shelterwood system kishor aryal

A term paper presentation on

Shelterwood system

Kishor RimalMSc. 1st yearRoll no. 5

Presentation outline

• Overview• Shelterwood Process• Shelterwood System Variations• Significance of Shelterwood system• Shelterwood system in Global context• Challenges of Operational Implementation• Conclusion• Recommendation

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.

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 yearsA shelterwood system can be perpetuated and used to regenerate a forest multiple times.

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

Shelterwood System Variations contd..

o Uniform Shelterwood SystemThe 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


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


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.


o Irregular Shelterwood System Gayer first described the concept of the irregular shelterwood methodThe 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


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.

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

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– North American continent ( Canada, USA)– tropical dry forests in Bolivia ( dispersed to Europe)– forest in Indian sub continent – …….

Challenges of OperationalImplementation

• 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

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

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 .

Thank You

Question and Quarries are heartily welcomed

shelterwood system kishor aryal

Education