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...

Agriculture Benefits of Biodiversity to

People depend on biodiversity for healthful, sustainable agricultural systems. Biodiversity is the ultimate source of all cultivated plants and domesticated animals, and it provides essential assistance in maintaining crops and pastureland. Farmers save billions of dollars each year thanks to the services of pollinators, microbes that help create productive soil, and natural predators that reduce the need for pesticides. For thousands of years humans have used the natural diversity of plants...

Carnivora

Order Carnivora is composed of predaceous mammals with large canine teeth and a car-nassial mechanism (specialized shearing blades formed by the occlusion of the last upper premolar and first lower molar). Interactions between the array of carnivore species and the single living human species are mixed. Many carnivores are trapped or hunted for their coats and flesh. Pinnipeds (walruses and seals) have been an important source of fur, food, oil, and ivory. For the last 11,000 years, populations...

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...

Freshwater

Freshwater occurs in minor amounts on the earth, but it is found virtually everywhere in the atmosphere, streams, lakes, permafrost, glaciers, ice caps, icebergs, and below the ground. Although the salty oceans contain 97 percent (1,322,000,000 cubic kilometers) of the earth's water, glaciers contain about 2 percent (29,200,000 cubic kilometers) freshwater on land and in the atmosphere accounts for only 0.635 percent (8,630,000 cubic kilometers) of the total. It is estimated that ground-water...

Measuring the Value of Biodiversity

As we can see, there are equally diverse and valid ways to value biodiversity. Throughout most of human history, there has been no need to quantify these values. However, given the recent, overwhelming impact of human activity on biodiversity, in part because of population growth and our technological capability, developing ways to measure biodiversity has become a necessity. We live in a world in which tradeoffs and decisions have dire implications for biodiversity. Apart from family, humans...

Medicine The Benefits of Biodiversity to

Biodiversity is essential to the maintenance of human health. Extracts from many species of plants and, to a lesser extent, animals are critical to treating infections, disease, and other illnesses. According to the World Health Organization, about 80 percent of people in the developing world still depend primarily on traditional medicine, and 85 percent of that medicine is derived from plants (Farnsworth et al. 1985). Biodiversity plays a central role in Western medicine also 57 percent of the...

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...

Fertilizers Lead to the Depletion of Oxygen in Aquatic Ecosystems

The use of synthetic fertilizer increased seven to eight times over the last forty years (Figure 2). The major effects of fertilizer come from nitrogen (N) and phosphorus (P). Nitrogen pollution is now the single greatest source of water pollution in lakes, rivers, and bays. About half of the nitrogen and phosphorus applied is not taken up by crops it is left in the soil or leaches into ground and surface water. In industrialized (First World) countries, about 70 percent of crops are fed to...

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...