT TO DECAY AND DIE NATURALLY. SEVERAL SHOULD BE LEFT PER ACRE. PERMANENTLY MARKING THESE TREES TO ENSURE THEIR PERSISTENCE THROUGH SEVERAL ROTATIONS IS DESIRABLE.
The recommended method of marking trees for cut includes marking defective and dying trees as well as mature trees for removal. Vigorous straight trees are left at a fairly high density to create a stand of tall trees with minimal branching. When this harvest rotation continues over time no standing dead or decayed trees are left to provide cavities for nesting birds or a substrate for other life such as insects or fungi. The process of trees falling down naturally and creating the pit and mound ground topography so familiar in our forests is also eliminated. Maintaining surface structural diversity will also lead to biological diversity. Fallen trees additionally provide coarse woody debris, well recognized as a critical habitat for many kinds of life. The organic matter in woody debris also contributes to soil replenishment, supplying humic materials, nutrients, and moisture holding capacity. Habitat trees are most useful when they are present throughout the stand and in a wide range of sizes including larger trees. Permanently marking these trees with a paint mark at the base of the tree is an unobtrusive way to continue their biological legacy over time.
CONIFERS (WITH THE EXCEPTION OF THE MORE COMMON BALSAM FIR) ARE DISAPPEARING IN MANY UPLAND NORTHERN HARDWOOD STANDS. EXISTING TREES SHOULD BE CONSERVED OR THEIR REGENERATION ENCOURAGED. SOMETIMES SILVICULTURAL METHODS THAT CREATE OPENINGS LARGER THAN A SINGLE TREEFALL ARE BENEFICIAL.
Upland northern hardwood stands that have been managed for several rotations have a strong tendency to become almost pure sugar maple stands. This is due to the prejudicial marking of other species considered of lower value and the disruption of natural processes that allow other species to become established. Conifers such as hemlock, white pine, and spruce were once much more common in these stands and provided important habitat diversity for birds and other life. Conifers are often so limited now in well drained northern hardwood stands that even if a suitable seedling site is available there are no mature seed trees in the area. The disturbance regimes that these stands naturally experience include not only small individual treefalls but also some events that create larger gaps more suitable for species other than sugar maple. The reproduction of species other than sugar maple often depends on these larger canopy gaps, the presence of woody debris, or the exposure of mineral soil through a tip-up or other disturbance. Mineral soil can also be exposed through the use of fire or mechanical scarification.
CLEARCUTTING -
Clearcutting is the complete removal of trees on a site, but is practiced at varying levels with considerable ecological differences. A clean-cut removing even very small trees is sometimes used to totally reduce competition for the new crop. A more typical clear-cut will involve the removal of all trees that are merchantable (at least 5" in diameter).
WHOLE TREE HARVESTING IS NOT COMPATABLE WITH SUSTAINABLE ECOSYSTEM MANAGEMENT.
Some machine used in clearcuts are whole-tree harvesters, chipping virtually the entire tree for harvest. Traditional methods leave the tops at the site. Due to the relative concentration of nutrients in various parts of the tree, whole tree harvesting removes considerably more nutrients from the site. Some low-nutrient sites do not have the natural capacity to replace these nutrients for sustainable tree production. Whole tree harvesting also eliminates woody debris trees, greatly reducing habitat value.
CLEARCUTS DO NOT MIMIC NATURAL PROCESSES. LEAVING STANDING HABITAT TREES SINGLY AND IN GROUPS WILL HELP PROTECT ECOSYSTEM VALUES.
Clearcutting has also been viewed in the context of natural disturbance processes. Wildfire or the catastrophic windthrow of 10's or 100's of acres can result in complete stand removal and the establishment of an even-aged stand. Wildfire was an important natural process in many ecosystems that are now clearcut but there are important differences. Many dead or damaged snags remain that provide the same ecosystem functions described in the previous section. Wildfire also typically leaves some areas untouched within the burn, creating a biological legacy that speeds ecosystem recovery. Catastrophic windthrow also often leaves trees standing in addition to exposing mineral soil at the root ball. Generally, natural disturbances are characterized by substantial biological and physical variation that is often lacking in a clearcut.
CLEARCUTTING IN ECOSYSTEMS THAT NATURALLY SUCCEED TO AN UNEVEN AGED STAND COMPROMISES OTHER ECOSYSTEM VALUES.
Clearcutting is often prescribed for ecosystems that normally do not have a disturbance regime that includes catastrophic stand-replacing events. The widespread stand conversion, to aspen or red pine, of ecosystems that normally would support a northern hardwood community is an example. These kinds of tree farms sacrifice the diversity of species and habitats found in a natural forest for the maximization of wood production.
OTHER SPECIES NEED TO BE ACTIVELY ENCOURAGED IN CLEARCUTS THROUGH THE RETENTION OF TREES, PARTIAL CUTTING, PLANTING, OR MINERAL SOIL EXPOSURE.
Species compositions are often changed through clearcutting. The ability of aspen to reproduce from its roots gives it a great competitive advantage to dominate a site after harvest, especially after more than one rotation. Encouraging tree biodiversity will provide more habitat and buffer the stand against insects and diseases specific to one species.
EXISTING PLANTATIONS SHOULD BE ALLOWED TO SUCCEED TO NATURAL MIXED STANDS OR INTERPLANTED WITH A VARIETY OF SPECIES TO INCREASE BIODIVERSITY. NATURAL REGENERATION OR MIXED SPECIES PLANTINGS ARE PREFERABLE TO SINGLE SPECIES PLANTATIONS.
Plantations are widespread in our region due to the lack of tree regeneration after the severe logging and fires near the beginning of this century. Plantations are lacking in biodiversity and natural habitat.
OTHER CONSIDERATIONS
SUSCEPTABLE WETLAND AREAS WITHIN TIMBER HARVEST AREAS SHOULD BE CLEARLY MARKED OFF LIMITS WITH AT LEAST AN ADDITIONAL 100 FEET BUFFER ZONE EXTENDING FROM EACH SIDE OF A STREAM OR WETLAND. WATER QUALITY MANAGEMENT PRACTICES ON FOREST LAND (MI. DNR 1994) SHOULD BE FOLLOWED TO PROTECT WATER QUALITY.
Wetlands and watercourses are especially vulnerable in forestry operations. Crossing these areas with harvesting equipment can cause severe rutting, compact the soil, and may permanently disrupt the hydrology of an area. Wetlands should be avoided by logging equipment and crossed by roads only if no other option is available. Buffer zones need to be increased beyond 100 feet if steep slopes are present. The presence of small wetlands within an upland area is also vital for a variety of bird and animal life. Dumping logging slash into these areas or otherwise degrading them will cause ecological deterioration out of proportion to their small size. Equipment fluids pollute wetlands and groundwater and should be properly recycled, not drained at the site. Fluid leaks can also be a pollution problem.
LIMITED AND TEMPORARY ROAD NETWORKS ARE PREFERABLE. ROADS OFTEN NEED TO BE REVEGETATED AFTER USE, ESPECIALLY IN AREAS WITH FINE-TEXTURED SOILS OR STEEP SLOPES. NATIVE PLANT SEED IS INCREASINGLY AVAILABLE AND SHOULD BE USED IF POSSIBLE.
In general, road building through forests should be kept to a minimum and carefully planned to reduce negative impacts. Roads provide corridors for weed species to invade and can also have negative impacts on wildlife. As much as possible, roads should be closed or obliterated following use to prevent ORV abuse, soil erosion, and to protect wildlife habitat.
SILVICULTURAL ACTIONS SHOULD NOT BE PRESCRIBED WITHOUT AN UNDERSTANDING OF THE SOIL ON THE SITE. BEST MANAGEMENT PRACTICES NEED TO BE DEVELOPED FOR SOIL TYPES.
Soils differ in their sensitivity to management. Modern soil surveys are available for most of the UP and provide valuable information about susceptibility to skidder rutting, high water tables, and seasonal wetness. Soil and root damage happen if rutting greater than a few inches is occurring. These ruts often persist for decades and should be avoided whenever possible. Below ground productivity should not be compromised on sites. As new information becomes available on microflora, mycorrhizae and other factors pertaining to tree growth it should be incorporated into management plans.
ECOSYSTEM CLASSIFICATION AND MAPPING ARE WELL ADVANCED IN OUR AREA AND NEED TO BE MORE WIDELY APPLIED.
Land classification and mapping techniques that show only tree cover types are inadequate because trees alone do not reflect the ecological charactersitics of a site. Ecosystem classifications and mapping that consider the soil, landform, hydrology, and all vegetation are more valuable in predicting how ecosystems will respond to management.
WILDFIRE SHOULD BE RECOGNIZED AS AN IMPORTANT NATURAL PROCESS. PRESCRIBED BURNING IS A VALUABLE MANAGEMENT TOOL IN FEASIBLE AREAS.
Wildfires, an important natural disturbance process, are now suppressed, resulting in a decline of fire-dependent ecosystems and species. While prescribed fires often lack some of the characteristics of wildfires because of their timing and intensity, they are still useful in maintaining habitat.
SINCE EXCESSIVE DEER POPULATIONS HAVE DETREMENTAL EFFECTS ON TREE REGENERATION AND HERBACEOUS SPECIES SURVIVAL, FOREST PRACTICES WHICH FAVOR DEER HABITAT SHOULD BE DISCOURAGED IN AREAS WHERE DEER NUMBERS ARE ALREADY TOO HIGH. SOME ECOSYSTEMS HAVE HIGH ECOLOGICAL VALUE OR ARE VERY SENSITIVE TO DISRUPTION THROUGH TIMBER MANAGEMENT. SPECIES-RICH FORESTED WETLANDS (CEDAR OR MIXED SPECIES) ON ORGANIC SOILS ARE A GOOD EXAMPLE.
Some forested communities are rare, or particularly sensitive. The organic soils in rich swamps are easily compacted or rutted by machinery even during winter operations, resulting in hydrologic disturbance, soil compaction, and the destruction of surface topography. The water table often rises when this kind of wetland is harvested, causing difficulties in tree regeneration and reducing the amount of soil available to support tree growth. Combined with the preferential browsing of deer, regeneration problems become severe. Until more information is available, timber harvesting in these ecosystems must be carefully planned if it occurs at all.
Sustainable forest management requires a thorough understanding of the ecological elements of the site, their limitations and capabilities. This includes, among other things, the site's unique soil, hydrology, stand history, natural disturbance pattern, and how these elements are integrated in the whole ecosystem. A good starting point is to establish an appropriate desired future condition that recognizes how and why these ecosystems evolved. Management actions can then be taken that (hopefully) will ensure future sustainability for all life that depends on this ecosystem.