Economic Botany 59(1) pp. 77–86. 2005  2005 by The New York Botanical Garden Press, Bronx, NY 10458-5126 U.S.A. INFLUENCE OF MARKET ORIENTATION ON FOOD PLANT DIVERSITY OF FARMS LOCATED ON AMAZONIAN DARK EARTH IN THE REGION OF MANAUS,AMAZONAS,BRAZIL 1 JULIE MAJOR,CHARLES R. CLEMENT, AND ANTONIO DITOMMASO Major, Julie (Department of Crop and Soil Sciences, Cornell University, Ithaca, NY 14853, USA; email: jm322@cornell.edu, phone: 607-255-1730, fax: 607-255-3207), Charles R. Clem- ent (Coordenac ¸a ˜o de Pesquisas em Cie ˆncias Agrono ˆmicas, Instituto Nacional de Pesquisas da Amazo ˆnia (INPA), Manaus, Brazil), and Antonio DiTommaso (Department of Crop and Soil Sciences, Cornell University, Ithaca, NY). INFLUENCE OF MARKET ORIENTATION ON FOOD PLANT DIVERSITY OF FARMS LOCATED ON AMAZONIAN DARK EARTH IN THE REGION OF MANAUS,AMA- ZONAS,BRAZIL. Economic Botany 59(1):77–86, 2005. Homegardens may serve as reservoirs of agro-biodiversity on highly fertile, anthropogenic Amazonian Dark Earth (ADE) soils of the Amazon basin. However, as these soils are used more intensively for market-oriented agricul- ture, we suspected a decrease in their agro-biodiversity. We present data obtained from surveys on 16 farms where ADE was present in the region of Manaus, Amazonas, Brazil. When farms were separated into two groups by market orientation, species richness on the farms was not significantly influenced by market orientation, but there was less dominance (i.e., more diver- sity) for homegardens in the low-market orientation group (P  0.1). The proportion of native species was not affected by market orientation. Hence, while the most market-oriented farms retained high species richness, homegardens located on them contained higher proportions of commercially interesting species. Key Words: Agro-biodiversity; Amazonia; Amazonian Dark Earth; market orientation; Terra Preta de I ´ ndio; genetic erosion. Although homegardens can take an infinite number of forms, they are usually characterized by high species diversity and complex multistra- ta architecture (Coomes and Ban 2004; Fernan- des and Nair 1986) that constitute an important input to the diet of the household (Nair 1993), as well as spices, medicines, stimulants, etc. (Trinh et al. 2003). They also provide shade near living areas while reducing erosion in high-rain- fall regions (Jose and Shanmugaratnam 1993). Homegardens can serve as key elements in the conservation of on-farm biodiversity (Eyzaguir- re, Martin, and Barrow 2001; Trinh et al. 2003), for example by offering refugia for species whose importance is diminishing, and by serv- ing as testing nurseries for new plant species or varieties (Eyzaguirre, Martin, and Barrow 2001). Farms of traditional smallholder populations in Amazonia are usually composed of several swidden agriculture plots and a homegarden lo- 1 Received 13 September 2004; accepted 22 Novem- ber 2004. cated close to dwellings. While cropping pat- terns in the swidden plots may vary from mono- cultures (e.g., manioc, Manihot esculenta Crantz) to multi-crop arrangements [e.g., mani- oc, maize (Zea mays L.), and dry beans (Phas- eolus sp.) grown together, or manioc with a mix- ture of fruit trees], the diversity of these swidden plots is always less than that in the homegar- dens. Such cropping patterns are also found on farms located on areas of Amazonian Dark Earth (ADE, locally known as Terra preta de I ´ ndio). These are highly fertile soils formed at the lo- cation of indigenous settlements in pre-Colum- bian times (Smith 1980; Woods, McCann, and Meyer 2000). Their fertility is usually consid- erably greater than that of surrounding local soils; ADE soils exhibit higher pH, phosphorus, and organic matter contents, as well as higher cation exchange capacity (Kern and Ka ¨mpf 1989; Lehmann et al. 2003). The production of high-value crops (e.g., vegetables) is possible on ADE without the often prohibitive amounts of external inputs that would be necessary on sur-