afforestation techniques for degraded lands
TRANSCRIPT
Vikas Kumar
Deterioration in the quality of land, top soil, vegetation and
water resources caused by exclusive or inappropriate
exploitation.
The term ‘degradation’ refers to irreversible decline in the
‘biological potential’ of the land.
Biophysical factors: land use and management, deforestation
and tillage methods.
Socio-economic factors: land tenure, marketing, institutional
support, income and human health.
Political factors: political stability forces that influence the
effectiveness of processes and factors of land degradation.
Wind erosion
Water erosion
Physical degradation
Chemical degradation
Climatic conditions
Terrain and landscape position
Vegetation
Edaphic factor
Management practices
Use of remotes sensing data
Direct observation and measurements
Ravine means “network of gullies”.
Causes of ravine formation
Destruction of forests
Unplanned cultivation
Destructive grazing
Severe water erosion
Integrated approach of soil conservation and vegetative
measures and restricted cutting of vegetation .
Protected these areas from biotic agencies
Soil conservation measure like
In moderate slopes ,contour trenching or bunding are done .
Steep gullies are stabilized by construction of gully plugging
and check dams.
.
Grasses :Panicum antidotale,Cenchrus ciliaris,which helps in
stabilisation of contour bunds.
Trees :Accia catechu and Dalbergia sissoo ,acacia nilotica
,prosopis julifera are selected for planting
Moving wind dislodges the soil particles and transported to
considerable long distances particularly in absence of
vegetation cover leads to formation of sand dunes.
These soils are having low organic matter, poor structure, low
clay content ,low microbial activity and moisture.
Sand dune fixation and stabilization through micro wind
breaks
Creation of wind breaks and shelter belts
Trees: prosopis julifera,acacia albida,azdirachta indica.etc
Shrubs and grasses: callygnum ppolygonoides,cenchrus ciliaris
pannicum antidotal,etc.
Hills have become barren and denuded because of large scale
and unrestricted felling's in forest areas
soil is shallow,stony,poor moisture content and low in nutrient
status
Run-off is excessive and erosion is severe
Grazing and illicit incidence are very high
Staggered contour trenching is practiced to help the soil and
water conservation .
Where slopes are very steep ,shallow “thallies” are prepared
for direct sowing.
Area fenced and closed for grazing.
In steeper slopes pits of size 30-40cm are dug and planting is
done.
Very hard trees is chosen for planting like Acacia ,eucalyptus
prosopis ,etc for tropical region and pinus roxburgii,cedrus
deodara,etc for temperate regions
Mining activities that extract ore or raw material from earth both
from surface as well as subsurface.
Open cast mining
Surface mining
Covering toxic or infertile material with soil or waste of better
quality.
Use of lime or gypsum to neutralize the acidic or alkaline soils
Leaching of salts by means of rainwater .fertilizing with
organic and inorganic fertilizers
Stabilizing of surface of very fine particles by mulching
Pits of size 60cm3 are usually dug up at spacing of 2m.
The pit should be filled with the fertile soil
Planting activities are carried out.
Areas exceeding optimum moisture content ,pore space become
partly filled ,aeration become difficult and less favourable for tree
growth these conditions are called water logged areas.
Afforestation of such lands needs special treatment which
includes
Drainage of excessive water
Reduction of salinity
Planting with suitable trees.
Improving drainage facilities by deepening drains
Removing of salinity by constructing series of mounds and
ditches
Tall and high transpiration rate of seedlings should be prefer
for planting
Suitable tree species: Casuarina equisetifoia
Syzyzium cumni
Terminalia arjuna
Eucalptus sps,etc
Skeletal soils
These soils are very shallow ,coarse,poor,eroded and
degraded.
These occurs both in low and high rainfall areas
Afforestation techniques
Contour trenches are or staggered trenches are made in order
to conserve soil moisture.
In rocky areas ,where soil particles are absent ,digging of deep
pits and filling them with soil brought from outside and
planting is done .
High rainfall areas:
cupressus torbolusa and C.arizonica
Pinus ponderosa ,etc
Low rainfall areas:
Eucalyptus terticornis
Acacia sps
Prosopis sps.,etc
Total precipitation usually less than 50mm.
Soils are neutral or alkaline in nature
Wind erosion is common
Short growing season
Trench cum pit type:
gentle slope areas
Digging of staggered contour trenches 4.3m long,60cm wide
at bottom and 1m wide at top at a spacing of 10m.
In between trenches pits of 60 cm and 1m deep are dug at 2m
spacing.
Trenches and pits are filled with 50;50 mixture of dug up soil
and fine silt
Trench cum drianage type
Low lying areas such as river banks and marshy lands.
To leach out salts from the root zone of plants, planting is
done in crow bar holes of 45 to 50 cm deep .
Choice of species:
Salix alba
S.fragilis
Populus alba
P.ciliata,etc
Saline soils
pH<8.5
exchangeable Na <15%
Dominance of neutral salts such as chlorides and sulphates.
Alkaline soils
pH>8.5
Exchangeable Na>15%
Carbonate of sodium are dominant soluble salts
Production of loose soil by breaking the clay pan or kankar
pan
Replacement of exchangeable sodium by addition of
amendments
Maintenance of soil fertility
Trench ridge method is used rather than the pit method of
planting
Digging of pits upto 90 to120cm are also followed for planting
purposes.
The species should be tolerant to salt and alkalinity.
Pongamia pinnata
Terminalia arjuna
Prosopis julifera
Albizzia amara,etc
Ridge-trench method
Sub-surface planting in auger holes of 30-45 cm deep.
Planting in deep trenches or furrows.
Eucalptus hybrid
Madhuca latifolia
Xylia xylocarpa
Pterocarpus santalinus
Tectona grandis
Pterocarpus marsupium
Land degradation will remain an important global issue for the
21st century because of its adverse impact on productivity,
environment, and its effect on food security and the quality of
life.
So there is an urgent need to address these issues through a
multi-disciplinary approach, but the most urgent need is to
develop an objective, quantifiable, and precise concept based
on scientific principles to solve these land degradation
problems.
Eswaran.H., Lal .L and Reich.P.F . An overview of land
degradation.
Degraded and Wastelands of India ICAR publications