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...

Environmental Factors Controlling Diversity

Water level is a critical factor in all wetlands. Since each kind of plant and animal can withstand only certain amounts of flooding, wet- Zonation of Birds, Mammals, and Amphibians in Relation to Water Level and Vegetation Source Keddy, Paul A. 2000. Wetland Ecology. Cambridge Cambridge University Press. fig. 2.3, pp. 88-89. (Reprinted with permission) Note Different water levels create different plant communities, which in turn generates diversity in birds, mammals, and amphibians. lands with...

Global Pesticide Production 19451985

Source Modified from Tilman, David, et al. 2001. Forecasting Agriculturally Driven Global Environmental Change. Science 292-284. Source Modified from Tilman, David, et al. 2001. Forecasting Agriculturally Driven Global Environmental Change. Science 292-284. World usage World usage excluding USSR World usage World usage excluding USSR Source Food and Agriculture Organization of the United Nations. http apps.fao.org (Accessed July 17, 2002). Note that the apparent leveling of world fertilizer use...

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,...

Palestinian Painted Frog

The Palestinian painted frog (Discoglossus nigriventer) formerly inhabited Lake Huleh (Lake Hula) in Israel and has not been recorded since the lake was drained in the 1950s. This species is known only from two adult and two tadpole specimens collected in 1940 on the lake's eastern shore in what was then Palestine (Mendelssohn and Steinitz, 1943) and a single adult specimen reported by Steinitz in 1955 (Werner, 1988). This species was the first of its genus to be reported on the eastern shore...

Pollution

Pollution is the release or discharge of a substance, chemical, or heat energy into the natural environment, including the air, water, or soil, as a result of human activities. Pollution can be poisonous to living organisms and can modify and degrade habitats. It affects every ecosystem on earth and, therefore, changes the way in which the environment can provide living organisms with the habitat and condi tions they need to survive. In this way, pollution threatens biodiversity. Toxification...

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...

What You Can DoChange Your Energy

The amount of energy we use and the ways we use it affect earth's biodiversity in every corner of the globe. As we burn fossil fuels to generate electricity, run our cars, and heat our homes, we release gases that contribute to global climate change, acid rain, and air and soil pollution. Ultimately, our reliance on fossil fuels is leading to a less habitable planet for ourselves and other species. By using energy more wisely and transitioning to cleaner, renewable energy sources, we promote a...

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...