1. What are my land use options in these soils? Collaborating Institutions Anthropological Center for Training and Research on Global Environmental Change, Indiana University Remote Sensing Laboratory, Dept. of Geography, Indiana State University Instituto Nacional de Pesquisas Espaciais (INPE), Brazil Empresa Brasileira de Pesquisa Agropecuaria (EMBRAPA), Brazil Study Site: Altamira Characteristics of the Study Site Altamira grew from a small riverine town based on rubber collection into a booming town of 85,000 due to agropastoral production stimulated by the Transamazon Highway built in 1971 It has one of the most significant patches of alfisols, or terra roxa estruturada eutrofica, in the Brazilian Amazon Rainfall is about 2000 mm/yr Matas de cipo co-exist with dense tropical forest in the region. Human Population Characteristics About 30% of the population are long-term area residents, known as caboclos; another 30% came from the South as colonos; about 20% came from the Northeast; about 20% came from the Central West About 21% had experience with bank credit About 20% were previous owners of land before migrating to the region Nutrient-rich soils (alfisols) are associated with greater overstory basal area Nutrient-poor soils (oxisols) are associated with greater understory development But total basal area is similar Basal Area and Soil Fertility In comparing Altamira with other study areas we found that: The best discriminator of rate of secondary succession was height increment That the nutrient-rich site consistently had faster height increment And that the difference accelerates through time Inter-regional Comparison On arrival, most colonists did not recognize differences between alfisols and oxisols Over the past 25 years, colonists have learned the differences and today there is a clear association between the percentage of the property in alfisols and crop choice (see figure above on crops and terra roxa) However, crop choice is constrained by the initial decision to locate on a specific property Those who arrived early to the frontier acquired most of the plots with terra roxa– and these plots have not been resold as often as poor quality property (see table) Choosing and Using Soils Differences in soil quality explain important differences in rates of secondary succession across regions. Differences in soil quality are associated with differences in species composition in regrowing forests Differences in soil quality explain much of the variance in crop choice and farmer persistence on rural properties Discussion There is an urgent need to give priority to soil quality assessment in advance of the construction of roads and settlement of colonists Doing so will reduce the high environmental and social costs resulting from uncritical clearing of land on poor soils that leads to farm failures, loan defaults, and loss of forest biodiversity – without benefit to the nation or local populations. Conclusion WHAT DIFFERENCE DOES SOIL QUALITY MAKE? INTER- AND INTRA-SITE COMPARISONS ON HOW AMAZONIAN SOILS AFFECT LAND COVER TRAJECTORIES, CROP CHOICE, AND LAND TENURE Emilio F. Moran Indiana University / ACT, USA Contact: moran@indiana.edu