Agroforestry, Subsystems of Agrisilviculture - Shifting cultivation, Taungya and

Intercropping, Tree architecture

© Vivek Srivastava

Agroforestry

Agroforestry

Agroforestry is an integrated dynamic system

Agro forestry as an enterprise

Windbreaks

AGROFORESTRY

• An efficient and integrated land use management system by raising of certain agricultural crops, forest tree species and or animals simultaneously or sequentially on the same unit of land with appropriate management practices which result in overall increase in the production, under a particular set of climatic and edaphic conditions and socio-economic status of local people.

TYPES OF AGROFORESTRY SYSTEMS

Functional basis -- production to protection

Socioeconomic basis - commercial to substance

Structural basis

AGROFORESTRY SYSTEMS i) Agri-silviculture ii)Silvipastoral system iii) Agrisilvipastoral system iv) Horti-silviculture system v) Agri-horticulture system vi) Agrihortisilviculture system vii) Multipurpose forest tree production(other specialized

agroforestry systems). viii) Apiculture with trees ix) Aquasilviculture or Aquaforestry x) Agrisilviaquaculture

Interrelationship

Agri-silviculture When agricultural crops are grown in

combination with forest tree species, the system is known as" Agrisilviculture "

For instance, when groundnut and arhar are grown as intercrop with Leucaena leucocephala and Sesbania aegyptica.

This crop combination with forest trees results in an increase in both grain as well as fodder yields.

Agri-silviculture system provides

• Food,• fuel, • fodder,• manure,• paper pulp and• packaging materials for the

rural people.

Ways to grow tree crops with agricultural crops

Tree species on the border of crop field or orchard.

Tree species and agricultural crops in alternate rows.

Tree species and agricultural crops in alternate strips.

Tree species and agricultural crops in mixed form

Based on the nature of the components

Improved fallow species in shifting cultivation The Taungya system Multispecies tree gardens Alley cropping (Hedgerow intercropping) Multipurpose trees and shrubs on farmlands Crop combinations with plantation crops Agroforestry fuelwood production Shelterbelts Windbreaks Soil Conservation hedges

SHIFTING CULTIVATION Forest land is cleared by cutting down all the

trees, shrubs, herbs and climbers near the ground level;

Felled material is allowed to dry and then set on fire;

Sowing is followed in cleared area

The cropping is done a few years on the same unit of land and then left for the regeneration of the bush (fallow period).

Clearing and burning of vegetation leads to a disruption of the closed nutrients cycle on the forested land.

Shifting Cultivation

Consequences However, burning causes raising in soil

temperature temporarily, more solar radiation is received on the bare soil surface resulting in higher,soil and air temperatures

This change in the temperature regime causes changes in the biological activity in the soil.

The addition of ash to the soil through burning causes important changes in soil chemical properties and organic matter content

After clearing and burning, a sharp increase of available nutrients may benefit the first crop but later on the soil becomes less and less productive and crop yields decline.

When raising of crops become non remunera tive, the cultivators abandon the site and move into other sites.

After a lapse of a few years again the same site is used for cultivation.

By that period cut tree regenerates and soil also regains in its fertility and productivity.

However, the next return has low productivity than the previous turn.

Shifting Cultivation

In India, shifting cultivation is practiced in

The north eastern hill region (Assam, Meghalaya, Manipur, Nagaland and Tripura) and Andhra Pradesh, Bihar, Madhya Pradesh, Orissa and Karnataka.

Shifting cultivation is called "Jhum" in north eastern hill region and "Podu" in AndhraPradesh and Orissa states.

The size of the plot varies from 1.0 to 2.5 hectares per family having members 3 to 5.

Demerits of shifting cultivation: Shifting cultivation is a faulty land use. It

enhances soil degrada tion by way of soil erosion.

It is a primitive method of cultivation in which crop yields are less and requires hardwork.

Due to complete cutting and burning of vegetation there is an abrupt changes in soil microbial population.

It causes environmental degradation. There is loss of nutrients from the soil through

run off, leaching and percolation.

Demerits The carbon, nitrogen ratio reduces due shifting

cultivation. The excessive run-off in the shifting cultivated

areas causes floods in the adjoining plains. Denudation of hill slopes takes place. Wild life in the shifting cultivated areas is badly

affected. It disturbs the fauna. Forest flora become weak and grow sparsely.

Ways for improving degraded areas Efficient land use management including

provison for horticultural crops, forestry crops preferably legume species and livestock like cattle, sheep and goats

Preventing loss of soil fertility by making contour bunds, graded".bunds, half moon teraces, levelling, drainage system and water utilization technology,

Soil management by growing cover crop, strip and mixed crop ping, erosion checking crops, relay cropping, green manuring and use of organic amendments and fertilizers.

Adoption of production based crop management by raising high yielding varieties, suitable crop planning, weed and water management, timely plant protection measures, application of fertilizers for restoring soil fertility and use of implements.

Adoption of soil enriching hedgerow intercropping, or 'alley cropping' aims at eliminating the fallow period altogether by combining tree species with agricultural crops.

The problems created by shifting cultivation can easily be overcome by adoption of suitable agroforestry models

TAUNGYA SYSTEM The 'Taungya' is a Burmese word, consisting of

'Taung' means hill and 'ya' means cultivation i.e. cultivation in the hills

Taungya is also a shifting cultivation in which cultivators are allowed to plant forest 'tree species and to raise agricultural crops in between rows of forest tree species simultaneously, and cared for about 3 to 5 years.

Thereafter, cultivators are required to shift to another patch of land.

Origin of TaungyaThe aim of Taungya system is both wood

and food productionTaungya was reported to have started first

in Burma in the year 1850 for replanting vast areas under teak plantation, and in Java in 1856.

Taungya was introduced to India by Brandis, in 1856. The first plantations were raised in 1863 in North Bengal

Places of practice

It is practiced in Kerala, West Bengal, Uttar Pradesh, Tamil Nadu, Andhra Pradesh, Orissa, Karnataka, and North eastern hill regions.

This system provides employment opportunities to unemployed rural people.

It is also suitable in the area where land shortage is very acute.

Crops and trees

a)Trees Tectona grandis Bamboo Santalum album Tamarindus indica Acacia nilotica Acacia mearnsii Ceiba pentandra Cashew, Rubberb) Crops Millet, pulses, groundnut,cotton

Types of Taungya

Departmental Taungya

Leased Taungya

Village Taungya

Main crops of TaungyaJowar, bajra, paddy, maize, lentil, wheat,

mustard, rapeseed. gram.

arhar, urad, soybean, castor, sunhemp, barley. potato, sweet popato tapioca. til, groudnut, turmeric, ginger etc.

Taungya system

State Tree crop Associated agricultural crops

Uttar Pradesh - Shorea robusta, T ectona Maize, paddy, sorghum,pi-

grandis, Acacia catechu, geon pea, soybean, wheat,

Dalbergia sissoo, Eucaly- barley,chickpea,rape seed

ptus spp.,Populus spp. and miscellaneous

Kerala - Tectona grandis, Bombax - Paddy, tapioca, ginger,

ceiba, Eucalyptu spp. turmeric

Assam - Shorea robusta paddy

TamilNadu - Tectona grandis, Bamboo, - Millets, pulses,groundnut,

Santalum album, Tamarin- cotton, tapioca, potato

dus indica, Acacia meamsii,

Ceiba pentandra, Cashew,

Rubber

Merits of Taungya Weed and climbers growth is suppressed.Employment opportunities to unskilled

unemployed rural peopleRegeneration of forest species is cheap.There is full utilization of available land for

the production of food crops.This is an important way to integrate rural

development programmes.Increases forest wealth of the country

Taungya

Demerits of Taungya Exposure of land leads to erosion and loss of

soil fertility. There is an exploitation of human labour. Danger of epidemics is expected due to raising

of agricultural crops. Forest trees are not adequately cared by

cultivators once they are settled. Cultivators may claim for legal right on land Insecure land tenure.

Comparision

Intercroppingspatial arrangement of crops.the annual and perennial crop components

are simultaneously present on site but are spaced in such a manner that they became mutually supportive rather than competing.

Under such circumstances, they may jointly yield higher outputs per hectare per year.

Intercropping

Arrangement

Four subsystems of Intercropping

Border tree planting

Alternate rows

alternate strips

Random mix

Border tree planting lines of trees specifically

as boundary markers, live fences, wind-breaks or fire-breaks.

protecting or stabilizing the site

producing green manure as organic fertilizer

producing fuelwood.

Alternate rows "alley", "avenue",

"corridor", "zonal", or "hedgerow" cropping

found most effective for erosion control and slope stabilization.

Alternate strips

A "strip" differs from a row in that it is composed of two or more rows

Strip intercropping

Random mix displays no specific or

orderly placement of the component crops

the plants actually occupy their own special ecological niches and are able to coexist very well.

Home gardens of Indonesia and the Philippines

Sunflower chick pea

Acacia (Acacia confusa) - Tea (Camellia sinensis)

Agroforestry System (Forestry-Fishery-Agronomy) with water canal

Wheat Intercropped in Paulownia Nursery

Poplar (Populus euramericana 1 - 214) - Wheat Intercropping

LOPPING AND PRUNING

• Q. Is Tree Pruning The Same As Tree Lopping And Tree Topping?

A. The short answer is ‘No’ but this needs some explanation because of the widespread belief that they are the same.

• The Standard defines lopping and topping as: lopping is ‘the practice of cutting branches or stems between branch unions

or internodes’ Topping is ‘reducing the height of a tree through the practice of lopping’

• The Standard says lopping and topping are unacceptable because:• They increase the rate of shoot production and elongation.• The resulting regrowth is weakly attached and becomes prone to failure or

collapse.• The natural habit of the tree destroyed.• They may reduce the lifespan of the tree.• ·They predispose trees to fungal infections and insect attack.

• When lopping cuts are made in order to reduce the height of a tree, the overall process is referred to as tree topping.

• Topping is a world wide tree mutilation practice that must stop! Topping not only destroys a tree’s dignity, but it weakens the tree and makes it a high hazard risk. If a tree must be topped it is time for a new tree.

What Happens To A Tree After It Has Been Lopped?

Lopping and topping inevitably removes the leaves. Without leaves the tree cannot capture sunlight and manufacture sugars for transport to the roots. Without leaves, the cooling effect of water transpiration ceases and the tree can no longer move water and nutrients upwards from the soil. In essence the entire physiology of the tree is disrupted. Some tree species respond to topping and lopping by growing ‘emergency’ shoots (epicormic shoots) whilst others including many Eucalyptus species are killed outright.

A short time after the lopping, new shoots will emerge from below the lopping cuts. Known as epicormic shoots, they arise from suppressed buds retained just under the bark cambium. Removing the uppermost branches stops the downward flow of bud suppressing chemicals. With no suppression from above, the dormant buds burst through the bark skin to act as emergency light receptors as the tree attempts to establish a new canopy using energy stored in its woody parts and especially in its roots.

Short rotation energy plantations

Fast-growing tree crops grown in carefully tended plantations for rotations shorter than 15 years have an important role to play, because of their numerous ecological benefits. This special type of forestry is concerned with maximization of wood biomass output per hectare for energy production. Highly productive pioneer species are willow and poplar species as a short rotation coppice (SRC) system.

It involves the establishment of plantations using genetically improved, clonallypropagated, plant materials (i.e. willow and poplar species) at a density of

~15000 plants ha−1, which are coppiced at the end of the first year and then managed on a three-year rotation (Th arakan et al., 2003). The biomass produced from short rotation coppice (SRC), such as willow and poplar, may have a number of uses: as a fuel for electricity generation plants; for the production of charcoal; as a soil amendment for clay caps; or simply as a carbon sink for atmospheric CO2.

• Technically speaking, energy plantation means growing select species of trees and shrubs which are harvestable in a comparably shorter time and are specifically meant for fuel. The fuel wood may be used either directly in wood burning stoves and boilers or processed into methanol, ethanol and producer gas.

Tree architecturePollarding

• Pollarding is a pruning system in which the upper branches of a tree are removed, promoting a dense head of foliage and branches. It has been common in Asia and Europe since medieval times and is practiced today in urban areas worldwide, primarily to maintain trees at a predetermined height.

Suitable for...Pollarding is a pruning technique used for many reasons, including:• Preventing trees and shrubs outgrowing their allotted space• Pollarding can reduce the shade cast by a tree• May be necessary on street trees to prevent electric wires and

streetlights being obstructed

Pollarding a tree is usually done annually, and would need to be carried out every few years to avoid potential problems.

• The best time for pollarding many trees and shrubs is in late winter or early spring. However, bear in mind the following:

• Summer can be a suitable time to pollard. However, the new growth may be poor as a result of the scorch, drought or heavy shade cast by neighboring trees

• The least favourable time for pollarding is the autumn, as decay fungi may enter the pruning cuts

• Once young trees or shrubs have reached the desired height, you can begin to pollard them. This involves choosing a framework:

• On a shrub, this might be one stem cut to a metre high – a mass of stems will grow from the top

• With a tree, it is more typical to leave a trunk supporting three or five branches – these branches are cut back to a desirable length and the twiggy growth appears at these ends

• Initially, the new branches are held weakly in place as they grow rapidly from underneath the bark, rather than from within the tree. As the wood lays down annual growth rings, the union strengthens, often forming a thickened base where the shoot meets the trunk. Over a number of years, a swollen 'pollard head' forms where new shoots grow each year.

Hedging

• A hedge or hedgerow is a line of closely spaced shrubs and tree species, planted and trained to form a barrier or to mark the boundary of an area. Hedges used to separate a road from adjoining fields or one field from another, and of sufficient age to incorporate larger trees, are known as hedgerows. It is also a simple form of topiary.

Canopy architecture

OVERSTORY LAYER• Also called

emergent layer.• Consists of giant

emergent trees that tower above the surrounding canopy.

• The air is much drier and moderately strong winds blow through their branches.

CHARACTERISTICS• Trees are huge• A height of 213 feet (65 m) with horizontal

limbs that stretch over 100 feet (30 m).• Often covered with epiphytes (non-parasitic

plants which take no nutrients from the host plant but use it for support)

• Example lichens, mosses, liverworts, and algae.• The most successful and most plentiful

predators of vertebrates in the canopy are the birds of prey, such as eagles.

CANOPY LAYER• Found directly

beneath the overstory layer (emergent layer).

• The primary life sustaining layer with an abundance of food and forms a natural roof over the remaining two layers beneath.

CHARACTERISTICS• Canopy rising to 150 feet above

ground .• Trees elevations, creates a highly

reflective shield that protects them from the higher levels of intense sunlight.

• This almost shield filters out 80% of the light, preventing light from penetrating the forest.

• Consists of a thick layering branch system of limbs and vines that create natural vistas and form a natural umbrella.

• Absorbs ultra-violet rays from the sun protecting the plant and animals species beneath the canopy layer from UV rays.

• Retains moisture and makes a natural shield to prevent “wash-outs” during the flooding caused by heavy rain from the tropical rainy seasons.

• Many Epiphytic Plants, commonly called “air plants” like Bromeliads and Orchids grow in the canopy Layer.

• Roots of these plant do not reach the ground or live in soil.

• Instead they thrive by absorbing moisture and nutrients through an aerial root system by attaching themselves to a host.

• A home to many species, including birds, butterflies, monkeys, parrots, the slow moving sloth, tree frogs, toucans, jaguars and leopards.

UNDERSTORY LAYER• Directly underneath

the canopy layer and on top of the forest floor.

• Growth here is very dense.

• This layer is a dark, sometimes almost impenetrable natural habitat like vines, shrub and broadleaf trees.

CHARACTERISTICS• Provides superior camouflage and many

of the species who live here crossover between this layer and the canopy layer.

• Average 12’-15’ feet in height and have exceptionally large leaves to compensate for the lack of sunlight.

• The leaves are so large in fact, just one single leaf could be used for an umbrella.

• Many species living in this layer like darkness.

(nocturnal)

• Several animal species such as tree frogs, bats, owls, and an amazing array of insect species like the famous team working “Leaf Cutter Ants” can be found.

• Intermingling between layers is done by many species but especially by the many varieties of Monkeys, Sloths, Jaguars and Leopards. 

FOREST FLOOR• The Forest Floor is

the ground layer. • No sunlight

reaches the Forest Floor cause it is very dark.

• Quality of the soil is extremely poor and very few plants are found growing in this area.

• Examples of the plants: moss, ferns and some low growth plants and vine roots.

• It is rich in microorganism and this environment makes quick work of decomposition making a natural compost that is exceeding rich. 

• Beetles, Frogs, Lizards, Snakes, Termites, and insects of every kind thrive by the millions in the moist, dark climate of the Forest Floor.

LIGHT PENETRATION

INTRODUCTION• The light penetration level varies by

each layer.• Maintains under storey vegetation

and determines the degree of suppression or vigour of its growth.

• Each canopy layer consist of different types of plants and have their own specific characteristic and structure that can help in the light competition.

• All plants must compete to get sunlight for photosynthesis.

PHYSIOGRAPHIC LOCATION TO LEAF POSITION

• Light incident on a leaf varies with leaf angle and canopy position

• Plants can change the amount of energy they absorb by changing their effective “physiographic location”

• Heliotropic leaf movements: Some plants follow the sun by moving leaves to maximize absorption (diaheliotropism) or minimize by moving parallel to the sun (paraheliotropism)

CANOPY COMPOSITION AND DISTRIBUTION

• This affects both light quantity and light quality

• Light quantity diminishes through the canopy but all canopies are not equal.

• Incident light (PAR) at the forest floor may be different between types of forest in this world.

WHY WOULD THE PAR IS DIFFERENT BETWEEN THE

FOREST??1. Species – leaf optical properties2. Density – how much is there, LAI, LAD, etc

*Leaf Angle Distribution  refers to the angular orientation of the leaves in the vegetation *Leaf area index refers to leaf area per unit ground area

3. Architecture – Canopy structure, shape, orientation and heliotropic leaf movements give each plant its own characteristic light absorption characteristics

PHOTOSYNTHETICALLY ACTIVE RADIATION (PAR)• PAR is the amount of light available

for photosynthesis, which is light in the 400 nm to 700 nm wavelength range.

• Light is a waveform which can be measured in terms of wavelength.

• The range of human vision(400 to 700 nm) in term of wavelength is called the visible spectrum.

Conclusion

 When being well managed agroforestry can support food production, increase the total efficiency and stability of the system, provide a diversity of outputs, enhance the natural resource base, and overall is likely to be a better option than a solely crop based system, particularly in lower potential areas.

REFERENCE www.fao.org www.centerforagroforestry.org www.answers.com/topic www.agroforestry.co.uk/silvoar.html www.aftaweb.org www.ncrs.usda.gov www.unl.edu/nac/agroforestrynotes www.sustainableharvest.org/m www.ncga.com Text book of Agro forestry –Chundavat..

Thank you