The SYPR Integrative Assessment Model: Complexity in Development

Be it global environmental change or environment and development, landuse and land-cover change is central to the dynamics and consequences in question in the southern Yucatán peninsular region. Designing policies to address these impacts is hampered by the difficulty of projecting land use and land cover, not only because the dynamics are complex but also because consequences are strongly place-based. This chapter describes an integrated assessment modeling framework that builds on the research detailed in earlier chapters in order to project land-use and land-cover change in a geographically explicit way. Integrated assessment is a term that describes holistic treatments of complex problems to assess both science and policy endeavors in global environmental change (Rotmans and Dowlatabadi 1998). The most common form of integrated assessment is computer modeling that combines socioeconomic and biogeophysical factors to predict global climate. Advanced in part by the successes of these global-scale models, integrated assessment has expanded to structure knowledge and set research priorities for a large range of coupled human–environment problems. Increasing recognition is given to the need for integrated assessment models to address regionalscale problems that are masked by global-scale assessments (Walker 1994). Such models must address two issues to project successfully land-use and land-cover change at the regional scale. First, change occurs incrementally in spatially distinct patterns that have different implications for global change (Lambin 1994). Second, a model must account for the complexity of, and relationships among, socio-economic and environmental factors (B. L. Turner et al. 1995). The SYPR integrated assessment model, therefore, has a fine temporal and spatial grain and it places land-use and landcover change at the intersection of land-manager decision-making, the environment, and socio-economic institutions. What follows is a description of an ongoing integrated assessment modeling endeavor of the SYPR project (henceforth, SYPR IA model). The depth and breadth of the SYPR project poses a challenge to the integrated assessment modeling effort since some unifying framework must reconcile a broad array of issues, theories, and data. The global change research community offers a general conception of how environmental change results from infrastructure development, population pressure, market opportunities, resource institutions, and environmental or resource policies (Stern, Young, and Drukman 1992).

Spatially Explicit, Statistical Land-Change Models in Data-Sparse Conditions

A range of research interests beyond global environmental change science increasingly calls for advances in land-change models and, specifically, models that have fine-grained locational outputs. The rationale for such modeling about land change has been articulated elsewhere in this book (Ch. 1; Introduction to Part IV) and need not be reiterated here. It is important to note, however, that advances in question are assisted by the advances in the analytical sophistication of geographical information systems, hardware (GPS) that permits geographical coordinates to be established easily in the field, and for land-change studies, increasing temporal and spatial resolution of satellite imagery. Much of the first phase of land-change models that incorporate these systems and data has been empirical-based, time series assessments, such as Markov-chain models (e.g. Turner 1988), that let the record of land change determine future projections, or the spatial level of assessment has been large-grain (e.g. counties, states, regions). The SYPR project seeks a different approach demonstrated here: to test theories of land change in regard to their ability to explain fine-grained land change in the region at different spatial scales of assessment. Two complementary econometric modeling approaches are used here to investigate the factors that affect deforestation at the regional and household scales of analysis. Both approaches use the individual satellite pixels as the data on land-use change, from the classification of TM imagery described in Ch. 6. A regional model spans the entire study area of agricultural ejidos, and links the satellite imagery with publicly available geophysical data and socio-demographic government census data. The second model focuses exclusively on the parcels associated with the household survey data collected specifically for this project, discussed in Part III, especially Ch. 8. This latter approach uses the same geophysical data of the aggregate approach, but uses the much richer socio-demographic data derived from the linkage of individual farm plots and the satellite imagery via the sketch mapping exercise described in Chs. 8 and 9. While both models take a theoretical approach of individual maximization, they differ in a number of ways, the most important of which is the role of time in the decision-making process.

The Semi-Market and Semi-Subsistence Household: The Evidence and Test of Smallholder Behavior

Understanding household farming behavior among smallholders is an essential element of land-change studies inasmuch as a considerable portion of the world is dominated by land-users of this kind. Smallholders (peasants in some literature) are especially important within the tropical forests of Mexico, and the southern Yucatán peninsular region is no exception. This region, as elsewhere in the tropics, is characterized by underdeveloped markets and the consequent partial engagement of frontier farmers as market participants. Sparse exchange opportunities resulting from remoteness, low population density, and poorly developed infrastructure constrain these farmers to maintain a strong focus on consumption production, especially in terms of staple foods. Indeed, until the late 1960s, households in the region were totally subsistence-based and had virtually no experience with the agricultural market. Today, smallholder farmers retain consumption production, though a growing proportion also produce crops for sale. While this dual position in the market and in subsistence is an increasingly prevalent feature of smallholder farmers throughout the developing world, studies of deforestation commonly ascribe to them a wholly commercial orientation by employing profit-maximizing theoretical structures as a basis for econometrically modeling their land-use decisions (e.g. Chomitz and Gray 1996; Cropper, Griffiths, and Mani 1999; Cropper, Puri, and Griffiths 2001; Nelson, Harris, and Stone 2001; Nelson and Hellerstein 1997; Panayotou and Sungsuwan 1994; Pfaff 1999). In essence, the assertion of profit-maximization rests on the assumption that agents are fully engaged in markets, from which it follows that production, being strictly a function of farm technology and exogenously given input and output prices, is entirely independent of consumption and labor supply (Barnum and Squire 1979). This chapter explores the implications of relaxing the perfect-markets assumption for the modeling of semi-subsistence and commercial land-use decisions. By introducing variables measuring the consumption side of the colonist household, evidence is presented to suggest that, consistent with mixed or hybrid production themes (e.g. Singh, Squire, and Strauss 1986; Turner and Brush 1987), farmers operating in a context of thin product and/or labor markets do not exhibit behavior corresponding to that of a commercially oriented profit-maximizing farm.

Subsistence Sustained: Swidden or Milpa Cultivation

From the modern settlement of the southern Yucatán peninsular region to the present, smallholder farmers have followed a system of cultivation variously labeled swidden, slash-and-burn, or shifting within agricultural typologies (Watters 1971; but see Denevan 1992), and known as milpa in the Yucatán and Maya lowlands. Milpa cultivation has been so pervasive historically and geographically throughout the peninsula and the subject of such an extensive literature, that its description is only briefly reviewed here. Understanding the character and dynamics of this system of cultivation, including its long-term prognosis for continued use within the development of the region, is essential for understanding land changes and modeling them, although recent changes in cropping strategies portend the emergence of a ‘new’ kind of milpa. Swidden cultivation in the region, as elsewhere in Middle America, is invariably undertaken as an outfield activity—located at some distance from the farmstead—and is accompanied by small but complex housegardens or solares adjacent to and surrounding the house (e.g. Killion 1992; but see Gómez-Pompa 1987). The house-garden not only provides shade for the abode, it provides fruits, nuts, medicinal and ornamental plants, and a place for cropping experiments (Keys 1999). The extent and elaboration of house-gardens in the southern Yucatán peninsular region appears to be tied to the length of residency and, perhaps, ethnicity of the resident. Maya people, for example, tend to maintain large and elaborate solares. House-gardens tend to be smaller, even unrecognizable to the untrained eye, in the few densely settled communities in the region (e.g. Xpujil). As these gardens are not yet a central element of the broader dynamic of land change in the region, they are not given further attention here. The outfield or swidden supplies maize (Zea mays L.), planted in several varieties and serving as the consumption staple. Depending on the household, some portion of the maize crop may be sold. This ‘dual’ production function has been part of swidden in the region at least since the opening of Highway 186, reflecting government policy promoting commercial maize production (Ch. 7) and the abundant land awarded to individual ejidatarios at that time.

Three Frontiers of the Southern Yucatán Peninsular Region and SYPR Project

Frontiers advance and retreat, both figuratively and literally. At this moment they are advancing in three ways relevant to the subject of this book and the ongoing project on which it is based. First, after more than a century of reductionist hegemony, various science communities worldwide increasingly recognize the need to improve complementary, synthesis understanding—a way of putting the reductionist pieces of the problem back together again in order to understand how the ‘whole’ system works and to identify the emergent properties that follow from the complex interactions of the pieces. Synthesis understanding is not, of course, new. In the late eighteenth century, Immanuel Kant argued for it as one of the pillars of science in the reorganization of knowledge in the European academy (Turner 2002a) and designated geography as one of the ‘synthesis sciences’. Its contemporary rediscovery, however, rests in the science of global environmental change (Lawton 2001; Steffen et al. 2002), especially efforts to model complex systems, such as those in ocean–atmosphere–land interactions, and has been expanded by emerging research agendas seeking to couple human and environment systems, often registered under the label of ‘sustainability science’ (e.g. Kates et al. 2001; NRC 1999). Second, within these developments landuse and land-cover change (or, simply, land change) is singled out because of its centrality to a wide range of environmental concerns, including global climate change, regional–local hydrological impacts, biodiversity, and, of course, human development and ecosystem integrity (e.g. Brookfield 1995; NRC 2000; Watson et al. 2001). The need to advance an integrated land-change science is also increasingly recognized, one in which human, ecological, and remote sensing and geographical information systems (GIS) sciences are intertwined in problem-solving (Liverman et al. 1998; Klepeis and Turner 2001; Turner 2002b). And central to this effort is the need to advance geographically (spatially) explicit land-change models that can explain and project coupled human-ecological systems, and thus serve a wide range of research and assessment constituencies, from carbon to biodiversity to human vulnerability (IGBP 1999; Irwin and Geoghegan 2001; Kates et al. 2001; Liverman et al. 1998; Veldkamp and Lambin 2001). These two developments—synthesis science and integrated land science directed towards geographically explicit land-change models—constitute the broader intellectual and research frontiers to which this work contributes.

The Ejido Household: The Current Agent of Change

The ejidatario is the primary agent of land change in the region today, recognizing that this decision-maker is influenced by various policies and programs, both federal and NGO in origin (Ch. 7). Although colonization of the region, especially during the past forty years, has produced a diverse mix of ethnicities, cultural attributes, and economic characteristics, it is still appropriate to speak of a typical ejido household. The characterization of these households detailed here is based in large part on a SYPR project survey conducted in 1997 and 1998, designed to represent the entire study region. Subsequent surveys have been directed to specific issues, such as chili (Ch. 10) and the role of institutions; information from these studies is specified when used here. Most production within the ejido sector of the study region is organized around the semi-subsistence farm (or dual) household (Ch. 11). This unit of production is both a family and an enterprise (Ellis 1993), with the implication that decisions concerning what, how, and how much to produce are made in response to both market signals and the biological and cultural imperatives of the family unit. This chapter explores the socio-economic and farm characteristics of the sampled ejidatario households and presents relevant descriptive statistics. The data demonstrate that the ejido household has been exceptionally dynamic since the late 1960s, moving from a primarily maize-production orientation to a more diversified household economy. A standardized questionnaire with formal and open-ended components was used to elicit socio-economic and land-use data from ejidatario heads of household. In order to ensure a representative sample, data collection proceeded according to a stratified, two-stage cluster sample, with ejidos as the first stage unit and ejidatarios as the second stage unit (Deaton 1997; Warwick and Luinger 1975). The strata were delineated such that ejidos from across the region were represented in the sample, thereby capturing variability in both environmental conditions and in the influence of proximity to roads and markets. This strategy resulted in the random selection of eleven ejidos followed by the random selection of 199 ejidatario households (see Vance 2000 for details), which produced 188 completed surveys.

Forest Extraction to Theme Parks: The Modern History of Land Change

Modern-day deforestation in the southern Yucatán peninsular region began in earnest in the late 1960s. The composition of the region’s forest and options for land uses, however, were partly shaped by eighty years of activity leading up to the 1960s, just as it was by the ancient Maya over a millennium ago (Ch. 2). Most of the modern impacts began in the twentieth century and are traced here through three major episodes of use and occupation of the region: forest extraction, 1880–1983; big projects and forest clearing, 1975–82; and land-use diversification, conservation, and tourism, 1983 to the present. Each episode corresponds to different visions of how the region should be used and to different human–environment conditions shaping the kind, location, and magnitude of land change. Understanding these changing conditions underpins all other assessments of the SYPR project. The episode of forest extraction spans the bulk of the modern history of the region. It began in the late nineteenth century and ended with the demise of parastatal logging companies in the 1970s and early 1980s, due primarily to the depletion of reserves of mahogany and Spanish cedar throughout the region. Before this episode fully expired, a new one, that of big projects and forest clearing began, marked by large-scale rice and cattle schemes undertaken in the mid to late 1970s and early 1980s. This episode accelerated the road construction that began in the latter part of the 1960s, and it witnessed expanded settlement linked to colonization programs. The Mexican debt crisis of 1982 brought this episode to an abrupt halt, triggering the search for a new alternative to developing the frontier. This search, made in the context of neoliberal economic reforms, led to the establishment of the Calakmul Biosphere Reserve in 1989 and other, more recent initiatives, defining the most recent episode of land-use diversification, conservation, and tourism. From the collapse of the Classic Maya civilization to the twentieth century, the occupation of the region was sparse (Turner 1990), the forest serving as a refuge during the colonial period for those Maya fleeing Spanish domination along the coasts and in the north, especially during the Caste War of the middle nineteenth century, when the northern Maya revolted against Mexico (Jones 1989).

Institutions, Organizations, and Policy Affecting Land Change: Complexity Within and Beyond the Ejido

Despite decades of colonization and development initiatives, the southern Yucatán peninsular region remains an economic frontier. The term ‘frontier’, however, hides a complex political economy of social, political, and economic structures in which land managers operate. Presently, multiple interest groups vie for influence, increasingly positioning themselves around sustainability concerns, and attempting to reconcile the competing goals of economic development and environmental preservation. The major political institutions and organizations promoting conservation and development in the region fit into five categories: federally decreed land management regimes, federal and state secretariats, local community-based groups and institutions, national non-governmental organizations (NGOs), and international accords. These institutions and organizations aim to influence land-use decisions in the dominant land access unit, the ejido. The relationships among ejidos, social movements, NGOs, government policy, and international activity in the region are examined here, highlighting how even within a frontier economy, conservation and development visions increasingly influence resource use. Before the Mexican revolution of 1910–17, 96 per cent of Mexico’s rural people were landless (Sinha 1984). These rural poor supported the revolution, in large part, to break up grand haciendas (estates) and to allow campesinos (peasants) access to agricultural land. Ejidos, one of four landtenure types federally mandated, were designed to provide campesinos access to land that could not be transferred easily and thereby taken from them. Based on interpretations of pre-Hispanic land tenure, Article 27 of the Constitution established ejido land to be communal, ruled by an ejido assembly (consisting of all members with land rights in the ejido, or ejidatarios), and used in ejido-defined usufruct. Prior to 1992, when the law was reformed, ejidatarios were prevented from selling their land, renting it, or using it as collateral, and from negotiating deals with private investors. Perhaps more important than these official guidelines, however, are the perceptions of ejidos by state officials. Established, in part, to protect ‘indigenous’ people and not open to privatization, the ejido was stigmatized as ill-suited for modernization (Oasa and Jennings 1982). A bimodal Mexican agrarian policy followed (de Janvry 1981; Tomich, Kilby, and Johnston 1995) in which the potential productive role of ejidatarios was largely ignored (Oasa and Jennings 1982; Sonnenfeld 1992; Tomich, Kilby, and Johnston 1995).

Land Cover and Land Use: Classification and Change Analysis

Despite its international designation as a hotspot of biodiversity and tropical deforestation (Achard et al. 1988), the micro-scale land-cover mapping of southern Yucatán peninsular region remains surprisingly incomplete, hindering various kinds of research, including that proposed in the SYPR project. This chapter details the methodology for the thematic classification and change detection of land use and cover in the tropical sub-humid environment of the region. A hybrid approach using principal components and texture analyses of Landsat TM data enabled the distinction of land-cover classes at the local scale, including mature and secondary forest, savannas, and cropland/pasture. Results indicate that texture analysis increases the statistical separability of cover class signatures, the magnitude of improvement varying among pairs of land-cover classes. At a local level, the availability of exhaustive training site data over recent history (10–13 years) in a repository of highly detailed land-use sketch maps allows the distinction of greater numbers of land-cover classes, including three successional stages of vegetation. At the regional scale, finely detailed land-cover classes are aggregated for greater ability to generalize in a terrain wherein vegetation exhibits marked regional and seasonal variation in intra-class spectral properties. Post-classification change detection identifies the quantities and spatial pattern of major land-cover changes in a ten-year period in the region. Change analysis results indicate an average annual rate of deforestation of 0.4 per cent, with much regional variation and most change located at three subregional hotspots. Deforestation as well as successional regrowth is highest in a southern hotspot located in the newly colonized southern part of the region, an area where commercial chili production is large. The objectives of this chapter are to describe and evaluate: (1) an experimental methodology that iteratively combines three suites of image-processing techniques (PCA, texture transformation, and NDVI); (2) the statistical separability of distinct land-cover signatures; and (3) a post-classification change detection for the region from 1987 to 1997 in order to derive regional deforestation rates, and identify the spatial pattern of deforestation and secondary forest succession. Specifically, a region encompassing 18,700km2 (those land units completely within the defined region; Fig. 7.1) was mapped using a maximum likelihood supervised classification of lower-order principal components of Landsat TM imagery after tasseled-cap and texture transformations.

Forest Types and their Implications

The southern Yucatán peninsular region contains the largest and most rapidly disappearing continuous tract of tropical forest in Mexico (Flores and Espejel Carvajal 1994; Delfín Gonzales, Parra, and Echazarreta 1995; Acopa and Boege 1998). Vegetation in the region is a mosaic of forest types with different structural appearances (Flores and Espejel Carvajal 1994; Hernández-Xolocotzi 1959; Miranda 1958) that primarily reflect variation in environmental and edaphic conditions (Ibarra-Manríquez 1996). However, the structure and tree composition of forests in the region, as elsewhere in the central Maya lowlands, has been and remains strongly influenced by human activity (Ch. 2). In spite of the abundance of botanical work throughout the Yucatán peninsula, little attention has been devoted to characterizing the forests in this frontier region quantitatively, and the variation and distribution of forests remain poorly documented. Yet, it is precisely this kind of documentation that is required for integrated land studies of the kind that the SYPR project is undertaking (Turner et al. 2001). Since the third decade of the twentieth century, botanical interest has focused on the flora of the Yucatán Peninsula, especially that located in the historically more accessible portion of the peninsula (Ibarra-Manríquez 1996). Early twentieth-century studies (Lundell 1938; Standley 1930) led to a broad classification of the primary vegetation as deciduous tropical forests (Miranda 1958), or evergreen tropical forests (Rzedowski 1981), controlled in distribution by the northwest to southeast precipitation gradient, distinctive dry season, and karstic terrain (Ch. 2). Today, the entire region is appropriately labeled a seasonally dry tropical forest (Bullock, Mooney, and Medina 1995). During the rainy season (May–October) most species have their canopies fully displayed and light is a limiting factor in the forest understory (Martínez-Ramos 1985, 1994). For the remainder of the year, monthly precipitation usually does not exceed 100mm. During the lowest rainfall months (February–April), water may become limiting and considerable defoliation takes place, especially in the north and west. Other factors controlling forest structure and composition include topography, twentieth-century land-use history, and hurricanes (Brokaw and Walker 1991; Cooper-Ellis et al. 1999).