Ironically, an exotic grass introduced by human beings now threatens the sagebrush ecosystem that expanded so dramatically as a result of human beings and their cattle. The sagebrush populations exploded after overgrazing removed the cold-adapted native grasses. Those grasses used to carry periodic, low-intensity fires that would burn up encroaching brushes. The grass, on the […]

For humans, ecosystems are great natural factories producing food, fiber, fuel, and structural material. These useful products are manufactured by organisms using energy from the Sun, and we harvest that energy by using these ecosystem products. The products and productivity of ecosystems depend on their climate. Where temperature and rainfall cycles permit, ecosystems provide a rich bounty. Where temperature or rainfall cycles restrict […]

Many of the world's equatorial and tropical regions are home to the rainforest ecosystem. This ecosystem is perhaps the most diverse on Earth, possessing more species of plants and animals than any other. Very large tracts of rainforest still exist in South America, south Asia, and some parts of Africa. Ecologists regard this ecosystem as a genetic reservoir of many species […]

This chapter is the first of two chapters that look at biogeography. Biogeography focuses on the distribution of plants and animals—the biota—over the Earth. It identifies and describes the processes that influence plant and animal distribution patterns. Ecological biogeography looks at how the distribution patterns of organisms are affected by the environment. Historical biogeography focuses on how spatial distribution patterns of organisms arise […]

An ecosystem is a closely woven web of plant and animal life within a particular type of physical environment. Africa has five main kinds of ecosystems: coastal environments, deserts and semideserts, mountain environments, savanna grasslands, and forests. Each ecosystem has its typical environment and climate, and the people who live there have adapted to its conditions and learned to use […]

THE CONCEPT OF the ecosystem began with the establishment of the science of ecology which is credited to Ernst Haekel, a German zoologist who coined the term ecology in 1869. He based this term on the Greek word oikos, meaning “a place in which to live.” It was another 60 years before the term ecosystem […]