Chapter 2. Population dynamics and the local environment: concepts and issues

This chapter introduces some key terms, concepts and issues useful in understanding local phenomena in population dynamics and environmental management. Short case examples are used to illustrate some topics on population and natural resources, and a list of indicators is provided for those interested in measuring the status of populations and the environment. The content of the chapter can be used to guide the preliminary analysis of a community or region in which one expects to conduct participatory action research, and provides clues as to the kind of information to look for in existing data sets and reports. Readers wishing to proceed directly to participatory action research methodologies may skip ahead to Chapter 3. Additional details on the formulas and indicators discussed in this chapter may be found in Annex A.

Human populations are dynamic entities; the numbers and distribution of inhabitants in a given region (whether geographically or socio-politically defined) are constantly shifting due to births, deaths and migration. Regarding the total number of persons in a region, the calculation is very simple. Changes in population size are obtained by adding births and in-migrants and subtracting deaths and out-migrants in a given time period. Yet, not only changes in population size, but also the characteristics of the population can be of great significance for the local environment. Therefore, in addition to the total numbers of persons and the number of persons per unit of land, it is also useful to consider the distribution of a population in a territory with regard to various characteristics, e.g., age, gender, occupation, etc. (see Annex A for the exact definition of various indicators).

Population density

The concentration (or dispersal) of people in an area is a key indicator for assessing the relationship between a population and its territory. Commonly called the 'population density', this measurement is usually expressed as the number of residents per unit of land surface (e.g., persons per square kilometer).

Box. 2.2: Nucleated and scattered settlement patterns among peasant farmers Peasant households may be concentrated in large villages (nucleated settlement pattern), traveling every day from their home to their plots, or they may be dispersed in order to live near their fields (scattered settlement pattern ). As a rule of thumb, in areas where the land is fertile, where water is constantly available and where agricultural production is almost completely based on cereals and beans (for example, in the valleys of large rivers or where man-made irrigation systems have been built) a scattered settlement pattern prevails, along with a high population density. In areas where fertility of soil and/or water availability are major constraints and where small-scale agriculture is combined with cattle herding, we may expect to find a low population density with a nucleated settlement pattern. A third combination is typical of tropical rain forest societies: a very low population density combined with a scattered and semi-nomadic settlement pattern (i.e., people moving to a new place every 5-10 years). This represents a two-fold strategy for procuring food, consisting of slash-and-burn horticulture of tubers and plantains for calories, combined with hunting, fishing and gathering for proteins and micro-nutrients.

At the local level, the density of human populations is affected by environmental constraints, as well as by technological, socio-economic and political factors. For example, hunter-gatherer populations that rely on wild food over relatively large territories are generally scattered and dispersed (see Box 2.1). In contrast, technological improvement and efficient management of domesticated plants and animals allow agricultural and pastoral communities to support higher densities of population per unit of land.

Taken by itself, however, the average density figure may be too rough an estimate to be meaningful. The calculation of population density can be refined by considering alternative denominators for the surface area that are ecologically or politically significant. For example:

• In 1977, Egypt had an overall density of 39 persons per square kilometer of its total land area; but due to the size of its deserts, this was actually about 1,276 persons per square kilometer of arable land.
• In 1992, the average density of the Shuar-Achuar population of the Morona-Santiago Province in the Ecuadorian Amazon was approximately 5.18 persons per square kilometer, but the actual density per square kilometer of legally entitled land was 18.7.

Settlement patterns

The way in which a population exploits and manages natural resources has major implications on its 'settlement pattern' (i.e., the way in which people live, work and, generally speaking, stay together). There are two basic types of settlement patterns:

• sedentary - people live permanently in a given place and continuously exploit the surrounding territory;
• nomadic - people move continuously over a large territory, and exploit its resources in a specific location only periodically.

A sedentary settlement pattern is typical of communities and societies that depend on agriculture for their survival (see Box 2.2 above). Nomadism is typical of herder populations who must constantly provide forage and water for their animals (see Box 2.3 below).

Pure sedentarism and nomadism are two ways of interacting with the environment that lead to opposing geographical distributions of populations. There are, however, many intermediate arrangements. For example, among the Batswana (of Botswana) rural dwellers traditionally had a tripartite arrangement. During the cold part of the year, they were at the 'village', in the wet season at the 'lands' for planting and in the dry season at the 'cattle post' for herding. Many, if not most, rural communities combine a certain degree of nomadism and sedentarism (see Box 2.4 below).

Density and settlement patterns of human populations are also determined by economic and political factors. Not all the needs of a rural community can be fulfilled locally. Tools for working the fields, weapons for hunting animals, kitchen and housekeeping implements, clothes and personal commodities, drugs and medicine, and magic and religious salvation are almost always obtained through markets or trading centers that allow exchange with the external world. Contemporary slash-and-burn horticulturists, hunter-gatherers, nomadic herders and peasants with irrigated fields all depend, to a varying extent, on urban populations (much as urban populations also depend on these rural groups, e.g., for food, animal products, etc.).

Access to marketplaces for selling rural products and buying urban-made commodities is, in fact, a key element in determining geographical location and distribution of rural settlements. In addition, denser urban settlements attract people because they provide (or are supposed to provide) political and military safety, as well as coordination of efforts for building and maintaining infrastructures (e.g., roads, bridges, irrigation systems, etc.).

Urban/rural interdependency has been a constant feature since the earliest urban centers and states. Modern technology and services that provide education, health, credit, and technical assistance have made towns and central governments ever more important to rural life. Still, many ecological, economic, political, and social problems affecting rural communities are deeply rooted in past and current inequities in the relationship between village and town, community and state, and peasants and bureaucrats.

Migration

Migration can be a significant component of demographic change in small communities and a key factor affecting the way in which human populations relate to their environment. Immigration and emigration are not, however, usually documented routinely at the local level. Moreover, each local community is likely to have some unique migration characteristics (e.g., young men in rural southern Africa going to work in the mines; young women in West Africa going to towns for trading). For many communities, temporary or even semi-permanent migration is a key survival strategy during periods of drought, natural disaster or civil disturbance.

Based on the period of time involved, three main migration patterns can be identified:

• permanent migration (e.g., young adults leaving with their children to settle permanently in another location);
• temporary migration (e.g., men and/or women leaving for more than one year to find work and remit money to their families); and
• seasonal migration (e.g., active population looking for gainful employment for periods of less than one year).

In most developing countries, urbanization in the form of permanent emigration from rural areas to large cities has become a major trend, related to demographic, ecological, economic and socio-cultural changes. Southern Africa has seen rates of urban population growth that are double the overall growth of the national populations; because of wars, refugee movements and the social upheavals of apartheid, more than 40 percent of the region's population now live in urban areas. Urbanization at these levels causes tremendous problems. Housing and other services are often unable to keep up with demand, leading to squatter settlements and unsanitary conditions. Urban and peri-urban areas strain the capacity of accessing water and fuel resources. Cities also produce huge amounts of waste, polluting the water of rivers and lakes.

In the past 20 years, various agencies have attempted to control the trend towards urbanization by launching large-scale agricultural development, watershed management and colonization projects. The principal ration-ale behind these projects is the concept of integrating previously under-exploited regions into the national economic system. The 'surplus' of rural population generated by natural growth is supposed to be redistributed among these areas (see Case Example 2.1 below).

The socio-economic consequences of such ruralization initiatives are controversial and politically very sensitive. Resettlement and colonization, for instance, can be carried out at the expense of the pre-existing communities in the new settlement areas. These communities, which frequently consist of ethnic minorities, may be greatly affected by a large inflow of immigrants, which they do not have the political power to control or discourage. Immigration may affect the natural resource base of these communities, bringing about resource scarcity and complex cultural changes, often with disruptive effects. Ethnocide or genocide of indigenous peoples are among the potential negative outcomes of colonization and resettlement.

Case Example 2.2: History, conservation and human rights - the case of the Yanomami in the Amazon of Brazil and Venezuela The survival of the Yanomami people and their forest environment has been increasingly endangered in Brazil, with the encroachment of gold miners into their territory, and more recently also into Venezuela. The invasion of 40,000 to 100,000 gold miners in the 1980s had serious negative impacts on the Yanomami's health, socio-cultural fabric and natural environment. This has been possible because of insufficient protection and regulation from the governments of both countries. Road construction and mining operations caused significant deforestation, game population displacement, soil erosion, mercury contamination and other forms of pollution in Yanomami territory. In addition, previously alien forms of social problems are becoming increasingly common, including poverty, alcoholism and prostitution. Further, epidemic diseases such as influenza, malaria and tuberculosis, introduced to the area by the miners, have had a devastating effect on the population of villages. In 1993, a violent massacre of Yanomami villagers, mostly women and children (at the hands of disgruntled miners), was reported around the world. In late November 1993, 16 more Yanomami were found dead in Venezuela, probably from mercury poisoning, a slower but equally fatal consequence of gold extraction. Adapted from: Sponsel, 1996

Case Example 2.3: The impact of rural migration on the environment in Burkina Faso The Mossi Plateau, so named because it is the core area of Burkina Faso's largest ethnic group, covers approximately half of the country's land surface. The plateau is in the Sahelian zone, which is characterized by variable rainfall (600 to 900mm per year), poor soils and sparse vegetation. Despite the environmental challenges of life on the plateau, it is home to the majority of Burkina Faso's population, and densities are in excess of 45 to 75 persons per square kilometer. These densities, combined with rapidly growing populations, have led to extensification of agriculture, soil exhaustion, and over-cutting of forests for firewood. By contrast, the southern and western parts of Burkina Faso are relatively sparsely populated, and are characterized by more favorable climatic regimes. Population densities are on the order of 15-25 persons per square kilometer, rainfall is in excess of 1,100mm, the vegetation is less degraded and soils are of higher quality. The juxtaposition of these two zones has led in recent years to a large stream of migration from the Mossi Plateau to the south and west of the country, parts of which were only recently opened up for settlement since the eradication of river blindness in the 1980s. Many areas, however, were already populated by local ethnic groups prior to the arrival of Mossi from the central plateau. The scale of the migration was such that, in one village, the population quintupled from 1,402 to 7,955 inhabitants from 1975 to 1985, a 19 percent annual growth rate! In contrast to the largely male seasonal labor migrations of the past, these new Mossi migrations involve entire households who settle permanently in the new territory. In many receiving areas, Mossis are beginning to outnumber the local inhabitants. This migration has had political and environmental repercussions. On the political side, the Mossi often set up parallel structures of village governance, rather than subordinate themselves to the local village head. This has created conflicts in some instances. Secondly, locals complain that the Mossi bring with them cultivation practices that are ill-suited to the local environment, and that deforestation has been exacerbated because the Mossi cut the forests for export to urban centers. Although the Mossi have set up their own administrative structures, they have not challenged the role of the local Chef des terres to assign lands for cultivation. In the migration-receiving areas, villages practice a form of community land management in which the Chef des terres allocates lands to peoples of his own ethnic group and to immigrants coming from outside. A newly arrived migrant can only gain rights to cultivate a piece of land if he has been 'sponsored' by a local resident or an immigrant who has been in the village over three years. In the face of unprecedented migration levels, this traditional form of land management may be contributing to problems of land degradation. First, because usufructuary rights represent rights to cultivate but not to the land itself, there is no incentive to make improvements to one's land. On the contrary, farmers are encouraged to harvest as much as possible from the land while it is in the family's possession. Secondly, the significant increase in demographic pressure on the land has led to over-exploitation and a decrease in the number of fallow years. Permitting farmers greater security of tenure may constitute an improvement. Whether or not a new form of land management would be culturally acceptable is a question that might make an interesting subject for a participatory action research process. Adapted from: Yaro, 1995

Gender roles and sex distribution

Women play an essential role in shaping the population outlook of a community. In addition to bearing and rearing children, they frequently take care of the sick and the elderly. Women are also the developers and custodians of a wealth of unique knowledge and skills, often closely related to the environment. Most cultures ascribe special responsibilities and roles for environmental care to women. Gathering water and fuel for household consumption is often exclusively done by women or girls. World-wide, girls and women are responsible for an important percentage of food production, and in some communities this contribution can range up to 90 percent.

Nonetheless, women's economic contributions are too often underestimated. Development initiatives, and the attendant new technologies and increased economic power, tend to be taken over by men and may thereby worsen the role of women in society. The breakdown of traditional customs and rules (e.g., due to urbanization and shifts from an extended to a nuclear family pattern) contributes to their disadvantages. For instance, female-headed households, which generally depend on a single income-earner, are likely to be among the poorest households. Environmental deterioration results in dramatic increases in the workload of women, who must travel further to gather fuel wood and spend more hours in carrying water.

Women are generally omitted or relegated to minor roles in most development activities. Although women supply the majority of the labor when local projects require it, they have the least access to information, educational opportunities or participation in decision-making. This is particularly unfortunate because women, as the principal caretakers of rural families, are extremely practical. If not excluded from the process, women could contribute a degree of common sense which is too often missing in development planning (Bergdall, 1993).

A gender analysis of population can be of great use in planning or implementing programs involving the use of natural resources, since in many societies access to and control over the resources are gender-based (see Chapter 4). Basic demographic questions about population and women can help to reveal the nature of the labor force, as well as gender-based roles in the household, in the community, and in various sectors.

A key indicator of women's status is education (see Annex A, section A.7). In fact, a strong correlation has been seen in many studies around the world between mothers' formal education and decrease of infant and child mortality, decrease of household size, and increased acceptance of family planning and child spacing methods.

The sex ratio is an indicator of the sex distribution of the population, and it is defined as the number of men per 100 women (see Annex A, section A.2). If it is under 100, it means that there are more women than men in the population; if it is over 100, there are more men than women. When the sex ratio dips below 90, it is often an indication of very high male out-migration. In such areas, it is common to see many female-headed households.