Conservation engineering and agricultural terracing in Tlaxcala, Mexico

This research examines the practice of hillslope terracing in the state of Tlaxcala, Mexico. It explores how one popular terrace form, zanja-bordo (ditch-and-border) terraces, is employed in two distinct, though sometimes related contexts: (1) producing crops (agriculture) and (2) protecting natural resources (conservation). It first traces the use of zanja-bordo terraces in traditional agriculture in the region, highlighting some of the major elements of their form and function, issues surrounding their antiquity, and their possible role in the landscape degradation so prevalent in the region today. Moving from this agricultural context, the dissertation next examines the role of zanja-bordo terraces in landscape restoration efforts in Tlaxcala. It demonstrates the key role that active and prolonged maintenance plays in long-term efforts to restore previously degraded farmland back to productive capacity. The dissertation then examines more broadly how government programs to promote zanja-bordo terracing in the region impact farmers, whose ancestors have been building zanja-bordo terraces for centuries. Findings from the collection, synthesis, analysis, and groundtruthing of written data on governmental terracing projects in the state reveal that while perhaps well intentioned, these programs did little to promote sustainable agricultural development or environmental conservation in the region. Finally, the dissertation moves above the 3,000-meter mark to examine the relatively recent phenomenon of high-elevation terracing in Mexico's national parks. Conceived as a means of erosion mitigation, water conservation, reforestation, and even fire suppression, government agencies now construct zanja-bordo terraces throughout the understory of many of Mexico's subalpine forests. A case study of the la Malinche (Malintzi or Matlalcueyatl) National Protected Area illustrates some of the difficulties in examining each of the claimed benefits of terracing in these environments. Whether for agriculture or restoration, as a techno-developmental strategy, or as a tool for soil and water conservation, zanja-bordo terraces are shown to be an adaptable and effective hillslope management technology. This dissertation demonstrates, however, that successful adaptation and implementation of zanja-bordo technologies into different contexts largely depends on the effective planning, monitoring, and maintenance of terrace structures and processes. Ultimately, the sustainability of zanja-bordo terracing relates more to issues of contextualization and human motivation than to questions of technological innovation.