Angiosperms

Angiosperms, commonly known as flowering plants, are the largest and most diverse group of plants, with 275,000 species representing more than 80 percent of all green plants. As a consequence, they are the principal components of the earth's terrestrial vegetation and are the most economically important group, as the principal source of foods, fiber products, timber, medicinals, dyes, spices, and ornamentals. In terms of number and phytomass, they contribute to the food chain in many ways. The...

Agricultural Ecology

The origins of agriculture can be traced back to Mesopotamia, whence it spread to the fertile crescent of southwestern Asia. In Africa, ancient climatic changes forced humans to make adaptations in their way of life. About 10,000 years ago, as drought and desertification spread from the north into central Africa, nomadic hunter-gatherers began to settle and live by fishing and planting the seeds culled from wild grains in the wet ground left behind by seasonally receding lakes. In the boundary...

Indigenous Conservation

Definitions of so-called first peoples as aboriginal, indigenous, autochthonous, or native are made in relation to later immigrant population groups occupying the same or adjacent territories. Although there is no universally accepted definition of indigenous peoples, the term is generally understood to refer to those tribes, nations, or ethnic groups historically inhabiting lands before the advent of colonizing settlers. In addition, they are usually minorities within larger societies,...

Pollination

Pollination involves the transfer of the male gametophyte in seed plants, or pollen, to the receptive surface of the female organs, the stigma, for fertilization of the ovule. Although many plants are capable of self-fertilization, only some weedy and ephemeral plants routinely do so. Some seed plants disperse pollen by wind, such as many conifers the grasses, sedges, and rushes (Poaceae, Cyperaceae, and Juncaceae) and temperate species of oaks and beeches (Fagaceae), elms (Ulmaceae), birches...

Positive Interactions

Positive interactions are cooperative relationships between species that result in better growth, reproduction, and survival for at least one species involved in the interaction, without negatively affecting the other species (Morin, 1999 Stiling, 1999). Positive interactions influence biodiversity by creating alliances between species that allow them to coexist. The benefits of these associations are numerous. They include the provision of food, habitat, and more specialized services such as...

Preservation of Species

The conservation of species involves the use of strategies and techniques that can be classified into three broad approaches in the wild, in captivity, and in-vitro (germ cells). Knowledge of these approaches is essential to understanding how conservation management practices conserve biodiversity in real life applications. In the wild, or in-situ, conservation is defined by the Convention for Biological Diversity (1992) as the conservation of ecosystems and natural habitats and the maintenance...

Topsoil Loss of

When soil is exposed, it is removed by wind and rain. For example, rain pounding on the surface of soil breaks it apart, making it easy for running water to carry it away. At first, erosion may be sheets of water running down a slope. However, as time goes on, flowing water may become concentrated in tiny channels, or rills. With time these may enlarge to gullies, making the fields unusable because equipment can't get around. As the gullies enlarge and widen by lateral erosion, the stream banks...

Wallace Alfred Russel

Born in 1823, in Usk, England, a small town near the Welsh border, Alfred Russel Wallace was raised in genteel poverty. His first employment was helping his brother John survey land parcels for a railroad. While still in his twenties, he taught school in Leicester, where he met young Henry Walter Bates, who shared his passion for natural history. On weekend bug-collecting jaunts, the would-be adventurers discussed such favorite books as Darwin's Voyage of the H.M.S. Beagle (1845) and dreamed of...

Haplochromine Cichlids of Lake Victoria

The haplochromine cichlid fish of Lake Victoria demonstrate both the exuberance of species radiation and the tragedy of mass extinction, the first to occur during historical times. These tiny, colorful fish, which constituted 80 percent of the fish biomass in Lake Victoria prior to 1978, now account for less than 2 percent (Kaufman, 1992). This decline has been caused by a combination of human influences. The cichlids are a very large and diverse family of freshwater, perchlike fish...