LAND DEGRADATION
Land degradation indicates temporary or permanent long-term decline in ecosystem function and
productive capacity. It may refer to the destruction or deterioration in health of terrestrial ecosystems, thus
affecting the associated biodiversity, natural ecological processes and ecosystem resilience. It also considers
the reduction or loss of biological/economic productivity and complexity of croplands, pasture, woodland,
forest, etc. Across the world, over 20% of cultivated areas, 30% of forests and 10% of grasslands are
suffering from degradation, affecting about 1.5 billion people.
This degradation may be the result of numerous factors or a combination thereof, including anthropogenic
(human-related) activities such as unsustainable land management practices and climatic variations. Note
that degradation processes e.g. erosion do occur naturally, and are generally balanced by the rate of soil
formation. However accelerated degradation is typically associated with human modification of the
environment.
Degradation encompasses deforestation (tropical and temperate forests) and desertification of drylands
(arid, semi-arid and sub-humid regions). Almost 75% of the drylands in Latin America and the Caribbean
are under moderate to severe desertification.
Underlying causative factors of land degradation, and environmental mismanagement in general, are poverty
and undervaluing of natural resources. In both cases people focus on immediate economic gain irrespective
of damage to the same resources they are dependent on. The latter in particular promotes inefficient use and
wastage of resources.
Causes of or contributors to land
degradation include:
▪ Clearance of vegetative cover
▪ Soil erosion by wind or water
▪ Natural conditions e.g. soil type,
topography (e.g. steep gradient),
weather/climatic conditions e.g.
high intensity rainfall, natural
hazards
▪ Invasive species
▪ Pollution
▪ Drought i.e. precipitation is
significantly lower than average
recorded levels for a prolonged
period.
▪ Unsustainable agricultural practices
▪ Habitat alteration e.g. urban
expansion
Figure 1: The cycle of processes leading to and perpetuating land
degradation (Source: FAO)
Resultant effects or impacts include:
▪ Decline in the chemical, physical and/or biological properties of soil e.g. lower organic content and
nutrient levels, salinisation, pH changes in soil (acidification or alkalinisation)
▪ Reduced availability of potable water
▪ Lessened volumes of surface water
▪ Depletion of aquifers due to lack of recharge
Impacts on livestock and agriculture e.g. loss of animals due to dehydration, reduced yields
Water and food insecurity, famine
Biodiversity loss
General reduction of the ability for the community to depend on the natural environment for
livelihood
▪ Decline in economic productivity and national development
▪ Conflict over access to resources
▪ Mass migration
▪
▪
▪
▪
Soil types
The FAO has a classification of over 30 different soil types. Soils
vary by climate due to the impacts of temperature, precipitation,
vegetation type, nutrient and organic matter content, degree of
leaching, etc. Soil can be described by a number of physical and
chemical properties including particle size, colour, texture and pH.
Soils are stratified into horizons due to processes of weathering
(breakdown of rock), transport and deposition (i.e. eluviation and
illuviation), and decomposition of organic matter; with the A
horizon being the topsoil, and the R horizon being the bedrock.
Figure 2: Erosion due to deforestation
(Source: Wild Madagascar)
Colour gives a general indication of the
organic (and thus nutrient) and iron content
of the soil. With more organic matter the
soil is darker. Soils with high iron content
are usually found in the tropics. With good
aeration and drainage the soils have a bright
red colour. Without these features the soil is
more yellow in hue.
Figure 3: Generalised soil profile
Soil texture is influenced by particle size and
humus (decayed organic matter) content.
Soil particles are defined as:
0.05-2mm sand (very fine to very coarse)
0.002-0.04mm silt
< 0.002mm clay
The most basic categorisation of soils is as follows:
▪ Sandy soil – generally light, large soil particles, with rapid drainage and low organic content, 80-100%
sand
▪ Clayey soil – heavy soil, fine particles, low infiltration rate, practically impermeable when wet, very hard
when dry, 50-100% clay
▪ Loam – approximately 25-50% sand, 30-50% silt, 10-30% clay by volume
Ferralsols (FAO), otherwise known as oxisols (USDA), are most common in tropical rain forests, and are
typically red to yellow in colour due to the presence of iron, aluminium oxides and hydroxides.
As it rains, the litter
on the forest floor
causes acidification
(drop in pH) of the
water, which leaches
the soluble minerals
from the top layers.
Decay of litter is
very rapid, due to
the moisture and
humidity.
Thus,
nutrient uptake by
vegetation is also
very rapid. These
combine so that the
soils have very low
standing
nutrient
content.
Figure 4: Examples of variation in soil type (Source: Australian Natural Resources Atlas)
Figure 5: Soil types and attributes by latitude (Source: Encyclopaedia Britannica)
Erosion
There are various modes of erosion by water:
▪ Splash – results from the impact of raindrops on the soil surface.
The bombardment causes the displacement/detachment of soil
particles. The impact can dislodge particles as far as 3 feet. As they
resettle elsewhere they block soil pores and lower infiltration
capacity of the soil. Splash erosion also causes soil disintegration
(destruction of soil structure). Maintenance of vegetative cover
remedies this condition.
▪ Sheet – when rainfall
intensity is greater than
Figure 6: Splash erosion (Source:
infiltration a layer of water
NRCS/USDA)
moves across the soil
surface, transporting a uniform layer of soil. This layer
typically contains fine particles and a significant proportion of
the nutrients and organic matter.
▪ Rill – deep, fast-flowing channels are scoured into the ground
from the concentration of surface (sheet) water, detaching
and transporting soil particles. Flow velocity (and thus degree
of erosion) may be reduced by a rough surface e.g. grass, Figure 7: Sheet and rill erosion (Source:
ploughing or reduce in gradient. Alternatively the soil surface NRCS/USDA)
may be hardened to prevent movement.
▪ Gully – forms from the deepening and widening of rills, and
cannot be repaired using tillage equipment. This occurs as water
erodes the face or undercuts the head wall, causing upslope
migration; or via undercutting and collapse or slumping of side
walls. Once established gully erosion is difficult to mitigate and
requires a combination of control measures e.g. re-vegetate gully
floor and walls and the upstream catchment, divert surface
drainage away from the gully.
Wind erosion is more Figure 8: Gully erosion (Source:
NRCS/USDA)
common in arid and semi-arid
climates, and in periods of drought. It removes the most fertile
layer of soil, hence reducing soil productivity. Deposition of the
soil onto plant surfaces reduces their capability for photosynthesis
and respiration.
Figure 9: Wind
NRCS/USDA)
erosion
Airborne particles make visibility difficult, cause respiratory
problems and can cause sedimentation of watercourses when they
settle. Chemicals such as pesticides in the soil can also cause water
pollution.
Suspended particles can also cause erosion of solid
(Source:
surfaces (e.g. rock, walls) by abrasion.
Habitat alteration
Not only is it a major cause of biodiversity loss, changes in habitat also contribute to land degradation.
Most obvious is the conversion of forest lands to agriculture. Land clearance methods are often destructive
in themselves, denuding large swathes of land by slash-and-burn which robs the land of its nutrients and
water, and destroys its living organisms. Thus the soil is less fertile to begin with. Particularly with tropical
forests, the soil productivity is deceptive because the rich biodiversity is fed by rapid decomposition-uptake
processes leave very little nutrients lingering in the soil. Therefore farmers must apply many fertilisers and
other chemicals to raise the productivity. These pollute the soil and groundwater. Often cleared forests are
used for grazing cattle and other livestock. Overgrazing is often a problem, which leaves the soil exposed to
erosion. The productivity of the soils rapidly declines and in a matter of a few years it is no longer profitable.
The farmers move onto the next patch of forest, burn it down, and the cycle repeats itself.
Changing natural lands into urban or industrial environments is also very damaging. Urbanisation and
industrialisation both result in high population densities and intensive use of natural resources. They also
disrupt natural cycles and processes e.g. inhibiting natural drainage systems and reducing groundwater
recharge, remove large amounts of vegetation and soil, and release large amounts of pollution from
factories, vehicles and power stations. Soil contamination is more prevalent and pronounced in these areas
due to human activities e.g. dumping of chemicals and oils, leaching from landfills and open dumping,
discharge of effluents to the soil, infiltration of polluted water, leaking of storage tanks, or overflow of
overloaded septic systems.
Construction, mining and agriculture in unsuitable areas can also exacerbate degradation in areas that are
naturally prone. They remove the vegetative cover leaving the soil exposed to erosion. Soils that are prone
to slippage will be even more vulnerable with the vibrational impact of construction activities, the load of
homes and offices, etc. plus increased water introduced to the soil from domestic activities, septic tanks, etc.
Any damage inflicted if a disaster occurs will be more severe due to the danger to life and infrastructure. As
the demand for housing and tourism expansion in the region continues such areas will be under increasing
pressure for development.
Agricultural practices
Intensification and increased mechanisation of agriculture have led to the abandoning of many sustainable
traditional agricultural practices in favour of increased yields and faster production. Various methods,
techniques and equipment now used in agriculture at different scales are destructive to the soil and water
resources, and consequently gradually decrease the productivity of the land and thus the viability of the
industry. These include:
▪ Overgrazing of pasture land
▪ Overcultivation of cropland and monocropping
▪ Waterlogging and salinisation of irrigated land
▪ Overextraction of wells, rivers and dams
▪ Land clearance e.g. slash-and-burn, deforestation
▪ Excessive and continuous fertiliser, herbicide and pesticide use
▪ Conversion of unsuitable lands to agriculture e.g. use of marginal lands, clearance of tropical forest for
livestock rearing
Overcultivation and monocropping are usually associated with high levels of mechanisation which can
compact the soil, leaving the land bare between harvest and planting, both of which increase the potential
for erosion, and continuous loss of nutrients with application of large quantities of fertilisers. Monocropping
deprives the soil of specific nutrients because the same crop is always planted. Traditional agricultural
practices incorporated inter-cropping (planting e.g. yams and sweet potatoes between rows of cane or
banana trees) and rotation cropping (e.g. growing a cycle of potatoes, peas, yams and tomatoes one after the
other on the same plot of land). These help to secure the soil and prevent erosion, and ensure nutrients are
not depleted because different crops have varying nutrient requirements for growth. Legumes in particular
are usually planted in rotations because they fix nitrogen in the soil, a nutrient which is usually very limited.
Fallow or “rest” periods were also used in the past. Once every few years nothing was planted to allow the
soil to recuperate so that organic matter and nutrients re-accumulate and soil structure rebuilds.
Poor irrigation practices can lead to waterlogging which means there is no air in the pore spaces of the soil,
thus none available for plants. Salinisation is the excessive accumulation of salts in the soil, which can render
it infertile. This can occur due to a variety of reasons e.g. when irrigation
water has high salts content, when water evaporates leaving salt deposits
to build up, where there is poor drainage, or in areas with shallow water
table when capillary action brings the water to the surface where it
evaporates leaving the salts.
Ploughing straight downhill increases the
rate and severity of soil erosion because it
creates instant rills which can be
deepened into gullies. Good practice
Figure 10: Severe salinisation of
would dictate that when cultivating on
soils (Source: NRCS/USDA)
slopes there are a number of soil
conservation methods that should be used. Terracing divides the soil into
steps/levels with flat or nearly flat surfaces that can be planted on. This is
used where there is little mechanisation. Contour ploughing uses the shape of
the terrain and goes around or across the hillside. Strip cropping is similar to
inter-cropping, but instead of planting between rows, several rows of a crop
are planted before switching to another crop. Thus alternating bands of e.g. Figure 11: Terraces for rice cultivation
cotton and soybeans are created. This not only helps with maintaining soil (Source: S. McCouch, 2004, PLoS
fertility but creates barriers to water and minimise erosion. The use of these Biology)
practices is dependent on the gradient of the slope and the amount of rainfall received in the area.
Other tillage practices which influence soil conservation range
from conventional to reduced to conservation (ridge, strip,
mulch, none) tillage. These show progressive decrease in
mechanisation and removal of crop residue. Leaving the crop
residue increases the organic matter content of the soil as it
decays between the harvest and planting, and prevents soil
erosion.
Sustainable Land Management
The term SLM can be used to describe the utilisation of
terrestrial
resources (soils, plants, water, etc) for the production
Figure 12: Contour strip cropping and trees
for windbreaks (Source: NRCS/USDA)
of goods to satisfy changing human needs, without detriment
to the long-term productive potential of these resources and their environmental functions. In short, SLM
involves the use of land and its resources by various users without compromising ecological integrity,
biodiversity or natural capital:
▪ biodiversity – the array of species, populations, habitats and ecosystems
▪ ecological integrity – general health and resilience of natural systems, including the ability to assimilate
wastes and withstand stressors e.g. pollution, ozone depletion, climate change
▪ natural capital – stock of productive soil, forests, clean air, freshwater, ocean and other renewable
resources that underpin the survival, health and prosperity of human communities.
SLM is critical to minimising and rehabilitating the effects of land degradation, and ensuring optimal use of
resources for sustainable development and poverty alleviation. It seeks to resolve conflicts between
ecosystem function and the pressures on them due to intensifying social and economic development
activities. According to the FAO, SLM stands on four principles:
▪ user-driven and participatory approaches
▪ integrated use of natural resources at the ecosystem and farming system levels
▪ multilevel and multi-stakeholder involvement – farm, community, national, users, technical experts,
policy makers, etc
▪ targeted policy and institutional support, including incentive mechanisms for adopting SLM and income
generation at the local level
This framework aims to ensure that causes of degradation and mitigative measures are correctly identified,
and the policy and regulatory environment facilitates the implementation of the most suitable management
measures.
SLM can be approached by investigating signs of unsustainable activity e.g. soil degradation, biodiversity
loss, increased incidence of plant disease, water quality decline. Such indicators are a consequence of
resource exploitation and inappropriate land management, the causes of which are often political and
societal rather than technical or agronomic. SLM can also apply “options analysis” for land management
where different possible solutions are explored for their effectiveness in addressing the causes and impacts
of land degradation. Key questions are: why do land users employ inappropriate practices, or what inhibits
them from applying more appropriate technologies? Frequently, resource users are aware of degradation but
are not in a position to rectify it, often due to political and economic circumstances e.g. insecure land tenure,
misuse of subsidies and incentives, market price distortions, etc.
These complementary paths help to form solutions from political, technical and economic perspectives. The
complex inter-related causes of or contributors to land degradation must be identified to effectively design
remedial interventions. Activities to be considered must also include those which support training and
education; improve knowledge, local planning procedures and land management skills; create awareness;
enhance institutional development; and address pertinent policy issues. Such measures would ensure that the
work done to combat land degradation is not reversed because people and governments continue in their
old practices, but that they would acquire new knowledge and skills, and make policy improvements.
Several tools are available to assess the costs and impacts of land degradation and the changes and benefits
of implementing SLM. These would aid more informed decision making and strategic planning regarding
the approach to SLM that should be taken. These include assessing ecosystem services and economic
valuation [greater detail in the UNDP-GEF Environmental Economics Toolkit].
Barriers cited by regional governments as being prohibitive to the attainment of SLM throughout the
Caribbean include:
▪ limited access to appropriate information and technology
▪ inadequate technical and human capacity
▪ unsustainable land use practices
▪ deficiencies in institutional infrastructure e.g. lack of inter-agency coordination, ill-defined jurisdictions
and management roles
▪ failure to institutionalise and reinforce measures and capabilities arising as outputs from previous
projects
▪ high turnover rates of technically skilled personnel in government agencies
▪ inadequate or non-existent research and monitoring programmes for provision of accurate, timely data
to improve decision making
▪ conflicts between users and their goals
▪ insecurity of land tenure
▪ lack of specific national policies governing land management
▪ existence of regulations that are directly contradictory to sustainable land and environmental
management and development e.g. condoning vulnerable lands and sensitive ecosystems to tourism
▪
▪
▪
▪
▪
development, sanctioning developments in hazard prone locations, permitting gas stations and
mechanics operations within aquifer basins
ineffective implementation of tools that already exist e.g. land use zoning, development planning
lack of administrative support
insufficient financial resources
real or apparent inability of farmers to invest in soil conservation measures due to limited resources
cultural absence of a sense of personal responsibility and stewardship
With funding secured from GEF, and with implementation assistance from the UNDP, a number of
countries in the region are embarking on SLM projects to combat the problems associated with land
degradation. Among these are Grenada, Dominica, Barbados, St. Lucia, Belize, Jamaica and St. Kitts-Nevis.
A major component common to all these projects is the emphasis on capacity building and inter-agency
integration of functions and activities to address several of the barriers listed above.
CASE STUDY: Haiti
The family situation
The average size of a Haitian farm is about 2.5acres. On these 2.5acres there lives a typical Haitian family which has seven to eight
children and two parents. The family speaks the official language of the country, Creole, and all are poorly educated with an average of
a sixth grade education. The parents are between the ages of 25 and 28 and the children are between ages 3 and 9. The children
attend school but it may be sporadic and the parents hope that they will have the chance to complete eight years of school.
The small hut that the family calls home is the size of an average living room and very poorly built. Often many generations live in this
hut that is made of mud with a thatched roof or possibly scraps of lumber and rags. There is a glass-less window and a door-less
doorway.
The family is isolated in the highlands where running water, electricity and indoor plumbing have yet to reach them. The family is
surrounded by mountains and land that has been stripped bare. The father received this land by a claim of long term use. But during
his time of ownership he has stripped the land of trees that he can use for energy. This is a frequent occurrence in Haiti which once
had 37% of its 27,750km2 covered with forests. It is now below 1%.
This rampant deforestation has led to the fertile topsoil being blown
or washed away, swept out to the ocean or silting streams. The erosion
of the topsoil has restricted the quantity of crops the family will grow
and their ability to export them to make more money or feed
themselves.
The two children, one boy and one girl ages seven and eight, are the
minority in the area due to the rampant epidemic of neonatal tetanus
at the time of their births. The family has also suffered one stillborn
and two other deaths due to diarrhoea at eleven months and two years.
The family has an average calorie intake of 1,300 calories per person.
The average calorie intake for an adult female is about 1,800 calories
and for an adult male is about 2,500 calories. The family is primarily
self sufficient raising their own produce consisting of corn, beans, sweet potatoes, cassava, tomatoes and green, leafy vegetables. The
main foods in their diet are starches. If available fruits like pineapples, bananas and citrus fruits are consumed. The family only eats
rice if money is available or if a food relief package comes in to the village.
The family farm also raises two goats, four pigs, free range chickens and a few cattle. The goats that are raised are highly adapted to
rugged terrain and sparse vegetation. Goats are the most abundant animals in Haiti, about 54% of all farmers in Haiti raise goats. The
pigs that the farm raises are Creole pigs. Creole pigs are cheap and easy for the family to raise and are also a valuable asset; an asset
that could be sold or slaughtered at any point in time to cover a shortage in food or a shortage of money. Even with the production of
meat animals the family eats very little meat. The farm is located on a hillside and the soil retains very little nutrients. Rainfall often
does not coincide with the planting season which leaves a very low yielding crop.
There is no source of water on the farm so the mother has to spend the greater part of the day getting water and cooking the small
meals for the family. Their total income for the year is US$300-$400. This is mainly from the father who goes to the Dominican
Republic to work as a labourer in the fields for $0.35 an hour. If there is extra funding the family hopes to sharecrop another plot. If
there are extra vegetables that the family grows they will sell them and buy cheaper ones. The children are expected to do chores on
the farm and attend school but sometimes that proves difficult due to the lack of food and resultant fatigue.
Constantly declining agricultural productivity
Basic necessities are what the Haitian family is lacking: affordable health care, alternate energy sources, a dependable, clean water
source, modern sanitation system, and education for the farmers in the area. There is need for better roads and transportation
systems for the farmers to more efficiently move their products or supplies. The quality of food in Haiti is poor, and to increase
quality and productivity fertiliser, more modern tools and technology and better seed quality are needed.
The most significant factor in the poverty and hunger of the Haitian farmers is the extremely poor soil quality and the lack of
knowledge that the farmers have in sustainable farming techniques. The farming practices used are primitive and have changed very
little since the island was first inhabited by the Spanish. Use of
modern farm equipment has not been possible on the small, hilly
farms so shovels, digging sticks and machetes are still the norm.
The average farm is extremely limited in the production of food
for the family and rarely has food remaining to sell for a
supplemental income.
The situation in Haiti is slowly worsening as more soil continues to
erode and the land is deforested. On average Haiti loses 37065
acres of soil annually. There are insufficient funds going toward
agricultural development in the country. The Ministry of
Agriculture is allotted a very small budget relative to the
proportion of the population dependent on agricultural livelihoods.
The family’s situation varies with the seasons; but their condition is perpetually worsening with the constant erosion of the soil. The
family is malnourished with half of the needed calories for growth and maintenance of their bodies. The income of the family is around
half of what they need for basic necessities.
Progress and poverty
Haiti is the poorest country in the Western Hemisphere, with
80% of the population living below the poverty line and 54% in
abject poverty. The population is growing at an average rate of
2.493% a year (2008 est.) and urban expansion rose by 4%
between 1971 and 1982. The Gross Domestic Product in Haiti was
$11.14 billion in 2007. A macroeconomic programme developed in
2005 in conjunction with the IMF helped realise 3.5% economic
growth in 2007, the highest since 1999. According to 2003
estimates 52.9% of the population is literate. This is compared to
1982 when 65% of the population had no education. However, the
rapid urban expansion results in a decline of the rural population. Consequently Haiti is neither producing enough food nor making
enough money to support its growing population.
Nearly all of the 30 million trees planted in the 1980s during a USAID US$22.8mil project have been cut down to make charcoal for
cooking. The lack of soil cover makes the land increasingly vulnerable to severe and flash floods during the hurricane season. A new
reforestation programme, “Floresta” has begun in Grand Colline.
Reports in 2003 indicated the situation in Haiti was worsening with 4 million malnourished people, the majority of which are in rural
areas. A silent food crisis has emerged. Agriculture, the main source of income, has been damaged by drought in the northwest and
flooding in the northeast over a period of four years earlier this decade. National food production is subsequently continuing to
decrease leaving much of the population hungry.
Photos: Ariana Cubillos (AP Photo Daylife)
RESOURCES
The United Nations Convention to Combat Desertification (UNCCD) entered into force in 1996.
http://www.unccd.int/convention/menu.php
http://www.unccd.int/convention/text/convention.php
http://www.unccd.int/cop/reports/lac/lac.php
Land degradation is one of the Global Environment Facility’s (GEF) 5 focal areas
http://www.undp.org/gef/undp-gef_focal_areas_of_action/sub_land_degradation.html
http://www.undp.org/gef/undp-gef_focal_areas_of_action/sub_undpgef_focal_areas_of_action_documents/UNDPGEF_LaDeg_Presentation_GEFAssembly_Oct02.ppt#309,
1,
http://www.undp.org/gef/undpgef_publications/publications/interlink%20droughtdesertif%20water_fc%20gm%20unccd.doc
Capacity building and mainstreaming of SLM for LDCs and SIDS projects are being undertaken in 47
countries worldwide, funded by UNDP-GEF
http://www.gsu.co.za/
http://www.gsu.co.za/PublishedDocuments/tabid/64/Default.aspx
FAO databases and information systems
http://www.fao.org/tknet/topics/area_view?areaId=infsys&lang=en
http://www.fao.org/corp/statistics/en/
Check in particular:
FAOSTAT http://faostat.fao.org/
ECOCROP http://ecocrop.fao.org/ecocrop/srv/en/home
SIDS http://www.fao.org/sids/
TERRASTAT http://www.fao.org/ag/agl/agll/terrastat/
FORIS http://www.fao.org/forestry/country/en/
CEHI (the Caribbean Environmental Health Institute, based in St. Lucia) has been designated with the lead
role in provision of technical support services to the CARICOM Member States implementing SLM
projects under the GEF LDC-SIDS Portfolio Project.
http://www.cehi.org.lc/SLMLDC-SIDS/cehi_slm_main.html