Showing posts with label Silviculture. Show all posts
Showing posts with label Silviculture. Show all posts

Wednesday, July 11, 2018

Seed Certification

aroma aromatic beans brown
The seeds after being collected and before being stored or used has to accompany a certificate giving the information like the species, date of collection of the seed, locality factors like the elevation, aspects, climatic and soil conditions, characteristics of the mother trees, method of collection, processing, method of storage, name of the collecting person, quantity of seed, date of dispatch, condition of seed at the time of dispatch, etc.


It ensures the germination percentage which help to estimate the quantity of seeds required to produce the desired number of seedlings of given species.

It is useful for provenance test as the observation of growth pattern and availability of seedlings and trees grown from seeds of various provenances will provide the knowledge of fitness of the provenance for the plantation of given site of certain species.

It helps to achieve the objective of plantation by predicting the quality and form of the products of the trees.

Besides it also helps in knowing the quality of the   mother trees, vigorous of the growth and the degree of suitability to the site of plantation.

Storage of seeds

bunch of nuts served on bowls
Storage of seeds is essential to meet the demands of seeds having right physiological and genetic characteristics during all the time.The objective of the proper storage is to maintain the viability of seeds for longer period. It helps to maintain the longevity as well. Several Species  Leguminosae and Malvaceae families have high longevity.

The methods of control of oxygen, moisture content and temperature that reduces the rate of respiration without otherwise damaging  the seed is likely to be effective in extending the longevity during storage. Seeds stored under good conditions and which have maintained higher germinative capacity can safely be used but it is not good to use seed lot in which the germinative capacity has been severely curtailed. Insects has also to be taken care of. Suitable insecticides regularly has to be used to avoid any insect damage. Cold storage facility also provide longevity. Silica gel is used to keep moisture content of 7 to 9 percent  in impermeable containers .

Seed Processing of Forest Trees

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 The objective of Seed Processing is to produce good quality seeds for sowing. The Processes are Pre-cleaning, Pre-curing, Cleaning.

Pre-cleaning involves cleaning of twigs, barks, leaf litter and other impurities before they are sent for extraction. It can be done by hand and by flotation and fruits be separated by blowing and winnowing.

Pre-curing involves the deliberate storage for ripening of seeds and slow air drying of seeds/fruits.

Cleaning of sound seeds from impurities can be done by screening and sieving,sorting,winnowing,flotation. Screening and sieving remove almost all impurities which have different size than the hole in sieve or screen. Sorting according to length may remove longer and shorter impurities. Cleaning by winnowing is a common practice.Likewise, Flotation method can be used to separate out impurities having different specific gravity than that of seed.

Seed Collection of tree species

Seed collection is very important part of the plantation project or to fulfill the objective of afforestation and reforestation.
brown pistachio nut lot
The seeds should be collected from the selected tree following different guidelines. The seeds should be collected from healthy vigorous trees of reasonably good form that are making more than the average growth.The seeds produced by immature and mature trees are sometimes infertile so middle aged trees has to be chosen for collection.Poorly deformed, diseased, abnormal, insect infested trees has to be avoided. The seedlings that are produced from the isolated trees of naturally cross- pollinating species,( are likely to be self pollinated ) are weak or malformed and seeds few with low viability. Dominant and Co-dominant trees are mostly chosen and vigorous wolf-trees are also avoided.

Bamboo and Rattans

agriculture bamboo botanical bundleBAMBOOS are tall, perennial, arborescent grasses, belonging to Poaceae family. There are 50 genera and approximately 1326 species generally inhibiting the humid tropical, sub-tropical and mild temperate regions of the world. It is found  in over 18 million hectares of land, of which 75% lies only in Asia.The rhizomes of the Bamboo may be short and thick and clustered together and produce Bamboo in well defined clumps. Mature Bamboo clumps produced new shoots every year throughout the rainy season. The shoots develop then rapidly within 2-3 months and reach their full height and diameter.

abstract background bamboo close upRATTANS belong to the family Palmae/Arecaceae. 600 species of Rattans belonging to 13 genera are reported to be distributed worldwide concentrated in Africa and South East Asia.Rattan is an ideal raw material for cottage industries. Its industrial use is in furniture, walking sticks, polo sticks, umbrella handles, basket making, mats, ropes, and various other articles.

Sunday, July 8, 2018

Silviculture of indigeneous tree species in Nepal

Recommending any particular silvicultural system for a species is not a good idea. The silvicultural system for a particular forest stand should be formulated or selected on the basis of species, forest condition, forest owner's objectives and so on.

Sal ( Shorea robusta)

Silvicultural characteristics 

Strong light demander, Good coppicer , Seedling die back due to frost, drought, fire , and dense overstorey, Annual seeders but good seed years after every 2 years, Light winged seeds and seeds dispersed by winds.

Silvicultural Systems

Selection system, Irregular shelterwood system, Uniform shelterwood system, One cut shelterwood system, Clearfelling system, Coppice with standards, Coppice with reserves, Simple coppice.


Khair (Acacia catechu)

Silvicultural characteristics

Strong light demander, Seedlings are susceptible to severe frost, Drought resistant, Coppices well unless it is under shade of other species, Seeds produce in abundance, Seeds dispersed by wind and water, requires protection from grazing and browsing.

Silvicultural systems

Clearfelling and Plantation, Simple coppice, coppice with standards, Seed tree method.


Sissoo ( Dalbergia sissoo)

Silvicultural characteristics

Strong light demander, Good coppicer, Annual seeder and seeds produced abundantly, Seeds dispersed by wind and water, Older seedlings can tolerate mild frost, Should be protected against grazing and browsing.

Silvicultural systems

Seed tree method, Clearfelling and plantation by Taungiya, Two storyed high forest system, Simple coppice, Coppice with standards, Coppice with two rotation system.


Chilaune ( Schima wallichi)

Silvicultural characteristics

Not frost hardy,Coppices very well, Good seed year are frequent , Winged light seeds dispersed by wind, Moderately shade tolerant but later it benefits from full overhead light, Capable of colonizing plantations of other species.

Silvicultural systems

Simple coppice, coppice with two rotation, Coppice with standards, Selection coppice, Selection system.

 Katus (Castanopsis indica )

Silvicultural characteristics

Moderately shade tolerant, Frost hardy, Benefits from overhead light in later stage, Young seedlings are frost tender, Coppices well.

Silvicultural systems

Simple coppice, Coppice with two rotation, Coppice with standard, Selection coppice, Selection system.

Deodar( Cedrus deodara)

Silvicultural characteristics

Shade bearer and young seedlings benefit from side shade, Winged Seeds dispersed by wind, Young seedlings don't suffer from frost, Very sensitive to fire, Good seed years after every 3 years, Most of the seeds fall close to the parent tree, Profuse regeneration in favorable sites.

Silvicultural Systems

Single tree selection, Irregular shelterwood system, Uniform shelterwood system (40-50 seed trees/ha).




Sunday, July 1, 2018

Glossary of Silviculture

Afforestation- It may be defined as the establishment of a forest by artificial means on an area from which forest vegetation has always or long been absent.

Advance Growth/Advanced Regeneration/ Advanced Reproduction- The seedlings, saplings and poles of specie of the overwood that establishes naturally in a forest before regeneration felling started.

Broad-leaved Tree- Tree with hardwood and belonging to botanical group Dicotyledons.

Budding- It is the method of vegetative reproduction in which a bud with some portion of the bark of a genetically superior plant is grafted on  an inferior plant so that it may produce shoot when the old shoot of the stock is cut off.

Clone- All cuttings and grafts derived from one tree by asexual reproduction are collectively called a clone.

Cover Crop-  The subsidiary crop of low plants introduced in a plantation to afford soil cover between or below the main crop.

 Conifer- Tree bearing cones and generally needle shaped or scale like leaves, usually evergreen and belonging to the order Coniferales of the botanical group, Gymnospermae.

Coppice- It is the method of vegetative reproduction in which the trees, plants or the seedlings of a species when cut from near the ground level, produce coppice shoots. The coppice shoots are the shoots arising from an adventitious bud at the base of a woody plant that has been cut near the ground or burnt back.

Damping off- The killing of the young seedling by certain fungi that causes the decay of the stem or roots.

Die-back- The progressive dying, usually backwards from the tip, of any portion of the plant. It is caused by the adverse climatic and edaphic factors as well as adverse weed conditions.

Frost Hardy Species- The species which possess power to withstand frost without being damaged are called frost-hardy.

Frost Tender- The species which are killed back by the frost are called Frost-tender species.

Germinative Capacity- It is defined as the percentage, by number of seeds in a given sample that actually germinate irrespective of time.

Germinative Energy- It is defined as the percentage by number of seeds in a given sample that have germinated up to the time when the rate of germination reaches its peak.

Girdling- It may be defined as the cutting through the bark and  outer living layers of wood in a continuous incision all- around the bole of the tree.

Lopping- The cutting of a branch of a tree.

Mulch- Plant residues and other materials used as a covering for the soil.

Reforestation- The restocking of a felled or otherwise cleared woodland by artificial means. It is the raising of a forest artificially in an area which had forest vegetation before.

Regeneration- It may be defined as “the renewal of the forest crop by natural or artificial means.”

Seed Dormancy- It is a condition of mature viable seed in which germination is considerably delayed even though external conditions favors germination.

Shelterbelt- It is a wide belt of trees, shrubs, grasses, planted in rows which go right across the land at right angles to the direction of prevailing winds to deflect air current, to reduce wind velocity and to give general protection to cultivated areas against wind erosion and desiccating effect of hot winds.

Weeding- The tending operation done in the seedling stage in nursery or in a forest crop that involves the removal or cutting back of all the weeds.

Thinning- The felling made in an immature stand for the purpose of improving the growth and form of the trees that remain, without permanent breaking of the canopy.

Viability- It is defined as the potential capacity of a seed to germinate.


Forest Types of Nepal

Nepal has diverse climatic and topographical features which results in the contribution of different forest types in Nepal.Adapted from J.k. Jackson, here is the list of different forest types of Nepal.

  1. Tropical forest (up to 1000m)

        i.Shorea robusta Forest – The dominant species is Sal and other associates are           Terminalia alata, Anogeissus latifolia, Syzyzium cumini,etc.

ii.Acacia catechu- Dalbergia Sissoo Forest- It is mostly found along streams and rivers in deposited alluvium and often gravelly and will be eventually be succeeded by Sal or other types of forest.

iii. Other Riverain forest- This types of forest is not large and extends far from the stream banks. Jamun is dominant in western Nepal.

iv.Grassland- This type is usually found on poorly drained clays. Grass species such as Saccharam spontaneum, Eulaliopsis bipinata, Phragmites Karka.etc are found.

v.Terminalia- Anogeissus deciduous hill forest- It is confined to dry south facing slopes in the larger river valleys and up to 1200m in Western Nepal.

  1. Sub-Tropical Forest (1000m-1700m in East and 1000m 2000m in West)

i.Pinus roxburghii forest- It is found in the west of Nepal extensively. In the east, it is found in large river valleys. It is almost pure. In the far west at higher altitude, it may be associated with Olea ferruginea, Pistacia spps, etc. In transitional areas, it may be mixed with Schima wallichi or Shorea robusta.

ii.Schima-castanopsis forest – This Schima- castanopsis forest covers very large areas of the mid-hills, but much of it has been cleared for cultivation and very small passages are left.

iii.Alnus nepalensis forest- Alnus nepalensis is dominant and almost pure and associated in some places with Lyonia ovalifolia.

iv.Riverain forest with Toona and Albezia species- It is confined to narrow strips along streams and is very mixed in composition.

  1. Temperate Forest (2000m-3100m)

i.Lower temperate forest ( 2000m- 2700m)

a.Quercus leucotricophora and Quercus lanata

b.Quercus floribunda forest

c.Quercus lamellose forest

d.Lower temperate mixed broad leaved forest with abundant lauraceae

e.Pinus wallichiana forest

ii.Upper temperate forest (2700m – 3100m)

a.Quercus semecarpifolia forest

b.Upper temperate mixed broadleaved forest

c.Rhododendron Forest

d.Upper temperate coniferous forest

4. Sub- Alpine forest (3000m-4200m)

i.Abies spectabilis forest

ii.Betula utilis forest

iii.Rhododendron forest

iv.Juniperous indica steppe

v.Caragana steppe

  1. Alpine forest (up to 4500m)

It has no trees, but shrubby Rhodendrons and Junipers and some other shrubby species are found at lower elevations up to about 4500m.


Saturday, June 30, 2018

Silviculture and Silvicultural systems

Silviculture is defined as the art an science of cultivating forest crops. In other words, Silviculture  includes both Silvics and its practical application. Silvics is defined as the study of life history and general characteristics of forest crops with particular reference to environmental factors, as the basis for practice of the silviculture. 

Objectives of the Study of Silviculture

  1. Increasing the productivity of the forest

  2. To fulfill the multifarious requirements of the people with the cultivation of more valuable and useful species of trees

  3. Improvement of deteriorating natural forest and creating new man-made forest

  4. Maintaining the good forest condition of both natural and man-made forests by proper tending

A Silvicultural System is defined as a method of silvicultural procedure worked out in accordance with accepted sets of silvicultural principles by which crops constituting forests are tended, harvested and replaced by new crops of distinctive forms.

Silvicultural systems are primarily classified on the basis of the mode of regeneration and this is further classified according to the pattern of felling.

  1. High Forest Systems- These are the systems in which the regeneration is normally of seedling origin, either natural or artificial or a combination of the both and where the rotation is generally long.

          a.Clear -felling System

   b. Shelterwood System

          c. Selection System

          d. High Forest with reserve

          e.Two Storeyed High Forest

          f .Improvement Felling

2. Coppice Systems- These are those Silvicultural Systems in which the crop originates  mainly from coppice and where the rotation of the Coppice is short. These systems are further classified into several Silvicultural systems on the pattern of felling.

a. Simple Coppice system

b.Coppice with Standards system

c. Coppice with reserve System

d. The Coppice of two Rotation system

e.The Coppice Selection system

f.The Shelter wood Coppice System

g. The pollarding