Many of the problems associated with conventional clearcutting and site preparation can be minimized via careful forestry practices. These include minimizing the construction of roads, and when roads are necessary, constructing them at moderate grades and culverting them. They also include logging in such a way that disturbance of the forest floor is minimized (as by using cable or skyline yarding instead of skidding, or using helicopter logging). Uncut buffers along streams can decrease impacts on aquatic systems (and buffers of various widths are not mandated by both federal and state law, with widths varying, depending on whether the stream is perennial or intermittent, fish-bearing or not, and so forth).

These kinds of changes, however, do not address some of the most important and long term consequences of clear cutting and site preparation techniques - consequences associated with the loss of important structural legacies and fragmentation of landscapes, which have implications for the biological diversity of our forests. The relatively new approach of "ecosystem management," which was described briefly in an earlier section of these notes, aims to diminish these sorts of impacts as well.

Ecosystem management involves a shift in the focus of forest management from timber or single species to a focus on the entire forest ecosystem. Such a focus is, of course, appropriate for both government-managed and private lands, however the federal government is obligated by law to manage forests for "multiple use." Federal land managers are required to consider timber, watershed, wildlife, recreational and aesthetic wilderness aspects in their land management, and this has been the case for many years -- since long before the forest summit and the adoption of the Northwest Forest Plan. However, in practice, timber often was the primary focus of forest management. With the implementation of the Northwest Forest Plan, that has changed, and nontimber components of the forests are receiving increasing attention.

How can forested lands be managed to better meet multiple use objectives while still filling societies' need for timber products? One of the central philosophies of ecosystem management is that production of commodities and maintenance of ecological values need not be mutually exclusive; that is, there are alternatives between tree farms and total preservation.

"A Kinder And Gentler Forestry"

Dr. Jerry Franklin, who was at OSU for many years and is now at the University of Washington, coined this phrase as he worked with others to make the case that we can manage even our commodity producing forest lands in such a way that we also foster (or at least do minimal damage to) species that depend on intact, mature forests. He and others pointed out that we understand a great deal about the functioning of intact old-growth forests (as we discussed in a previous section of these notes). We also understand a good bit about how nature regenerated forests after disturbances such as fire and wind -- and about how variable those natural disturbances were in frequency, extent and severity. Typically, natural disturbances left behind much larger "legacies" of energy, nutrients, physical structures (e.g. snags) and even living organisms for the forest ecosystem that regenerates after the disturbance than do conventional clear cutting and site preparation. What is left on the site may be as important as what is removed in the harvest!

These ideas were incorporated in Option 9 prescriptions for how harvesting should be done on "matrix" lands -- those from which most timber will be removed (in terms of federal acreage, that is). These ideas have also been incorporated into the management of late successional reserves and adaptive mgmt areas, as described before.

SO ON MATRIX LANDS, WHAT KINDS OF PRACTICES WILL WE SEE?

Clear cuts as we have known them are to be a thing of the past on most federal lands in western WA, OR, and northern CA. Instead, logging and site preparation will aim, in part, at creating managed forests with higher levels of structural diversity than result from conventional practices. We saw earlier how important key structural features -- and structural diversity - are for wildlife, other forest species, and for ecosystem functions. How will the new methods pay attention to these features?

(1) More down wood on land and snags will be left when timber is cut. The Northwest Forest Plan has prescriptions for this; loggers must leave, for example, a renewable supply of down logs in a variety of age classes. (Different sizes (ages) and decay classes of coarse woody debris support different communities of plants and animlas.)

(2) Logging operations must maintain logs in streams to maintain stream productivity and fisheries.

Both of these practices arise from the philosophy that "decadence in moderation is probably a very good thing." Dead material in forests is, as we've seen, very important to their function and composition.

(3) Loggers must leave some large green trees behind as another way of maintaining structural diversity and providing carry over from the previous stand. Regulations call for leaving at least 15% of the standing green trees behind, often referred to as "logging with green tree retention." The spatial pattern of these trees is not specified by the regulations; that is, whether they should be left as scattered trees or in clumps (and it isn't clear yet which pattern will be best in terms of the trees providing a refuge during the disturbance, inoculum for the new stand (e.g., of nitrogen-fixing lichens and mycorrhizal fungi), and future structural diversity.) The forest that re-grows after logging then will have a mixture of tree sizes and ages, including some of the larger older trees, rather than being an even-aged homogeneous "plantation style" forest. Further, these remnant trees can ameliorate site conditions (which are often quite harsh after clear cutting) and provide refuge for many animal and plant species that might otherwise be eliminated from cutover areas.

Some past logging practices did leave some standing green trees anyway. For example, shelterwood cuts left some overstory trees to moderate site conditions and make it easier for young trees to get a start, and seed tree cuts left standing green trees to furnish seeds for the next generation of trees. However, in both cases, loggers typically went back in and removed these trees after 5 - 10 years. Under the new management prescriptions, the trees will be left there, where they will play the compositional and functional roles previously discussed.

(4) Surveys and management for "sensitive species," as listed in the Northwest Forest Plan, are required; that is, for species that seem to depend on old-growth forest conditions for some or all of their life needs. If any of these sensitive species are found during pre-timber sale surveys, logging plans must take them into account. The subsequent steps depend on how sensitive the species is considered to be, and range from simply noting that the species occurs there to not being able to harvest at all within a wide area around the site where the species was found.

(5) Different methods of site preparation are also required. Slash burning is to be minimized. Much of the legacy of a forest is in the forest floor, in coarse woody debris and in slash. The forest floor contains organic material on which many organisms depend and which provides a slow release of nutrients, becoming available as the trees grow. It is also a repository for buried seed, mycorrhizal inoculum, and, of course, aids infiltration of water which minimizes runoff. Slash should now, for the most part, be burned under only two circumstances: (1) when the site will not be replanted (that is, when natural regeneration by seed is the method for reestablishing trees) or (2) when it poses a severe fire hazard. When slash is to be burned, loggers are to avoid scarifying the soil; that is, to pile the slash with minimal seed bed preparation. Recall that soils are often scarified - scraped to mineral soil - to aid the germination and establishment of the tree species that are most valuable for timber? In fact, some studies suggest that while some conifer species do germinate and establish best on mineral soil, their subsequent growth is better on an undisturbed forest floor (likely due to nutrient availability and persistence of mycorrhizal fungi).

What will become of the slash if it isn't burned? It will often be lopped (cut into smaller pieces) and scattered instead, where it will gradually decompose. Prescriptions for slash disposal will vary with the site.

Use of herbicides is also reduced under the Northwest Forest Plan.

(6) Rotation lengths will be more variable than in the past. Typical rotation lengths (intervals between successive cuttings of a given forest) have been on the order of 70 years, but this will change. Some very long (200+ years), and other rotation lengths will be used. This change is a reflection of our understanding that natural disturbances vary in frequency over the landscape, and the belief that forest management should reflect that natural variability. Note that we are not talking about managing just for "naturalness sake" but with the idea that such management will be more sustainable for all aspects of the forests than the previous style was.

(7) Some landscape level considerations will also change. The size, shape, and spatial distribution of cuts will be designed with a focus on minimizing habitat fragmentation and protecting stream drainages. For example, managers will try to create buffers of relatively long rotation forests around existing old-growth preserves, which would serve as "core areas." These buffers will serve to minimize edge effects (discussed previously).

Until recently federal lands in the PNW were logged on a "staggered setting" -- scattering relatively small 40 acre cuts around on a checkerboard pattern. This harvest pattern had been followed since the 1950's, and many of the motivations for it were well-intentioned. The ideas were to disperse small cuts around on the landscape, rather than creating larger cut over areas (in part because the public objected to big, unsightly clear cuts). The small cuts also created an abundance of "edge" habitat, which is favorable for some wildlife species (some big game mammals and game birds, in particular). These smaller cuts also allowed for the construction of a "good" road network (i.e., lots of road miles covering the landscape), which made fire control easier. Finally, smaller cuts enabled conifers to seed in well, when natural regeneration was being relied on.

What people didn't realize , however, was that staggered setting patterns basically maximized fragmentation of the landscape. (I'll show a figure in lecture illustrating the projected landscape level consequences of "business as usual" versus the newer approaches to laying out harvest units and considering rotation lengths.) Remaining patches of older forest became smaller and smaller over time. The older, unharvested patches that remained were dominated by edge effects, and, while some species thrive on edges, many of the species that are native to our forests do not! Further, there was often a lot of blow down of residual trees along the margins between recent cuts and unharvested forest patches, which eroded still further the intactness of the uncut fragments. In addition, staggered setting resulted in few (or no) corridors linking patches of mature (or old-growth) forest with each other, and the road network created barriers to movement of some species and provided easy access for humans and weed seeds into otherwise remote areas (in addition to the effects of roads on water and soil loss…). The new approaches will aggregate more closely areas that are being managed similarly, and will decrease fragmentation compared to staggered setting patterns. New minimum fragmentation cutting patterns began in some areas in the late 1980's. These try to place new cuts adjacent to earlier cuts instead of in the middle of uncut blocks. As the figure I'll show in class illustrates, such patterns retain relatively large blocks of continuous interior forest habitat until later in the cutting cycle. They also allow drainage's to be undisturbed for longer intervals instead of their experiencing chronic disturbances.

(8) Finally, rather than replanting with monocultures (using one tree species; particularly Douglas-fir in our area), sites will often be replanted with mixtures of species. This not only protects the forest against disasters such as insect or disease outbreaks (like the problems that can occur in monoculture agriculture as well), but a greater diversity of tree species supports a greater diversity of associated species as well - and more closely matches the unmanaged forest condition

LIKELY BENEFITS CONFERRED BY ECOSYSTEM MANAGEMENT

Federal lands in the "matrix" designation (the lands from which most of the federal harvest will come) will, thus, be managed very differently than in the past. Many of the changes, as you can see, arise from understanding how unmanaged forests function - how they are able to be so retentive of nutrients, to diminish flooding and soil erosion, to support excellent tree growth century after century, and to provide habitat for the diversity of species that make them their homes. Considering our previous discussion about the characteristics of old-growth forests, and the particular structural features that provide them with many of these characteristics, I think you can see how the changes will be beneficial.

It is also important to remember that, if we confine the battle for preservation of native biodiversity to just setting aside preserves (wilderness areas and so forth), we will probably lose the battle (as Jerry Franklin and other forest ecologists have been telling us for decades). What are the problems with relying on preserves, and continuing to harvest timber from other lands, as in the past?

(1) Preserves are often too small to support viably-sized populations of many species. (See our previous discussion of minimum viable population sizes.)
(2) Preserves are vulnerable to change -- either by natural disturbances (e.g., fire) or anthropogenically-induced changes, such as climate change.
(3) A preserve is only a preserve as long as the government in power at the time wants to retain it. That is, they are subject to political shifts in priorities.
(4) Remaining old-growth patches (whether currently in preserves or not) are often very isolated from other patches -- not interconnected - because of habitat fragmentation introduced by past logging practices.

That is, preservation of biodiversity (and ecosystem functions) can't be just a "set aside a preserve" issue. The battle must be broadened to include commodity lands as well, and that is what we hope the changes underway in federal forest management in the PNW will do. The changes are not a substitute for preserves - preserves remain important -- but will be useful in addition to them! The same can be said about preservation of any ecosystem - we must, increasingly, as remaining undisturbed areas dwindle in size, turn our attention to finding ways to "have our cake and eat it too." That is, to extract some commodities from the land, while allowing it to retain its value as a functioning ecosystem.

To return to the index of topics in this section on forest management, click PNW. To return to the master Table of Contents for this BI 301 web site, click the contents box at the bottom, or for reminders on how to move about within and among these pages, click "Navigate."

Page maintained by Patricia s. Muir. Last updated November 25, 2002.