The Southern Yucatán Peninsular Region Project:
Deforestation and Land Change in a Season Tropical Forest and Economic Frontier
The Southern Yucatán Peninsular Region (SYPR) project was designed from the outset as a fully integrated, land change science effort, devoted to understanding deforestation and land-use change in the Southern Yucatán (SY) in the full dimensions of the coupled human-environment or social-ecological system as subsequently articulated in the GLP Science Plan. On-going since 1997, the project has involved partnerships among Clark University, El Colegio de la Frontera Sur [Chetumal y Campeche units], Harvard University, Rutgers University, and the University of Virginia.
The SY, that portion of southwestern Quintana Roo and southeastern Campeche, Mexico residing above 150 m elevation, occupies the uplands or meseta rising above the Caribbean and Gulf coastal plains of the Yucatán Peninsula. The region maintains a critical ecocline of seasonal tropical forests connecting the xeric forests of northern Yucatán and the humid forests of Petén, Guatemala. The Calakmul Biosphere Reserve is situated in the center of the SY, and its southern border meets the Maya Biosphere Reserve in Petén, marking the largest expanse of protected tropical forests in Mexico and Central America, a critical element of the MesoAmerican Biological Corridor.
The SYPR operates on the assumption that by understanding land change in its own right powerful insights are gained about the processes and dynamics specific to the human or environmental subsystems and their interactions. The range of expertise brought to bear in the design and implementation of the project includes over 40 sponsored researchers in the ecological, social (especially geography and economics), and GIS (including remote sensing) sciences.
The project began in 1997 with the aim of documenting, explaining, and modeling land changes and some of their ecological consequences. Landsat and Landsat ETM and aerial photography were used to develop a rich suite of land cover classes and document their changes from 1987 to 1997. The land classes included four types of tree cover, agricultural lands, three stages of successional growth, and savanna-tular (marsh). The rates of deforestation of older growth forests were shown to be large, even within the Calakmul Biosphere Reserve. These changes were associated with large-scale agricultural projects and a substantial increase in the rural population, rising to more than 37,000 people by 2000 (from 2,500 in 1960) and stimulated by the establishment of ejidos (communally owned lands) throughout the SY for emigrant populations from elsewhere in Mexico. This period of land change activity was marked by the expansion of the invasive bracken fern, its persistence amplifying the need for more deforestation.
With the emergence of El Mundo Maya (a state-sponsored effort to promote eco-archaeo-tourism that includes the Calakmul Biosphere Reserve) and state-led neoliberal reforms, emphasis was placed on muting new deforestation through various NGO-sponsored “green” activities (e.g., agroforestry) and direct payments from the state, while farmers experimented with commercial jalapeño (chili) cultivation. This high risk endeavor created winners and loser, with winners investing their profits in illegal immigration to the United States, such that by the early 2000s an emerging “remittance” economy was developing. Agriculture refocused on extant open land, reducing deforestation but sustaining large patches of “permanently” disturbed vegetation (cultivated, pasture, successional growth, and bracken fern).
By the mid-2000 the project had developed an in-depth understanding of the forest, biota, and nutrient dynamics of the environmental subsystem and the structural and decision making dynamics of farming household. It also had developed both econometric and agent-based models linked to land changes observed in Landsat imagery. This knowledge and capabilities permitted the project to expand to questions of coupled system vulnerability, and more recently, to the search for a sustainable land architecture (SLA). SLA refers to the win-win dimensions of the design of the landscape—the implications of the configuration of the landscape to serve both the ecological and human needs and wants as defined by various stakeholders (e.g., farmers to reserve agents). This effort requires that the projects models add an optimization component, an effort under exploration at this time.
Selected Findings and Products of the SYPR 1997 to Present
Land Change and Observation-Monitoring
- Annual rates of deforestation between 1987 and 2000 was 0.2% (» 409 km2 of older growth forest fell); the rate was generated by significant cutting of older between 1987 and 1995 (0.4%/annum), and a focus on sustained disturbed land thereafter.
- Deforestation was not uniform in the SY but concentrated on the eastern and western edges of the region and in the south-central area where agricultural ejidos and private ranches reside.
- Forest fragmentation increased 107% between 1987-2000; edge density increased and forest compactness decreased.
- Smallholder deforestation focused on upland forest types.
- 14 land classes identified (86% accuracy) using step-wise classification procedure known as In-Process Classification Assessment (IPCA).
- Three upland forest types captured by stature and deciduousness; three successional vegetation phases observed.
- The driest forest type is the least cut and disturbed; the more humid forests are the most cut and disturbed.
- Selva alta, the most humid forest, is underrepresented in the reserve compared to the SY at large.
- Bracken fern has expanded to take over 43 km2 of land once under cultivation or pasture; some patches are older than 30-35 yrs.
- Modis 1 km active fire product detects agricultural burning by frequency and spatial fire patterns (highest in El Nino yrs); given slash-and-burn cultivation it provides improved temporal resolution for cultivation.
- Selective logging in the early and middle of the 20th C effectively eliminated mature hardwood species (Spanish cedar and mahogany) from the SY forests.
- Disturbed forests change significantly in species and abundance.
- Individual tree species phenology and degree of deciduousness strongly vary along the ecocline.
- Chicle (zapote), a keystone tree species, cannot reach fruiting stage in successional forests.
- It would appear that (under investigation) the tapir (zapote disperser) and chicle maintain a positive feedback relationship, such that successional forests reduce the abundance and distribution of both species throughout the SY.
- Forest productivity declines with repeated deforestation, generating lower potential crop productivity and lower carbon sequestration rates.
- Available phosphorous, a limiting nutrient, declines with repeated deforestation, generating lower crop productivity and potentially generating a more stunted vegetation.
- Successional forest growth, on average, has a 40% lower canopy level than older growth forest.
- After 55 years of development efforts, the SY remains an economic frontier, and, farmers continue to search for commercial opportunities in thin markets.
- Environmental and market vagaries make commercial chili production a high risk venture; chili is controlled by intermediaries.
- About 45% of households follow a high risk “commercial” strategy, using income gained from chili and other crops to purchase agricultural inputs; about 55% of households follow a lower risk, mixed subsistence-commercial strategy.
- Households with little land tend to combat bracken fern invasion and vice versa.
- Various state and NGO sponsored activities explore “green” activities with firm economic rewards, none of which have been overly successful.
- Various programs facilitate women’s access to land with little impact on household farming practices, but some women have used these programs and community organizations to make improvements in socio-political capital.
- Illegal male immigration to the US has increased, improving household income, and altering gender relations and land uses through the development of a remittance economy; households with male heads in the US cultivate less but plant more pasture than those with male heads present.
- Despite past cattle failures, pasture and ranching has increased in the mid-2000 (by 0.67% yr-1), accounting for the majority of deforestation and recutting successional growth.
- Household decision making is consistent with theory expressing quasi-market (or mixed market-subsistence) production.
- Increased explanation of household decisions relative to land uses is obtained by combining structural and agency factors.
- SYPRIA, an agent based integrated assessment model has been developed.
- short-term population past projections of land use matched realty well; those based on past land use performed poorly.
- Assuming greater role of commercial cultivation proves more robust in land use models.
- Modeling indicates little movement towards private land ownership, consistent with reality.
- Two spatially (linked to the Landsat TM pixel) explicit econometric models have examined various dimensions of land change: discrete choice logit model and dynamic hazard model.
- The hazard model performed slightly better in predicting land transitions at the household level than did the logit model.
- A Seemingly Unrelated Regression examines structural vs agency variables in land use decisions, demonstrating that combining the variables provides improved statistical relationships.