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Silviculture |
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Silviculture
Establishing and managing trees and forests
for timber
The word silviculture
comes from Silva, the
Latin word for wood. It refers to the establishment and management
of trees for wood production. The potential to manipulate tree
and forest growth so as to enhance their value or the benefits
they provides makes silviculture the
most powerful tool of the farm forester. For example, as a result
of careful pruning a tree that might otherwise only be of value
for firewood can be turned into high value veneer or sawlog.
Alternatively, a regrowth native forest dominated by just one
tree species could be thinned to promote regeneration thereby
enhancing its biodiversity.
A silvicultural
regime is a series of management interventions
imposed on trees or forests over time, from establishment through
to harvest and regeneration. Initially, decisions must be made
about initial spacing, layout and establishment methods. Later
the owner must decide about the type and timing of thinning,
pruning, fire, grazing and harvesting. Choosing to let nature
take its course is also a silvicultural decision. However, not
intervening in a forests growth pattern is rarely the
most appropriate strategy for achieving farmers preferred
outcomes.
Forest growth is largely determined by how
the mix of plants in the forest respond to the soil and climate
in which they are growing. Silvicultural design and intervention
enables farmers to direct this growth in an attempt to maximize
the economic, environmental or aesthetic value of the forest.
There are six aspects of silviculture that forest growers need
to consider:
what to grow the
forests genetic composition
preparing the site for a forest
modification of the physical
environment
spacing and thinning after establishment
managing
the competition between trees.
pruning
treatment of individual trees.
managing pests, weeds, diseases and
fire forest
protection
harvesting timber and other forest
products harvesting
options and techniques.
Silvicultural examples for timber plantations
The following examples of different plantation
silvicultural regimes illustrate the practical application of
the six aspects of silviculture:
High
volume production regimes: pulpwood, firewood and biomass
Sawlogs
without pruning
Sawlogs
with pruning
Managing
individual trees for sawlogs
Native forest silviculture
Although based on the same principles, native
forest silviculture is a special case in that there are often
complicating factors such as government regulation, multiple
age structure, and a greater number of tree and understorey
species to consider.
Native forest silviculture
It is possible to balance timber production
from native forests or plantations with other values. For example,
land degradation control strategies, agricultural production
methods and biodiversity principals can be integrated into a
forest design where the emphasis is on producing high value
timber products. Understorey native species can be grown between
widely spaced pruned trees, enhancing environmental values.
And small gap or selective logging that does not greatly jeopardise
aesthetic or wildlife values may be a viable option in native
forestsfor example in rainforestswhere the value
of the extracted timber is high.
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