Agricultural Colonization, Settler LULC Dynamics, and
Secondary Plant Succession: Factors Influencing Land
Fragmentation, Carbon Sequestration, and Landscape
Structure in the Ecuadorian Amazon
1998-2002: NASA LandCover/Land Use Change Program
The rate and degree of landuse/landcover change (LULCC) associated with
deforestation and agricultural extensification will be indirectly examined over nearly
three decades from the early 1970s to the late 1990s through the development of a
satellite time-series. The driving forces that ultimately underlie the process of
deforestation in the Ecuadorian Amazon will also be assessed relative to social,
biophysical, and geographical influences. From 1990 to 1998, however, the driving
processes will be examined in detail through longitudinal population surveys of 450
households in 1990 and re-surveyed in 1998, taking as its starting point the presence of
small farmers in the frontier. The surveys will provide an opportunity to better
understand the land use/landcover (LULC) practices of migrant farmers -- the effects on
agricultural extensification, habitat fragmentation and its implied ecological implication,
secondary plant succession, carbon sequestration, and settler threats on sensitivity
ecological habitats through the deforestation of corridors, riparian zones, and established
biological reserves within the study area. These land management decisions are the
outcome of a dynamic process occurring at multiple scales, the household or finca, sector,
and region. This requires the analysis of multitemporal household- level data on settler
characteristics and LULC patterns over time in the context of the community and the
The focus on the Ecuadorian Amazon region is particularly significant for
environmental and socio-economic reasons. The western-most region of the Amazon
River basin, bordering the Andean mountains and occurring at the headwaters of the
Basin, possesses several major centers of endemism (Whitmore and Prance, 1987; Myers,
1994). One site, the Napo center (Prance, 1987) overlaps the proposed study area in
Napo and Sucumbios. The region is also one of Myers' (1988) global “hot spots” of
biodiversity deserving preservation, yet is continuing to undergo rapid settlement and
deforestation. Two of the major national conservation areas in Ecuador are immediately
contiguous to the colonization areas of the 1990 survey, Cuyabeno and Yasuni, and are
being intervened by illegal spontaneous migrant settlers. This process invasion into
biological reserves will be measured over time for the first time in the proposed project
through the satellite time-series.
The proposed study site in the northeastern Ecuadorian Amazon region also offers
a particularly suitable laboratory for exa mining LULC behavior of the population of
semi-commercial spontaneous settlers in the western Amazon basin, where settlement has
a different character than that of eastern Amazonia. The rural population in Ecuador’s
Amazon region consists largely of migrant settlers with high fertility and mortality,
where the "natural" process is not confounded by chronic, violent conflict and land
disputes (as in much of Brazil) or by extensive coca growing (as in Peru). Nor are rapid
urbanization, large-scale logging operations, or even large ranches found in Ecuador as in
the other frontier countries. The nature of frontier settlement in our study area thus lends
itself to a "cleaner" understanding of patterns and process of land use and possible
agricultural intensification in a context of increasing population pressure on a declining
Small farm households are considered the primary driving force of conversion of
primary tropical forest to other land uses, so it is essential to understand the impacts of
their land use patterns for forest succession, standing biomass and other land cover
types/measures, in order to develop a dynamic model of regional carbon sequestration (as
well as for understanding, biodiversity and other ecological and biophysical processes
beyond the scope of this study). Accurately documenting and modeling changes in
LULC associated with spontaneous settlement requires an approach linking multiple
levels of analysis --household plots (fincas), sectors, and the region as a whole. Such a
study requires many sources of data, including accurate field surveys of LULC,
household level socio-demographic data, and accurate spatial coverages of patterns of
LULC, confirmed by ground-based observations and formal verification. The present
research design accounts for these data needs and analysis requirements.
Research Questions and Objectives
A. Deforestation, Agricultural Extensification, and Land Management Practices
I. What are the rates of different types of land conversions at the finca, sector
and regional levels? Typical land conversion types include forest-to-crop, forest-to-
pasture, crop-to-pasture, crop-to-fallow, pasture-to-fallow, fallow-to-forest
(abandonment). It is likely that conversion rates vary across scales from the finca to
the region. It is also likely that conversion rates change over time and that the spatial
and temporal considerations are conversion-type specific.
II. What are the social, biophysical, and geographical factors and processes that
drive land-use/land-cover conversion characteristics? Social factors include
family size and demographics, educational level, past agricultural experience, family
life cycle, duration of residence, economic status; biophysical factors include soil
conditions, topography, water supply, surrounding land uses, existing LULC
characteristics at time of settlement; and geographical factors include proximity to a
road, proximity to a town, proximity to a school, size of local market, access to banks
(credit and loans). In this case "land-conversion characteristics" refer to the rates and
types of conversion.
III. Are there clear and consistent patterns in the way these factors and processes
are manifested in the landscape? That is, based on question II above, are there
some fundamental patterns in the variables that drive land conversion that produce
consistent patterns of conversion across the region? For example, do roads, towns,
and existing agricultural settlements drive land conversion in ways that are consistent
enough to be used in predictive models of LULC conversion?
IV. Are there scale dependencies in the links between these factors and observed
land conversion rates and patterns at the finca, sector, and regional levels? For
example, changes at the finca level and changes at the regional level are likely driven
by different primary factors.
B. Land Management and LULC Structure
I. Are there consistent patterns across fincas in household-level land
management decisions that govern the structure (i. e. composition and spatial
organization) of landuse within fincas? That is, do most fincas exhibit the same
patterns of land conversion and land use as driven by the social, biophysical and
geographical factors investigated in section A above? Composition refers to the
proportions of a finca that are in each LU or LC. Spatial organization refers to the
way those LULCs are arranged spatially within the finca. Composition and spatial
organization together are referred to here as "structure".
II. Does the lag time between sector settlement and finca development affect the
structure of land management within the finca? For example, do fincas that were
developed early in the evolution of a settlement undergo different land-conversion
processes than fincas that are developed well after a settlement has been established?
III. Does finca structure converge on a steady state over time? If so, how long
does this process take? That is, do the rates of change, spatial organization, and
composition of a finca settle into a steady state after a certain period after initial
IV. What are the sensitivities of within-finca land management practices to
changes in social, biophysical, and geographical factors and processes? That is, it
is expected that the social, biophysical and geographical factors will change over
time. How do these changes affect the management and structure of fincas that are
already well established?
C. LULCC and Site Suitability for Agricultural Extensification
I. Is there apparent variability in agricultural sustainability throughout the
study area given typical finca management practices? Agricultural sustainability
can be determined through stability in land- use practices between the two dates of the
survey for the sampled fincas.
II. Are there biophysical, social, or geographical factors that explain this
D. Household Decision-Making and Secondary Plant Succession
I. Is land abandonment or long-term fallow part of the typical land management
regime in the study area? This region is unique from others in the Amazon basin in
that it has more fertile soils. Also, because of the slash-and- mulch approach (as
opposed to slash-and-burn) used in the region there is a longer term release of
nutrients into the soil. As a result, land abandonment may not be part of the
agricultural cycle or it may require a longer time frame.
II. If so, what is the nature of secondary plant succession on these abandoned or
fallow lands and how do they differ from undisturbed forest?
E. Deforestation and Landscape Ecology
I. Given the spatial organization of conversion patterns at the finca, sector, and
regional scales, what are the implications for effective viable habitat area at
these scales? Actual habitat area may include relatively undisturbed areas that are
largely dissected by disturbances associated with agricultural development.
Therefore, much of the "actual habitat" may not actually be usable by many species of
organisms. "Effective habitat" includes only those areas that are large and
homogeneous enough to provide viable habitat to the original inhabitants and
populants of the area. This question will involve the identification of habitat
corridors between effective habitat areas, evaluation of forest fragmentation as an
indicator of habitat viability, and proximity measures to determine the relative
isolation level for remnant forest patches. At the regional scale we will focus
primarily on general spatial organization of the forest/non- forest matrix.
II. What are the rate, extent, and spatial patterns of LULC conversion in the
Cuyabeno Reserve and Yasuni National Park? What are the nature of threats
imposed as a consequence of deforestation and land fragmentation to lands occurring
adjacent to and within biological reserves and riparian zones within the study area,
and do such activities affect biodiversity and ecosystem sustainability?
F. Remote Sensing and Population Survey Data for Multi-Scale Modeling
I. Can we develop a remote-sensing based model of LULCC for the entire region
by linking ground-based data to a time -series of remotely sensed data? The
longitudinal survey data will serve as a reliable source of training and validation data
for a remote sensing model of LC conversion. This model can then be used to extend
data on land conversion throughout the region where ground data are not available.
II. Can we enhance and improve the above remote sensing model through input
of social data and known plot development processes? Given an understanding of
the social, biophysical, and geographical drivers of land conversion it may be possible
to develop a GIS-based model of conversion that integrates information on new
roads, towns, locations and dates of new settlement initiation, increased
mechanization, and economic factors suc h as changes in market prices for certain
commodities with remotely sensed data to model and predict future land conversion
Background and Significance
Recently, there has been considerable debate about the nature of the links between
human populations and the environment. The neo-Malthusian argument that population
growth leads to environmental degradation through extensification of landuse has not
been supported by scientific studies (i.e., Bilsborrow, 1994; Marquette and Bilsborrow,
1994). Within the natural sciences, research on Amazon LULCC has elucidated
ecological processes but neglected human dimensions (i.e., Uhl and Jordan, 1984). A
more comprehensive approach is necessary, in which the impacts of a growing and
changing population on the immediate environment are mediated by the standard of
living, technology, public policies, and socio-cultural factors (Bilsborrow and Geores,
1992; Jolly, 1994) together with the biophysical and the geographical domains.
Conceptualizing the popula tion-environment nexus as involving relationships among
people, their institutions, and natural resources is termed a "regional political ecology"
approach (Blaikie and Brookfield, 1987; Schmink and Wood, 1987). In this approach
resource use decisions of households are linked to broader socio-economic and political
forces that affect LULCC. Fortunately, recent research on small farmers and their role in
land degradation has begun to link economic, cultural, and environmental factors,
emphasizing the econo mic rationality of small farmers as well as their ability to adapt and
persist under stressful conditions (e.g., Netting, 1993; Collins, 1986; Little and Horowitz,
1987). Applied to LULC in Amazonia, this model suggests the need to understand the
decision- making processes of individual migrant farmers regarding the use of their plots.
This is likely to vary according to household needs, labor supply, location, output prices,
and national policies, international market effects, and natural resource endowme nts. In
addition to recognizing more complex linkages between the human population and
ecological impacts, spatial patterns must be taken into account by explicitly locating
individual actors within their biophysical landscape, thus relating resource use decisions
to natural characteristics such as soil quality, terrain, and climate across different natural
units or scales and across time.
The Study Site: Ecuador's Amazon Region
The proposed study will take place in the Amazon region of Ecuador, the
headwaters of the Amazon and a place of extremely high biodiversity that differs in
crucial ways from most of the Brazilian Amazonia. Agricultural settlement has been
almost entirely spontaneous, average soil fertility is higher, and year-round rainfall
prevents burning. Ecuador's Amazon region comprises five provinces: from north to
south, they are Napo, Sucumbios, Pastaza, Morona Santiago, and Zamora Chinchipe
(Figure 1, Appendix A). Ecuador's 1990 census population for the region was 371,000 of
which 273,000 are rural. The Amazon region continues to experience a high rate of
population growth, over 5% per year in the last intercensal period, 1982-90, double that
of the country as a whole. Almost one-half of its population was born outside the region,
two-thirds coming from the Sierra, and most since the mid-1970s (INEC, 1991).
Government policies have encouraged this migration, as the Amazon region has been
perceived as an area with almost infinite space and resources (CLIRSEN, 1986; Larrea,
1987) and thus an "escape valve" to relieve socioeconomic imbalances in other regions.
Access to the northern Amazon was initially made possible by the petroleum
boom, which began in the early 1970s and led to road construction to support petroleum
exploration and extraction. Petroleum has since provided over one-half of Ecuador's
export earnings and federal government revenues. Access and land occupation in the two
northern Amazonian provinces have been in part by-products of petroleum production.
The view of the Amazon as an escape valve for farmers from the crowded Sierra also has
appeal for geopolitical reasons, since it allows high rates of population growth to be
accommodated without major social upheavals such as land reforms.
Public forest lands in the Ecuadorian Amazon have been occupied first by settlers
who then seek legalization of land claims from IERAC. IERAC certifies these claims,
generally to parcels of 40-50 hectares, once settlers present evidence of land clearing for
agriculture, according to the 1978 Law for (Amazon) Settlement (INCRAE, 1987).
Migrants follow the new roads into the region, which lead to the major towns in the study
site -- Lago Agrio, Coca, and Shushufindi, occupying lands along the roads in a landuse
pattern known as respaldos, layers of landholdings developed parallel to the main road.
The first migrants tended to occupy the first layer, or linea (line) along the road;
subsequent settlers occupied lines increasingly farther from the road. This process has
continued up to 14 respaldos in the 1990 population survey area, though two to five is far
more common. Initially, the settlement policy produced a relatively homogeneous size
distribution of land plots. However, with increasing in- migration and declining soil
productivity, it is believed that land sales and consolidations have occurred subsequently,
though no hard evidence exists.
Land quality and soil type vary widely across the sample: 46 percent of the
settlers farm what they reported to be black (good) soil; another 24 percent red soils,
which are acidic and of low fertility; 5 percent, lowland alluvial soils with poor drainage;
and 25 percent, a combination. Few settlers complained about soil quality, consistent
with the understanding that superior soils (inceptisols) exist in this part of the Amazon
region. Two-thirds, however, also reported declines in yields on their plots during their
time in the Amazon. Soil type is dominated by ferralsols (FAO/UNESCO, 1971) or
oxisols (USDA classification) which predominate in the Amazon river basin. These
sedimentary soils are of low natural fertility, but possess excellent physical structure; the
main limitation for agricultural is its fragility when subject to cultivation and the rapid
decline of nutrients (FAO, 1976). The western fringe of the Amazon Basin, including the
proposed site in Ecuador, is dominated by xanthic ferralsols.
A polyculture system has evolved in the study area based on "slash-and- mulch"
cultivation, which can be distinguished from the “slash-and-burn” system used elsewhere,
in that the felled vegetation is not burned. Due to the lack of a dry season and high
annual precipitation (2,800 mm/year) in Ecuador, the slash-and- mulch system is a
rational adaptation and differs from that of most other Amazon frontier regions. The
polyculture system integrates annual crops such as corn and rice; semiperennials such as
plantains, bananas, and yucca; and tree cash crops such as coffee and cacao. Eighty- five
percent of the households marketed some crops, mostly coffee. Cattle were raised on
two-thirds of the farms, but most owned only a few head. Families also raised chickens
Since 1990, the main colonization zones in the Amazon have become more
densely populated as the rainforest frontie r becomes more restricted to new settlement,
and as fragmentation of existing plots occurs. The proposed survey will document
whether accelerating and more concentrated deforestation, is occurring, as well as the
degree of subdivision of plots, plot fragmentation. Increasing inequality in the size of
land-holdings in the region is also expected to occur as the second generation of settlers
seeks to make a living. Evidence from the 1990 population survey suggests this has
begun to occur -- more recent settlers have smaller plots on average, and the proportion
of settlers on sub-divided plots is larger than in settlers who arrived before 1985.