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Silvicultural Practices and .. New Forestry..
(Presented at "New Forestry' In the 90's", a workshop sponsored by Coos Chapter, Society of American Foresters and Southwestern
Oregon Community College in Coos Bay, Oregon, April19, 1990)
by
Dean S. DeBell
Principal Silviculturist
USDA Forest Service
Pacific Northwest Research Station
Olympia, Washington
I NTROD UC TIO N
What is "New Forestry?" More specifically, what does it mean in terms of silvicultural practices? Many different
ideas have been discussed or proposed under the banner of "New Forestry." The phrase itself provides little
indication of the intent or nature of the concepts, but it does stimulate questions regarding old versus new,
and to some people, it has connotations of relative goodness or ecological soundness. In my opinion, the
New Forestry movement in the Douglas-fir region is one aspect of a larger national quest for consensus on
the objectives of forest land management and the practices by which they are achieved. The movement has
offered many ideas that may be useful in achieving consensus and also in enhancing the productivity and
condition of our forest lands. There are also some aspects of it that concern scientists and practitioners in
forest resource management.
This general quest by society seems to be focusing on three major items:
1. A desire for multipurpose or multiresource forest management; that is, management of individual
parcels of land to meet a wider range of objectives. This goal is sometimes described as "simulta­
neously producing commodities while maintaining ecological values."
2. A correlated desire that a wide range of practices--including new ones that provide alternatives to
existing ones, at both stand and landscape levels--be used to attain the objectives
3. A desire for broad-based participation in the setting of objectives and also in selection of manage­
ment tools, at least on public lands.
The general premise is that multipurpose management will result in "greater good for greater numbers of
people over the long run," and that such management will be environmentally sound and will have greater
public acceptability than does the continual dedication of stands to meet single uses or solve specific
problems. This premise commonly is described in terms of a pie and the futility of continuing to cut the pie
into smaller and smaller pieces to meet increasing specific demands. It has also been compared to having
a larger sandbox for many interest groups to play in. Many of us intuitively believe the concept has validity
in a biological sense and a social sense, but it has been neither tested nor evaluated conceptually for the
current situation in the Pacific Northwest. Nevertheless, this idea has great appeal, particularly to administra­
tors of public agencies and political representatives who must deal with the escalating land management
conflict.
SILVICULTURAL PRACTICES
Given the apparent public desire for multipurpose forest management, silviculturists are joining with other
resource specialists to develop and test prescriptions that meet a wide range of management objectives. The
prescriptions must involve landscape-level and stand-level considerations, but this paper is restricted to to
the stand. Current management on much Pacific Coast forest land is dominated by clearcutting, slashburn­
ing, and planting Douglas-fir. To practice multiresource forestry, we need a larger silvicultural toolbox--one
containing additional options and modifications of existing options. Many of these options may benefit timber
as well as nontimber uses and values. Early trials with some of them are already in place on public and private
lands.
Within the New Forestry movement, much of the recent discussion on stand-level prescriptions has been
confined to developing increased structural diversity within stands. Suggested practices have focused on
retaining green trees and leaving more coarse woody debris on the ground. This focus probably results from
a current preoccupation with the old-growth issue. A broader outlook is needed, however, to achieve the
benefits associated with multiresource forest management. There are other approaches to increasing struc­
tural diversity within stands, and there are other forest characteristics of importance--including those associat­
ed with early seral stages and pure, even-aged stands. These too play significant roles in overall biodiversity
and in providing both commodity and noncommodity (or ecological) values in our forests. The problem facing
forest managers is to determine and provide a mix that meets the needs and desires of society and at the
same time meshes well with inherent opportunities and constraints of specific forest sites and landscape
settings.
Several silvicultural options that might prove useful in multipurpose management strategies. They involve
treatments that influence species composition, stand structure, rotation length, and "carryover" of woody
debris when stands are harvested.
Species composition --lnterest has increased in establishing or retaining other species (that is, species in
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addition to Douglas-fir) in pure and mixed stands. The objectives are many, and they range from solutions
for specific site problems (for example, root rot or low soil nitrogen) to providing more diverse habitat for
wildlife.
Red alder stands, for example, may be planted on lands severely riddled with ?he/linus root rot. Growing an
alder crop in rotation with Douglas-fir also provides an opportunity for increasing soil nitrogen levels, which
presently limit productivity on more than two thirds of Douglas-fir sites. Alder management recently has
become more attractive because regional markets for solid wood have expanded and a world market for pulp
has developed. There is now concern in Oregon and Washington for sustaining the supply of alder and other
hardwood species.
Now that stock resistant to blister-rust is available, western white pine is receiving increased consideration
for planting throughout the region. White pine has high economic value, grows well on a variety of sites, and
has rapid juvenile growth rate. Its inclusion in present genetic improvement and planting programs provides
for the return of a significant component of the original biological diversity to many sites in the Cascade Range
and elsewhere.
Various mixtures of western redcedar, red alder, and Douglas-fir have been proposed to meet certain goals.
An interplanting of red alder with Douglas-fir at Wind River Experimental Forest in southern Washington
provides an excellent example of the potential for species mixtures. Fifty years ago, red alder seedlings were
interplanted throughout a 100-foot-wide strip centered in a 4-year-old Douglas-fir plantation. Today, the
Douglas-fir trees in that strip are much taller and larger in diameter than those outside it in the pure plantation;
their foliage is darker green and the soil beneath them is more than 1000 pounds per acre richer in nitrogen.
Mixtures of western redcedar and Douglas-fir have been suggested for several purposes, as have mixtures
of redcedar and alder.
Stand structure.--Many approaches have been suggested for providing greater diversity in stand structure
of managed stands. They include measures that influence stand density as well as the number of canopy
layers.
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Proposals related to stand density involve planting or thinning to very wide spacings. Such wide spacings
have recently generated considerable interest in the region. Coupled with pruning, they offer the possibility
to greatly shorten time needed to produce large-diameter, high-quality logs. Such regimes also provide
opportunities for maintaining--perhaps even intentionally manipulating--understory species over a much
longer period. Some species, such as Ceanothus, may provide benefits related to wildlife habitat and soil
improvement.
Interest also has been expressed in creating small openings within stands to improve habitat for some wildlife
species. This could be accomplished intentionally at planting, through precommercial or commercial thin­
ning, or through a group selection silvicultural system. Many of us, of course, fear that Phellinus root rot will
lead to more openings than are needed for such purposes on much land in the Douglas-fir region.
Proposed practices that may be useful for increasing the number of canopy layers include clearcutting with
reserve trees, irregular shelterwood cutting, uneven-aged silvicultural systems, underplanting of heavily
thinned stands, and several opportunities specific to mixed species stands. The suitability of these practices
obviously will differ with forest type and specific site conditions. The practice discussed most commonly is
green tree retention or clearcutting with reserve trees. This approach involves retaining of some portion of
the overstory when vigorous, mature stands are harvested. These residual trees can supply added structural
diversity to meet wildlife needs, as well as provide an eventual source of large snags and down trees. Such
objectives may be enhanced by topping the trees by saw or with dynamite, and snag formation can be
manipulated by using any of several means to kill trees on some schedule. From a timber standpoint, such
retention also offers an opportunity to produce some larger trees with higher quality wood characteristics on
sites managed on a much shorter rotation. Of course, this approach is not appropriate in stands where the
residual trees may be susceptible to windthrow, and it is unsuitable in stands infested with dwarf mistletoe-­
unless the management objectives are very limited.
Rotation length.--On National Forests, rotations are generally set to approximate culmination of mean annual
increment of stem wood. In actuality, this peak is not well defined, and there is a wide range of ages that would
meet the general intent. If the goal is multipurpose forest management, however, we probably should think
of the "peak in accretion" in terms of a wider range of products and values. When all costs, benefits, and
strategies of forest management are fully considered, there may be good reasons for rotations either longer
or shorter than those now planned. And they may differ substantially with site and objective for the same
species. Taking red alder, for example, soil-improving benefits may peak before culmination of mean annual
stem increment, whereas optimal conditions for some wildlife species may culminate much later.
Unmerchantable remnants of existing stands.--Most old-growth and many mature second-growth stands
contain snags and down trees, many of which could be retained to provide what has been termed a "biological
legacy" for the next rotation. Such retention is already practiced to varying degrees on public ownerships.
Combining selective retention of green trees, snags, and down trees with initial wide spacing of planting stock
may offer an accelerated pathway to some "old-growth" conditions in young managed forests.
Generai.--The results of some practices proposed for New Forestry or multipurpose forest management look
like old, old forestry or even "preforestry." They undoubtedly remind foresters of conditions that would have
been regarded as poor stocking, inadequate utilization, and high grading if timber production were the
primary objective. The intent, however, is quite different. We have much to learn about managing stands for
other purposes and for combinations of uses. Although most foresters may lack experience in some areas,
such as managing for biodiversity, the profession has a long heritage and is a storehouse of much pertinent
knowledge. We need to ensure that this heritage, including past experiences with fire, insects, and diseases,
is considered fully in the search for multipurpose silvicultural prescriptions.
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SOME CONCERNS
This discussion of silvicultural options would be incomplete if I did not mention some aspects of New Forestry
and related movements that concern many scientists and practitioners in forest resource management.
One concern is the "naturalistic ideology" that has influenced some proponents of the movement and also
permeates the thinking of some lay persons concerned with resource management issues. This influence led
to one silvicultural plan that included as goal statements such things as "manage forests for natural functions"
and "emulate natural processes." Such goals obviously lack clarity: how are subsequent developments
monitored to see if goals are met? Such ideology may lead to acceptance or selection of practices based
on relative "naturalness"--when their effect actually may run counter to more concrete objectives and desires
of forest owners and users. It may also result in failure to consider some very useful practices, merely because
they are regarded as "unnatural" or "highly manipulative." One way to avoid such problems, including those
associated with the opposing ideology of intensive manipulation, is to focus specifically on the objectives of
management for a given site or stand. This must be done within the overall context of the landscape or
drainage. focusing on well-defined objectives will help avoid the pitfalls associated with either ideology. It will
foster consideration of all options available: options emulating natural processes, other options enhancing
or channelling natural processes, and also those options developed to overcome shortcomings in natural
processes.
A second concern relates to statements or implications that strong scientific evidence supports the proposed
management practices. Given the present lack of pertinent experimental data and experience, the bases for
such proposals are more appropriately described as hypotheses--albeit logical and interesting ones. The
hypotheses have been developed primarily from data collected to characterize properties and processes in
unmanaged and, in many instances, old-growth ecosystems. Many statements on the nature and condition
of these characteristics in young, managed forests are largely conjecture. Moreover, the inference that the
proposed practices will produce the values and attributes desired in young stands represents a second-order
leap of speculation. Potential risks and problems have rarely been analyzed or mentioned, though they may
be considerable for some values and uses. One of the most timely examples in this respect relates to habitat
for the northern spotted owl. Some of the proposed New Forestry practices obviously could provide structures
used by spotted owls, but habitat for red-tailed hawks and great horned owls would also be enhanced. It could
be argued that the net effect of such practices would be increased spotted owl losses due to predation and
displacement. Thus, the scientific committee responsible for the Spotted Owl Conservation Plan suggested
silvicultural experiments based on the hypotheses rather than relying on some of the proposed practices at
this time. Similar situations exist for assumptions about social acceptability (such as visual appearance) as
well as other biological and economic matters.
A third concern is that a few advocates--certainly not all--have attempted to build a case for New Forestry by
belittling current practices. This is neither necessary nor desirable. Although the approach may be well
received by some audiences, misleading statements have negative effects in the long run. An accurate
understanding of present knowledge on such matters is essential to resolving the current turmoil in forest
resource management. Misleading and irresponsible comments have been made with regard to decline in
stand productivity, the merits of planting versus natural regeneration, genetic improvement programs, and
nutrient amendments. Although most cultural practices were developed with a focus on timber production,
the tools themselves and the scientific knowledge underlying them have usefulness in managing forest
vegetation to meet a variety of present and future needs.
CLOSING THOUGHTS
Given the intensity of current forest management conflicts, it is natural for people caught in the middle to look
for panaceas and short-term solutions. Despite concerns with certain aspects of New Forestry and related
movements, I believe the emerging focus on multiresource management of public forest lands holds much
promise. Silviculturists and other foresters will find it challenging to work closely with other resource special­
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ists and to design management systems that provide a greater mix of products and forest conditions.
Planning and implementing broad-scale trials with these concepts should be done judiciously, however. We
need to focus on well-defined goals; we should proceed with a cautious attitude (not make statements or
promises that may destroy future credibility), and we must maintain a commitment to evaluation, develop­
ment, and, as appropriate, midcourse adjustments. In this, I am encouraged by the national Forest Service
program entitled "New Perspectives for Managing the National Forest System" and the cooperative research,
development, and application program recently begun by the Pacific Northwest Region and the Pacific
Northwest Research Station. These programs will help land managers and their agencies avoid the pitfalls
associated with current and past ideologies, and they will provide opportunities to evaluate a range of
management options. We will need a broad array of sound silvicultural practices to capture the social,
economic, and environmental possibilities that occur in the vast forests of this region.
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