CIPEC - Population Growth and Forest Cover Change in the Río Plátano Biosphere Reserve, Honduras, by David Dodds

Population Growth and Forest Cover Change in the Río Plátano Biosphere Reserve, Honduras

Center for the Study of Institutions, Population, and Environmental Change
Indiana University
408 N. Indiana Ave.
Bloomington, IN 47408

E-mail: ddodds@indiana.edu

The Miskito population of Honduras has experienced high rates of growth in the last four decades. This population growth has increased pressures upon local resources necessary for livelihood, especially agricultural lands cleared from rain forest. This study constructs a time series of demographic data, aerial photographs, and satellite imagery to quantify changes in population and agricultural extensification for three communities within the northern Río Plátano Biosphere Reserve. Over the period 1960 to 1996, both population and agricultural area increased, but not proportionately: population more than quadrupled in size, but forest area disturbed by agriculture slightly more than doubled. Though this finding might seem to support a Neo-Malthusian hypothesis (that population is outstripping resources), ethnographic and historical information show that people are responding in multiple ways to population growth: to increase agricultural production they are extending areas under swidden cultivation and are beginning to adopt more intensive agricultural technologies; as good lands become scarce, they are more willing to organize to defend land against encroachment; and as market incorporation and prices increase, women state desires for decreased family size. Thus, the data support alternative arguments to the Neo-Malthusian scenario: responses are multiple, including economic adjustments to scarcities, and structural responses to market opportunities.

In 1991, the National Research Council's Committee on Population assessed the state of knowledge concerning population and land use change. In their report, Population and Land Use in Developing Countries, the committee concluded that, despite the interest and importance of understanding the impact of population growth on land use change, "there is a relatively small body of carefully designed research that begins to provide answers..." (Jolly and Torrey 1993:1). The committee identified several key difficulties for such research: (1) lack of a general framework of analysis allowing systematic comparison of "countries or areas in very different circumstances;" (2) "the challenge of precisely matching demographic and ecological data that generally are not collected over the same geographic regions;" (3) weakness in "identifying and quantifying the set of causal connections between demographic and land use changes;" and (4) a focus on conversion of land to human use, rather than measurement of land modification (Jolly and Torrey 1993:1-2).

Five years later, the National Research Council's Committee on Human Dimensions of Global Change held a conference, producing the volume, People and Pixels (Liverman et al. 1998), which reviewed recent research combining remote sensing and geographic information systems (GIS) with more traditional social science research methods (e.g., censuses, surveys, and ethnography). The contributors to People and Pixels have made important progress in addressing some of the methodological difficulties of studying population and land use, but many of the theoretical difficulties remain. Authors of the lead article argue that remote sensing and GIS technologies can be useful tools allowing social scientists to place humans in their spatial context, connect across levels of analysis, and construct time series data on environmental change (Rindfuss and Stern 1998). While People and Pixels is path-breaking in representing evolving state-of-the-art research methodologies, few of the articles directly address high-level questions about the relationship between population and environment. Many of the articles construct research around mid-level hypotheses or research problems. For example, Entwisle et al. (1998:121) ask, "Did land use/land cover in the 1970s and early 1980s, affect the subsequent out-migration of young adults" in Nang Rong, Thailand? In this case, the researchers are successful at applying these integrative research methodologies to the research problem posed. Since the application of remote sensing and GIS to social science problems is relatively new, it makes sense that researchers have first focused on mid-level questions.

In this paper, I propose that it is also useful to generate hypotheses about population and environmental change from higher-level arguments about this relationship. Three broad types of arguments have emerged in the literature. I will call these the Big Three population-environment arguments which may be characterized as follows: (1) Neo-Malthusian, in which population growth promotes environmental degradation and human misery; (2) economic, in which population growth promotes scarcity of resources to which humans adjust in various ways; and (3) structural, in which the structure of social institutions, and flows of resources within these structures, are the primary variables responsible for environmental change. A fourth and emerging argument is that human responses to conditions of population growth are multiple, encompassing various aspects of the Big Three arguments.

In this paper I employ a variety of data sources and methods to understand linkages between population growth and agricultural land use change among the Miskito Amerindians of Honduras. Population data are derived from censuses (national and local) and reproductive history interviews. Land cover data are derived from aerial photography and satellite imagery. In addition, ethnographic fieldwork, involving surveys and participant observation, is critical for providing a qualitative and historical context within which to interpret the quantitative analyses of population and land use change. The quantitative data show that the study population has quadrupled in size while the forest area disturbed by agriculture has more than slightly doubled. A cursory glance at these findings might seem to support a Neo-Malthusian hypothesis: that population is outstripping the availability of local resources. However, I will argue that the response of the Miskito to conditions of high population growth is multiple, and best supports economic and structural arguments.

This paper contains eight sections covering the following topics: I, this introduction; II, theoretical background on population-environment arguments; III, the study site and data; IV, background on the natural environment and cultural ecology of the Mosquitia; V, population and population change; VI, agriculture and land cover change; VII, a discussion; and VIII, methodological considerations and directions for future research.

The history of ideas about linkages between population and environment is long and contentious. Nevertheless, three broad types of arguments have emerged in the literature (see reviews by Jolly and Torrey 1993, Jolly 1994, Harper 1995:166-171, Pebley 1998). summarize these arguments below, and add an emerging fourth argument as well.

1. Neo-Malthusian Arguments: In its simplest form the Neo-Malthusian argument states that population growth causes environmental degradation and human misery. The classic example is Malthus' idea that population may grow exponentially while supplies of a resource (notably crop yields) may only increase linearly in yield (Malthus 1798, Chapter I). Thus, through time, an increasing gap between a population and the resources necessary to sustain it will result in a population crash involving death, sickness, social strife, etc. Key to the Malthusian scenario is the idea of feedback loops, or environmental checks (positive and negative) on population. Biologists and natural scientists have made this argument most forcefully about the human population (e.g., Ehrlich 1968, Ehrlich and Ehrlich 1992). Other researchers are more moderate and warn of ultimate global disaster if population growth and resource use go unchecked, but allow that humans may yet find solutions to these problems (Meadows et al. 1972; Meadows et al. 1992).

2. Economic Arguments: Economic arguments emphasize various aspects of adjustment to scarcity in the face of population growth. As key resources become scarce, humans may adjust by increasing labor efficiency, substituting other resources, innovating new technologies, creating new resource management institutions, or implementing conservation. In subsistence economies, reductions in soil fertility and crop yield may promote behaviors which intensify production, such as shortening of fallows, adoption of new crops and technologies (e.g., draft animals, fertilizers) and increased labor per unit area of land (Boserup 1965, 1981). Much of the anthropological literature, archaeological and ethnographic, documents such processes (Harner 1970, Brown and Podolefsky 1976, Johnson and Earle 1987, Johnson 1989, Netting 1993). Other versions of the economic argument identify forces of the market which promote substitution, innovation, and efficiency; thus population growth is good because it results in "progress" (Simon 1981, 1990; Simon and Kahn 1984). With regard to institutional adjustments to scarcity, various researchers demonstrate that in the face of population and market pressures, people may create local institutions of natural resource management which are highly effective in maintaining the quality of threatened resource stocks (Ostrom 1990, Agrawal and Yadama 1997, Varughese 1998).

3. Structural Arguments: Structural arguments identify the structure of social institutions and flows of resources within such structures as the primary explanatory variables for environmental degradation. In this argument population may be a problem, but it is secondary to inequalities in resource distribution, resource consumption, and political-economic power. Poverty and population growth may be interconnected problems resulting from larger political economic structures. Structural arguments have been made in various ways: for example, the Neo-Marxian school of dependency theory identified unequal trade between cores of consumption and peripheries of production as a cause of economic underdevelopment (Chilcote and Johnson 1983); another approach emphasizes inequalities of political economic power (e.g., multinational corporations) which promote unequal resource use and poverty (Lappé and Collins 1978, Commoner 1992). A number of social scientists have also proposed "political ecology" as a research orientation which more explicitly links political power, economic production, and trade with environmental degradation (Schmink and Wood 1987, Stonich 1993, Greenberg and Park 1994, Durham 1995). By way of example, the growing population of poor farmers in southwest Honduras may degrade the local environment; but this is because farmers live on marginal lands not under the control of more powerful political and business elites who acquire and retain ownership of the best lands for production of acquacultural products and export crops (Stonich 1993).

4. Multiple Responses (An Emerging Argument). It is also possible that a variety of concurrent processes may explain population-environment interactions. Bilsborrow and Ogendo borrow from Kingsley Davis' (1963) idea of the multiphasic response in fertility decline, to posit that there may be no single response to population growth, but rather a suite of responses. This suite of responses arises under new conditions via the following phases: (I) tenurial, (II) land appropriation or extensification, (III) technological, or (IV) demographic (Bilsborrow and Ogendo 1992:38). Though it may be debated (and tested with further case studies) whether or not "phases" of adjustment occur with some kind of temporal ordering, the idea of multiple responses is attractive because it allows for the decision-making of intelligent human actors along various dimensions of their problem universe. Thus, analyses which aggregate social and environmental data above the level of the household or farm will reflect the sum of multiple strategies across individual actors.

The Mosquitia region of eastern Honduras offers a unique opportunity to test these four arguments about population and environment. First, various sets of population and imagery data are available for the same temporal period (1960-1996) for an area covering approximately 2,000 >km², despite being located in one of the most remote corners of Central America (Figure 1). Second, the region is relatively isolated--in the areas occupied by indigenous populations, no roads connect with the interior of Honduras-access is by air or sea. Third, Honduran Miskito society has historically been organized by egalitarian political structure; thus there are few indigenous institutions which might strongly shape resource use. The importance of the second and third points is that variables which might intervene between population and the environment, such as developed transport routes or natural resource management institutions, are relatively weak (though not absent as I will argue later)-thus population effects should map more directly onto the landscape than in many other possible study sites. A fourth advantage of conducting research in the Mosquitia of Honduras is the author's familiarity with the region and its people, having spent approximately three years there during eight visits over the last fourteen years (1984, 1985, 1986, 1990, 1991-92, 1994, 1997, and 1998)-this provides some temporal perspective for assessing ongoing changes in the study site.

This study focuses on three Miskito communities, and their principal agricultural territory, at the westernmost edge of Miskito territory, a region of eastern Honduras now included within the Río Plátano Biosphere Reserve and within the political department of Gracias a Dios (Figure 2). Gracias a Dios covers an area of 16,630 km² and is defined by borders to the west at the 8500'W longitudinal line, to the south by the Río Coco (the national border with Nicaragua), and to the north and northeast by the Caribbean Sea. The Río Plátano Biosphere covers about half of the Department of Gracias a Dios, and was created in 1980 and extended in 1997 to span a large region between the Río Tinto Negro and Río Patuca (Herlihy 1997; see Figure 2).

The particular area of focus in this paper is the plain of Banaka in the Laguna de Ibans watershed (Figure 3). Banaka is the principal agricultural zone utilized by three coastal Miskito settlements (Belen, Cocobila, and Ibans) and is a geographically bounded region which affords a microcosmic view of Miskito swidden agriculture--at a geographic scale amenable to research combining fieldwork with remote sensing. The geographic extent of this three-community study, including settlement areas, agricultural areas, swamps, lagoons, and other waterways traversed by these three communities is about 200 km². (Future analyses will cover approximately 2,000 km² once all available aerial photographs have been interpreted and registered in GIS coverages.)

The analysis of this paper is based on several periods of fieldwork and sources of data. Ethnographic fieldwork was conducted during 1991-1992 and included detailed surveys in the community of Belen on agricultural holdings of 40 households and reproductive histories of 74 women (Dodds 1994). Additional demographic fieldwork was conducted during June-August 1997 to collect reproductive histories for 200 women in villages neighboring Belen (Dodds 1997). Secondary population data (from government censuses) were collected during the 1992 and 1997 fieldwork. Ground verification fieldwork to aid Landsat imagery analysis was conducted during May-June, 1998.

Population data for communities in the study site are from the national censuses of 1974 and 1988; and a census conducted by the Cocobila health center in 1996 (Table I). Though the first national census to include Gracias a Dios was in 1961, census data by community were not available from the Honduran census bureau for 1961--only published figures for the department and two municipalities (DGEC 1961), but these are nonetheless useful data since these can be used to derive reasonable estimates of population size by backward projection (discussed later).

Remote sensing imagery provides data for three GIS coverages, one derived from aerial photographs, and two derived from satellite imagery. For this paper, a set of six photographs at 1:60,000 scale taken in February and March, 1960, comprise the earliest land cover data. These photographs were interpreted visually to distinguish two categories of land cover (forest, human disturbance); interpreted polygons were drawn manually onto mylars bearing the imprint of the topographic maps at the scale of the photograph. To minimize edge distortion, the center of each photograph was used for interpretation and drawing of polygons. Polygon-bearing mylars were then scanned, registered with UTM coordinates, and digitized into an ArcView GIS coverage. Two Landsat Thematic Mapper (TM) images of the area were obtained from the US Geological Survey's EROS Data Center (World Reference System-2, Path 16, Row 49). These scenes, acquired by TM sensors on February 16, 1989, and January 21, 1995, were chosen for analysis since they are relatively free of cloud cover and occurred at the same point in the annual climatic cycle (early dry season). Using IDRISI software, the two Landsat TM scenes were registered to UTM grids on maps in the 1:50,000 scale series of the Honduran Instituto Geográfico Nacional. Imagine (ERDAS) software was then used to radiometrically calibrate the raw digital numbers in bands 1, 2, 3, 4, 5, and 7, to correct for sensor drift, sun angle, and atmospheric effects (see Schweik and Green 1999).

Before proceeding to the analysis of data, it is useful to understand the context of population and land use change with regard to characteristics of the natural environment and Miskito cultural ecology.

The biome of the Honduran Mosquitia is categorized as Very Humid Tropical Forest, one of eight life zones in Honduras (Agudelo 1987:8-10; SECPLAN et al. 1989:30-32). In this life zone, climate is characterized by 2000 to 4000 millimeters of annual precipitation and 18 to 24 Celsius mean annual temperature; elevations extend from sea level to 900 or 1000 meters above sea level (Agudelo 1987:8). In Honduras, the Mosquitia constitutes the largest geographic extent of this life zone, though broadleaf forests of this zone were originally extant along the now populated coast and coastal valleys of northern Honduras. In addition to rain forest, the Very Humid Tropical Forest of the Mosquitia contains a variety of other ecological communities: pine savannas, mangrove swamps, and swamp marshes (Monroe 1968 in SECPLAN et al. 1989:32). Species composition of the Mosquitia is primarily neotropical, similar to much of lowland South America (cf. for flora, West 1964; for fauna, Stuart 1964:337ff; generally, Leonard 1987; Nietschmann 1973). The area has been noted for its importance as a cross-over zone for nearctic and neotropical species generally (Stuart 1964:337ff), and for mammals in particular (Marshall et al. 1982, Emmons and Feer 1990, Marineros and Martínez 1988).

The natural vegetation cover of the Banaka plain and the surrounding hills is broad leaf rain forest. Typically located inland from sea level to mid-high elevations, the rain forest of the Mosquitia is composed primarily of broadleaf evergreen species such as Colyphyllum cf. chiapense, Cedrela odorata, Ceiba pentandra, Ficus spp., Luehea seemanii, and Virola spp. (Froehlich and Schwerin 1983:44) with occasional deciduous species like cortés (Tabebuia guayacan) and San Juan (Vochysia hondurensis) (Agudelo 1987:9). A number of rain forest species, such as mahogany (Swietenia macrophylla) and rubber (Castilla elastica), have been economically important to the region during the last two centuries (Floyd 1967, Naylor 1989). In mature rain forest, a dense canopy extends 25 to 40 meters above a relatively open forest floor. Trees typically bear thick trunks, and are smooth and straight with high branching. Epiphytism is abundant as evidenced by presence of Bromeliaceae, Araceae, orchids, ferns, and mosses; also common are large ferns (genus Cyathea) and a variety of palm genera (Bactris, Astrocarym, Chamaedora) (Agudelo 1987:9).

The plain of Banaka covers approximately 12 km² at 10 to 20 meters above sea level (see Figure 4). To the west and northwest, the plain is bounded by the Cerro de Banaka ridge (345 m peak) which is the eastmost endpoint of an extensive transverse range dropping from the Honduran interior toward the Caribbean Sea. To the north and northeast, the Banaka plain is bounded by a low-lying swamp (Drapaptara = Miskito "big mud") which also borders the brackish Laguna de Ibans. A stream, Crique Banaka, drains approximately 40 km² of mountainous topography to the southwest of Banaka, and flows along the foot of the Cerro de Banaka through the swamp and into the Laguna de Ibans. This stream is the major means of access to the plain, via canoe across the Ibans lagoon, for residents of the coastal villages. Water level in the Crique Banaka fluctuates dramatically by season; during the dry season (February-May), canoes must often be hauled across shallow sandbars, and during rainy season the current may be so strong that poling upstream is impossible. Data from the nearest weather station in Río Sico Abajo, 18 km due west of Banaka, shows mean annual precipitation at 3,171 mm; the month of least rainfall is March (66 mm) and the month of heaviest rainfall is November (501 mm) for the years 1965-1991 (ENEE/GtZ ms). Every one or two years it is common for the entire plain to flood during an especially heavy downpour, causing inhabitants of the plain to wait out the flood in canoes tied to their house posts until flooding recedes, usually within an hour. This flooding, however, is important since it replenishes the entire plain with sediments useful for agriculture. On the plain, soils are generally dark and loamy, though surrounding slopes often exhibit red clay.

The Miskito, in contrast to many other indigenous peoples of the Americas, have thrived since contact with Europeans, expanding in both population and territory since the mid-1600s. Miskito culture, is in fact, a "contact" culture created by the mixture of indigenous Americans with African and European peoples. The contemporary Miskito continue to practice traditional subsistence activities (swidden agriculture, fishing, and hunting) in a manner technologically similar to many forest peoples of the neotropics, and maintain many indigenous elements of their language, social structure, and cosmology. Yet since contact with Europeans, and continuing today, they have also participated peripherally in the larger market economies of northern Europe and the United States; this experience has shaped Miskito interest in participating in commercial activities when possible (Helms 1969, 1971).

Similar to many peoples of the lowland neotropics, the Miskito practice swidden agriculture in areas of secondary and primary forest which are cleared and burned to create field plots (cf. Conklin 1961, Beckerman 1987). Eventually fields are abandoned and left fallow, during which time forest regrows upon the plot. After lying fallow for a varying number of years, the same plot may be cut and planted again. Similar production systems in Amazonia have been termed swidden-fallow agroforestry (Denevan and Padoch 1987) and this well describes the Miskito whose cultigen production includes root crops, a limited amount of grains (rice, maize), and fruit trees. Previous researchers have described Miskito agriculture in detail, most notably Conzemius (1932:60-65), Helms (1971:123-146), Nietschmann (1973:130-149, 238-242) and Dodds (1994:241-290); but see also Cattle (1977:47-52), Woodward (1988:34-37). Swidden agriculture as practiced in Banaka is very similar to that of other Miskito elsewhere in Honduras or Nicaragua.

Miskito fields are typically cropped for two years before they are abandoned to forest regrowth. However, the number of years before abandonment depends upon factors such as the type of crop planted, distance from the village to the field, etc. For example, fields of banana and plantain varieties (Musa spp.) can produce for up to 15 years if weeded often; by contrast, manioc fields are often simply abandoned after two years. Also, perennial fruit trees may be planted in field plots after an annual crop has been harvested; these trees may produce, and their fruit still be harvested, many years after a field is initially cleared, planted, and left to fallow. The same plots of ground are often re-used for planting after being left fallow. In 1992, the Belen Miskito were clearing about 40% of their lands from mature forest, and 60% from successional (fallowed) plots. When planting occurred in fallows, the fallow times reported by the Miskito of Belen were from 1 to 40 years, with median and modal fallow times of 5 years (mean 6.9 years).

A fallow length of five years is short for a forest fallow system as defined by Boserup (1981: Table 3.2); under her model we might expect a fallow time between 15 and 25 years for the Miskito. However, in the case of the Miskito, the short fallow time seems not to be an indicator of land scarcity and agricultural intensification (as per Boserup). The emic reason given by Miskito farmers for the five-year fallow is that it is easier to clear secondary forest than primary forest--therefore, planting in secondary forest is desirable because it saves labor. If a farmer cuts secondary forest before five years of fallow have passed, the plot is usually full of dense weeds and underbrush which are difficult to cut. Waiting longer than five years also increases labor as established woody species grow thicker and more difficult to cut. The emic view of the Miskito is supported by research of ecologists who have studied forest regeneration after slash-and-burn farming methods. Uhl and Jordan have documented, for a rainforest in Venezuela, that the under story of a naturally regrown swidden plot begins to thin at approximately 5 years (1984:1479). Similarly, agricultural data for the Kekchi Maya of Belize shows that though mean areal yield (kg/ha) for maize is lower in fields cut from secondary forest, mean yield per labor time (kg/man-hour) is higher in fields cut from secondary forest--largely as a result of reduced labor time in clearing secondary, as opposed to primary, forest (Wilk 1991:97-99, Table 6.2).

Among the ethnic groups inhabiting Gracias a Dios, the largest is the Miskito (79%), followed by the ladino or mestizo/Hispanic population from the interior (16%), the Garífuna (3%), the Tawahka Sumu (2%), and the Pech or Paya (<1%) (1988 national census, DGEC 1990a:167). In Honduras, the Miskito number approximately 35,000 people dispersed throughout 141 settlements (Dodds 1994; Herlihy and Leake 1993).

The Miskito population has experienced high rates of population growth during the last four decades, as indicated by a variety of available census information. The population of Gracias a Dios, tripled over the 27 year period covered by national censuses: from 10,905 in 1961 to 33,684 in 1988 (national census data; DGEC 1980, 1990b). A 1994 census by the Ministry of Public Health (MSP) placed the total population of Gracias a Dios at 47,011 persons indicating a quadrupling since 1961. Depending on the type of data and method of analysis, rates of population growth for Gracias a Dios range from 2.79 to 3.94 percent per annum (Dodds 1997). Fertility is high with a Total Fertility Rate of 8.3 live births per woman (Dodds 1998). Mortality rates are relatively low for a rural area in a developing country: the infant mortality rate is 40 per 1,000 live births, and life expectancy at birth is relatively high at approximately 60 years (Dodds 1998). Though Gracias a Dios is the least populated department of Honduras, rates of in-migration are relatively low based on available census data. However, this may be changing as land-needy campesinos migrate from the Honduran interior eastward, some entering the Río Plátano Biosphere Reserve and competing with indigenous populations for land (Herlihy and Leake 1992, Herlihy 1997). The outcome of high fertility rates and relatively low rates of mortality and in-migration is a high rate of intrinsic population growth.

For the thirteen coastal communities in the northern Río Plátano Biosphere Reserve, the available census data show that population increased by a factor of 3.35 over the period 1974-1996 at an average annual rate of 5.49% (Table I). Focusing specifically on the population of the three communities (Ibans, Cocobila, Belen) which maintain agricultural activities in Banaka, the population increased by a factor of 2.47 over the period 1974-1996 at an average annual rate of 4.1% (Table II). However, we want to know about the population change since 1961, the first year in which the national census included the Department of Gracias a Dios. Since the data from this census are not available by community, but only municipality, we must estimate the size of the three communities in 1961. Assuming that these communities grew at the same rate of 4.37% per year shown by data for the municipality of Brus Laguna for the period 1961-1974, we can backwards project using this rate of growth from a comparison of the 1961 and 1974 census (Table III). Using the estimated population size for Belen, Cocobila, and Ibans (summed together) as a base indexed to 1961, these communities have grown in size by a factor of 4.36 over the period 1961-1996 (Table III).

Under these conditions of rapid growth, what impact has the Miskito population had upon the local landscape?

As population has increased, so has the area of forest disturbed by agriculture in Banaka.Table IVshows the areas disturbed for the years 1960, 1989, and 1995 as calculated by GIS vector coverages interpreted from aerial photographs and Landsat imagery (see Figure 4). The area disturbed by agriculture increased from 282 hectares in 1960, to 707 hectares in 1995, an increase by a factor of 2.5 over thirty five years. Agricultural land area expanded at an average annual rate of 2.06% per year during 1960-1989, accelerating to 5.38% per year during 1989-1995. Since it is possible that some intensification of agricultural production has occurred during this 35 year period, it may be useful to know the number of persons being supported per hectare of land disturbed by agriculture. The "Persons/Ha" column of Table IVshows that this number increased from about 2 to 3.5 persons per hectare, an increase by a factor of 1.74. Does this number indicate agricultural intensification? As will be discussed below, this number should be interpreted with caution since population pressure may also be distributed onto agricultural lands outside of Banaka.

Table Vsummarizes all of the change indices for population size in persons, disturbed forest in hectares, and persons per hectare supported, across the period 1960-1996. Does growth in the three-community population size parallel growth in hectares of agricultural disturbance through time? By standardizing against a base figure for the earliest data (1961 population and 1960 aerial photographs), the data show a striking pattern of divergent growth: population has more than quadrupled (change index 4.36) while agricultural area has slightly more than doubled (change index 2.5) as depicted in Figure 5.

It is clear that agricultural land and population have increased together: more people has resulted in less trees. Figure 5depicts the central puzzle of this paper: population growth and agricultural area have expanded together, but not proportionately. During the period 1960-1996, population increased in size by a factor of 4.36, yet the area of agricultural lands expanded only by a factor of 2.5. How can this be explained? And which population-environment argument is supported by these data? Below I discuss these data with regard to the Big Three arguments but find that the argument of multiple response is the best fit.

1. Neo-Malthusian Processes. A cursory glance at the graph of Figure 5, might seem to indicate a Malthusian scenario: that population is growing faster than resource use. However, over the 36-year period of this study, the Miskito have not suffered acute resource scarcities that would be evidenced by famine, lack of fuel, etc. Therefore, trends visible in population and remotely sensed imagery do not seem to indicate great ecological stress in recent history (though the future may be less certain). Though population growth is driving agricultural extensification and deforestation, the rates of population growth and deforestation are not the same: area of agricultural lands in Banaka has not kept pace with population growth in the three communities. Other aspects of the Miskito economy must be making up for the diminishing per capita area under cultivation.

2. Economic Processes. Population is growing at a faster rate than agricultural area, so this may indicate indirectly that other processes are underway. Possible explanations are the following: (1) extensification of agricultural lands in areas beyond Banaka; (2) wage labor in the lobster industry which allows households to purchase foods and reduces the need for subsistence planting and clearing new forests (Dodds in press); and (3) intensification of agricultural production. Intensification of agricultural production may be occurring in various ways. During ethnographic fieldwork, I have observed the Miskito engage in attempts to increase agricultural production and save labor by (a) adopting herbicides to reduce weeding labor, especially for rice; (b) adopting hybrid varieties of bananas, manioc, and rice to resist pests and increase yields; and (c) increasing use of coastal land around or between villages, especially for manioc which can grow fairly well in sandy soil.

The economic argument may also best explain the rise of incipient social institutions to protect local forests and resources. As forests vital to the livelihood of the Miskito have become scarce or threatened, especially by in-migrating ladinos, the Miskito have begun to organize to defend their resources. Examples are the following: (1) in 1985 Miskito men from various villages formed a large work party to blaze a boundary through the forests from the Río Tinto Negro and to the south of the Laguna de Ibans-this was to serve as a territory marker in case of disputes with in-migrating ladinos; (2) MASTA, an indigenous federation of the Miskito is changing from an organization largely run by Miskito school teachers to a representative body composed of leaders elected by local area chapters; and (3) in the Reserve, with the help of a German and COHDEFOR project, villages are forming local councils to manage local watersheds according to their own management criteria (Peter Herlihy, pers. comm.).

3. Structural Processes. It is clear that larger economic and political structures are involved in changing relationships between Miskito population and environment. As mentioned above, participation of coastal settlements in lobster work, an international export industry, affects local household economies and forest use (Dodds in press). A more striking example of political-economic structures visible upon the landscape is to compare the scale of recent forest conversions on opposite sides of the Río Tinto Negro (see Figure 6). To the west of the Río Tinto Negro, outside the boundary of the Río Plátano Biosphere Reserve, the ladino population within the Río Sico and Río Paulaya watersheds has converted large areas of forest to cattle ranching: cattle pastures may be kilometers wide. Here, ladino smallholders and a few large ranchers are producing cattle for markets in Honduras and Guatemala. By contrast, to the east of the Río Tinto Negro, within the Río Plátano Biosphere Reserve, the small subsistence plots of indigenous agricultural areas (Miskito, Garífuna, and Pech), barely show up as tiny dots within the imagery. Thus the impact on resources through links to markets for the indigenous communities is minimal when compared to the effects visible by commercial cattle production by the non-indigenous population.

4. Multiple Responses to Population Growth. Can the findings of this analysis be synthesized? Here it is useful to conceive of a variety of concurrent processes which may explain population-environment changes in the study site. Bilsborrow and Ogendo argue that there may be no single response to population growth, but rather a suite of responses: land-use changes may occur as phases of adjustment to new conditions as follows: (I) tenurial, (II) land appropriation or extensification, (III) technological, or (IV) demographic (Bilsborrow and Ogendo 1992:38).

The Miskito study communities exhibit all four responses to population growth at varying degrees of intensity. Tenurial adjustments are still incipient as evidenced by new village formation (e.g., Banaka which became an "official" village in 1996), marking of territories against outsiders, and increasing willingness of the Miskito to organize politically at village and regional levels to represent and defend their interests. Extensification of agricultural lands is the strongest and clearest response to population growth as shown by remotely sensed data. Technological changes are also somewhat incipient and involve agricultural experimentation and small shifts in geographic location of swidden agriculture, but not large scale adoption of intensive chemical-dependent or mechanized agriculture. Demographic responses are minimal with regard to behavior: over the last three decades, fertility has remained steady or increased slightly, while mortality has decreased (Dodds 1998). Despite continued high fertility, women express desires for smaller family size. Based on a 1997 demographic survey in three indigenous communities of the northern Río Plátano Biosphere Reserve, the total fertility rate is 8.3 live births per woman. However, women would prefer on average 4.5 children (Dodds 1998). The most common explanation for desired lower fertility is that "things are expensive now." This statement is consistent with an increasing sense that overall livelihood resources are scarce, at least for the lifestyle which coastal people prefer, which includes ability to buy commercial goods in stores, to send their children to government schools, and to pay for health care when necessary.

Thus as Miskito population has grown and easily accessible resources have become more strained, the Miskito have responded in multiple ways. The data do not easily support just one of the Big Three population-environment arguments. Remote sensing and population data, when contextualized with knowledge obtained by ethnographic fieldwork, disallows a simplistic Neo-Malthusian explanation of the disparity between population growth and land cover change.

This study has attempted to link population change with land cover change, using a variety of data sources and methods. What lessons can be learned with regard to methodology and directions for future research? First, regional (multi-watershed or multi-community) analysis may provide more comprehensive and robust results when attempting to link population to environmental impact. Second, digital remote sensing data are useful in a variety of ways ranging from simple vector polygons derived from visible color composite displays to raster-based supervised classification maps.

Why might regional studies provide more robust results? Because the Miskito practice a dispersed form of agriculture, links of households or communities to the landscape are distributed in a one-to-many relationship. This is similar to patterns observed by researchers in the Nang Rong Project in rural Thailand (Entwisle et al. 1998:134). Among the three focal communities of this study (Belen, Cocobila, Ibans), Banaka is not the only area used for agriculture. Belen residents report that 49% of their agricultural lands are located in Banaka; more generally, 60% in the Laguna de Ibans watershed, 32% in the Río Tinto Negro, and 4% in the Río Plátano watersheds (percents rounded from data in Table VI). Some households in Belen maintain fields in all three watersheds. By contrast, Cocobila residents reported that only 9% of their lands are located in Banaka. For Cocobila, the most important planting areas are on the Río Tinto Negro (65%), followed by the Laguna de Ibans watershed (35%) which includes Banaka and other streams such as Paru and Knatapara (percents rounded from data in Table VI). Land holding data are not available for Ibans, but are likely to be close to the pattern of Cocobila, since these two villages are linked by many ties of kinship. Thus, as the three-community population has grown, extensification of agricultural lands may have occurred in other areas as well as Banaka, particularly along the Río Tinto Negro but also Río Paru and other streams on the south side of the Laguna de Ibans. This methodological difficulty points to the importance of scaling issues in population-environment research. A regional (e.g., three-watershed) analysis, currently in preparation, will provide more comprehensive and robust results for assessing environmental impact of population because of geographic overlaps in household and community land use.

Second, vector polygon coverages derived from visual interpretation of color composite images are useful for quantifying broad changes on the landscape, but do not make full use of information which may potentially be derived from digital Landsat data. A supervised classification of vegetation cover derived from digital data (e.g., Brondizio et al.1994) may allow more direct measurement of population pressure than does the calculation of the population-to-land ratio. The population-to-land ratio has increased from 2.05 persons/ha to 3.56 persons/ha over the period 1960-1996-this may indicate intensification since more people are being supported per unit of land. However, since agricultural extensification paralleling population increase may have occurred in areas outside of Banaka as well, the increasing population-to-land ratio may be an artefact of analysis constrained to one geographic region. A more direct measure of agricultural intensification would be a decrease in the fallow-to-crop area ratio, since this would indicate shortening fallow times within the boundaries of the total area of agricultural disturbance (see Boserup 1965, 1981; Fearnside 1986). Changes in the ratio of fallow-to-crop area should be possible to obtain using radiometrically calibrated reflectance data classified to discriminate active crop areas from successional fallow areas.

To conclude, the Big Three population-environment arguments should be more explicitly addressed in the hypothesis testing of future research. However, results may be complex and researchers may find multiple responses to conditions of population growth-this will necessitate further methodological refinements in social science research design to capture relevant variables of human behavior visible in remotely sensed data.

I thank Cynthia Croissant and Jane Southworth for their preparation of satellite imagery, Rebecca Ieong and Fei-Chi Tuang for interpretation of aerial photographs, and Salvador Espinosa for data entry during this project. Funding of the Fulbright-Hays Program, the Inter-American Foundation, the Mellon Foundation via RAND Corporation's Small Grants Program for Central American Demography, and the National Science Foundation (Grant SBR 9521918) is gratefully acknowledged. An earlier version of this paper was presented at the Annual Meetings of the Latin American Studies Association, Chicago, Illinois, September 24, 1998.

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Population Growth and Forest Cover Change in the Río Plátano Biosphere Reserve, Honduras

Abstract

Introduction

The Big Three Population-Environment Agruments (Plus One)

The Study Site And Data

Background: Natural Environment and Cultural Ecology

Natural Environment

Miskito Cultural Ecology

Population and Population Change

Agricultural Land Cover Change

Discussion

Methodological Considerations and Directions for Future Research

Acknowledgements