UNITED NATIONS POPULATION INFORMATION NETWORK (POPIN)
UN Population Division, Department of Economic and Social Affairs,
with support from the UN Population Fund (UNFPA)

Population and Land Degradation (Annexes 1-5)

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collaboration with the Population Programme Service, Women and Population 

Division of the Food and Agriculture Organization of the United Nations.  

For further information, please contact Mr. Jacques du Guerny, Chief of 

the Population Programme Service, via email: jacques.duguerny@fao.org

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From:  Population and Land Degredation.  Rome: FAO, Women and Population 

Division, Population Programme Service, September 1995.





                               ANNEX 1



                              FIGURE  4



                           THE EARTH LAND



                  TOTAL AREA:  13 BILLION HECTARES





         *"Other land" includes barren and developed land.



  ================================================================



                 SOIL AS A CRITICAL NATURAL RESOURCE







      Soil-is much more than a simple medium for crop production.

It is a dynamic ecosystem, a living membrane that cycles life-

sustaining nutrients between bedrock and atmosphere.  Good soils are

home to some of the world's highest and most diverse Population of

species, including earthworms, insects and microorganisms that help

plants absorb nutrients and even protect against disease.23/  These

organisms break down dead plant and animal tissue to form humus, the

dark and crumbly carbon-based portion of soil.  Healthy soils rich

in humus soak up water, invite airflow and resist erosion.  Humus-

poor soils shed water, restrict root growth and break apart in rough

weather.  Soil ecosystems are threatened by the progressive loss of

organic material as farmers abandon organic for chemical fertilizers

and offer the land less fallow, or resting, time.  Currently,

however, little research is being conducted on the species

composition and biological properties of soils.



      Soil may hold three times as much carbon as all the world's

plants, 24/  but its carbon content is diminishing.  Since the drawn

of agriculture, an estimated 60 billion tons of soil carbon have

risen from the soil to the atmosphere as climate-warming carbon

dioxide.  This amount is equivalent to a decade of global fossil fuel

combustion at current rates.25/



      Cultivated soils lose not only humus and organisms but also

micronutrients needed for plant and human health.  Fertilizers

replace nitrogen, phosphorus and potassium in soils, but rarely much

else.  As crop after crop is reaped front the soil and shipped

elsewhere, with little return of comparable organic material to the

soil, there is no assurance that sufficient micronutrients will

remain in the soil for future crops and future generations.26/, 27/





23.   Committee on International Soil and Water Research and

      Development, 1991.  Toward Sustainability:  Soil and Water

      Research Priorities for Developing Countries.  Washington, DC:

      National Academy Press.



24.   National Research council, 1993.  Sustainable Agriculture and

      the Environment in the Humid Tropics.  Washington, Dc:

      National Academy Press.



25.   Kevin G. Harrison, Wallace S. Broecker and Georges Bonani 1993.

      "The Effect of Changing Land Use on Soil Radiocarbon".

      Science, vol. 262 (October 29).



26.   Margaret R. Biswas, 1994.  "Agriculture and Environment:  A

      Review, 1972-1992."  Ambio, vol. 23, No. 3 (May).



27.   Judith McGuire, 1993.  "Addressing Micronutrient Malnutrition."

      SCN News. No. 9, United Nations Administrative Committee on

      Coordination.



      Source:  Engelman and LeRoy (1995).





======================================================================





                            ANNEX 2



             Regional patterns of land degradation



     The extent of the degradation problem and its patterns

vary notably among regions:



  -  Africa has 25% of wasteland (the highest proportion among

     regions), 12% lightly or moderately degraded and 4%

     strongly or extremely degraded land (also the highest

     proportion). The main type of degradation by far is the

     loss of topsoil (76% of the degraded area) followed by

     the loss of soil nutrients (9%). Burkina Faso, Burundi,

     Ethiopia, Madagascar, Lesotho, Morocco and Rwanda are

     particularly affected.



  -  North and Central America has 6% wasteland, 6% lightly or

     moderately degraded and 1% strongly degraded land. The

     main types of degradation are the loss of topsoil (75% of

     the degraded area) and terrain deformation from water

     erosion (16%, but 40% in Central America). Costa Rica, El

     Salvador and Panama are the most affected countries.



  -  South America has 1% wasteland, 11% lightly or moderately

     degraded and 1% strongly or extremely degraded land. The

     main types of degradation are loss of topsoil from water

     erosion (39% of the degraded area), loss of soil

     nutrients (28%) and terrain deformation from water

     erosion (12%). Brazil is particularly affected.



  -  Asia has 11% wasteland, 15% lightly or moderately

     degraded (the highest proportion among regions) and 3%

     strongly or extremely degraded land. Again the main type

     is loss of topsoil (71% of the degraded area), the next

     being terrain deformation (16%); salinization (7%) is

     significant. China, India, Thailand and Vietnam are

     particularly affected.



  -  Australasia has 11% wasteland, 11% lightly or moderately

     degraded and a negligible proportion of strongly or

     extremely degraded land. For 95%, degradation consists in

     the loss of topsoil.



  -  Europe has a negligible proportion of wasteland, 22%

     lightly or moderately degraded and 1% strongly or

     extremely degraded land. The main types of degradation

     are loss of topsoil from water erosion (61% of the

     degraded area) and compaction (15%).



     The table below quantifies the area not affected by

degradation or wasteland, as a proportion of total land area,

by region.



    Proportion of total area in stable and other terrain not

    degraded by human action, wasteland excluded, by region.



    ---------------------------------------------------------

     North America...... 91%     WORLD.............. 74%

     South America...... 85%     Asia............... 71%

     Australasia........ 78%     Central America.... 62%

     Europe............. 77%     Africa............. 59%



    ---------------------------------------------------------



==========================================================================





                              Annex 3.



                     THE CONSEQUENCES OF EROSION





      Source:  FAO (1992).







=====================================================================



                              ANNEX. 4





                       LIVESTOCK & ENVIRONMENT







      Livestock have been criticised for damaging the environment

in a number of ways.  However, the role of livestock as agents of

environmental damage has often been misunderstood and,

consequently, misrepresented.  Current independent opinion based

on research in the field presents a more balanced and positive

view of livestock and their role in sustainable agriculture in

developing countries.



      CRITICISM:  "Demand for pasture has resulted in

deforestation in the Amazon and Africa"



      *   In Africa livestock are not important components of

rainforest agricultural systems and it is rare in Africa and

elsewhere for forests to be cleared for small scale livestock

production.



      *   Where forest has been cleared for livestock production,

as in the Amazon, it has been by large companies responding to

financial incentives to clear forest and re-seed with pasture.

Often government and external finance has been involved and they

must carry the blame, not livestock or small scale livestock

producers.





      CRITICISM:  "Overgrazing in semi-arid areas destroys

vegetation and leads to desertification"



      *   "Livestock have been charged with wholesale devastation

of African rangelands and irreversible destruction of soils -

desertification.  Heavy grazing has changed vegetative cover, but

has not seriously decreased the productivity of rangelands.  The

greatest threat to this region comes from human populations and

expansion of cultivation.  There is no solid evidence linking

livestock to this process."



(Winrock International Institute for Agricultural Development

Report 1992)



      *   "There are good scientific arguments for the case that

pastures are more productive when they are grazed low - in other

words when they appear more desert-like.  Up to a point, plants

produce more new and fresh growth if they are encouraged by being

grazed, and they may be less vulnerable to drought if they are

kept small."



(Andrew Warren, University College, London.  Report to U.N. 1991)





CRITICISM: "Over-stocking of pastures and concentration of cattle

around watering points accelerates soil erosion"



      *   The two conventional wisdoms - that on the one hand

livestock numbers have been rising for a long time, well beyond

the calculated sustainable carrying and that on the other hand the

productivity of rangelands has been falling for a long time - do

not lie at all well together."

(Ridley Nelson, senior researcher, World Bank working paper 1988)





      *   "The view that cattle watering points act as centres or

poles of desertification is now questioned.  Only under extreme

densities of cattle is soil erosion serious.  Overgrazing has been

greatly over-estimated as an environmental problem."

(Andrew Warren, University College, London.  Report to U.N. 1991)





Where managed correctly the benefits of livestock to the

environment and economy greatly outweigh any potential damage.

Contributions to a healthy environment include the ability of

livestock to utilize foliage and forage that grow on marginal land

and to recycle many otherwise wasted products into high value

products.







                       LIVESTOCK & ENVIRONMENT







      Livestock in marginal lands



Vast areas of the world are semi-arid or arid. Crop production is

extremely risky or impossible and only grasses, shrubs and trees

grow with any certainty.  These provide grazing and browse to

livestock, which are the only means of survival for millions of

pastoralists.



      Traditionally pastoralists established complex systems of

management which were sustainable.  Given supporting services such

as marketing, it is possible for pastoralists, through their

livestock, to use arid -land vegetation and to convert it to

valuable high quality products.



      Preventing erosion and adding fertility



      Where rainfall is sufficient, crops and fodder trees can be

intercropped to mutual benefit.  Fodder hedgerows planted on the

contour provide forage for livestock and simultaneously protect

the soil from wind and water erosion.  Deep-rooted perennial

species replenish soils with minerals from lower levels while

leguminous trees provide nitrogen to soil and protein-rich feed.



      Where livestock are a risk to crop land they may be confined

in stalls or yards and forage can be cut and carried to them.

Manure from enclosed livestock is a valuable and convenient source

of fertilizer.



      Livestock as source of pollution



      Livestock manure has been cited as a source of pollution but

accumulation of excreta and contamination of groundwater with

nitrites is primarily a problem with large-scale, intensive

livestock systems.  In smallholder systems, dung is valued as a

fertilizer.



      Ruminant livestock (cattle, sheep and goats) produce methane

as an end product of digestion.  As a result ruminants have been

criticised for contributing to the greenhouse effect and global

warming. However, this must be seen in perspective:



      *   Methane from ruminant digestion forms only some 2.5% of

the total greenhouse gases:  gas emissions from cars, power

stations, industries and domestic fires are much greater





      *   Emissions of methane from livestock have increased at a

much slower rate in recent years than emissions from direct human

activities.



      *   It is possible to reduce the production of methane by a

factor of 4 to 6 per unit of milk produced by feeding ruminant

animal a nutritionally balanced diet.



      *   Methane produced per unit of meat could be reduced by

increasing meat production from non-ruminant species.





      Recycling through livestock



      Feeding crop residues to livestock and using their dung as

fertilizer and soil conditioner benefits the environment directly.



      Soils treated with dung have better structure, water

retention and draining capacity.  As a result crops grow faster,

providing good ground cover and erosion may be reduced.



      In practice, properly managed livestock have an integral

role in sustainable agricultural systems in many developing

countries.



===================================================================



                              ANNEX. 5



                Machakos:  A Qualified Success Story





      With effort, farmland can be conserved and even improved as

local population grows rapidly.  This is the lesson offered by the

1.4 million-hectare Machakos district near Nairobi in Kenya.  What

is not clear, however, is that such conservation successes can be

sustained indefinitely as populations continue to grow.



      A region of steeply sloping land that receives rare and

erratic rainfall, Machakos was first settled by the Akamba people

in the early part of the 20th century.  By the 1930s, it had been

severely degraded by overuse, with less than 5 per cent tree cover

and soil erosion visible in 75 per cent of the inhabited area.

Some observers predicted ecological collapse.  Instead, the

reverse happened.  Over the next six decades, the population of

Machakos expanded almost six-fold, to 1.4 million.  Yet soil

erosion decreased, tree cover increased, and the district moved

closer to self-sufficiency in food.  More people were talking

better care of scarce, and therefore precious, land, even as they

coaxed more production out of each hectare.



      Surprisingly high population densities may be compatible

with sustainable land use under certain conditions.  Within

Machakos, many farmers were able to diversify their income by

finding non-farm jobs, applying the additional income to land

conservation.  Education, land tenure, community-government

partnerships and prominent leadership roles for women also

enhanced conservation efforts.64  But this does not support the

idea that population growth per se is good for land.  The

diversity of natural vegetation and wildlife in Machakos has

declined, and local soils may also be deteriorating in quality,

although only limited data is available.



      Key natural thresholds may eventually be exceeded in

Machakos.  The fact that yields and some indicators of soil

quality improved between 1930 and 1990, despite the rapid

population growth, demonstrates the capacities of committed and

resourceful farmers.  Yet this experience hardly suggests the

district's human population could increase sixfold yet again and

still improve yields and reduce soil erosion.  Finding the balance

between people and land remains a critical task.


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