Natural Regeneration of few tree species

Course no. FOR 501

Course Title : SILVICULTURE

Assignment Topic: Natural regeneration of few species

Submitted to Submitted by

Dr. M. B. Tandel Vikas kumar

(Assistant professor) M.Sc. (FORESTRY)

Aspee college of horticulture & Forestry Aspee college of horticulture And forestry,

Navsari, Gujarat Navsari, Navsari

Email ID: [email protected]

Contact No.: 9995093698

Regeneration-

The Renewal of forest crop by natural or artificial means .

NATURAL REGENERATION-

Regeneration through self sown seed or by coppice or

root suckers .

Sources- 1. From seed- seedling crop-high forest .

2. From vegetative parts -coppice crop-

low forest / coppice forest .

Natural regeneration from seed :

It depends upon-

1. Seed production-

2. Seed dispersal-

3. Germination-

4. Establishment-

1.Seed production:

1. Species - moderate or good seed year .

2. Age of trees – middle aged trees .

3. Size of the crown- middle-aged mature trees with well developed crown .

4. Climatic factors – warmer climate favours .

5. Other locality factors – like insects attack and girdling , fire injury .

Tab:1 below table shows the interval between moderate

and good seed yeas of important Indian species :

Species Moderate seed yr Good seed yr

1. Abies pindrew

2. Cedrus deodara

3. Picea smithiana

4. Pinus

roxburghii

5. Shorea robusta

6. Terminalia

tomentosa

7. Dalbergia sissoo

6

3

3

3

2

2

2

10-11

4-5

5-6

4-5

3-4

3-4

2-3

2. SEED DISPERSAL :

WIND- All coniferous species , Acacia catechu, Acer,

Adina ,Bombax, Betula, Casuarina, Chloroxylon, Dalbergia,

most of the Dipterocarpus Holoptelia, Populus, Pterocarpus

marsupium, Rhododendron, salix, Terminalia.

WATER- most swampy and mangrove species ,teak

Trewia, Dalbergia etc.

GRAVITY- oak, Chestnut , walnut , Aesulus etc.

BIRDS- Diospyros Mulberry, Prunus, Trema,

Pyros melanoxylon.

ANIMALS- Anthocephalus, Zizyphus, Prosopis juliflora,

Acacia arabica.

3. SEED GERMINATION :INTRNAL FACTORS-

a. Permeability to water-

b. Permeability to oxygen –

c. Embryo development- fully developed at the time of

seed fall also may remain dormant .

d. After ripening- chemically not developed seed

undergo the process of after ripening .

e. Seed viability- potential capacity of seed to

germinate .

f. Seed size-

g. Germinative capacity and Germinative energy-

Germinative capacity- the percentage ,by number ,of seed

in a given sample that actually germinate , irrespective of

time.

Germinative energy- the percentage ,by number ,of seed in

a given sample that have germinated up to the time when the

rates of germination reaches (i.e. number of seed germinating

per day) reaches it’s peak.

h. Plant percent- percentage of the number of seeds in a

sample that develop into seedling at the first growing season.

2.EXTERNAL FACTORS-

Moisture- activates the dormant embryo by softening

the seed coat

a) Oxygen-

a) Temperature- higher the temperature greater the

germination.

b) Light and heat- most species are indifferent to light

condition for their germination.

c) Seed bed- light burning or shrub cutting

Seed year-

• a year in which a given species bear seed

abundantly.

• designate as good, moderately good, poor or very

poor .

Seedling year-

• a year in which a given species produces

abundant first year seedling .

• designate as good, poor, or very poor.

•A good seed year is not necessarily a good

seedling year .

4. Seedling establishment :

Development of young regeneration, natural or artificial, is considered safe from normal adverse influences .

longer needs a special protection or tending operation ( other than cleaning, thinning and pruning ) .

Factors affect establishment of seedlings are :

1. Development of roots- fast root growth seedling less mortality.

2. Light condition –as young regeneration grow in age , require more light.

3. Soil condition - soil should have adequate moisture , nutrients and proper soil aeration.

4. Competition- for light, soil nutrients soil moisture, growing space.

5. Crop composition- mixed crops are more favorable for

establishment of natural regeneration.

6. Biotic factors- like grazing, burning, lopping & others

forms of human interference like removal of timber etc.

7. Other factors- Drip- by exposing roots of tiny seedlings.

e.g. Sal ,Teak.

Temperature- very high and very low temperature kill the

seedlings.

Precipitation- drought , rainfall distribution leads to

mortality of seedlings.

In short, Development of a forest from seed under

natural condition is depends on :

1.Adequate and well distributed seed supply.

2.Favourable condition for the

-germination of seeds.

-development and establishment of seedling.

3. Favourable condition of undergrowth , ground cover

and overhead canopies so that seedling receive not

only adequate light also free from root competition.

4. Protection against all kinds of injuries.

5. Tending.

6.Control over mixture.

Following operation were carried out to

obtaining natural regeneration :

1. Disposal of lot of felling refuse & creation of

clean ground by cutting and burnt down.

2. Sowing or planting.

3. Strip form of regeneration.

4. Weeding & cleaning and at pole stage has to be

thinned.

Sources for obtaining seeds or seedlings

in natural regeneration of clear-felled

areas :

1. From the adjacent standing mature forest .

2. Seed already lying dormant in the clear-felled areas .

3. Ripe seed on the mature trees before they were clear-felled .

4. Advanced growth already present in the clear-felled area .

5. Coppice crops .

Fig. Clear-felling system.

Natural regeneration under clear

strip system :

Progressive strip system –Progresses successively in one direction ( usually against the prevailing direction of the wind ) across the regeneration area .

Alternate strip system –

Clear-felled strips alternate with unfelledstrips of similar width though they may narrower or wider also .

fig. Shelter wood

system

Regeneration felling :

Seeding fellings –

canopy is opened to provide enough light for the

seedlings to come up and ensure their survival in

the initial stage.

Secondary fellings –

mother trees are removed in a series of fellings.

Final fellings –

only when ensuring regeneration has established

itself.

Following operation were carried out to obtaining

natural regeneration :

1. Seed supply – distribution of middle age trees, aspects, presence of advance growth.

2. Light requirement & canopy manipulation –

Size of regeneration, system followed and areas.

Methods to reduce undergrowth density are- regular cutting back, controlled burning, uprooting, use of weedicides.

3. Soil condition – Compact, undecomposed organic matter, excess or shortage of moisture are not favourble.

4. Burning – beneficial effect on natural regeneration and soil condition mostly in Sal, Chir, Teak.

5. Slash disposal – treatment or handling of slash for reducing hazards from fire, insects, fungi and providing the seeds with access to the soil.

6. Tending operation and protection against damage by animal.

Following operation were carried out to assist

in establishment of natural regeneration :

Removal of trees of and above the exploitable

diameter .

Thinnings in tress below the exploitable diameter

.

Cultural operations .

Natural regeneration from vegetative

parts : Coppice – plants cut from near ground level, produce a

flush of fresh seeds .

Root sucker – root of a plant partially or wholly cut to produce shoot .

Cutting – part of stem, root or branch is planted in soil .

Layering – roots developed on a girdled portion of a branch .

Grafting – cut part is grafted to another

Budding – bud is grafted to bark of another plant.

Natural regeneration by coppice

:

Seedling coppice – coppice shoots from the

base of seedlings which have been cut back .

Stool coppice – coppice shoots growing from a

stool or a living stump .

Factors affect natural

regeneration by coppice :

Coppicing power .

Age .

Season of coppicing .

Height of stump .

Rotation, silvicultural system .

Cedrus deodaraCommon name: Deodar, Himalayan Cedar

Family: Coniferae

Development & ripening of cone :

No growth in young cones untill the following spring, by the end of June

or during July they become full sized, and are pale yellowish green.

They turn chocolate-brown in colour during august, & ripen from the end

of September to middle or end of November.

Time occupied from first appearance of female cone to the ripening of cone

is about 12½ to 13½ months.

The ripe cones are erect, brown, ovoid or ellipsoidal 3-4.5 inches long by 2 –

3.5 inches in diameter.

Cones break up on the tree itself

Scales & winged seeds fall on the ground and only the persistent axis

remaining on the tree.

Cones are collected off the trees immediately before they open in early

September to early October.

They are placed in sun for a week & break up.

Natural Regeneration:

Seed years: Every third year is a good seed year with

abundant cone bearing trees.

Seed dispersed in Oct-Nov remains on the ground

throughout the winter, under the snow and germinates in the

spring during Mar-Apr

Germination takes earlier in the warmer than the cooler

aspects.

Teak :

The factors affecting natural regeneration

of teak are discussed under the following

heads :

seed

light

frost

soil

weeds.

Seed (Teak) :

Teak usually seeds abundantly .

Shedding of the beginning of dry season is beneficial, as it gets

weathered by alternating dry and wet season in the

premonsoon period .

The hard seed coat beneath the spongy layer of seed protects

it from premature germination during the premonsoon rains .

Seed requires some warmth and light for germination , and in

cool shady places, the seeds may lie dormant for years .

Sowing seed in shaded and exposed plots resulted in 1 and 17

percent germination respectively .

When light was admitted to the shaded plot after two years, the

dormant seeds got germinated .

Light (Teak) : The establishment of teak seedling also

depends largely on light .

In moist localities the seedlings may need light

from the beginning, but in dry and hot localities,

a sudden influx of light may kill the seedlings .

In the peninsular tracts, light shade of

Dendrocalamus strictus is helpful for

regeneration (Kharche,1974) .

Frost (Teak) :

Seedling shoots are killed by frost, but the

root stock may given rise to stronger

shoots each year, until it is able to rise

above the lever of frost .

Soil (Teak) : Soils having adequate porosity and humus are

particularly suitable for regeneration of teak .

In case of dry type of teak forests, limitation of

soil moisture has a telling effect on the survival

of seedlings, Mulching with a layer of grass and

leaves with a little soil in such areas keeps the

ground clean of weeds for the whole year And

help to secure the regeneration .

In case of moist type of soils, if the ground

cover is dense and adequate, natural

regeneration occurs only in patches .

Fire (Teak) : This burning is usually followed by a good crop

of young teak and other species. The young

crop is weeded usually three times during the

first rainy season and subsequently until it is

established .

In the dry type of teak forests the seasonal fires

are harmful and may kill the seedlings .

Light burning is however, considered

beneficial.

Weeds (Teak) : Weed growth and ground vegetation are the obstacles to the

establishment of natural regeneration .

weeds like Lantana definitely discourage teak regeneration .

Little regeneration survives under vigorous bamboo stands,

however light canopy of bamboo is helpful in the dry and semi-

moist type of forests .

Effect of weeds is seen through dense shade, annual fires in

the area and desiccation of seedlings .

On the whole, it is seen that the regeneration is inadequate,

unreliable and deficient in the natural forests and has to be

supplemented with artificial regenerations .

Germination starts in the rainy season and continues for some

time .

Seed may lie dormant for 1-2 years .

For germination sufficient moisture and high temperature is

essential (Ghosh, 1977) .

The growth of the seedling depends upon the soil type, weed

competition, intensity of shade and availability of moisture .

The growth is better in porous soil than on clayey and stiff soils.

The effect of moisture is evident on the alluvium favourably

situated to receive annual floods where the dense natural

regeneration will come up .

However, after the receding of water, the drought brings about

heavy mortality, Natural regeneration therefore remains a

unsolved problem .

Acacia nilotica :

Albizia lebbeck : In spite of the large quantities of the seed produced almost

annually, the natural regeneration is decidedly scanty and

sporadic .

Various reasons are attributed for the failure of the regeneration

viz. the fallen and uncovered seed is badly attacked by insects

quickly after rains .

Browsing and grazing by deer and cattle also causes mortality.

The ideal conditions for natural reproduction appear to be

loose, fairly moist soil; freedom from weeds, light shade

preferably from the side in the beginning and absence of shade

once the seedlings have established themselves .

Terminalia arjuna :

Dense natural regeneration is often found in

forests where the seed has accumulated

alongside stream banks, germination

commences after the seeds are fairly soaked by

pre-monsoon showers .

The seed does not germinate readily, if

exposed to the sun .

Though heavy shade is injurious, side shade is

advantageous (Kadambi,1954) .

Natural seedling in the forest, may die-back for

6-7 years, developed .

Vateria indica :

Plentiful natural regeneration is obtained in the

neighborhood of seed-bearers as the heavy

seed falls close to the tree .

The seedling withstand a considerable amount

of shade , but are sensitive to drought, frost and

fire .

Top canopy shade and lateral growing space

help the progress of natural seedling .

Retention of 70-100 trees in the top canopy per

ha for shade .

Pinus roxburghii: The chir pine sheds its seed from April to July .

The seed does not remain dormant and may begin to germinate

within ten days of falling, provided sufficient rain-fall preceeds .

The seed germinates under shade of pine forests, however,

under conditions of insufficient light, the resulting seedling

rapidly die-off(Troup,1921) .

Factor affecting natural regeneration are viz :

Nature of seed bearers

Light

Drought

Topography and soil

Soil covering and undergrowth

Fire

Grazing and grass-cutting etc.

Eucalyptus tereticornis :

The main impediments to natural regeneration

in Karnataka are regarded to be : destruction of

seed by ants, young seedling smothered by

leaf-litter, weeds and grass .

Eucalyptus leaves are toxic and contain

germination inhibitors, the seed germinating on

the leaf litter fail to reach the soil .

For establishment of natural regeneration

favorable conditions like good soil moisture,

absence of noxious weeds, worked up soil and

closure to grazing are all required .

Dalbergia latifolia :1. Root suckers: A long tap root is developed in the early

stages of growth. The roots are dimorphous. The root, which

becomes subsequently thickened, has other main roots;

smaller nutrition roots and fibrous rootlets devoid of buds .

The entire root system spreads both downwards as well as

sidewards into the soil cover .

Numerous root suckers are formed which lead to the

multiplication of the species. Root suckers are best developed

in moist conditions .

2. By seeds: Seeds fall onto the forest floor during the pre-

monsoon period and germination occurs under favourable

conditions .

Mortality in such a situation may be due to the extreme dry

conditions; grazing; browsing; trampling by cattle; or poor

drainage etc .