Adult evergreen Ramon( Brosimum alicastrum Sw. Moraceae) trees can thrive on the shallow soils atop limestone of northern Yucatan despite limited soil water storage capacity, and do not require irrigation during the annual dry sea- son. We hypothesized that early development of deep roots to reach moist subsoil layers or groundwater is critical to the performance of ramon trees growing on thin soils (~5 cm deep) over limestone bedrock. We conducted an isoto- pic study in a non-irrigated ramon plantation aimed at determining the sources of water used by trees of different age (5 or 9 years old) at the peak of the dry season. Pit excavation showed that Brosimum alicastrum roots were mostly concentrated in the upper soil and bedrock layers. About 5-year-old trees showed a much sharper decrease in shoot water content (21%) than 9-year-old ones (10%) during the dry season. Foliar d 13 C values were significantly higher in 5-year-old trees (-27.5 ± 0.3&) than in 9-year-old ones (-28.5 ± 0.3&), indicating greater water use efficiency and water stress levels in the younger age group. The d 18 O signature of stem water did

Utilization of bedrock water by Brosimum alicastrum trees growing on shallow soil atop limestone in a dry tropical climate

The Huastec Indians of northeastern Mexico manage their forests in an indigenous system that integrates commercial and subsistence production. Elements of primary and secondary forest coexist with introduced species in this diverse silvicultural structure which complements the swidden and permanent agriculture fields of the Huastec farmstead. The forest’s direct production of the food, timber, and fuel resources discussed here buffers the Huastec peasant family against market fluctuations and the failed harvest of a single crop. The Huastec system of forest management offers an alternative pattern to the agroforestry and plantation schemes now being suggested for development in the tropics. It is an alternative that provides protection for wild genetic resources while it contributes to the combination of commercial and subsistence agriculture so important for the successful modernization of peasant agriculture. The documentation of this system demonstrates that ethnobotanists and economic botanists have an important but unrealized role to play in the protection of biotic resources and in the development of sustained yield agroecosystems for peasants. The contributions of ethnobotanists are particularly valuable because they can find where and why useful wild species persist in agroecosystems. A greater effort to direct the attentions of policy makers to the value of ethnobotanical knowledge is needed.

Development policy, forests, and peasant farms: Reflections on Huastec-managed forests’ contributions to commercial production and resource conservation

Maize field weeds or agrestals are widely used in central Mexico as potherbs (quelites) and forage. This work presents quantitative data on these uses from the village of San Bartolo del Llano, Municipio de Ixtlahuaca, Valley of Toluca, an area with a relatively intensive, semicommercial agriculture. We interviewed 24 families of the village and 10 vendors at the market of Ixtlahuaca regularly during one rainy season (1995) on type and quantity of weed use. Also, the weed vegetation was surveyed and we interviewed 49 farmers on their farming practices and on costs. All of the 74 weed species found in maize fields were useful as forage, potherb, medicinal, or ornamental. Within the village, 11 species were eaten; an average family consumed 4.5 kg of wild potherbs per month during the rainy season. In Ixtlahuaca, 2150 kg of 10 species were sold, worth 3054 pesos (US $611). For quantity and gross economic value, forage was much more important. On the average, 1 ha of maize field produced a harvest of 1.5 t of green forage, worth about 25% of the gross value of the maize harvest, and 55% of its net value. The combination of maize with forage weeds for stabled animals constitutes an interesting integrated farming system. The weeds increase the useful biomass of the field, improve nutrition of the farmers, do not reduce the yield of the main crop, as the fields are kept weed free during the critical period, and provide erosion control, shade, and green manure.

Weeds as crops: The value of maize field weeds in the valley of Toluca, Mexico

Mexico that stands out as a megadiverse country is the fifth nation in terms of species richness. The country is home to 25,000–30,000 species of plants and currently 7461 useful plants are registered, of which 2168 are edible according to ethnobotanical data base of Mexican useful plants (BADEPLAM). In this chapter, edible plants are divided into six subcategories and describe some of the edible species recorded across different ethnobotanical research conducted in different regions of Mexico. We conclude that although the food habits in the country have undergone drastic changes in recent decades, and not always for the better, numerous food plant resources in Mexico continue to be widely utilized mainly by rural populations.

Biodiversity and Edible Plants of Mexico

The results from an autecological study of the growth, reproduction, and population dynamics of Brosimum alicastrum (ramon) in southern Mexico are applied to the controversy surrounding the use of this species in Maya subsistence practice. The frequent occurrence of B. alicastrum near ruins is explained by its competitive advantage on shallow limestone soils coupled with a continual input of bat-dispersed seed. Populations of the tree at Tikal are then compared with other naturally occurring populations as an example of how a detailed ecological analysis may furnish valuable insight into the historical use of a plant species. The Tikal populations are shown to be atypical in terms of phenology, productivity and breeding systems, suggesting that some form of artificial selection may have been practiced by the Maya.

Observations on Maya Subsistence and the Ecology of a Tropical Tree

Brosimum alicastrum is a large, evergreen tropical tree which is widely distributed in Mexico. Its protein-rich seeds and leaves may be used for food and forage, and several medicines and beverages can be made from parts of the tree. Although an important alternative food in pre-Columbian times, the current use of the tree is very limited. Recent studies indicate that its increased use would be extremely beneficial, and that the most immediate means for accomplishing this are the collection and processing of seeds from natural forests and the establishment of plantations for forage.

Enrique Pardo-Tejeda

Papers

Brosimum alicastrum (Moraceae): uses and potential in Mexico