Carlos F. Mena

Frontier Land Use Change: Synthesis, Challenges, and Next Steps

Abstract Profound social, economic, and environmental changes that include new land management practices are often associated with advancing agricultural frontiers. We argue that existing approaches to case studies do not allow for clear generalization or the systematic testing of hypotheses. As an alternative, our study uses Mills method of agreement approach to synthesize results from seven long-term case studies of land cover change in frontier areas. We identify a number of generalizations that hold across the specific case studies. We also identify changes in the spatial organization of land use in agricultural frontier areas, which are typically characterized by agricultural expansion, growing population, and transportation improvements. We then evaluate the methodological strengths and weaknesses of Mills method of agreement based on use in this study. Finally, we argue that agent-based models, using virtual landscapes and the logic of demographic standardization, are an important next step to facilitate methodologically defensible comparisons across case studies.

Contrasting Colonist and Indigenous Impacts on Amazonian Forests

To examine differences in land use and environmental impacts between colonist and indigenous populations in the northern Ecuadorian Amazon, we combined data from household surveys and remotely sensed imagery that was collected from 778 colonist households in 64 colonization sectors, and 499 households from five indigenous groups in 36 communities. Overall, measures of deforestation and forest fragmentation were significantly greater for colonists than indigenous peoples. On average, colonist households had approximately double the area in agriculture and cash crops and 5.5 times the area in pasture as indigenous households. Nevertheless, substantial variation in land-use patterns existed among the five indigenous groups in measures such as cattle ownership and use of hired agricultural labor. These findings support the potential conservation value of indigenous lands while cautioning against uniform policies that homogenize indigenous ethnic groups.

Small farmers and deforestation in Amazonia

This chapter discusses the relationship between small farmers land use and deforestation, with particular attention paid to the past 30 years of Amazonian colonization in Brazil and Ecuador. Our analysis calls attention to common features uniting different social groups as small farmers (e.g., social identity, access to land and resources, technology, market and credit), as well as the variability between small farmers in terms of time in the region (from native populations to recent colonists), contribution to regional deforestation, types of land use systems. At a regional level, small farmers contribute to the majority of deforestation events, but ate responsible for only a fraction of the total deforested area in Amazonia. We discuss three misconceptions that have been used to define small farmers and their contribution to the regional economy, development, and deforestation: (1) small farmers have backward land use systems associated with low productivity and extensive deforestation and subsistence production, (2) small farmers contribute to Amazonian deforestation as much as large farmers, and (3) small farmers, particularly colonist farmers, follow an inexorable path of deforestation unless curbed by government action. We conclude the chapter discussing their growing regional importance and the need for more inclusive public concerning infrastructure and services and valorization of resources produced in rural areas of Amazonia.

Trajectories of Land-use and Land-cover in the Northern Ecuadorian Amazon: Temporal Composition, Spatial Configuration, and Probability of Change

This paper explores the temporal composition of the main Land-use/Land-cover (LULC) trajectories, examines the spatial configuration of the trajectories, and derives the probabilities of transitions in the Northern Ecuadorian Amazon (NEA). This research uses a time-series of classified Landsat images that ranges from 1974 to 2002, and a set of spatial socioeconomic, demographic, and accessibility data assembled in a geographic information system. The LULC trajectories are analyzed for the Northern Intensive Study Area (NISA) using image algebra, and for the whole region, the NEA, using cluster analysis, landscape ecology principles, and spatial logistic regression models. In general, the trajectories are dominated (i.e., in terms of area) by recent transitions that contain forested classes (i.e., primary forest or succession), as well as the consistent representation of pasture through time. This exploratory analysis of LULC transitions suggests a set of clusters that form a core and periphery pattern in the NEA. This research shows how these clusters and probabilities of change can be used to characterize trajectories of LULC in the region.

Integration of Hyperion Satellite Data and A Household Social Survey to Characterize the Causes and Consequences of Reforestation Patterns in the Northern Ecuadorian Amazon

The integration of Hyperion and Ikonos imagery are used to differentiate the subtle spectral differences of landuse/land-cover types on household farms in the Northern Ecuadorian Amazon (NEA) with an emphasis on secondary and successional forests. Approaches are examined that include the use of Principal Components Analysis to compress the Hyperion hyperspectral data to its most vital spectral channels; linear mixture modeling to derive subpixel fractions of land-use/land-cover types through the generation of spectral endmembers; and supervised and unsupervised classifications to map forest regrowth, agricultural crops and pasture, and other land-uses on 18 survey farms that are spatially coincident with the imagery. A longitudinal socio-economic and demographic survey (1990 and 1999) is used to characterize household farms; a community survey (2000) is used to assess nearby market towns and service centers; GIS is used to represent the resource endowments of farms and their geographic accessibility. Statistical relationships are examined using Spearman rank correlation coefficients to assess the linkages among a number of selected social, geographical, and biophysical variables and secondary and successional forest on household farms. Relationships suggest the importance of household characteristics, farm resources, and geographic access of secondary forests on surveyed household farms that were previously deforested and converted to agriculture through extensification processes. Results support the integrated use of hyperspectral and hyperspatial data for characterizing forest regrowth on household farms, and the use of multi-dimensional social survey data and GIS to assess plausible causes and consequences of land-use/land-cover dynamics in the NEA.

The spontaneous emergence of silvo-pastoral landscapes in the Ecuadorian Amazon: patterns and processes

With the continuing decline in the global extent of tropical forests, agriculture-dominated landscapes now cover approximately 50xa0% of the tropical biome. In this context, our ability to understand and influence biodiversity and carbon sequestration in the tropics depends in large part on our understanding of actively managed landscapes. Approximately two-third of deforested lands become pasture in the Neotropics, and therefore, significant changes in their structure represent a potentially important development in terms of carbon sequestration and biodiversity, especially as ecosystem service payment schemes such as REDD+ emerge. The spontaneous emergence of silvo-pastoral landscapes, or pastures with trees, in formerly treeless pastures in the southern Ecuadorian Amazon represents just this kind of potentially significant shift in the structure of landscapes. In this paper, we try to explain this change in pastoral landscapes. Field surveys indicate variable densities of trees in pastures, with stem densities ranging from 30 to 400 per hectare. Analyses of interviews with the heads of small cattle ranching enterprises suggest that cattle ranchers pursue an intentional management strategy of allowing trees to regrow in working pastures to an extent that is ecologically significant. These findings confirm that even cattle ranches, albeit small in scale, can simultaneously produce food and provide important ecosystem services like carbon sequestration.

Interactions of social, terrestrial, and marine sub-systems in the Galapagos Islands, Ecuador

Galapagos is often cited as an example of the conflicts that are emerging between resource conservation and economic development in island ecosystems, as the pressures associated with tourism threaten nature, including the iconic and emblematic species, unique terrestrial landscapes, and special marine environments. In this paper, two projects are described that rely upon dynamic systems models and agent-based models to examine human–environment interactions. We use a theoretical context rooted in complexity theory to guide the development of our models that are linked to social–ecological dynamics. The goal of this paper is to describe key elements, relationships, and processes to inform and enhance our understanding of human–environment interactions in the Galapagos Islands of Ecuador. By formalizing our knowledge of how systems operate and the manner in which key elements are linked in coupled human–natural systems, we specify rules, relationships, and rates of exchange between social and ecological features derived through statistical functions and/or functions specified in theory or practice. The processes described in our models also have practical applications in that they emphasize how political policies generate different human responses and model outcomes, many detrimental to the social–ecological sustainability of the Galapagos Islands.

Scenario planning for tourism management: a participatory and system dynamics model applied to the Galapagos Islands of Ecuador

ABSTRACT This paper presents a decision-support system based on a system dynamics model designed to examine tourism management in the Galapagos Islands. A participatory approach was used to integrate the views of multiple stakeholders in the Galapagos Islands and to build an understandable, graphical representation of the impacts of tourism and residential population growth. Each subsystem is examined through hypotheses involving three scenarios of tourism growth that are associated with different residential population expansions. A number of integrative and linked social-ecological effects in our model have been shown to severely shock the natural environment of the Galapagos and saturate the capacity of several socio-economic subsystems. Major concerns of the expanding human dimension in the Galapagos are represented by (1) the growing number of introduced species that threaten the Islands’ unique natural environment, and (2) the rapid saturation of the Galapagos National Parks tourism reception capacity. The model relies upon real data to specify rules, relationships, and rates of exchange that are derived through statistical functions and/or functions specified in theory or practice. The presented decision-support system is a quantitative scenario-planning tool that can be used by policy-makers to achieve an enhanced understanding of the Galapagos Islands as a coupled human–natural system.

A validated agent-based model to study the spatial and temporal heterogeneities of malaria incidence in the rainforest environment.

BackgroundThe Amazon environment has been exposed in the last decades to radical changes that have been accompanied by a remarkable rise of both Plasmodium falciparum and Plasmodium vivax malaria. The malaria transmission process is highly influenced by factors such as spatial and temporal heterogeneities of the environment and individual-based characteristics of mosquitoes and humans populations. All these determinant factors can be simulated effectively trough agent-based models.MethodsThis paper presents a validated agent-based model of local-scale malaria transmission. The model reproduces the environment of a typical riverine village in the northern Peruvian Amazon, where the malaria transmission is highly seasonal and apparently associated with flooding of large areas caused by the neighbouring river. Agents representing humans, mosquitoes and the two species of Plasmodium (P.falciparum and P. vivax) are simulated in a spatially explicit representation of the environment around the village. The model environment includes: climate, people houses positions and elevation. A representation of changes in the mosquito breeding areas extension caused by the river flooding is also included in the simulation environment.ResultsA calibration process was carried out to reproduce the variations of the malaria monthly incidence over a period of 3xa0years. The calibrated model is also able to reproduce the spatial heterogeneities of local scale malaria transmission. A “what if” eradication strategy scenario is proposed: if the mosquito breeding sites are eliminated through mosquito larva habitat management in a buffer area extended at least 200xa0m around the village, the malaria transmission is eradicated from the village.ConclusionsThe use of agent-based models can reproduce effectively the spatiotemporal variations of the malaria transmission in a low endemicity environment dominated by river floodings like in the Amazon.

Shifting Baselines in the Galapagos White Fin Fishery, Using Fisher’s Anecdotes to Reassess Fisheries Management: The Case of the Galapagos Grouper

This study links social and ecological aspects of the white fin fishery in San Cristobal Island. This is a traditional fishery focused at first on the Galapagos grouper (Mycteroperca olfax), a top predator and an iconic species of the archipelago as part of a traditional dish to celebrate Easter on the continent. We used anecdotal information and perceptions provided by three generations of fisherman to understand the impacts of fishing on the dried and salted fishery. Significant differences were found among fishers’ groups surveyed and interviewed for this study. The oldest group indicated a greater past abundance of the Galapagos grouper than the other two younger age groups. The close relationship between fishers and their activity have generated certain knowledge about marine environments, its species, and the dynamics developed in their fishing areas, creating a perception of changes in this fishery.