What is Close-to-Nature
Silviculture in a Changing World?
Kevin L. O’Hara
University of California - Berkeley
What’s in a name?
new perspectives retention forestry holistic forestry
ecoforestry 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
nature-based forestry
holistic forestry
near-natural forestry
ecological silviculture
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
Number of trees
Diameter distribution - Washington Cascades
45
40
35
30
25
20
15
10
5
0
WL
GF
DF
LPP
2
6
10
14
18
22
Diameter (cm)
26
30
34
38
(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…
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•
•
•
•
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!