what is close-to-nature silviculture in a changing world? kevin l. o’hara university of california...
TRANSCRIPT
What is Close-to-Nature Silviculture in a Changing World?
Kevin L. O’HaraUniversity of California - Berkeley
What’s in a name?
new perspectives retention forestry holistic forestryecoforestry restoration forestry new forestry ecological
silviculture back to nature irregular forestry
common sense forestry continuous cover forestry excellent forestry close-to-nature
forestry ecosystem management near-
natural forestry nature-based forestry ecological silviculture holistic forestry sustainable forestry
diversity-oriented silviculture new forestry
Close-to-nature
• Possibly the original “natural silviculture” movement
• Close-to-nature, and other names/movements, are reactions to abusive practices
• Attached to single tree selection silviculture• Evolved to emphasize species mixtures and
irregular age/stand structures• Successful in central Europe
Pro Silva organization
Founded 1989
Movement primarily in central Europe
Pro Silva Principles
• “guaranteed continuity of naturalness”• “Adopt a holistic approach involving continuous forest
cover” • “Selection felling and tending at all stages of
development” (i.e., selection systems)• “Working towards a balance on as small a scale as
possible between increment and harvesting in each management unit”
• “use of natural regeneration”• “Restricting the use of exotics…”
Plenter System
• Single-tree selection system in central Europe• Is it “natural”• “we can conclude that, as a general rule,
plentering is a man-made system, which need man’s intervention in the form of structure intervention … to maintain it in the long run.”
– J.-P. Schutz 2001
What is “Natural”
• Depends on context (background, location, relation to other stands, etc)
• Unmodified by humans• Perception may not be rooted in ecology• Changes with time• Perception of “balance of nature”
“Naturalness”
• A fuzzy concept• A social construct (culture, values, beliefs)• A conditioning response• A condition with minimal human interference• Natural or naturalness is desirable in our
cultures• Some view all management as undesirable
Disturbance Emulation
• Common theme of contemporary silviculture• Viewed as contributing to “naturalness”• Involves using silviculture to follow types and
frequencies of disturbances• Requires knowledge about disturbance
regimes• But not really new
Ranges of variability
• Historical range of variability– applies to disturbance regimes– and therefore to silviculture
• Future range of variability– integrates knowledge of historical range of
variability with– social values– guiding principles to meet human needs and
provide ecosystem services
Examples from western North America
Western larch
Lodgepole pine
Douglas-fir
Grand fir
Diameter distribution - Washington Cascades
051015202530354045
2 6 10 14 18 22 26 30 34 38
Diameter (cm)
Nu
mb
er o
f tr
ees
WLGFDFLPP
(Cobb et al. 1993)
North American silviculture
• Fortunate to have very good understanding of “natural” disturbance patterns
• Very few places were traditional single tree selection works
• Instead, it is a complex set of variable disturbance regimes and species adaptations to these regimes
• Requires a highly varied silviculture – not just one approach
Is “close-to-nature” a bad idea?
• Basic premise is good• Extremely important to understand natural
processes• Name has become a surrogate for “light”
silviculture, for selection systems (particularly single tree selection), and natural regeneration options
• Perhaps becoming too restrictive• Perhaps false advertising?
The future…• Climate change• Invasives• Pollution• New disturbance regimes• Greater human demands on forests
Better than nature!
• If forests are managed to provide the values that humans desire, then we have already improved on natural processes
• Outside known historical ranges of variation• Meeting management objectives in ways that
nature cannot
Marsh was a keen observer who noted the potential improvement of natural forests through silviculture
Summary Points
• New age labels that use the words “nature”, or “balance”, or “holistic” are really just advertising
• The silvicultural approaches of close-to-nature are neither natural, nor sound silviculture in many forests
• We should not to limit our options by excluding artificial regeneration, exotics, unprecedented species mixtures, or even-aged silviculture
• Our responsibility is to be better than nature, to meet human needs in ways that are sustainable and build upon our unique understanding of forest dynamics
Better than nature!