what is close-to-nature silviculture in a changing world? kevin l. o’hara university of california...

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

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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!