Ecosystems

ECOSYSTEMS ARE DEFINED as communities that involve dynamic interactions among living elements (such as animals, plants, and microorganisms), and the inanimate elements of their environments. All parts of an ecosystem need to work together to maintain the proper balance of the system, and it is necessary for all ecosystems to function in conjunction to maintain balance.

The term ecosystem was first used in 1930 by Roy Clapham (1904–90), an appointee to the Demonstratorship in Botany at England's Oxford University. At the time, Clapham was studying plant ecology under the guidance of Botany Department Chair Arthur Tansley (1871–1955), a pioneer in the field of ecology. Two decades after Clapham and [Page 351]Tansley first articulated the concept of ecosystems, ecologists began including the study of ecosystems as a distinct field of study within the discipline of ecology. Scientists have since identified eight major ecosystems: the temperate forest, tropical rain forests, deserts, grasslands, the tundra, the taiga, the chaparral, and the ocean.

An ecosystem may be as small as a puddle or pool of water, or as large as the Sahara Desert or the Atlantic Ocean. The ecosystems of the tropical forests provide a classic example of the extent of ecosystems. In these forests, thousands of vegetable and animal species that live in the air and on the ground interact with millions of surrounding organisms. Within each ecosystem, the habitat is a physical element that combines the natural and adaptive conditions of particular species. All ecosystems are dynamic. Changes may be temporary in response to outside events such as forest fires or natural disasters, or they may occur according to established cycles. Commonly occurring factors that affect changing ecosystems are nutrient availability, temperature, light intensity, grazing intensity, and species population density. Six ecosystems are identified as most necessary for supporting life on Earth; agroecosystems, forest ecosystems, freshwater ecosystems, grassland ecosystems, coastal ecosystems, and urban ecosystems. The integral relationship between these ecosystems and human life is demonstrated by the fact, half of the world's jobs are dependent on agriculture, forestry, and fishing. In the poorest sections of the world, 70 percent of all jobs are derived from these industries.