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

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.

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.

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: jacques.duguerny@fao.org

****************************************************************************

Population and the environment:

a review of issues and concepts

for population programmes staff

II.

POPULATION AND LAND DEGRADATION

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;

- 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

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

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

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,

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,

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.

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

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

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%

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

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

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

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.

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.

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

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

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

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

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

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

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

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.

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

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,

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

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

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

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

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,

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.

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

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

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.

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

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

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

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).

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

(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

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

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/

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

(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

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

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

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

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

to social features-in particular the role of women as resource

managers.

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NOTES

1/ See Marcoux (1994).

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.

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

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

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.

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