3. Silviculture is the practice of controlling the growth,
composition/structure, and quality of forests to meet values and
needs, specifically timber production. It is the art of growing and
cultivating forest crops, based on a knowledge of silvics (the study
of the life history and general characteristics of forest trees and
stands, with particular reference to local/regional factors). The focus
of silviculture is the control, establishment, and management of
forest stands.
4. Silviculture is the art and science of managing forests
for desired outcomes, such as wildlife habitat,
aesthetics, and timber production. This is
accomplished by applying different types of cuttings at
different times in your forest’s development. These are
called silvicultural treatments, and long-term planned
sequences of these are called silvicultural systems.
5. 5
Planting
How many trees per unit area (spacing) should be planted is not an easily answered
question. Establishment density targets or regeneration standards have commonly been
based on traditional practice, with the implicit aim of getting the stand quickly to the free-to-
grow stage. Money is wasted if more trees are planted than are needed to achieve desired
stocking rates, and the chance to establish other plantations is proportionately diminished.
Enrichment planting
A strategy for enhancing natural forests' economic value is to increase their concentration
of economically important, indigenous tree species by planting seeds or seedlings for
future harvest, which can be accomplished with enrichment planting (EP). This means
increasing the planting density (i.e., the number of plants per hectare) in an already
growing forest stand.
Spacing
Over-crowded regeneration tends to stagnate. The problem is aggravated in species that
have little self-pruning ability, such as white spruce. Spacing is a thinning (of natural
regeneration), in which all trees other than those selected for retention at fixed intervals are
cut. The term juvenile spacing is used when most or all of the cut trees are
unmerchantable. Spacing can be used to obtain any of a wide range of forest management
objectives, but it is especially undertaken to reduce density and control stocking in young
stands and prevent stagnation, and shorten the rotation, i.e., to speed the production of
trees of a given size. The volume growth of individual trees and the merchantable growth of
6. 6
Thinning
Thinning is an operation that artificially reduces the number of trees growing
in a stand with the aim of hastening the development of the remainder. The
goal of thinning is to control the amount and distribution of available growing
space. By altering stand density, foresters can influence the growth, quality,
and health of residual trees. It also provides an opportunity to capture
mortality and cull the commercially less desirable, usually smaller and
malformed, trees. Unlike regeneration treatments, thinning's not intended to
establish a new tree crop or create permanent canopy openings.
Pruning
Pruning, as a silvicultural practice, refers to the removal of the lower
branches of the young trees (also giving the shape to the tree) so clear knot-
free wood can subsequently grow over the branch stubs. Clear knot-
free lumber has a higher value. Pruning has been extensively carried out in
the Radiata pine plantations of New Zealand and Chile; however, the
development of finger joint technology in the production
of lumber and moldings has led to many forestry companies reconsidering
their pruning practices. Brashing is an alternative name for the same
process.
7. REGENERATION:-
Regeneration is basic to the continuation of forested, as well as to
the afforestation of treeless land. Regeneration can take place through
self-sown seed ("natural regeneration"), artificially sown seed, or
plant seedlings. In whichever case, the performance of regeneration
depends on its growth potential and the degree to which its environment
allows the potential to be expressed. Seed, of course, is needed for all
regeneration modes, both for natural or artificial sowing and for
raising planting stock in a nursery.
Natural regeneration is a "human-assisted natural regeneration" means of
establishing a forest age class from natural seeding or sprouting in an
area after harvesting in that area through selection cutting, shelter
(or seed-tree) harvest, soil preparation, or restricting the size of a
clear-cut stand to secure natural regeneration from the surrounding
trees.
The process of natural regeneration involves the renewal of forests by
means of self-sown seeds, root suckers, or coppicing. In natural
forests, conifers rely almost entirely on regeneration through seed.
Most of the broad leaves, however, are able to regenerate by the means
8. ARTIFICIAL REGENERATION:-
8
Artificial regeneration has been a more common
method involving planting because it is more
dependable than natural regeneration. Planting
can involve using seedlings (from a nursery),
(un)rooted cuttings, or seeds.
The fundamental genetic consideration in
artificial regeneration is that seed and planting
stock must be adapted to the planting
environment. Most commonly, the method of
managing seed and stock deployment is through
a system of defined seed zones, within which
seed and stock can be moved without risk of
climatic maladaptation.
The regulations stipulate that source-identified
seed lots may be either a general collection,
when only the seed zone of origin is known, or a
stand collection from a specific latitude and
9. The distinction between forestry and silviculture is that silviculture is applied at
the stand-level, while forestry is a broader concept. Adaptive management is
common in silviculture, while forestry can include natural/conserved land without
stand-level management and treatments being applied.
10. 10
The Adaptive Silviculture for Climate Change (ASCC) project is
establishing a national network of long-term silvicultural research
sites across multiple regions and a diversity of forest types to test a
range of adaptation approaches and to provide managers with the
tangible demonstrations needed to inform climate-adaptive decision-
making in their forest management.
With an uncertain climate future, land managers are facing uncharted
forest dynamics, and the science to support decision-making is
evolving. We need to be nimble, manage our forests alongside science as
it develops, and be courageous in trying innovative and collaborative
practices. The ASCC project has taken that approach to help us use the
best available science while also contributing to research that will
further inform our future decision-making.
SILVICULTURE FOR CLIMATE CHANGE
11. 11
The study is designed to develop and test
silvicultural systems along an adaptation gradient
including no action, resistance, resilience, and
transition using definitions modified from Millar. By
designing, implementing, and monitoring a spectrum of
treatments across this adaptation gradient, managers
and scientists will be able to learn how well various
adaptation options accommodate a range of potential
future climate change conditions, at an operational
spatial scale, and across a variety of ecosystem
types and geographic regions.
The “adaptive” nature of the ASCC project includes
not only the design of adaptation actions and
associated metrics but also the adaptation of
management over time to maintain the treatment stands
within the silvicultural system designed for each
treatment. Additional effort and investment would
probably be required to maintain the species
composition and structure of stands under the
silvicultural system designed for
12. MAJOR CLIMATE CHANGE
PROJECTIONS
12
Over the last century, the region's climate has become modestly warmer and
wetter (Handler et al. 2014). However, like many other regions, projections
for future climate change are more extreme (based on Geophysical Fluid
Dynamics Laboratory [GFDL] A1F1 model scenario). Average annual temperature
by the end of the 21st century is expected to increase by 8.8° F (compared
with the 1971–2000 period), but with seasonally disproportionate
temperature increases (9.8° F increase in winter, 5.4° F increase in
spring, 11.4° F increase in summer, and 9.1° F increase in autumn).
This model projects a slight decrease in average annual precipitation of
−0.4 in. but a substantial decrease in summer annual precipitation of −4.8
in. Combining temperature and precipitation into potential
evapotranspiration-to-precipitation ratios suggests slightly moister annual
conditions by the end of the 21st century but substantially drier summer
conditions, with the potential for greater drought stress during the
growing season.
13. POTENTIAL IMPACTS AND
EXPECTATIONS
13
When considering impacts during project scoping, we focused on
projections in tree habitat suitability based on Tree Atlas (Prasad et
al. 2007) and LANDIS II (Scheler et al. 2007) modeling results for
Minnesota (Handler et al. 2014). The overall projection is that tree
habitats in Minnesota will have shifted measurably to the northeast by
the end of the 21st century. This will involve a decline in habitat for
most of the boreal tree species typical of the study ecosystem, an
increase in habitat for several of the associated north temperate tree
species, and increased habitat for several tree species new to the
region.
Workshop participants examined these tree habitat projections and also
assessed the current condition of the selected forest type (overly
dense, fire excluded) to justify their decision on the study location.
The overarching sentiment was that the forest is vulnerable to climate
change, on the cusp of major change in tree species composition, and may
14. 14
Photos showing four treatments on CEF in Minnesota: no action control (A), resistance (B), resilience
(C) (with the gap on the left-hand side of the photo, the thinned matrix on the right-hand side), and
transition (D) treatments. (Photos courtesy of Eli Sagor, 2015.)
15. Treatments were implemented on the CEF ASCC
installation in winter of 2014–2015, with
ongoing research and management activities
planned for at least the next 10 years.
Although in its infancy, the project has
already served as a focal point for several
tours and training sessions, including the
National Advanced Silviculture Program, a
University of Minnesota climate change
summit, the Minnesota Society of American
Foresters 2015 and 2016 summer meetings, and
the Forest Stewards Guild 2016 national
meeting. The experiment was featured as part
of a Minnesota Public Radio piece on climate
change. Plans for the future include hosting
a tour for the 2016 Silviculture Instructors
Tour and several future meetings.
Progress and activities