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Causes of Environmental Degradation
Deforestation disturbs animal habitats.By Jared Skye
The primary cause of environmental degradation is human disturbance. The degree of the environmental impact varies with the cause, the habitat, and the plants and animals that inhabit it.
Habitat Fragmentation
Habitat fragmentation carries long term environmental impacts, some of which can destroy entire ecosystems. An ecosystem is a distinct unit and includes all the living and non-living elements that reside within it. Plants and animals are obvious members, but it will also include other components on which they rely on such as streams, lakes, and soils.
Habitats become fragmented when development breaks up solid stretches of land. Examples include roads which may cut through forests or even trails which wind through prairies. While it may not sound all bad on the surface, there are serious consequences. The largest of these consequences are initially felt by specific plant and animal communities, most of which are specialized for their bioregion or require large areas of land to retain a healthy genetic heritage.
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Area Sensitive Animals
Some wildlife species require large stretches of land in order to meet all of their needs for food, habitat, and other resources. These animals are called area sensitive. When the environment is fragmented, the large patches of habitat no longer exist. It becomes more difficult for the wildlife to get the resources they to survive, possibly becoming threatened or endangered. The environment suffers without the animals that play their role in the food web.
Aggressive Plant Life
A more critical result of habitat fragmentation is land disturbance. Many weedy plant species, such as garlic mustard and purple loosestrife, are both opportunistic and invasive. A breach in the habitat gives them an opportunity to take hold. These aggressive plants can take over an environment, displacing the native flora. The result is habitat with a single dominant plant which doesn't provide adequate food resources for all the wildlife. Entire ecosystems are threatened with extinction, according to the National Resources Defense Council.
Some weeds are so invasive and aggressive that they are declared noxious by the federal or state governments to prevent them from destroying unspoiled areas. The cultivation or even the sale of noxious weeds is prohibited by law.
Human Sources of Environmental Deterioration
Humans and their activities are a major source of environmental degradation.
Water and Air Pollution
Water and air pollution are unfortunately the common causes of environmental degradation. Pollution introduces contaminants into the environment that can maim or even kill plant and animal species. The two often go hand in hand.
Acid Rain
Acid rain occurs when sulfur dioxide from coal plant emissions combines with moisture present in the air. A chemical reaction creates this acid precipitation. Acid rain can acidify and pollute lakes and streams. It causes similar effects to the soil. According to the U.S. Environmental Protection Agency (EPA), if enough acid rain falls in a given
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environment, it can acidify the water or soil to a point where no life can be sustained. Plants die off. The animals that depend upon them disappear. The condition of the environment deteriorates.
Agricultural Runoff
Farming creates agriculture runoff issues.
Agricultural runoff is a deadly source of pollutants which can degrade environments, so much so that the EPA identifies agriculture as the primary source of water pollution.
Surface water washes over the soil and into lakes and streams. When it does so, it carries the fertilizers and pesticides used on the farm lands into water resources. Introducing poisons into waterways will have dire consequences. Fertilizers, whether or not they are organic, carry equal risks.
Fertilizers containing large amounts of phosphorus can cause explosions of algae in lakes. As the algae die, bacteria start to breakdown the organic material. It soon develops into a situation where bacteria are using up the available dissolved oxygen in the water. Plants, fish, and other organisms begin to die off. The water becomes acidic. Like acid rain, lakes become dead zones with conditions so toxic that neither plants nor animals can live in these environments.
Urban Development
According to many noted ecologists, including those at Cornell University, urban development is one of the primary causes of environmental degradation. As populations increased, so did the need for land for homes and farms. Wetlands were drained. Prairies were plowed over. Today, less than 50 percent of the nation's wetlands still exist, according to the North Carolina State University Water Quality Group. National Geographic states that only five percent of the native prairie remains.
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Environmental degradation is one of most urgent of environmental issues. Depending upon the damage, some environments may never recover. The plants and animals that inhabited these places will be lost forever. In order to reduce any future impacts, city planners, industry, and resource managers must consider the long term effects of development on the environment. With sound planning, future environmental degradation can be prevented.
Natural Causes
Mother Nature causes environmental problems, too.
While environmental degradation is most commonly associated with the activities of humans, the fact is that environments are also constantly changing over time. With or without the impact of human activities, some ecosystems degrade over time to the point where they cannot support the life that is "meant" to live there.
Things like landslides, earthquakes, tsunamis, hurricanes, and wildfires can completely decimate local plant and animal communities to the point where they can no longer function. This can either come about through physical destruction via natural disaster, or by the long-term degradation of resources by the introduction of an invasive alien species to a new habitat. The latter often occurs after hurricanes, when lizards and insects are washed across small stretches of water to foreign environments. Sometimes, the environment cannot keep up with the new species, and degradation can occur.
Understanding Degradation
There are a number of reasons that ecosystems degrade over time. While it may not always be the fault of humans, humans still need to recognize the extent to which they rely on the resources that the natural world provides. In this sense, environmental responsibility and stewardship are very much a matter of self-preservation, and are an integral part of healthy resource management practices.
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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 (Text)
***************************************************************************
This document is being made available by the Population Information
Network (POPIN) of the United Nations Population Division (DESIPA), in
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: [email protected]
****************************************************************************
Population and the environment:
a review of issues and concepts
for population programmes staff
II.
POPULATION AND LAND DEGRADATION
Page 6
September 1995
========================================================================
FOREWORD
This paper is the second in a series designed to bring to the
attention of Country Support Team Advisers (and staff of UNFPA
programmes concerned) state-of-the-art information on major
population-environment issues and methodological advice for dealing
with such issues in the context of population policy work and
population/development programmes.
The purpose of each paper is to help fellow population
specialists at the regional and country level carry out such tasks
as:
- promote awareness of population and environment linkages
and related issues qua relevant elements in development
policies;
- help integrate environmental concerns and considerations
in population policy analyses;
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- help design or carry out population-centred research in
support of development policy studies; or
- help design data collection and monitoring systems on
population/environment issues.
For this purpose, each paper provides factual information on
the environmental issue(s) under review, tries to elucidate the role
of population variables, proposes analytical tools and examines
statistical information problems where appropriate.
The first paper focused on water resources issues.1/ The
present one deals with land degradation, a global problem of crucial
importance in view of the vital functions of soils in the survival
of the people.
This paper is addressed to Country Support Team Directors,
Advisers on Population and Development, and FAO Advisers. Suggestions
for further distribution and requests from field projects are
welcome.
Alain Marcoux
FAO/UNFPA TSS
========================================================================
CONTENTS
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1. LAND DEGRADATION: TYPOLOGY OF ISSUES 4
1.1 Erosion 4
1.2 Chemical deterioration 5
1.3 Physical deterioration 5
1.4 On "desertification" 6
2. EXTENT AND IMPACT OF LAND DEGRADATION 6
2.1 Incidence by type of degradation 6
2.2 Impact of land degradation 7
3. CAUSES OF LAND DEGRADATION:
THE ROLE OF POPULATION FACTORS 9
3.1 The causative factors 9
3.2 Population and land degradation processes 12
3.2.1 Deforestation and overexploitation
of vegetation 12
3.2.2 Overgrazing 13
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3.2.3 Improper agricultural management 15
3.3 Population and technological factors 17
3.4 Social and institutional factors 20
3.4.1 Agrarian structures and poverty 20
3.4.2 Land tenure 22
3.4.3 Markets and public policies 23
4. CONCLUDING REMARKS 24
4.1 Population in the chains of explanation
of land degradation 24
4.2 Relevance for population programmes 25
REFERENCES 28
NOTES 31
ANNEXES
======================================================================
If the soil on which agriculture and all human life depends
is wasted away then the battle to free mankind from want
cannot be won.2/
Land, like water, is a vital resource to humankind (see Annex
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1); but that resource is easily overrated. Only 11 percent of the
world's land area presents no limitations for agricultural use; on
some 28 percent the climate is too dry, and on 10 percent it is too
humid; on 23 percent the soil has critical chemical imbalances, and
on 22 percent it is too shallow; the remaining 6 percent is
permanently frozen (FAO, 1980). In addition, various forms of
degradation attack that resource as a result of various natural and
human-made factors. This paper is devoted to a review of some related
issues.
1. LAND DEGRADATION: TYPOLOGY OF ISSUES
The concept of land degradation "refers to the deterioration
or total loss of the productive capacity of the soils for present and
future use" (FAO, 1980). Such loss occurs mainly because of various
forms of erosion (by wind and water) and of chemical and physical
deterioration. This typology, as established for the Global
Assessment of Soil Degradation (GLASOD) project (ISRIC/ UNEP, 1991),
is reviewed hereunder and will be used in the rest of this paper.
1.1 Erosion
The most common form of erosion is the loss of topsoil under
the action of water or wind. Water runoff carries the topsoil away;
this occurs under most climatic and physical conditions. Displacement
of topsoil by wind action is more widespread in arid and semi-arid
climates than under more humid conditions. The loss of topsoil
reduces fertility because [a] as the soil becomes denser and thinner,
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it is less penetrable by growing roots and may become too shallow
for them; [b] the capacity of the soil to retain water and make it
available to plants is reduced; and [c] plant nutrients wash away
with soil particles.
A more extreme form of erosion is terrain deformation. Water
may cause the formation of rills (i.e. small channels, which can be
ploughed over) and gullies (i.e. deeper channels, cut by larger water
flows and difficult or impossible to level by ploughing). It may also
cause the destruction of riverbanks, and mass movement (landslides).
Wind action may create deflation hollows and dunes. Finally, the
covering of the land surface by wind-carried particles (or
overblowing) is also recognized as a specific form of degradation.
Erosion risks depend both on natural conditions and on land use
patterns. The climate (especially rain intensity), slopes, vegetation
cover, and nature of the soil are important.3/ With regard to land
use, any human activity which entails the removal of the protective
vegetation cover (forest, shrubs, grass etc.) fosters erosion; so do
improper measures such as ploughing along slopes.
1.2 Chemical deterioration
Chemical deterioration may consist in:
(a) The loss of soil nutrients (mainly nitrogen, phosphorus and
potassium) or organic matter. In part, nutrients are lost through
erosion: "in the humid tropics, many nutrients are leached during the
intense rainstorms, especially on unprotected land"; in addition,
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they can be "depleted by the crops themselves, particularly if the
same crops are grown on the same land year after year" (FAO, 1983).
Depletion is widespread where "agriculture is practised on poor or
moderately fertile soils, without sufficient application of manure
or fertilizer" (ISRIC/UNEP, 1991).
(b) Salinization, or the concentration of salts in the topsoil,
which may occur because of: (i) poor management of irrigation
schemesþhigh salt content of irrigation water or insufficient
attention to drainage can easily lead to rapid salinization of the
soils, especially in arid areas where high evaporation rates foster
the process; (ii) the intrusion of seawater or saline groundwater in
water reserves of good quality;4/ or (iii) human activities which
increase evaporation in soils on salt-containing material or with
saline groundwater (ISRIC/UNEP, 1991). Salinization has "a
deleterious effect on soil productivity and crop yields" (FAO, 1994);
in extreme cases, "damage from salinization is so great that it is
technically unfeasible or totally uneconomic to reverse the process"
(FAO, 1983).
(c) Acidification, which may occur either because of excessive
application of acidifying fertilizer or because of drainage in
particular types of soil; and
(d) Pollution of various origins (waste accumulation, excessive
use of pesticides or manuring, oil spills etc.), can strongly reduce
the agricultural potential of lands.
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1.3 Physical deterioration
Three types of physical deterioration are recognized:
(a) Soil compaction, usually resulting from the use of heavy
machines on unstable soils or from cattle trampling; sealing and
crusting, usually caused by the impact of raindrops. These conditions
make tillage more costly and impede seedling emergence. Also, by
restricting water infiltration, they cause faster run-off and water
erosion.
(b) Waterlogging, i.e. the rise of the water table to the root
zone of plants, caused by an excessive input of water with respect
to drainage capacities. It is typical of irrigated areas, but may
also occur through river flooding. Waterlogging also increases
salinity (see above). As with salinization, the causes of
waterlogging are in part physical and in part related to agricultural
practices, namely inappropriate irrigation.
(c) Subsidence (i.e. lowering of the land surface) of organic
soils, which can be caused by drainage or oxidation.
1.4 On "desertification"
A note about the concept of desertification is needed. The
United Nations Conference on Desertification, which popularized the
word, defined it as "the reduction or destruction of the land's
potential, finally resulting in the appearance of desert conditions"
(United Nations, 1977). Gorse and Steeds (1987) write about a process
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of decline in the biological productivity of land that results in
"desert, or skeletal soil that is irrecuperable".
Although in principle one should use the concept only in
reference to processes which have resulted in desert conditions þor
will shortly and inevitably do soþit is often used in a broader
sense. UNEP (1991) defines it as land degradation in arid, semi-arid
and dry sub-humid areas resulting mainly from adverse human impact.
The particular attention to dry climate settings owes much to the
droughts of the 1970s and early 1980s and the alleged expansion of
the Sahara.5/
The term "desertification" has some annoying aspects. It
provides no information on the nature of the degradation, nor on the
nature of possible corrective actions. It misstates problems: "The
concept of expanding deserts and advancing sand dunes has become the
dominant image in the public's eye rather than [...] less visible and
much more serious problems" (Liamine, 1993), in particular "more
subtle, more complex, pulsating deteriorations, sometimes with
reversals, but at least with substantial periodic remissions,
radiating out from centers of excessive population pressure" (Nelson,
1990). And it seems to designate an absolute evil, while the
salinization of an irrigation area, although reversible, may be a
greater loss than the washing away of the last inch of topsoil in a
marginal area.
For FAO (1986a), desertification "is only one extreme aspect
of the widespread deterioration of ecosystems under the combined
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pressure of adverse climate and agricultural exploitation". The rest
of this paper will implicitly cover "desertification" in this sense,
but usually will not isolate it from land degradation phenomena in
general.
2. EXTENT AND IMPACT OF LAND DEGRADATION
2.1 Incidence by type of degradation
The GLASOD study, covering most of the world's land surface
(ISRIC/UNEP, 1991), found that globally 15% of the land area was
degraded as a result of human activities 6/ ; the respective impact
of the various forms of degradation at the global level was estimated
as reported in Table 1 (next page). Annex 2 provides details on
patterns of degradation at the regional level.
Table 1. Incidence of 10 forms of land degradation at the
global level (percentage of total area degraded)
Loss of topsoil....... 70.0% Pollution............. 1.1%
Terrain deformation... 13.0% Overblowing........... 0.6%
Loss of nutrients..... 6.9% Waterlogging.......... 0.5%
Salinization.......... 3.9% Acidification......... 0.3%
Compaction............ 3.5% Subsidence............ 0.2%
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The impact of salinization and waterlogging must be measured
with reference to irrigated areas. FAO (1994) estimates that, out of
some 240 million hectares currently irrigated, about 30 are severely
affected by salinity and another 60 to 80 are affected to some
extent. Of the four countries with the largest irrigated areas
(together accounting for half of the global area) salinity affects
28 percent of irrigated land in the USA, 23 percent in China, 21
percent in Pakistan and 11 percent in India (Umale, 1993).
The rate at which degraded areas expand is poorly known on a
global scale, because there exist no preceding data with which to
compare GLASOD results. Estimates vary commonly between 5 and 12
million hectares lost annually (out of a total 4.8 billion hectares
of arable land and pastures). FAO warns that much progress still
needs to be made on land use data collection before this and other
important trends are adequately known.
The extent of the threat is certainly considerable: on the
basis of its classical study on potential population-supporting
capacities of the lands, FAO (1984) estimated that without soil
protection measures, close to 550 million hectares of rainfed
cropland could be lost during 1975-2000, with percentage losses
ranging from 10 percent in south America to 38 percent in Asia. In
addition much of the remaining cropland would lose some fertility due
to the degradation of topsoil, with an overall loss in production
potential in the order of 30 percent.7/
2.2 Impact of land degradation
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Some typical consequences of land degradation are illustrated
in Annex 3. Let us review on- and off-farm effects, then look briefly
into the question of aggregate effects at the sector level.
The main on-farm effect of land degradation is a decline in
yieldsþor an increased need for inputs to maintain those yields:
since "subsoils generally contain fewer nutrients than topsoils, more
fertilizer is needed to maintain crop yields. This, in turn,
increases production costs. Moreover, the addition of fertilizer
alone cannot compensate for all the nutrients lost when topsoil
erodes" (FAO, 1983). Where degradation is serious, the plots may be
either abandoned temporarily or permanently, or converted to inferior
value uses, e.g. cropland being converted to grazing land, or grazing
land left to shrubs.
With salinization and waterlogging in irrigated areas,
reductions in yields are even bigger because the starting point is
higher: field studies indicate reductions in yields oscillating from
30 to more than 80 percent; values around 50 percent are the most
common (Pinstrup-Andersen and Pandya-Lorch, 1994). The economic loss
resulting from such reductions in the very raison d'etre of the heavy
investments made is highly significant.
A complete picture of erosion costs should include offsite
effects. It has been argued that measurements of soil erosion from
test plots "typically overestimate the consequences for productivity,
since the eroded soil can remain for decades elsewhere in the farming
Page 18
landscape before it is delivered to the oceans. Thus, a portion of
on-site erosion represents a transfer of assets rather than a
complete loss from the standpoint of agricultural productivity"
(World Resources Institute, 1993). This argument should not be
carried too far. First, as the same source adds, geographic shifts
in productivity have potentially important distributional
consequences: it is not unimportant that topsoil washed from slopes
held by the poor ends up in valley bottoms held by the better-off,
or is lost by a mountainous country to the benefit of downstream
countries. Also, the fine soil particles for the most part are
carried to waterways and seas; along the way they may make water
unsuitable for human consumption, silt up dams, irrigation systems
or river transport channels. Eventually their nutrients are
permanently lost for agriculture, but cause nutrient loading and
eutrophication, damaging aquatic life systems and fisheries.
Indeed, even the better soils of many parts of developing
regions are gradually becoming less productive; some fertility
declines affect the very areas which call for urgent and sharp
production increases; one key reason is the "mining" of soil
nutrients by cropping without adequate replenishment. Land is also
taken out of production because of chemical pollution from all
origins including industrial and urban waste.
It is difficult to estimate the total losses caused by land
degradation worldwide. According to FAO (1992) about 25 billion
metric tons of soil (17 tons per cultivated hectare) erodes each
year. Translating this into an estimate of foregone production is
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even more difficult, since the effect varies from place to place
depending on the mix of productions, and the hypothetical reduction
in yields. Only crude estimates are possible. According to Sfeir-
Younis (1986), the food production of rainfed croplands could decline
by 19 to 29 percent over the 1985-2010 period. Brown et al. (1990)
estimated that land degradation worldwide causes the loss of roughly
14 million tonnes of grain annually, i.e. half the quantity needed
to cover the needs of the additional global population for the same
period.
In addition, eroded land becomes more vulnerable to climatic
variations; its fertility may collapse entirely after a year of
drought. "When production conditions are adverse [...] the margin of
productivity or of survival for a producer on degraded land is
smaller than that of a producer on better managed land [...] Land
degradation, as well as drought, has been partly responsible for the
severity of famine in agricultural areas of Ethiopia and Sudan"
(Blaikie and Brookfield, 1987).
Whether land productivity declines, or steps are taken to
restore productivity and prevent further losses, "the yield of labour
[...] is adversely affected. Land degradation, therefore, directly
consumes the product of labour, and also consumes capital inputs into
production" (Blaikie and Brookfield, 1987). Wellbeing diminishes
because it takes longer and harder work hours to obtain the same
product, not to mention taking protective measures on the fields,
fertilizing more intensively, or reaching more distant fields and
pastures.
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This added burden usually falls disproportionately on women
(except for land clearing work), because they are predominantly
involved in food crop cultivation and activities connected with
livestock. Also, decreases in the productivity of traditional
agriculture often are decisive in triggering out-migration (usually
of males), with consequent increases in the workloads of those left
behind, including children.
On less frequent, but dramatic occasions, land degradation
forces population displacement. Hundreds of thousands of hectares
have to be abandoned each year being too degraded for cultivation or
even grazing. This may mean that the population which depended on
those areas for subsistence must seek other lands to settle on. In
India, for instance, wasteland accounts for about 38 percent of the
land area (about the same as the total cropped area). Most of that
area was cultivated at some time in the past, but cultivation was
given up (mostly during this century) because of land degradation,
and the people formerly cultivating it were displaced to distant
areas (Maloney, 1991).
Also in India, it was estimated in 1990-1991 that about 8
million hectares were damaged by waterlogging or salinity from
irrigation and that as many as 1.5 million farmers had been displaced
by those problems since Independence. In Pakistan "irrigated land
[was] going out of production at the rate of 100 hectares a day";
many displaced farmers moved to the newly irrigated areas in Western
Punjabþlikely to face the same situation a few years later (Maloney,
1990). Others went to swell the numbers of urban slum dwellers.
Page 21
3. CAUSES OF SOIL DEGRADATION: THE ROLE OF POPULATION FACTORS
3.1 The causative factors
Figure 1 (page 10) illustrates the factors of land degradation
as described in section 1, distinguishing natural conditions and
human actions which facilitate or cause the different kinds of
degradation. It is worth noting that those factors have different
roles: some directly cause degradation; others merely enable the
action of the former. For instance, in the case of erosion, the
direct cause is the action of water or wind. That action is enabled
by a series of conditions, both human-made (deforestation, ploughing
slopes etc.) and natural (steepness, soil texture etc.). In the case
of salinization, the direct cause can be the intrusion of saltwater
in groundwater reserves, and overuse of freshwater the enabling
factor; or, the direct cause can be the mix of excessive irrigation
and insufficient drainage, with aridity an enabling or accelerating
factor.8/
Figure 1. Causation links between human actions,
soil degradation and natural conditions.
Table 2 classifies human actions and natural conditions, as
seen in Figure 1, into "direct factors" and "enabling factors"
categories. With these distinctions in mind, let us try to discern
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the role of population changes in the causative factors of land
degradation.
Table 2. A classification of factors of land degradation
------------------------------------------------------------
Human actions: Natural conditions:
------------------------------------------------------------
Enabling Deforestation Topography
factors: Allow overgrazing Soil texture
Excessive use of Soil composition
vegetation Aridity, drought
Ploughing slopes Vegetal cover
Removing grass for Hydrographic
cultivating regimes
-------------------------------------------------------------
Direct Use of machines Strong rains
factors: Driving cattle Floods
Shortening fallow Strong winds
Excessive water
input/insufficient
drainage
Excessive acid
fertilization
Excessive use of
chemicals/manure
Domestic/industrial
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waste disposal
-----------------------------------------------------------------
The GLASOD project quantified the impact of damaging human
activities, classifying these into five broad categories, as follows
(ISRIC/UNEP, 1991):
1/ Deforestation and removal of natural vegetation for cropping or
cattle raising, large scale commercial forestry, road
construction, urban development etc.
2/ Overgrazing (destroys soil cover, causes compaction and fosters
the encroachment of undesirable shrub species).
3/ Agricultural activities. Improper land management includes
cultivation of fragile soils, reduced fallow, uncontrolled use
of fire, "practices that result in the net export of soil
nutrients", diversion of rivers for irrigation purposes, or
irrigation of inadequate soils (FAO, 1993b).
4/ Overexploitation of vegetation for domestic use (use of the
vegetation for fuelwood, fencing etc., where the remaining
vegetation no longer provides sufficient protection from soil
erosion).
5/ (Bio-)industrial activities, causing pollution.
The GLASOD assessment then attributed degradation in each
surveyed area to one or two of these causative factors; Table 3 shows
Page 24
their respective impacts. While at the global level deforestation,
overgrazing and agricultural activities have relatively similar
incidence, at the regional level patterns differ markedly.
Overgrazing dominates in Australasia and Africa, agricultural
activities in North America and deforestation in the other regions.
Domestic overuse of vegetation is negligible in developed regions but
quite significant in Africa. Pollution is marginal, except in Europe.
Table 3. Incidence of the five causative factors of land
degradation, by region (percentage of degraded area)9/
---------------------------------------------------------------
Defore- Over- Agric. Overex. (Bio-)
station grazing activit. veget. indust.
----------------------------------------------------------------
Africa 14% 49% 24% 13% *
N./C.America 11% 24% 57% 7% *
South America 41% 28% 26% 5% -
Asia 40% 26% 27% 6% *
Australasia 12% 80% 8% * *
Europe 38% 23% 29% * 9%
WORLD 29% 35% 28% 7% 1%
---------------------------------------------------------------
Although erosion may take place without human intervention, in
practice it usually is started or/and accelerated by human actions
which cause the disappearance of the protective cover of natural
Page 25
vegetation or damage soil structure. Let us examine the role of
population factors in the occurrence of such practices.
3.2 Population and land degradation processes
This section reviews the possible linkages between population
factors (population size, geographic distribution, age/sex
structures, and changes in these), on the one hand, and the main
causative factors, i.e. the first four, on the other.10/
3.2.1 Deforestation and overexploitation of vegetation
The destruction of forests is caused for the most part by land
clearance for agricultural purposes. "Both slash-and-burn
agriculture, when land is not allowed to lie fallow as long as
traditional practices dictated, and permanent clearing for modern
farms, are taking a toll" (FAO, 1983). Shifting cultivation entails
"cutting trees and shrubs and tall grasses, burning the litter,
growing crops for 2 to 5 years on the cleared land, and then allowing
the natural cover to return to regenerate the soil [...] the fallow
period may last any time from 5 to 15 years, depending on the soil
and type of vegetation" (FAO, 1983). Such operations are estimated
to have contributed some 60 percent of the expansion of farmland
between 1973 and 1988.11/ The removal of vegetation cover starts or
accelerates soil erosion under rain and wind action, and "burning for
weed control [...] encourages leaching and soil loss" (Cruz, 1994).
Land clearing in shifting cultivation is largely driven by
population growth, through the growth in requirements food and other
Page 26
agricultural products. Comparatively, forest clearing for pastures
is a minor factor on a global scale (although it is important in
certain countries). There also are examples of rapid deforestation
for commercial agriculture. These seem of growing importance,
particularly in Latin America and Asia. But, so far and globally,
forest clearing has been more typical of situations of subsistence
agriculture (in addition, population growth also is a factor in
commercial agriculture). As for logging, it concerns smaller areas,
does not destroy the whole vegetation, and does not involve the
destruction of organic matter, roots, seeds etc. that forest burning
does; it does play an enabling role by opening access roads, but it
does not create the need for land clearing.
The other cause of destruction of the vegetation cover is its
overuse by households, mainly from fuelwood collection. To cover
vital energy needs, most households in developing countries resort
to "free" gathered biomass fuels, including crop residues and animal
dung but, most of all, fuelwood. When the annual use of wood exceeds
the sustainable yield of wooded areas, forests and woodlands are
gradually destroyed. This in turn triggers or accelerates soil
erosion.
Around 1980, FAO estimated that about 2 billion people (or 3/4
of the population of developing countries at that time) depended on
biomass for their daily energy consumption (FAO, 1983). But close to
1.4 billion of these could not meet their requirements without
compromising future fuelwood supplies, and it was expected that the
number would increase to 3 billion (2.4 billion in rural areas) by
Page 27
the year 2000.
The impact of population growth on fuelwood consumption in the
vast areas concerned is direct, since energy needs are essentially
proportional to population. Another feature of population dynamics
plays an important role, namely urbanization. A first effect arises
from population concentration, which makes the impact on resources
felt acutely over a peripheral zone which typically suffers
disproportionately from deforestation. A second effect arises from
changes in habits: urban dwellers frequently prefer charcoal to wood;
this increases the impact on wood resources per consumption unit.
Overall, population pressure is determinant in vegetation loss,
especially in areas with limited land reserves and energy sources.
In the high population density areas of West Africa, for instance,
"concentrations of demand for arable land and fuelwood lie at the
root of resource abuse. It is in these areas that patches of
desertification are the most visible" (Gorse and Steeds, 1987).
3.2.2 Overgrazing
Excessive pressure on the vegetal cover by animals can be a
crucial problem, especially in developing countries where rangelands
usually are much more crowded than in the developed world (FAO,
1983). While livestock does not necessarily cause environmental
problems (see Annex 4), overgrazing can be a major factor in land
degradation, causing half of the damage assessed in Africa and one-
fourth in other developing regions. Cases such as the damage caused
by goats in the Mediterranean area and elsewhere are well known. In
Page 28
Africa, the increase in cattle numbers and the decline in the quality
of rangelands have been significant during the recent decades (FAO,
1986b). These two trends are obviously incompatible in the long run,
and local crises are likely in the future.
Nomadic grazing in semi-arid areas is an environmentally
compatible, effective land use system developed over the centuries
by pastoralists; but local collapses of such systems are being noted
with increasing frequency. When more and larger herds compete for the
same rangelands, they may exceed the natural productivity of the area
and destroy the vegetal cover, accelerating erosion. In the Sudan for
instance, the growth of the pastoralist population and increased
livestock density have led to the extension of grazing activity into
forests and semi-arid marginal lands, causing degradation in both
zones (Bilsborrow and DeLargy, 1991).
For the most part, however, the relationship between human
population dynamics and overgrazing is not a matter of the
pastoralist population growth driving the changes in livestock
density. Rapid changes in the livestock population usually are driven
by external forces such as decisions by outsiders (e.g. when
sedentary populations entrust cattle to nomad groups) or animal
health factors (e.g. eradication of the Tsetse fly). Economic
circumstances, or special goals such as the need for security,
causing families to increase stocking densities, also play a part.
As for proper crises, they frequently are brought about by a rapid
decline in pasture resources available.
Page 29
In this context, droughts often are the trigger: "In dryland
grazing areas, large numbers of cattle and sheep tend to build up
during years of normal rainfall, too many to be supported during
years of drought. When the inevitable drought arrives, graziers are
naturally reluctant to cut back on herds after a single dry year.
When it becomes apparent that the drought will be prolonged and
serious, many ranges are already overgrazed" (FAO, 1983).
An important population factor, though, is the growth of
neighbouring populations, inasmuch as it leads sedentary farmers to
expand the cultivated area. With the reduction of fallow and the
advance of agricultural "frontiers", nomad pastoralists are
increasingly restricted in their movements, and available ranges
decline in quantity and quality (e.g. Little and Horowitz, 1987;
Bilsborrow, 1992a). This increases density even if livestock size
remains the same.12/ Degradation here is a side effect of
agricultural extensification or intensification. (It is to reconcile
the different logics of agriculture and pastoralism and forestall
such conflicts that FAO promotes integrated agro-pastoral development
models.)
It is thus reported (Talbot, 1989) that in Kenya, population
growth among both the Maasai pastoralists and the sedentary
agricultural population led to competition for land between the two
groups, overgrazing and "desertification" in certain areas. The
above-cited Sudan case has a germane aspect in that the increase in
fuelwood demand, which contributed to deforestation and therefore
degradation, was enhanced by the growth in the population of
subsistence farmers. The sedentarization of nomads, leading to the
Page 30
concentration of populations and herds on restricted ranges, has
similar effects (Fratkin, 1981; Little, 1987). So do political
conflicts that "contribute to population and livestock concentration,
which in turn perpetuate ecological degradation and food shortages"
(Hjort af Orn„s and Salih, 1991).
3.2.3 Improper agricultural management
A set of improper practices has to do with land extension, the
main problem being the gradual extension of cultivation to sloping
areas and, in general, to so-called "marginal" areas (previously left
aside because of the fragility of soils or of other limiting
factors). This is a common phenomenon in situations of "land hunger",
i.e. of high population density vis-a-vis arable land. Population
growth "requires the extension of interference into new areas, and
the subjection of these areas to the high levels of damage that
follow initial interference. It requires the occupation of sites of
lower resilience and higher sensitivity, for which existing
management practices may be inadequate" (Blaikie and Brookfield,
1987).
Degradation then sets in, unless particular measures are taken
to protect soil structure and maintain fertility. But such measures
usually are absent, since this kind of practices takes place in
situations where low-cost solutions are sought because resources are
lacking to invest in land protection. Examples of populations driven
upland by the saturation of lowland resources, with ensuing
degradation and at times ecological collapse, are numerous: Ethiopia,
Page 31
Haiti, Nepal and the Philippines being perhaps the best known.
Population pressures play an obvious role in most of these
situations, but it must also be noted that unequal land distribution
can worsen those pressures notably.
A different set of improper practices has to do with faulty
intensification: shortening fallow, insufficient fertilization,
excessive fertilization, or the various forms of inadequate
management of irrigated areas.
The elementary way to extract (in the short run) more produce
from land which is not cultivated permanently, is to shorten the
fallow period to which it is subjected. Now, shifting cultivation
"works well where the ratio of land to people is high" so that the
land can "be left fallow long enough [...] The chief problem with
shifting cultivation today is that increasing populations and the
need for higher production to feed them are pressuring many farmers
to shorten or even eliminate the fallow [...] As a consequence [...]
yields are lower and soil damage greater" (FAO, 1983). The above
process is verified unless increasing fertilization compensates the
increased rate of use of the land. Of course, insufficient
fertilization as such þwhether under fallow or permanent croppingþhas
the same effect.
Numerous examples of this process have been documented. In
Africa, rapid growth in population densities has usually not led to
deep changes in traditional production systems. Some intensification
has taken place in the form of reduced fallow but, in the absence of
other technological changes, this has led "growing poor rural
Page 32
populations to increasingly degrade and mine the natural resources
[...] to ensure their day-to-day survival" (Cleaver and Schreiber,
1992).
In the West African Sahelian and Sudanian zones, traditional
production systems included techniques and enforceable rules for
assuring sustainable use of the modest and fragile (low soil
fertility, variable rainfall) resource base; those systems "have
increasingly been disrupted, above all by rapid population growth"
(Gorse and Steeds, 1987). In Egypt, "the land degradation situation
in the Nile Valley has worsened markedly due to: (a) the pressure of
an increasing population combined with the scarcity of cultivable
land, leading farmers to ask more of the land than it can yield"
(Kishk, 1986).
Under permanent cropping, the need for increased produce leads
to irrigation and fertilization, as well as to higher cropping
intensities (multiple crops during the course of one year). As seen
earlier, the typical land degradation problems arising from such
practices are salinization and waterlogging of irrigated areas, and
pollution by pesticides or fertilizers. The first two problems are
pervasiveþthey actually affect more than a third of irrigated areas
worldwide.
Fertilizing is frequently pointed at: "In some regions of the
developing world, notably areas in Asia with highly intensified rice
and wheat production, excessive fertilizer use poses serious
environmental risks" (Pinstrup-Andersen and Pandya-Lorch, 1994). A
Page 33
variant is that "the principal cause of environmental effects is
unscientific fertilizer practices and not excessively high rates of
application" (Rustagi and Desai, 1993).
Pesticides--intrinsically, poisons--are another classical
culprit: "improper pesticide use is common across much of the world
[...] for most insect pests, only small amounts of insecticides are
required, and [...] a large share of the insecticides applied is
essentially wasted" (Pinstrup-Andersen and Pandya-Lorch, 1994). In
Egypt, "irrigation practices and intensive agriculture that led to
various forms of serious degradation [...] Soils are polluted
primarily by pesticides, which are very intensively applied to the
fields (in particular the half-million hectares under cotton
plantations)" (Kishk, 1986).
As seen earlier, the damages caused to land by intensified
agriculture are largely avoidable through sound management. It would
thus seem that population pressure has no responsibility in that
degradation, other than the indirect one of triggering the move
towards potentially harmful production techniques. On the other hand,
population pressure, by reducing per caput access not only to land
but also to other resources, can lead to "cheap" intensification:
hence insufficient drainage (and waterlogging), insufficient
fertilization (and loss of soil fertility), or inadequate monitoring
of irrigation schemes, for instance.
Safeguarding sustainability during adjustments in production
systems is all the more problematic as population growth is more
rapid and adaptations must be devised and executed in haste. This is
Page 34
the case in much of sub-Saharan Africa. On the basis of cases from
Cameroon, Kenya, Malawi, Nigeria, Senegal and Tanzania, Lele and
Stone (1989) have shown that when population growth is rapid, the
adaptations involved in the "autonomous intensification" described
by Boserup are outweighed by the environmental damage caused by
deforestation and decline in soil fertility: higher yields and larger
incomes do not necessarily follow from higher population densities
or more frequent cropping. Pingali and Binswanger (1988), also using
evidence from Africa, concluded that farmer-generated technical
change is capable of sustaining slow-growing populations, but not
rapid growth in both rural population and urban demand for food.
In part, this is because high population pressure can "create
stresses within existing systems with well-tried management
practices. As the margin of subsistence grows narrower, so the
pressure to maximize short-term production will grow stronger. The
need to innovate will grow, but the means with which to innovate will
be lacking"; as for the wealthier landowners "whose own resources are
not gravely threatened by the þdownstreamþ effects of degradation on
the land of their poorer neighbours, [they] may welcome the growing
abundance of cheap labour and see no need to embark on larger
innovations which might be of benefit to all" (Blaikie and
Brookfield, 1987).
Clearly, these matters of technological change are crucial.
Technical stagnation renders resources critically vulnerable to
population pressure. On the other hand, adaptations in land
management may provide wide margins for the accommodation of growing
Page 35
populations. The next section examines how this dilemma relates with
the population variable.
3.3 Population and technological factors
When one reviews the experience of agricultural systems under
population pressure, the factors which happen to have been stagnating
(or changing slowly) in a given case tend to appear as the weak
elements of the system. In many rural settingsþ particularly but not
only in Africaþpopulation has grown rapidly during the past 20 years
or so, while technology and consumption levels have stagnated (or
worse) and land degradation has accelerated. This could suggest that
when population growth is rapid it becomes the decisive factor for
the final outcome.
Yet, when "technology" in turn undergoes a rapid adaptation
process, its changes can offset the effects of total consumption
growth (whatever the respective roles of population and per caput
consumption growth in the latter). Cases of such occurrences are not
too hard to find. Java for instance, "despite the serious erosion
that takes place in headwater areas and on land of high environmental
sensitivity that is unsuited to irrigated terracing, exemplifies the
high productivity obtainable under intensive management with
extremely high densities of population" (Blaikie and Brookfield,
1987). Mortimore (1993) pointed out that the Close-Settled Zone of
Kano (Nigeria) exhibited a stable agricultural system in a dryland
area, despite the high population density.
In a study of Kenya, Nigeria, Rwanda, Tanzania and Uganda,
Page 36
Hyden et al. (1993) also found that in certain places "farmers have
managed their lands, even under severe pressures, in a manner that
has permitted sustained use to date", and concluded that high
population densities could be accommodated in many parts of East
Africa. Tiffen et al. (1994) described a remarkable "success story"
observed in the Machakos District of Kenya (see Annex 5). They saw
the case as confirming "the autonomous effects of an increased
population, deriving from the availability of more mouths (more
demand), more hands (more labour), and more brains (more people
interacting more), accompanied by a reduction in the per capita costs
of physical and social infrastructure". What conclusions can we draw
from the variety of contradictory experiences?
The "success stories" first need to be qualified. Out-migration
has been a component of family strategies in most of the places
surveyed. For one reason or another (possibly but not necessarily
diversification) there has been, so to speak, an escape from local
agriculture. In fact, families, not the agricultural system, have
adapted to increasing pressures. The same observation would apply to
Machakos.13/ In the context reviewed by Hyden et al. (1993), taking
into account the intensified female labour contribution in situ to
compensate male migration, the authors saw "evidence that the rural
populace is working longer hours to feed itself". In other words,
labour productivity had declined, and net wellbeing with it. As to
environmental impact, inasmuch as families resort more to purchases
of agricultural products, possible damages are simply shifted to the
areas where production takes place.
Page 37
Otherwise, these stories do not show that rapid population
growth has a positive effect on environmental and economic outcomes,
but simply that it does not necessarily lead to a catastropheþsurely
a well-accepted statement anyway. There is no evidence that the same
(or greater) improvements could not have been made under slower
population growth; there is no evidence either that the improvements
are due to population growth rather than to any other factor. In
fact, the benefits listed by Tiffen et al. arise not from population
growth, but from a sufficient population density. They may be
convincingly associated with a density threshold, but it is unlikely
(as admitted by the authors) that they will continue to improve
indefinitely if population density keeps growing at the same pace,
as should be the case if population growth had an intrinsic positive
effect.
And there is of course no guarantee that comparable
improvements will occur for other populations growing at the same
rate (although that possibility is not excluded either, provided that
favourable economic conditions exist and policies are adequate). It
would be easy to point to situations (in Ethiopia and other parts of
Africa, the Philippines, Haiti, etc.) where population growth
conditions of the same kind as those observed in Machakos (or indeed
more benign) were associated with stagnation or even ecological
collapse. Naturally, such cases do not prove, either, that "rapid
population growth leads inexorably to environmental degradation", the
proposal which Tiffen et al. purport to disprove, but that few, if
any, actually propound.
In fact, the only correct question is: Would the outcome have
Page 38
been better (or worse, or identical) if population growth had been
slower? Clearly, neither observation nor experimental methods can
provide a definitive answer to such a question, so any answer is
debatable.
That technological change may be driven by population growth
(Boserup, 1965, 1981; Simon, 1986) is a matter of common wisdom:
"Necessity is the mother of invention". But, why ascribe to
population growth alone the effect of technological changes,
including those which bring levels of wellbeing above what they were
before the population reacted to reduced per caput resources?14/
There seems to be no other answer than the desire to improve levels
of living, in which case this can just as well occur in the sheer
absence of population growth. The hardship caused by diminishing
resources per caput may be a stronger incentive to innovate than
aspirations to more wellbeing, but "population pressures are a clumsy
and cruel stimulant to development" (Hirschman, 1958). Favouring such
pressures (with their uncertain efficiency and the attendant problems
of maternal and child health in high fertility settings) in the hope
of production gains is an odd proposition.
Policy-wise, it is critically important to address the
ambiguity in Boserup's hypothesis regarding the innovation process
itself. Blaikie and Brookfield (1987) ask: what is it that makes
population pressure result in degradation rather than innovation?
They point to a variety of explanations, including "the lack of
access to productive resources on the part of the cultivator", and
revolving around the various kinds of pressures which lead farmers
Page 39
to extract more from the land than it can sustainably give. The next
section provides an overview of those social and institutional
factors which mediate between pressures for increasing output on the
one hand, and the actual changes in land use on the other.
3.4 Social and institutional factors
3.4.1 Agrarian structures and poverty
Land degradation on a holding depends in part on how
intensively the land is exploited, and in part on the holder's
ability and willingness to undertake conservation measures. These two
factors in turn are influenced by farm sizeþalthough not in an
entirely linear manner.
Consider the contrast between large and small farms in an
agroecological zone. Small holdings may be "mined" in order to
extract enough for family subsistence; their holders cannot afford
leaving a large portion of the farm under fallow; the output does not
enable long-term investment in soil conservation or amelioration, or
productivity-raising implements. At the same time large (at times
absentee) landholders, who maintain or increase their well-being
simply by concentrating resources, need a lesser, more easily
sustainable rate of use: hence extensive exploitation schemes. They
also can easily take land out of production for anti-erosion works.
Certainly, faulty practices or an excessive rate of use can also be
found on larger farms; what is meant here is that they are not a
necessity in that case, because of their high resources-per-person
ratio.
Page 40
On the other hand, it has been argued that labour for
conservation works may be more readily available on smaller farms in
densely populated areas. Large estates would typically have to hire
labour for this task as they do for other purposes. An extreme aspect
of this question is the situation of areas where out-migration has
left too little manpower to carry out conservation works, e.g.
maintain terraces (Collins, 1987).
A "natural" factor in the fragmentation of land into small
holdings is population growth. "All across the developing world, farm
size is shrinking as farmers continue to subdivide holdings among
their children. In countries such as Malawi, Rwanda, Haiti, and
Bangladesh, population growth rates are high, and the non-farm sector
is still in its early stages of development. Farms now average less
than 0.5 hectares in some areas. Ever-increasing numbers [...] have
become nearly or entirely landless" (Clay et al., 1994).
Another factor, of course, is social inequality within the
population leading to skewed structures of land ownership. Pressures
towards land degradation are stronger in this case, because land
quality and vulnerability are usually not equally shared either:
"Inequities in land ownership may also encourage soil erosion. In
Andean Latin America, for example, wealthy ranchers often use the
relatively level valley floors to graze cattle, forcing the small,
poor landowners onto the steep slopes to produce subsistence crops"
(FAO, 1983). If the smaller holdings occupy marginal, more vulnerable
areas such as slopes or poorer soils in need of longer fallow or
Page 41
fertilizing, not only such areas will be needlessly settled, but also
they will likely be overexploited as their occupants cannot afford
restraint in resource use. The respective weights of demographic
pressure and social inequality in causing land fragmentation vary
from place to place; certainly, both aspects must be tackled.15/
Population pressure in turn contributes to unequal practices,
because a deteriorating population/resources situation leading to
decreasing average well-being contributes to trigger or accelerate
land concentration: "With more people, the increased demand for food
results in increased competition for arable land, tending to change
land prices. In the common situation in which farmers with small
plots have much less access to credit and new technology than those
with large plots, this may result over time in a smaller proportion
of the rural population owning land, smaller average size of plots
for the majority of small farmers who continue to own land, and an
increase in the average size of large farms. This process of
increasing socioeconomic differentiation has been well documented in
Latin America and may be occurring in Africa and Asia as well"
(Bilsborrow and DeLargy, 1991).
Overall, poverty is usually seen as adding considerably to
resource overuse in developing countries. "Poor households are often
virtually forced to overuse natural resources for daily subsistence.
Thus, landless farmers colonize tropical forests, or grow cassava and
maize on highly erodible hillsides. Rural households in fuelwood-
deficit countries strip foliage and burn crop and animal residues for
fuel rather than using them for fertilizer and this contributes to
desertification. Underemployed men in coastal villages overexploit
Page 42
already depleted inshore fisheries. A cycle of poverty and natural
resource degradation is established" (Repetto, 1987). For Blaikie and
Brookfield (1987), "since the expansion is carried out largely by
those displaced from older areas by poverty, or by other pressures
of social or political origin, the new land has to be managed by
those with the fewest resources to devote or divert to its
management"; Nepal provides an illustration of those situations where
"poverty is the basic cause of poor management, and the consequence
of poor management is deepening poverty".
But this view has also been said to be superficial. While
recognizing that the poor "are more likely to gather free fuels [...]
gather every last dried piece of dung for fuel, instead of leaving
it to fertilize the soil [or] migrate for work, leaving the wife at
home too burdened to take on any extra work to conserve the soil",
Harrison (1992) notes that "bigger farmers [...] are more likely to
use tractors [or] own more livestock [who, if] not properly managed,
can do more environmental damage than humans". He points at
situations such as that of Lesotho where the poorest "possess neither
fields nor livestock. Since they have no access to land, they cannot
degrade it. [...] those who do most damage [are those] who own cattle
and, among these, the wealthiest 23 percent who own 74 percent of the
cattle. Livestock degrade the highlands in the summer months. In
winter they eat stubble and trample down terrace edges".
Harrison also sees the tendency to move into forest or marginal
land more as a matter of generation (the young being the prime
candidates) rather than of socioeconomic category. As for getting
Page 43
hold of large concessions of forest land, clearing and farming them
with hired labour and tractors, the better-off are clearly the most
likely to do that. He notes that "even before it is degraded, a
marginal area by nature does not usually produce enough surplus to
lift its inhabitants out of poverty. Poor areas and poor people
destroy each other". There is much value in this analysis, as well
as in the observation that "consumption and waste per person is also
lowest among the poorest" and the conclusion that "all in all, the
poor probably tread lightest of all upon the earth, and do less
damage to the environment than any other group. They are victims, not
perpetrators" (Harrison, 1992).16/
It is also worth remembering that average access to natural
resources is unquestionably affectedþamong others, but often in a big
wayþby population density: population pressure "is an important and
reinforcing link in reducing that access to sectors of an agrarian
population" so that, while not causing inevitably land degradation,
it "may almost inevitably lead to extreme poverty when it occurs in
underdeveloped, mainly rural, countries" (Blaikie and Brookfield,
1987).
3.4.2 Land tenure
With regard to factors which foster or discourage land
conservation efforts, it has been argued that only private ownership
makes it worthwhile for peasants to care about the sustainability of
their farming methods: "systems of land ownership as well as tenure
and business arrangements which do not provide security to the
farmer" are held to be "major obstacles to conservation" (FAO, 1983).
Page 44
A number of authors þnotably E. Boserupþhave thus contended that the
move from collective to individual land ownership, which usually
emerges as land becomes scarce, promotes investments in the
productivity of landholdings.
Much has been made, in this respect, of the overuse of common
property resources (CPR), a feature which is present in many
societies: "Population growth is most likely to result in land
degradation when land is held in common without rules governing its
access" (Jolly and Torrey, 1993). The fate of CPR has been much
studied, e.g. in India by Jodha (1991), who noted that increased
population, along with changes in market relations and land
privatization, have led to declines in CPR size, increased pressure,
dwindling communal management; all this precipitated land
degradation. Cleaver and Schreiber (1992) also observed that rapid
population growth often is responsible for breakdowns in communal
land management, failures in resource control and local "tragedies
of the commons". But communal tenure does not have to lead to such
outcomes. Where strong social and cultural sanctions hold, use can
remain sustainable; the problem actually lies with open access
resources.17/
Also, traditional tenure systems have often been misunderstood
and underrated. For instance, "it is often suggested that communal
tenure is the norm in West Africa and that individuals therefore have
little incentive to make any long-term on-farm investments. This
argument is questionable on three counts. First, the term "communal
tenure" is used very loosely to cover different forms of ownership
Page 45
(by a chief, by a lineage...) and, more important, different forms
of management (by entire groups, by representatives on behalf of
group members, by individuals). [Second,] not all forms of communal
tenure entail disincentives for long-term investments". On balance,
lack of individual tenure does not appear to be an unsurmountable
obstacle (Gorse and Steeds, 1987), as long as population pressure or
other factors do not erode the rules which are essential to the
system.
The "Boserup argument" also "fails to address whether the
induced production changes are sustainable [and] does not deal with
the continuing changes in tenure that often occur after the change
to individual ownership", in particular the distributional aspects:
"as individual owners acquire land, the potential grows for
concentration of land in the hands of a few. In effect, the
development of Western-style land tenure systems in Africa has
sometimes led to the concentration of rights of access in certain
groups and removed indigenous means of determining usage (Jolly and
Torrey, 1993). Then rental and share arrangements emerge between
large landowners and those without sufficient productive land; but
"renters are less likely to make long-term investments, increasing
the potential for degradation" (Clay et al., 1994).
Indeed a number of studies have illustrated the differences of
behaviour between individual owners and renters. Rented lands usually
are the most degraded. But a closer look often reveals that renters
with long-term use rights can be quite as inclined to improve the
land as owners are. Security of tenure, not ownership, is decisive,
because it enables farmers to reap the benefits from their
Page 46
investments (or from their restraint). Conversely short-term land
leases are "among the most pernicious" arrangements from this
standpoint (FAO, 1983).
3.4.3 Markets and public policies
Many of the economic changes typically associated with the idea
of "modernization", including the economic role of the modern state,
have been seen to negatively affect the management of natural
resources, both at the local level by community authorities and by
individual peasants.
In many places, "increasing monetarization produced marked
changes in the institutions [...] extended family structures and
their careful resource management practices [broke] down, and the
authority of local communities, which might have taken political
measures to control resource abuse [...] was increasingly constrained
[...] Increasingly centralized political authority has also
challenged the capability of local decision-making bodies to manage
their environment" (Gorse and Steeds, 1987).
The pervasive "urban bias" in macro-economic management also
played its role, for instance by promoting "cheap food and fuel for
urban consumers [...] To the extent that low producer prices
discouraged more intensive production, and the unpredictable
behaviour of public marketing agencies increased farmers' risks,
land-clearing for further extensive production and/or the shortening
of fallow periods was promoted" (Gorse and Steeds, 1987).18/ More
Page 47
generally, cheap food and low agricultural prices have kept land
value low, making its conservation unattractive.
The promotion of cash crops by governments in the pursuit of
export gains also has often accelerated soil exhaustion, because the
main crops in this group (cocoa, coffee, cotton) happen to be very
nutrient-demanding. Water for irrigation has been vastly underpriced,
leading to overuse and related problems. Inadequate credit facilities
have rendered access to modern implements and inputs difficult for
small farmers, and are thus largely responsible for failures to
intensify cultivation. Added value generated by farmers has been
confiscated by state marketing institutions. In sum, the distortions
of agricultural policies beg redress also for the sake of land
conservation.
4. CONCLUDING REMARKS
4.1 Population in the chains of explanation of degradation
It must be clear at this stage that land degradation is the
result of many factorsþsome outside human controlþand that it is
"futile to search for a uni-causal model of explanation" (Blaikie and
Brookfield, 1987). It is probably impossible to argue satisfactorily
that one of the main categories of factors is generally decisive. For
one thing, the variability of situations at the local level is too
great to support any generalization. For another, population change,
social factors and technological factors are interlinked, so that it
is impossible to assign them autonomous effects.19/
Page 48
But, while no general truth can be proposed, it is necessary
in situations of ongoing or impending land degradation to look for
the factors on which to intervene. One useful concept in this respect
is that of "chain of explanation": the chain "starts with the land
managers and their direct relations with the land (crop rotations,
fuelwood use, stocking densities, capital investments and so on).
[The] next link concerns their relations with each other, other land
users, and groups in the wider society who affect them in any way,
which in turn determines land management. The state and the world
economy constitute the last links in the chain" (Blaikie and
Brookfield, 1987). A priori, population pressure seems to apply on
the very first links of the chain.
Except in accidental collapses of production systems under
exogenous forces (drought, war...) the common element in land
degradation is "pressure of production on resources" (Pavelis, 1983).
That pressure can arise from various factors including a large or
growing population, outside market demands, or the nature of crops
or livestock-raising. It can also arise from institutional, social
and economic conditions which lead to the extraction of surpluses
from the land managers, forcing them in turn to extract from the land
more than is sustainable. Such conditions are: heavy tax and tribute;
very low wages; denial of access to CPR; low commodity prices due to
state pricing policies or market distortions; farmer's indebtedness;
and so on.
In this context, population factors appear both as part of the
basic conditions within which the socio-economic system operates
Page 49
(population density with regard to resources) and of the forces which
affect its patterns of change (population growth, urbanization,
migration): density is relevant to the level of direct pressure on
resources; population growth and urbanization affect the volume of
market demands; urbanization absorbs land, and is conducive to biased
pricing policies; a large and growing rural labour force contributes
to low wages; excess demand for access to CPRs may lead to shut out
part of the population.
4.2 Relevance for population programmes
Policy-wise, tackling the land degradation issue will generally
entail addressing two separate questions: (1) How is land degradation
brought about? and (2) Why does land management fail to be effective?
(Blaikie and Brookfield, 1987). While the latter question leads to
seek interventions in the economic and social sphere, the former
directs attention to population and other "pressures". But both
require a correct understanding of the situation at hand.
Population growth usually appears as the major cause for
environmental (e.g. land) degradation in situations where other
elements of the local system (consumption levels, production
techniques, institutions, social structures) are stagnant. It seems
natural then to causally associate the changing elements, i.e. the
growing population and the worsening state of the environment.
This is not to deny that appropriate changes in the socio-
economic and institutional setting would have positive effects on
environmental dynamics, enabling the system to better absorb the
Page 50
stresses brought about by population growth. But the latter
proposition is of a hypothetical nature, and not a priori superior
to the alternative hypothesis that if population growth were slower,
environmental stress would be smaller. As far as interpreting the
facts is concerned, one can only say that degradation was driven by
population growth and enabled by unfavourable socio-economic
conditions.
In those cases where a series of adverse changes have occurred
(population growth, growing agrarian inequities, deteriorating terms
of trade for agriculture etc.), designating the main culprit of land
degradation (hence the main target for policy intervention) seems an
impossible problem to solve by objective means. In fact, the
diagnoses given in literature often seem dictated by intuition (if
not by prejudice) rather than by
sound analysis. But an interesting aspect emerges when diagnoses are
viewed in a policy perspective.
Take for instance the following conclusive statement from a
case study (DeWalt et al., 1993) in environmental degradation:
In southern Honduras, environmental degradation and social
problems often attributed to population pressure arise from
glaring inequalities in the distribution of land, the lack of
decent employment opportunities, and the stark poverty of many
of the inhabitants. It is not the carrying capacity of the land
that has failed to keep pace with population growth. Neither
is population growth the primary cause of the impoverishment
Page 51
of the Honduran ecology and its human inhabitants.
The statement may be correct, but its policy implications are
very weak. It suggests that it is unequal land distribution, lack of
employment and poverty that must be attacked in priority for the sake
of environmental relief. But those evils ought to be attacked in
their own right, regardless of the effect of that attack on the
environment! As for population, policies aiming at slower growth
never are justified by the sole purpose of limiting environmental
impact: there usually are, by common standards, more direct,
important benefits to such policies (including alleviating some of
the pressures leading to inequalities in access to resources,
unemployment and poverty).
The fact remains that population growth entails a greater rate
of exploitation of natural resources. Adjustments can be made on
other factors to diminish that impact, and where those other factors
have the main role, the potential for action is great. But
adjustments have costs, constraints may limit them, and it is best
anyway to tackle all the factors rather than a few, especially when
it is known that a "vicious circle" type of dynamics is at work.
An additional observation is needed. In considering the
possible value of changes in population dynamics, the role of labour
force dynamics is critical. All members of the population are roughly
equivalent contributors to demand for land products, but members of
the labour force are parts of the production system, and therefore
their movements affect not only overall population density but also
the functioning of that system. For instance, where high population
Page 52
densities have been put to use to develop labour-intensive land
management systems, "such systems require abundance of labour [...]
also for their maintenance. If some of that labour is withdrawn, as
by an increase in off-farm employment opportunities, or by emigration
[...] the consequences can be disastrous" (Blaikie and Brookfield,
1987). Barring such circumstances, however, it usually pays to
alleviate excessive labour pressure on the land by seeking to
diversify economic opportunities. But the earlier observation serves
as a reminder that action must be based on solid knowledge of the
system one deals with.
In view of the linkages identified in the preceding pages, it
appears that population-oriented research can contribute to situation
assessment and policy formulation with regard to land degradation
problems. The UNCED has outlined some relevant ideas in this respect
(United Nations, 1992), emphasizing the need for continuous
improvements in research, communication with decision makers and
public information.20/
A first objective would be "to assess human vulnerability in
ecologically sensitive areas", so as to identify priorities for
action. For this purpose, the study of demographic trends should be
part of all studies of changes in land use and quality (especially
at the local level). In the longer run, through accumulated knowledge
enabling comparative studies, the aim is "to develop a better
understanding of the relationships among demographic dynamics,
technology," cultural behavioral norms, and land resources. This
requires strengthened interdisciplinary research, emphasizing
Page 53
community-level experience.
The eventual aim, where land use is concerned, is the
formulation of integrated policies taking into account population
concerns. In this respect an immediate practical output should be an
identification of vulnerable geographic areas (taking into account
inter alia trends in population) as well as of vulnerable populations
(which are not necessarily those living in vulnerable areas). UNCED
also recommended country assessments of population-supporting
capacities, which have rarely been undertaken so far.
The relevance of demographic features appears also "in
formulating human settlement policies", for good planning of land use
entails taking account "of resource needs, waste production and
ecosystem health". In effect, policies dealing with population
distribution and migration appear clearly more relevant than those
affecting national population growth in our case. For populations in
subsistence economy, trends in density are directly relevant to
assess pressure on the land. But it remains necessary in all cases
to take into account the pressure exerted by market demands from
urban populations.
Finally, to further integration of the respective concerns,
"population programmes should be implemented along with natural
resource management and development programmes at the local level
that will ensure sustainable use of natural resources, improve the
quality of life of the people and enhance environmental quality".
This will entail developing locally appropriate frameworks for
action, based on a participatory process, giving special attention
Page 54
to social features-in particular the role of women as resource
managers.
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NOTES
1/ See Marcoux (1994).
Page 62
2/ Lord John Boyd Orr (first Director-General of FAO), in 1948.
3/ Some soils erode easily under the action of rain and runoff,
while others are remarkably resistant, mostly due to their
ability to absorb rainfall rapidly (FAO, 1983). That ability
is also important because it affects the formation of
underground water reserves which are so crucial for agriculture
and the populations in general.
4/ See preceding paper in this series. Such problems will
increasingly affect the world's coastal areas, currently
estimated to be home to two thirds of the world's population.
5/ The idea that the Sahara keeps expanding is much questioned
nowadays, on the basis of studies which show that vegetation
usually reoccupies the lost ground when rain returns. "The only
conclusion is that within a sparsely populated belt of some 200
km at the southern fringe of the Sahara, biological
productivity changes from year to year according to rainfall
fluctuations. In areas where the soil was destroyed, the
decline of biological productivity would be permanent" (UNEP,
1992: pp. 140-141)
6/ The proportion of degraded area to the total area minus
wasteland (which may be regarded as the "useful" area) is of
course higher: 17% globally, with highs of 25% in Central
America, 23% in Europe and 22% in Africa.
Page 63
7/ The final loss would be less because much of the land lost to
crops could be used as pasture; that loss would still amount
to 25 percent in Africa and central America, however.
8/ One may distinguish two slightly different types of "enabling"
factor. One creates conditions such that degradation can begin
(e.g., deforestation in an area where forested land was stable
despite water and wind action). The other creates conditions
such that degradation is more intense than it would be
otherwise (e.g., differing slope or soil texture in pieces of
land exposed to the same action of water and wind will result
in different rates of degradation; this could be labelled an
"accelerating" effect.
9/ "*" denotes a quantity too small to be rounded up to the
smallest unit (1% in this case), while "-" means nil.
10/ Many industrial activities are known to have potentially
deleterious effects on soil fertility because of emissions of
pollutants. Examples of serious damage can easily be found at
the local level (especially in eastern Europe), but it is
globally marginal in terms of areas affected. As for linkages
with population variables, the expansion of such activities is
driven by the levels and growth rates of aggregate incomes
rather than of population.
11/ See FAO estimates cited in Harrison (1992), p. 100.
12/ This can have an additional, altogether different effect, due
Page 64
to the lesser soil protection under crops as compared to
pasture, when dryland farmers "extend croplands into more
marginal lands during good years, pushing back graziers in the
process. When drought begins, the new cropland lacks defences
and the soil may emerge from the drought too degraded even for
livestock" (FAO, 1983).
13/ It would also apply to cases where diversification occurred
within the agricultural sector. In China, Wu et al. (1987) have
documented a more diversified exploitation of local ecosystems
(with e.g. development of fishponds) under population pressure.
This is different from the scheme of intensification fostered
by population growth: on the contrary, there has been
exploitation of new resources, i.e. extensification; low
productivity of traditional activities has been escaped, not
remedied.
14/ This point arises for instance in respect of a diagram in
Tiffen et al. (1994: p. 14) titled "Positive effects of
population growth". The said effects essentially consist in a
larger economy, including of course a larger production (=
larger total incomes), but the diagram registers this as
"higher per capita incomes". The "per capita" is an unsupported
insert.
15/ In a country with very unequal agrarian structures like
Guatemala, redistributing land entirely would "buy" no more
than twenty years at current population growth rates before a
Page 65
situation of saturation returns (R. Bilsborrow, communication
at the Round Table on Population, Environment and Development,
International Academy of the Environment, Geneva, 1993).
16/ Much as the poor are sometimes pointed at as the main actors
of environmental degradation, women, being the water and
fuelwood collectors, or the ones pushed up the slopes with
their animals or food crops, also are at times unjustly
accused.
17/ In Hardin's words (1968), it is the absence of enforced rules
("freedom in a commons") which "brings ruin to all" through the
pursuit by each individual of his/her self-interest.
18/ A similar mechanism has objectively promoted deforestation
through inadequate costs of wood collection.
19/ "Any attempt to find the cause of land degradation is somewhat
akin to a "whodunnit", except that no criminal will confess,
and Hercule Poirot is unable to assemble the suspects [...] for
the final confrontation. [...] However, any general statement
about the causes of land degradation is of a very different
order from the usual þwhodunnitþ, except perhaps in the case
of the Orient Express, where all the suspects were found
guilty!" (Blaikie and Brookfield, 1987).
20/ The quotations in this section are from chapter 5 of Agenda 21.
Page 66
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