Chapter 58 The Biosphere

Ecosystem effects on sun, wind and water Life on earth is influenced by the amount and variation of solar radiation and patterns of atmospheric and oceanic circulation Various seasons are a result of earth’s position to sun Elevation causes significant changes in temperature and moisture Curvature of paths of winds due to earth’s rotation – Coriolis effect

Earth’s Biomes

Biomes are major ecosystems that include characteristic vegetational structures and their associated climactic conditions Biomes are defined by the factors like temperature and moisture, along with soil structure and mineral content which influence its primary production Eight principal biomes – tropical rain forest, savanna, desert, temperate grassland, temperate deciduous forest, temperate evergreen forest, taiga and tundra

Freshwater habitats Freshwater covers 2% of the earth’s surface Concentration of dissolved oxygen in water is major determinant of properties of freshwater communities. Oligotrophic lakes have high oxygen and low nutrients Eutrophic lakes are opposite to Oligotrophic lakes

Marine habitats Oceans cover 70% of earth’s surface Ocean is divided into several zones depending on depth, light penetration and proximity to land or bottom: intertidal, neritic, photic, benthic, and pelagic zones Phytoplankton is the major primary producer Estuaries occur where freshwater mixes with saltwater. Contain intertidal zones with salt marshes or mangrove swamps

Human Impacts on Biosphere: Pollution and Resource Depletion Freshwater environments are threatened by point- source pollution, diffuse pollution and acid precipitation Deforestation of terrestrial habitats leads to loss of habitat, disruption of water cycle, acid rain and loss of topsoil Marine habitats are being depleted of fish and other species by overfishing, destruction of coastal ecosystems and pollution Stratospheric ozone depletion has lead to an ‘ozone hole’ formation that is allowing more harmful UV- B radiation to reach earth’s surface

Human Impacts on Biosphere: Global Warming Global warming is caused by increases in atmospheric concentration of greenhouse gases, like Co2 (methane and nitrous oxide) Co2 allows solar radiation to pass through atmosphere but prevents long wave radiation from leaving the earth, and is increasing surface temperature Changing sea levels, increasing frequency of extreme climatic events, and expansion of tropical diseases

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