Welcome to an overview of what Economic Botany has to offer.
It will be a distance learning course this spring 2000, so below are highlights of what I plan
to be doing in the TopClass format
LECTURE 10 HIGHLIGHTS FOR BIOLOGY 03074, ECONOMIC BOTANY: RAINFOREST ISSUES
Text for both editions: aspects of Ch. 15, 19, 25.
possible website: http://www.montana.com/manu/
(a virtual tour of a neurologist exploring for headache cures in Eastern Peru)
Tropical rain forest has features distinctive from our temperate forests:, including:
-high temperatures
-almost daily rain (much of it stemming from recycling of the transpired tree moisture)
-mineral-poor soil that is leached by the rain
-many species. Rain forests are high in biodiversity
Biodiversity is the number of different types of living organisms. A species consists of populations of similar organisms that can interbreed or are interbreedable. Diversity can be seen at different levels: genetic diversity, the variation within a species; species diversity, the number of different species; and ecosystem diversity, the variety of interactions of living things among themselves and where they live.
In direct human needs, biodiversity is useful in many areas, e.g., crop breeding. Indirectly, the great variety of species contributes to the stability of different ecosystems, and by losing species, we do not know which is/are the crucial species that support a particular ecosystem. Each species represents a unique gene pool, formed by thousands or millions of years of evolution.
Three main causes of rainforest deforestation
Subsistence agriculture. Many slash and burn in an attempt to get their own land. The first year's yield is rich, but the poor soil does not hold nutrients, so the process must be repeated.
Commercial logging. The problem is that in many countries, this logging is done at a much faster rate than the trees regrow.
Cattle ranching. Cattle can have up to six to ten years of grazing, after which a scrub savannah grows up.
Major tropical hardwoods:
Mahagony (Swietenia mahagoni, Meliaceae) is a tropical evergreen that grows to 30m+ in height. The wood is beautiful and hard
Teak (Tectona grandis, Verbenaceae) is a slender, tall (60m+) tree. The heartwood is durable, and changes from yellow to streaked chestnut tones during seasoning.
Examples of tropical rain forest products that would be sustainable on the local level in Brazil:
Natural rubber (Hevea brasiliensis, Euphorbiaceae). The rubber latex is collected from trees that are tapped in a sustainable process. Natural rubber is superior in resilience to synthetics.
Euphorbiaceae: the spurge family. Monoecious plants with unisexual flowers that typically do not have sepals or petals. The inflorescence is a reduced cymose cyanthium that in many cases is surrounded by large colorful bracts (poinsettia). Most spurges have milky, often toxic sap. Euphorbia, spurge; Manihot, cassava or manioc.
Brazil nuts (Bertholletia excelsa, Lecythidaceae) are seeds formed in large wooden spheres. The seedcoat of the seeds is hard and stony, as you've learned with your nutcracker. Almost all of the world's supply comes from harvesting wild plants. Sustainable harvests would be local enterprises.
Tropical plant drugs:
Rosy periwinkle, Catharanthus roseus (Vinca rosea), Apocynaceae, originally from Madagascar, is the source for vincristine (Oncovin) and vinblastine (Velban).
Apocynaceae, the dogbane family. 5 fused sepals, 5 fused petals, 5 stamens, gynoecium of 2 carpels fused at the stigmas and styles. The plants are herbs or shrubs with opposite leaves. 200 genera, 2000 species. Many warm weather plants that are poisonous. Rauvolfia, Indian snakeroot (source of reserpine); Nerium, oleander (ornamental bush known for its toxicity).
How much money is to be made with rain forest drugs? Mendelsohn and Balick (1997) estimate that each new drug discovered is worth $450 million to society as a whole. Given the track record so far, they estimate that there are about 320 major potential pharmaceuticals in tropical forests. Ethnobotanical screening of plants already used in traditional medicine could cut down on the exploration costs.
|main page| |background| |03028: Physiology| |03048: Anatomy|
|03050: Invertebrate Zoology| |03051: Vertebrate Zoology| |03074: Economic Botany|
|main page| |background| |03028: Physiology| |03048: Anatomy|
|03050: Invertebrate Zoology| |03051: Vertebrate Zoology| |03074: Economic Botany|
Please send comments and questions to: cronewil@hvcc.edu
Copyright 1999 by Wilson Crone
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This page updated on October 4, 1999