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Inventory
Undertaking inventory on a farm forestry plantation is an important part of
management to yield the best return to the tree grower.
Like in any business, you should undertake periodic inventories to find out how
much your stock is worth. By inventorying your farm plantation, you will be
able to find out how much wood you have at a particular time, and make an
estimate of how much it might be worth.
You can also use inventory to find out how fast the plantation is growing and
make comparisons to other growers or benchmarks.
Inventory will also assist you
to measure the response to various management activities including thinning,
fertilising and pruning.
It will also help you to plan, cost and check the
quality of these activities as you will have a more intimate knowledge of your
plantation.
Inventory will also give you valuable information such as stocking levels, and
basal area (the area of all the stumps in a hectare), which is important when
deciding when and how much to thin your farm plantation.
When your plantation is ready for harvest, inventory will assist you in
marketing the products, as you will know more reliably what products will be
produced, making it more attractive for potential buyers. |
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The
most efficient way of undertaking inventory is place sample plots in the
plantation and measure the diameters, heights and the quality of the trees to
give average statistics. This can be multiplied by the total area of the
plantation to provide total figures.
When undertaking a farm plantation inventory, you should:
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Seek
professional advice from your local forestry extension provider.
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Obtain a manual
for inventory and tree measurement.
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Use an analysis
package such as the free “Farm Forestry Toolbox”.
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Purchase,
borrow or lease the appropriate equipment.
A
well managed farm plantation will provide the best returns to the tree grower.
Inventory provides important information that will assist the farm forester to
make management decisions.
The following manuals provide procedures
and information for undertaking tree and forest measurements in your farm
forest. The manuals can be used as a guide and are suitable for farm foresters
or field officers providing advice to growers.
“The Farmer’s Forest: Multipurpose
Forestry for Australian Farmers” (http://www.mtg.unimelb.edu.au/publications/farmers_forest.htm)
Written in 2001 by Rowan
Reid and Peter Stephen, “The Farmer's Forest” is the manual for the Australian
Master TreeGrower (MTG) Program. It provides practical and scientific
information on farm forestry and tree and forest measurements. It shares the
experiences of farmers who have undertaken farm forestry projects through the
Master Tree Growers Program.
“Tree Measurement Manual for Farm
Foresters” (http://affashop.gov.au/PdfFiles/PC12760.pdf)
Produced by the Bureau of Rural Sciences
as an output of the National Farm Forest Inventory (NFFI), the “Tree Measurement
Manual for Farm Foresters” provides information, instructions and guidelines for
the farm forester to plan and carry out basic tree and stand measurement in
their farm forest plantations.
Form pruning
After
the initial rapid growth in the first spring, form pruning should commence, and
continue progressively until the trees are about 4 years old.
Form
pruning is more important in a eucalypt plantation, but should but should be
considered in a pine plantation.
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As
trees grow, especially in the early years, some can develop two or more main
stems, or leaders. These are referred to as double or multiple leader trees.
Double leaders significantly reduce the value of the final crop as one tree will
produce two smaller stems rather than one larger diameter stem, or multiple
stems with poor form. To gain the highest value from your plantation by
producing logs suitable for sawn timber, it is important to maintain a single
leader from as many trees as possible in your plantation. The more trees of
good form you have, the more options you will have to retain good stems when you
thin your plantation.
A
double leader tree can be made into a single leader by cutting off the competing
leader. The tree will grow over this stub quickly, and will not affect the
health of the tree, whilst concentrating the growth onto the main leader. |
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To
produce high value hardwood timber products, the ideal final stocking level is
between 200 and 400 stems per hectare, but may depend on the quality of the
site. Initial planting stocking is usually about 1000 stems per hectare, so you
don’t need to form prune all the trees, just those that will be part of your
final crop.
In your plantation, a few trees will be of such bad form that no
amount of form pruning will produce a high quality timber, but these trees will
be culled in the first thinning operation.
Form
pruning should commence when the trees reach 1.5 to 2.0m in height, providing
they are in good health.
Form pruning can be undertaken at any time throughout
the year, and doesn’t have to be done all in one go.
Trees should be
continually form pruned until they are out of reach however the farm forester
can undertake it progressively spending half a day when the weather is fine, or
between jobs, but it needs to be done before the trees get too big. |
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To
maximise your results from form pruning, follow these guidelines:
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Obtain a quality set of
long handle aluminium loppers, priced between $100 and $150. Regularly
maintain these by sharpening and oiling.
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Travel through your
plantation in a systematic way so that you cover all areas.
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Trees should only be form
pruned if they have more than one leader and the leaders are of similar height
and diameter.
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You should remove the
smaller of the two leaders, or the one of poorest form.
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Cut the non preferred
leader off close to where it joins the main stem, leaving as small stub as
possible
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Ensure that you make a
clean cut and don’t strip any bark from the tree as this can permit diseases
and insects to enter the stem.
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Lower horizontal branches
should be retained as these will not affect the form of the tree and they
provide leaves to help the tree grow. These may be removed in stem
pruning at a later date.
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As a general rule of
thumb, most trees will not need form pruning, some will need one cut, and a
very few will need two cuts. No trees should be given three cuts at the same
time.
Form pruning is essential for producing
high quality hardwood sawlogs from plantations. A relatively small effort early
in the life of your plantation will add significant value to the final crop.
Form pruning
Stem
pruning is an important part of any hardwood farm plantation as it adds value to
the final timber crop by increasing the quality of the wood produced from the
trees. Farm foresters should consider undertaking stem pruning progressively
from about age 2 through to about age 7.
Stem
pruning is the removal of lateral branches from the stem of the tree. This will
make the tree produce straight timber free of knots, or “clear wood”, which is
essential for timber or veneer production.
Eucalypt plantation trees grow very quickly compared to native forest and don’t
tend to shed their branches as easily. If the branches are not removed by stem
pruning the trees will be destined to produce only lower quality and lower value
products such as pulpwood.
Stem
pruning is not so essential for pine plantations as generally there is no
premium price for pruned logs in Australia. Stem pruning is essential however
in open grown, or heavily thinned pine plantations to keep branch size to below
7.5cm diameter. If the branch size is greater than 7.5cm, log value will be
decreased.
Stem
pruning should commence when the average diameter at breast height (dbh) is
about 14cm, which depending on the growth rates is usually around 4 years of
age. Trees should be pruned up to a diameter of approximately 9cm as this
confines the branch stubs and knots to the inner core of the tree between 9cm
and 14cm. Any growth outside this core after stem pruning will be high value
clear wood.
Stem
pruning should be undertaken progressively or in three stages, each time pruning
down to the 9cm diameter limit until you reach a height of 6.5m. This method
will produce a high quality 6m log, the requirement of most sawmills.
The
initial stem pruning can be undertaken using loppers to remove branches, however
if the pruning is delayed and the branches grow too big you may require a
pruning saw, which is much less efficient, and the bigger branch stubs will take
longer to heal. For the second and third pruning, you will require a ladder or
long handle loppers to reach up to a height of 6.5m.
When
removing the branches, it is important to:
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Cut branches off as close
as possible to the stem so that the tree can heal more rapidly.
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Ensure that no stripping
of the bark occurs that could allow an insect or disease attack to enter the
tree.
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Prune only trees that will
form part of the final crop (approximately 300 trees per hectare).
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Remove
lateral branches whilst they are still green as the tree will be able to heal
over the branch stub more rapidly, preventing any future decay in the tree.
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Ensure that green crown
remains for 50% of the height of the tree, as removing too many leaves will
inhibit growth.
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Obtain advice about
occupational health and safety requirements for second and third stage pruning
if you are working off the ground.
Stem
pruning is essential for producing high quality hardwood sawlogs from
plantations. Although pruning can be hard work, it can be done progressively
between normal jobs and it will turn low value pulpwood logs into high value
sawlogs, providing a much higher return for the tree grower.
Thinning
Farm
plantations are usually established at a stocking rate of approximately 1000
stems per hectare for eucalypts, and around 1300 for pines. To produce high
quality timber from a plantation, this stocking level needs to be reduced by
thinning during the life of the plantation.
At these stocking
rates, the trees will compete for light and grow tall and straight with small
lateral branches, reducing the chances for timber defects.
For a eucalypt sawlog
plantation, this stocking rate needs to be further reduced at about age 5 to
between 100 and 500 stems per hectare depending on the site quality. This
removes competition for water, nutrients and light and encourages the retained
trees to grow faster, and for them to reach sawlog size much earlier. Thinning
can be undertaken progressively, initially removing the poorest quality stems
before final selection of the crop trees. Thinned trees may be used for
firewood, pulpwood or posts.
In a pine plantation,
commercial thinnings are usually undertaken, where the smallest and poorest
quality trees are removed for pulpwood and posts on a number of occasions in the
plantations life, leaving the sawlogs for final harvest.
For the best result,
implement the following guidelines:
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Undertake an inventory to assess if
it is an optimal time for thinning.
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Select and mark the best trees
before commencing work.
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Try to keep an even stocking
throughout the plantation.
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Ensure no retained trees are damaged
by falling trees.
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Cut stumps to less than 10cm from
the ground.
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Control coppice on eucalypt stumps
using an appropriate herbicide or by physical means.
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Fall thinned trees into alternate
rows to maintain access to the plantation.
Thinning
is an essential part of farm plantation management as it is better to have 300
big trees per hectare that will produce sawn timber than 1000 small and medium
sized trees per hectare that will only produce lower value pulpwood.
An appropriately
thinned and managed plantation will promote the most growth on the best trees,
which will produce the highest value product.
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