Presented by
Arundathi Koliyabandara
Harvest
scheduling is a traditional exercise that has been carried out by forest land
managers on public and private lands alike. Industrial forest management has
generally been distinguished by a much higher rate of intensification than has
been the case on public lands. Whereas public land management has
characteristically balanced timber and non-commodity forest production. Industrial
plantation establishment has been dominated by profit maximization and cost
reduction through economies of scale. Forest companies are now facing the
challenge of scheduling spatially specific timber management activities over
time to achieve their traditional objectives and the new environmental goals.
A
good operational harvest schedule will satisfy the customers’ orders from areas
of forest while minimising transportation costs. Also, areas of the forest with
high quality trees will be used to provide high quality (high value) logs while
lower quality areas will fulfil low quality (low-value) demands, minimising the
conversion of high quality trees into low-value logs. Operational harvest
scheduling can be very difficult. Good operational harvest scheduling is an
activity where large immediate financial gains can be found. This is in
contrast to tactical planning where gains will be seen in two to three years,
or strategic planning with gains realised thirty or more years in the future. The
immediate gains of a good harvest schedule are listed below. Harvesting
costs are reduced, harvesting productivity is increased, larger volumes of high
quality logs are produced and transport costs are lowered. Harvesting is done
by two means as thinning and clear cutting. The conducting silvicultural system
and the economics and demand are important factors when scheduling the harvest.
There are commonly using harvesting systems as clear cutting, shelter wood,
selection and coppicing. Clear cutting is where all of the trees in a stand are
removed. Clear cutting diseased or insect-infested area is often necessary to protect healthy trees.
Shelter wood System is
designed to remove certain trees and establish new growth under the protection
of an over story of foliage. Sufficient mature trees are left standing to
shelter the site until new growth is well established. The using silvicultural
system depends on the objective.If a site is maintained to get timber and to
maintain aesthetics selection is used. Coppicing is used when fuel wood is
gained. If the prime objective is to get timber, clear cut is the method which
will be practised.
The rotation is also an important
consideration in harvest scheduling. It helps in deciding when to harvest the
stand. There are main rotations used in commercial forestry which can be stated
as technical rotation, biological rotation, income generation rotation and etc.
Technical rotation is suitable for providing timber, wood with specific
dimensions. In biological rotation the maximum volume production is expected.
The stand is harvested when maximum mean annual increment is reached. Income
generation rotation is a monetary rotation where the harvesting is scheduled at
the time where highest average income is gained.
Replanting of a harvested site is an
important managerial activity which depends on on social, cultural, economic
and environmental reasons. Use of the same species or different species is a
choice made by the management. When replanting is carrying out proper silvicultural
practices should be maintained to gain the final harvest such as nursery
establishment and maintaining, establishment of pits for planting, spacing,
block wise replanting ,weeding , fertilising, irrigation, thinning and pruning.
Intercropping can be practised based on the objectives.
In Sri Lanka some upcountry Eucalyptus
plantations are clear-felled and replanted with more suitable Eucalyptus
species. Some selected mature Pinus plantations too are clear-felled and
replaced with, Khaya, Hora, Eucalyptus and Mix species. Dry Zone Teak
plantations are re established mainly with Teak in the second rotation. However
in the areas where elephant damaged is high, Khaya was planted instead of Teak.
Carbon sequestration potential of a
plantation will be an added benefit and when scheduling harvest the area
leaving for conservation and proper practices of harvesting should be planned.
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