TWO STORIED HIGH FOREST
This is a form of crop comprising an upper story with lower one under it. Both the stories are of seeding origin. Each story being approximately even-aged and seedling the lower story is usually obtained by underplanting the original crop when trees have begun to open up and are no longer able to maintain the fertility of the soil.
In the second/lower storey, a shade bearing species is introduced. Both the stories are then encouraged to grow up subsequently with both are removed or the upper is felled, leaving behind the lower as an entire crop.
ADVANTAGES OF TWO STORIED HIGH FOREST:-
i. To derive the maximum production from a unit of land (the present-day concept of optimum land use).
ii. To furnish early returns on the investments in the form of thinning in the over wood.
iii. To enable the shade bearers to grow under a protective cover.
iv. To control the influx of weeds.
v. To obtain a species mixture-biodiversity
vi. The stand volume and yield from thinning in the over wood, increase gradually.
vii. Protection against soil erosion and loss of fertility.
DISADVANTAGE OF TWO STORIED HIGH FORESTS:-
I. Considerable damage to the Underwood, when thinning or fellings are carried out in the over wood.
II. It requires a high degree of skill on the part of the local forester.
APPLICABILITY OF TWO STORIED FORESTS:-
i. Two major species grown in the irrigated plantation at present are Shisham and Mulberry.
ii. In Germany mixed plantation of Scots pine and beech
iii. In UK Oak and Larch
iv. In India Chir pine and Oak
TWO STORIED IRRIGATED PLANTATIONS:-
The Shisham is a light demander while mulberry is shade bearer. Shisham produces firewood and also very good furniture wood when retained for long rotation. The chief use of Mulberry is the manufacture of sports goods. It does not differ from coppice with a standard system.
METHOD OF REGENERATION:-
Shisham is mainly formed of stump planting. Though a considerable part of the crop is derived from root suckers with some coppice in the sixth year of Shisham crop The first thinning is carried out leaving the plants at an average space of 10 feet’s. an underwood of mulberry is introduced at this stage by stump planting if it has not come up naturally through seed dropped by starlings or carried by irrigation water. Mulberry is fast growing then Shisham and dominates the Shisham. Vigilance is exercised to keep back the mulberry to maintain the desired ration 60% Shisham and 40 % mulberry. The usual rotation for Shisham is 18 years when both Shisham and mulberry are cut leaving about 20 Shisham standards per acre.
The area is again restocked with stumps inducing root suckers from the felled Shisham. Mulberry is again introduced in the first rotation.
At the end of the second rotation, the crop is felled leaving about 10 standards per acre from the standards of the previous rotation and 10 from the crop clear felled.
The same procedure is adopted during the third rotation. In this manner, a continuous supply of three rotation old standards is maintained.
If rotation for Shisham firewood is 18 years and the rotation for mulberry timber would be a few years less and the rotation for Shisham standards would be 54 years.
The thinnings are usually carried out during the six, eleven, and sixteen years.
PRESENT TREND IN SHISHAM:-
The above system is now under a process of transition to clear felling with artificial regeneration.
Keeping in view the alternative fuels e.g gas, electricity in the cities, towns, it is no longer justifiable to grow fuelwood in the irrigated plantation. The better portion of the irrigated plantation is, therefore, is set aside for raising Shisham timber at an expected rotation of about 60 years. This will effect thinning in the Shisham crop at 10 years intervals after the second thinnings.
Another trend is towards diversification in the species to be grown in the irrigated plantation, preference being given to medium soft woods e.g Simal, popular etc which can be used for the development of wood-based industries.
These would require a change from the present system to clear felling and planting. When the soil inferior or the command of irrigation is not good Shisham will be grown on the clear felling system with artificial, natural regeneration at the short rotation.
DOUBLE STORIED HIGH FORESTS:-
Natural double stories high forests are found in the Chir pine, Oak of Kumaun forests.
The Oak underwood decreases the flow of resin in the pine trees of over wood, but at the time it must have an excellent effect on the soil.
The two storied high forest system can only be justified when either
i. The two crops are almost equal in value
ii. Can grow healthy together on the same ground for, at any rate, the larger part of a rotation.
iii. The under storied crop reach maturity or is saleable at the same time as the major crop is due for felling.
It is not yet known how far an understory retards the growth of the main crop by root competition.
It has either assumed that a mixed crop always maintains the soil better than a pure crop.
Note: reliable evidence is needed to prove the above suppositions.
- A Silvicultural system which originates from seed or seedling plants resulting in the two-layered structure of forest crop is called Two Storied High Forest
- Eg Shisham and mulberry in Changa Manga
- Mainly applied in Irrigated Plantations
- The major spp grown in the irrigated plantation is at present Shisham and Mulberry
- The former is pronounced light demander while the later is shade bearer
- Shisham produces good firewood and also very good timber if retained; while mulberry is mostly used in the sports industry and besides used for timber production.
Method of regeneration:
- For shisham by stump planting or root suckers
- For mulberry by stumps
- At 6th year of shisham thinning is don
- Plant spacing is 10ft into 10ft
- Then, underwood mulberry is introduced
- Spp composition: 60% shisham, and 40% mulberry
- Usual rotation of Shisham is 22 years
- The area is restocked after debris burning and mulberry is introduced again
- At the end of the 2nd rotation, the crop is felled leaving about 10 standards per acre
- Same procedure for third rotation
- In this way, a continuous supply of rotation is maintained
- Leveling is done in the planting area
- 2 – 3 weeding during the first year
- Cleaning is carried out during 3rd year
- Seedling or root suckers are preferred over coppice
Thinning carried out during 6th, 11th, and 16th year.
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