Rinku Roy Chowdhury

Modeling tropical deforestation in the southern Yucatán peninsular region: comparing survey and satellite data

This paper presents some initial modeling results from a large, interdisciplinary research project underway in the southern Yucatan peninsular region. The aims of the project are: to understand, through individual household survey work, the behavioral and structural dynamics that influence land managers’ decisions to deforest and intensify land use; model these dynamics and link their outcomes directly to satellite imagery; model from the imagery itself; and, determine the robustness of modeling to and from the satellite imagery. Two complementary datasets, one from household survey data on agricultural practices including information on socio-economic factors and the second from satellite imagery linked with aggregate government census data, are used in two econometric modeling approaches. Both models test hypotheses concerning deforestation during different time periods in the recent past in the region. The first uses the satellite data, other spatial environmental variables, and aggregate socio-economic data (e.g., census data) in a discrete-choice (logit) model to estimate the probability that any particular pixel in the landscape will be deforested, as a function of explanatory variables. The second model uses the survey data in a cross-sectional regression (OLS) model to ask questions about the amount of deforestation associated with each individual farmer and to explain these choices as a function of individual socio-demographic, market, environmental, and geographic variables. In both cases, however, the choices of explanatory variables are informed by social science theory as to what are hypothesized to affect the deforestation decision (e.g., in a von Thunen model, accessibility is hypothesized to affect choice; in a Ricardian model, land quality; in a Chayanovian model, consumer–labor ratio). The models ask different questions using different data, but several broad comparisons seem useful. While most variables are statistically significant in the discrete choice model, none of the location variables are statistically significant in the continuous model. Therefore, while location affects the overall probability of deforestation, it does not appear to explain the total amount of deforestation on a given location by an individual.

Deforestation in the southern Yucatan peninsular region: an integrative approach

Abstract The tensions between development and preservation of tropical forests heighten the need for integrated assessments of deforestation processes and for models that address the fine-tuned location of change. As Mexico’s last tropical forest frontier, the southern Yucatan peninsular region witnesses these tensions, giving rise to a “hot spot” of tropical deforestation. These forests register the imprint of ancient Maya uses and selective logging in the recent past, but significant modern conversion of them for agriculture began in the 1960s. Subsequently, as much as 10% of the region’s forests have been disturbed anthropogenically. The precise rates of conversion and length of successional growth in both upland and wetland forests are tied to policy and political economic conditions. Pressures on upland forests are exacerbated by the development of infrastructure for El Mundo Maya, an archaeological and ecological activity predicated on forest maintenance, and by increased subsistence and market cultivation, including lands on the edge of Mexico’s largest tropical forest biosphere reserve. In this complex setting, the southern Yucatan peninsular region project seeks to unite research in the ecological, social, and remote sensing sciences to provide a firm understanding of the dynamics of deforestation and to work towards spatially explicit assessments and models that can be used to monitor and project forest change under different assumptions.

Ecological homogenization of urban USA

A visually apparent but scientifically untested outcome of land-use change is homogenization across urban areas, where neighborhoods in different parts of the country have similar patterns of roads, residential lots, commercial areas, and aquatic features. We hypothesize that this homogenization extends to ecological structure and also to ecosystem functions such as carbon dynamics and microclimate, with continental-scale implications. Further, we suggest that understanding urban homogenization will provide the basis for understanding the impacts of urban land-use change from local to continental scales. Here, we show how multi-scale, multi-disciplinary datasets from six metropolitan areas that cover the major climatic regions of the US (Phoenix, AZ; Miami, FL; Baltimore, MD; Boston, MA; Minneapolis–St Paul, MN; and Los Angeles, CA) can be used to determine how household and neighborhood characteristics correlate with land-management practices, land-cover composition, and landscape structure and ecosystem functions at local, regional, and continental scales.

Reconciling Agency and Structure in Empirical Analysis: Smallholder Land Use in the Southern Yucatán, Mexico

The agent-structure binary in human-environment relations has historically ascribed primacy to either decision-making agents or political-economic structures as the anthropogenic force driving landscape change. This binary has, in part, separated cultural and political ecology, despite important research weaving structure and agency in each of these and related subfields. The implications of approaching explanations of land use using this binary are illustrated systematically, drawing from empirical research on smallholder land use in the southern Yucatán of Mexico, a development frontier and environmental conservation region. The land-use strategies of mixed subsistence-market smallholder cultivators are explored through agent, structure, and integrated agent-structure models addressing parcel allocations to a suite of regionally evolving and/or extant land uses. The models are compared to illustrate what understanding is missed by a focus on either approach alone and what is gained by joining them. Results suggest that focusing on structure or agency alone may lead to inadequate and even erroneous characterizations of the variables that are of interest to the chosen approach. A sectorally disaggregated approach can identify suites of factors that drive particular land uses.

Assessing the homogenization of urban land management with an application to US residential lawn care

Significance This paper offers conceptual and empirical contributions to sustainability science in general and urban-ecological studies in particular. We present a new analytical framework for classifying socioecological measures along a homogenization–differentiation spectrum. This simple 2 × 2 matrix highlights the multiscale nature of the processes and outcomes of interest. Our application of the conceptual framework produces needed empirical insights into the extent to which land management appears to be homogenizing in differing biophysical settings. Results suggest that US lawn care behaviors are more differentiated in practice than in theory. Thus even if the biophysical outcomes of urbanization are homogenizing, managing the associated sustainability implications may require a multiscale, differentiated approach. Changes in land use, land cover, and land management present some of the greatest potential global environmental challenges of the 21st century. Urbanization, one of the principal drivers of these transformations, is commonly thought to be generating land changes that are increasingly similar. An implication of this multiscale homogenization hypothesis is that the ecosystem structure and function and human behaviors associated with urbanization should be more similar in certain kinds of urbanized locations across biogeophysical gradients than across urbanization gradients in places with similar biogeophysical characteristics. This paper introduces an analytical framework for testing this hypothesis, and applies the framework to the case of residential lawn care. This set of land management behaviors are often assumed—not demonstrated—to exhibit homogeneity. Multivariate analyses are conducted on telephone survey responses from a geographically stratified random sample of homeowners (n = 9,480), equally distributed across six US metropolitan areas. Two behaviors are examined: lawn fertilizing and irrigating. Limited support for strong homogenization is found at two scales (i.e., multi- and single-city; 2 of 36 cases), but significant support is found for homogenization at only one scale (22 cases) or at neither scale (12 cases). These results suggest that US lawn care behaviors are more differentiated in practice than in theory. Thus, even if the biophysical outcomes of urbanization are homogenizing, managing the associated sustainability implications may require a multiscale, differentiated approach because the underlying social practices appear relatively varied. The analytical approach introduced here should also be productive for other facets of urban-ecological homogenization.

Differentiation and concordance in smallholder land use strategies in southern Mexico's conservation frontier

Forest cover transitions in the developing tropics are conditioned by agricultural change. The expansion, intensification, and diversification of agricultural land uses are tied to regional economic/environmental regimes and decisions of local farming households. Land change science and agrarian systems research share an interest in the drivers of household strategies, land use impacts, and typologies of those land uses/drivers. This study derives a typology of farming households in southern Mexico based on emergent patterns in their land use combinations and analyzes their household and policy drivers. The results reveal broadly diversified household land use portfolios as well as three emergent clusters of farmstead production orientation: (i) extensive subsistence-oriented conservationists, (ii), dual extensive-intensive farmers, and (iii) nonextensive diversified land users. Household membership in these clusters is uneven and strongly related to tenancy, land endowments, wage labor, and policy subsidies. Although most households are following a nonextensive agricultural strategy incorporating off-farm incomes, the likelihood of a regional forest transition remains debatable because of the disproportionate deforestation impacts of the less common strategies. Conservation development policies in the region need to accommodate diverse smallholder farming rationales, increase off-farm opportunities, and target sustainable development with the assistance of community conservation leaders.

Ecosystem services in managing residential landscapes: priorities, value dimensions, and cross-regional patterns

Although ecosystem services have been intensively examined in certain domains (e.g., forests and wetlands), little research has assessed ecosystem services for the most dominant landscape type in urban ecosystems—namely, residential yards. In this paper, we report findings of a cross-site survey of homeowners in six U.S. cities to 1) examine how residents subjectively value various ecosystem services, 2) explore distinctive dimensions of those values, and 3) test the urban homogenization hypothesis. This hypothesis posits that urbanization leads to similarities in the social-ecological dynamics across cities in diverse biomes. By extension, the thesis suggests that residents’ ecosystem service priorities for residential landscapes will be similar regardless of whether residents live in the humid East or the arid West, or the warm South or the cold North. Results underscored that cultural services were of utmost importance, particularly anthropocentric values including aesthetics, low-maintenance, and personal enjoyment. Using factor analyses, distinctive dimensions of residents’ values were found to partially align with the Millennium Ecosystem Assessment’s categories (provisioning, regulating, supporting, and cultural). Finally, residents’ ecosystem service priorities exhibited significant homogenization across regions. In particular, the traditional lawn aesthetic (neat, green, weed-free yards) was similarly important across residents of diverse U.S. cities. Only a few exceptions were found across different environmental and social contexts; for example, cooling effects were more important in the warm South, where residents also valued aesthetics more than those in the North, where low-maintenance yards were a greater priority.

Household Land Management and Biodiversity: Secondary Succession in a Forest-Agriculture Mosaic in Southern Mexico

This study evaluates anthropogenic and ecological dimensions of secondary forest succession in Mexicos southern Yucatan peninsular region, a hotspot of biodiversity and tropical deforestation. Secondary succession in particular constitutes an ecologically and economically important process, driven by and strongly influencing land management and local ecosystem structure and dynamics. As agents of local land management, smallholding farmers in communal, i.e., ejido lands affect rates of forest change, biodiversity, and sustainability within and beyond their land parcels. This research uses household surveys and land parcel mapping in two ejidos located along the buffer of the Calakmul Biosphere Reserve to analyze how household socioeconomics and policy institutions drive allocations to successional forests in traditional crop fallows and in enriched fallows. Results indicate that household tenancy, livestock holdings, labor-consumer ratios, and receipts of agricultural subsidies are the strongest determinants of traditional fallow areas. Whereas the latter two factors also influence enriched successions, local agroforestry and reforestation programs were the strongest drivers of fallow enrichment. Additionally, the study conducts field vegetation sampling in a nested design within traditional and enriched fallow sites to comparatively assess biodiversity consequences of fallow management. Although enriched fallows display greater species richness in 10x10 m plots and 2x2 m quadrats, plot-scale data reveal no significant differences in Shannon- Wiener or Simpsons diversity indices. Traditional fallows display greater species heterogeneity at the quadrat scale, however, indicating a complex relationship of diversity to fallow management over time. The article discusses the implications of the social and ecological analyses for land change research and conservation policies.

Cash crops, smallholder decision-making and institutional interactions in a closing- frontier: Calakmul, Campeche, Mexico

In Mexico, since the revolution of 1910, agricultural development for subsistence and market has been a priority of diverse stakeholder groups, particularly farmers. Within the last ten years, Mexican federal agricultural policy shifted from a paternalistic to an enterprise model. This shift resulted in benefits for a few farmers while placing most producers at risk of economic failure. In addition to the impacts on the household economy, these policies influence land use and land cover. This paper explores the dynamics of chili production and how these dynamics are influenced by household and policy factors in the municipality of Calakmul in Campeche, Mexico. Jalapeño chili is the foremost market crop in Calakmul, until recently a development frontier for Mexico, and now the site of the largest biosphere reserve in that country and a landscape where priorities for forest conservation meet those for agricultural development. An integration of qualitative and quantitative methods enables a more complete understanding of this important and expanding land use in the region. En México, desde la revolución, el desarrollo agrícola para la subsistencia y el mercado ha sido una prioridad para diversos grupos, especialmente los agricultores. Durante la última década la política federal mexicana en relación a la agricultura ha cambiado de uno marcado de paternalismo hacia un modelo empresarial. Este cambio benefició a un grupo pequeño de agricultores, pero exponía la mayoría al riesgo de un fracaso económico. Por encima de los impactos en la economía doméstica, esas políticas impactaron en el uso del suelo y la cobertura de la tierra. Este estudio explora los dinámicos de la producción de chili y cómo ellos son influidos por los factores y políticas domésticos dentro el municipio de Calakmul, en Campeche, México. El chili jalapeño es el producto principal del mercado de Calakmul, desde hace poco en la frontera de desarrollo de México, pero ahora la ubicación de la reserva bioesférica más grande de México, y un paisaje en el cual las prioridades de conservación confrontan aquellas del desarrollo. Una integración de métodos cuantitativos y cualitativos permiten un mejor entendimiento de este importante y ampliando uso de suelo de la región.

Forest Change and Human Driving Forces in Central America

Three research projects, supported by the NASA Land Cover and Land Use Change (LCLUC) Science Program have been conducted in the Central America and Mexico (Mesoamerica) region. The first two projects were conducted in Northern Guatemala (Maya Biosphere Reserve) and the Southern Yucatan Peninsular Region (SYPR) of Mexico. The third project, focused on the Mesoamerican Biological Corridor, had broader coverage over the entire Central American region under a cooperative research memorandum of understanding between NASA and the environmental ministers of the seven Central American countries.