3. Overview
Shelterwood system
The shelterwood system is a silvicultural system in which
the mature trees within a forest stand, or a defined area
within a forest, are not all harvested at the same time.
Rather, the mature trees are removed in a series of cuts
over a period of time to encourage tree reproduction in
the stand and results in an even-aged stand structure
The retained trees or shelter trees serve two purposes.
First, they provide a seed source for regeneration across
the area Second, these retained trees provide protection
for the young trees from environmental conditions such
as sunlight, frost, drought and cold winds.
4. Shelterwood Process
This forest management system is typically implemented in three steps using three different types of cuts
•Preparatory cut
during the preparatory cut some of the lower canopy trees are removed from the stand
•Seed cut
during the seed cut more of the mature canopy trees are removed from the stand at a relatively
even spacing
•Removal cut
the remaining shelter trees are removed from the stand during this step
The whole series of operations normally takes 5–20 years
A shelterwood system can be perpetuated and used to regenerate a forest multiple times.
5. Shelterwood System Variations
• variations of the shelterwod system create a
more diverse spatial arrangement of trees
within the forest with final result as trees of
the same age and size and have an even stand
structure
6. Shelterwood System Variations contd..
o Uniform Shelterwood System
The canopy is uniformly opened up over the whole area of a
compartment to obtain uniform regeneration under the
shelter of remaining old crop
In this method the techniques are applied evenly throughout
the stand being managed. This method is often used in areas
where seedbed protection and aesthetics are critical
7. Shelterwood System Variations contd..
o Strip shelterwood system
The strip shelterwood system is a variation that applies the
shelterwood harvest steps in narrow strips adjacent to one
another progressing systematically from the preparatory cut down
to the removal cut. This arranges the forest into a unique vertical
structure such that trees get taller in a uniform fashion as moved
through the forest. This helps deflect winds up over the trees and
prevents tree mortality due to wind.
Modification in the system
•advancing narrow clear-felled strips
•wedge shelterwood
8. Shelterwood System Variations contd..
o Group Shelterwood System
In the group shelterwood system shelter trees are reserved in
patches throughout the forest. These patches are created after
regeneration is established in the openings created by the
removal cut. This method increased the spatial diversity in the
forest.
9. Shelterwood System Variations contd..
o Irregular Shelterwood System
Gayer first described the concept of the irregular shelterwood
method
The irregular shelterwood system differs from other methods in that it
results in an uneven-aged stand rather than an even-aged stand. This
results from extending the shelterwood system over a longer period of
time. This system also retains canopy trees throughout the process
rather than remove them in the removal cut. This method also improves
structural diversity and enhances aesthetics, wildlife habitat, and
biodiversity in forests
10. Shelterwood System Variations contd..
o Natural Shelterwood System
Natural shelterwood sytems are unique because they can only be
applied to stands that were previously unmanaged. In this system
the regeneration is seeded and becomes established under
natural, unmanaged conditions rather than through a preparatory
cut and seed cut. Forest stands that come under management
using this system can then enter the shelterwood system cycle for
future management.
11. Significance of Shelterwood system
• Marking and felling of trees of the over wood are simpler than selection
system
• Soil is not completely denuded so there is little risk of soil deterioration and
erosion.
• As the regeneration operations are carried out under the shelter of older
crop, there is little danger of invasion of the area by weeds and grasses
• The young crop is protected against adverse climatic factors such as cold,
frost, etc.
• As the regeneration is obtained from seeds obtained from best selected
trees, the new crop is superior.
• Suitable system for the regeneration of both light demander and shade
bearer species
• It makes supervision and control of various operations easy.
• From aesthetic point of view, the system is superior to clear felling system
• greater individual stem volume, increased lumber yield, and product value
12. Shelterwood system in Global context
• The shelterwood system evolved over early 19th
century from Britain.
• Irregular shelterwood came into consideration
during 1980s
• The method was first investigated by von Huber
in Bavaria (Spurr 1956)
• Applied for forest products regulation in
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North American continent ( Canada, USA)
tropical dry forests in Bolivia ( dispersed to Europe)
forest in Indian sub continent
…….
13. Challenges of Operational
Implementation
• Advance regeneration may be damaged by
cutting (Hannah 1988).
• Planning and prediction of growth and yield in
irregular shelterwood systems is more complex
• stand variability
• Harvesting cost increases
• Technical knowhow of execution
14. Conclusion
It is the system which imparts resource transfer from
one generation of trees to the other generation
It provides the ample opportunities that the older
trees continue to increase in value after the
regeneration process has begun.
Compared to clear cutting, shelterwood systems
cause less damage to the site ecologically and
aesthetically
15. Recommendation
The practices of silvicultural system are not as easy
as they sound. They require a long term vision and
intervention objectives of a owner/state of forest.
In our country like Nepal, where no any established
management system of forest but ample of
opportunities for it to grow as a major contributor
of national GDP, policy recognition for scientific
forest management is a must followed by collective
guidance from practitioners and researchers .
