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Chapter 50 (pgs. 1092-1119) An Introduction to Ecology and the Biosphere. AP Minknow The role of abiotic factors in the formation of biomes. Features of freshwater and marine biomes. Major terrestrial biomes and their characteristics. The Scope of Ecology
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Chapter 50 (pgs. 1092-1119)An Introduction to Ecology and the Biosphere AP Minknow The role of abiotic factors in the formation of biomes. Features of freshwater and marine biomes. Major terrestrial biomes and their characteristics.
The Scope of Ecology • 1.Define ecology and identify the two features of organisms that ecologists try to explain. Discuss examples of experiments that examine these features. • 2.Distinguish between the abiotic and biotic components of the environment. • 3.Describe the relationship between ecology and evolutionary biology. • 4.Distinguish among organismal ecology, population ecology, community ecology, ecosystem ecology, and landscape ecology. • 5.Define the precautionary principle and illustrate its usefulness with regard to the ecological issues facing society. • Factors Affecting Distributions of Organisms • 6.Describe the flowchart of inquiry used to determine what limits the geographic distribution of a particular species. 7.Describe the problem of introduced species and the specific problems posed by the introduction of African bees and zebra mussels. 8.Explain the "tens rule."
9.Explain how habitat selection can limit the range of otherwise suitable habitats. • 10.Describe and illustrate biotic and abiotic factors that affect the distribution of organisms. • 11.Explain how climate affects the geographic distribution of organisms. • 12.Define and illustrate the concept of a microclimate. • 13.Explain how the retreat of North American glaciers 16,000 years ago influenced the distribution of trees. • Aquatic and Terrestrial Biomes • 14.Distinguish among the various zones found in aquatic biomes. • 15.Define and compare the many types of freshwater and marine biomes. • 16.Describe the characteristics of the major terrestrial biomes: tropical forest, savanna, desert, chaparral, temperate grassland, temperate forest, taiga, and tundra. • The Spatial Scale of Distributions • 17.Explain why the distribution of a species is often not easily accounted for.
50.1 Ecology is the study of interactions between organisms and the environment • Ecology • Is the scientific study of the (complex) interactions between organisms and the environment • These interactions • Determine both the distribution of organisms and their abundance
Ecology and Evolutionary Biology • Events that occur in ecological time • Affect life on the scale of evolutionary time
Climate in northern Australia is hot and wet, with seasonal drought. Kangaroos/km2 > 20 10–20 5–10 1–5 Red kangaroos occur in most semiarid and arid regions of the interior, where precipitation is relatively low and variable from year to year. 0.1–1 < 0.1 Limits ofdistribution Southeastern Australia has a wet, cool climate. Southern Australia has cool, moist winters and warm, dry summers. Tasmania 50.2 Interactions between organisms and the environment limit the distribution of species.
Organisms and the Environment • The environment of any organism includes • Abiotic, or nonliving components • Biotic, or living components • All the organisms living in the environment, the biota
Climateprevailing weather conditions in a particular area. • Mainly formed by 4 abiotic factors • Temp, wind, water, light • Macroclimate • Global, regional, and local patterns • Microclimate • Very fine patter such as the climate for an ant population under a rock
50.4: Climate largely determines the distribution and structure of terrestrial biomes • Climate • Is particularly important in determining why particular terrestrial biomes are found in certain areas
Temperate grassland Desert Tropical forest 30 Temperate broadleaf forest 15 Annual mean temperature (ºC) Coniferous forest 0 Arctic and alpine tundra 15 100 200 300 400 Annual mean precipitation (cm) Climate and Terrestrial Biomes • Climate has a great impact on the distribution of organisms, as seen on a climograph Figure 50.18
30N Tropic of Cancer Equator Tropic of Capricorn 30S Chaparral Tundra Key Temperate grassland High mountains Tropical forest Temperate broadleaf forest Polar ice Savanna Coniferous forest Desert • Biomes are the major types of ecological associations that occupy broad geographic regions of land or water • are classified by their abiotic and biotic factors. Figure 50.19
Climate largely determines the distribution and structure of terrestrial biomes. • Because there are latitudinal patterns of climate over the Earth’s surface, there are also latitudinal patterns of biome distribution. • A climograph denotes the annual mean temperature and precipitation of a region. • Temperature and rainfall are well correlated with different terrestrial biomes, and each biome has a characteristic climograph. • Most terrestrial biomes are named for major physical or climatic features or for their predominant vegetation. • Vertical stratification is an important feature of terrestrial biomes. • The canopy of the tropical rain forest is the top layer, covering the low-tree stratum, shrub understory, ground layer, litter layer, and root layer. • Grasslands have a canopy formed by grass, a litter layer, and a root layer. • Stratification of vegetation provides many different habitats for animals. • Terrestrial biomes usually grade into each other without sharp boundaries. The area of intergradation, called the ecotone, may be narrow or wide. • The species composition of any biome differs from location to location. • Biomes are dynamic, and natural disturbance rather than stability tends to be the rule. • Hurricanes create openings for new species in tropical and temperate forests. • In northern coniferous forests, snowfall may break branches and small trees, producing gaps that allow deciduous species to grow. • As a result, biomes exhibit patchiness, with several different communities represented in any particular area. • In many biomes, the dominant plants depend on periodic disturbance. • For example, natural wildfires are an integral component of grasslands, savannas, chaparral, and many coniferous forests. • Human activity has radically altered the natural patterns of periodic physical disturbance. • Fires are now controlled for the sake of agricultural land use. • Humans have altered much of the Earth’s surface, replacing original biomes with urban or agricultural ones.
What Is a Biome? For each biome, plots of seasonal temperature and precipitation patterns are given. Activity of different types of organisms throughout the year are shown. Level of activity is shown by width of horizontal bar. Growth forms of plants are described, as are patterns of species richness (number of species).
What Is a Biome? General descriptions of the biomes cannot describe all the variation existing in each. Boundaries between biomes are somewhat arbitrary; in many places the biomes merge into one another.
What Is a Biome? Tundra Arctic and at high elevations. Vegetation is low-growing perennials. Arctic tundra is underlain by permafrost. Soils can be wet because of poor drainage. Animals migrate or go dormant for much of the year.
What Is a Biome? Boreal forest Long, cold winters; short summers. Dominated by evergreens in the Northern Hemisphere: can start photosynthesis quickly in the short growing season. Have only a few tree species. Dominant mammals, (e.g., moose and hares, eat leaves).
What Is a Biome? Temperate deciduous forest Precipitation is distributed evenly, but temperatures fluctuate dramatically. Forests dominated by deciduous trees that lose leaves during the cold season. Temperate forests with the most species were not covered by glaciers during the Pleistocene.
What Is a Biome? Temperate grasslands Dry much of the year; hot summers and cold winters. Much of this biome has been converted to agriculture. Rich in species; grasses, sedges, and forbs. Plants are adapted to grazing and fire.
What Is a Biome? Cold desert In continental interiors and rain shadows. Dominated by few species: low-lying shrubs. Plant growth concentrated in spring. Plants produce lots of seed that supports seed-eating birds and rodents.
What Is a Biome? Hot desert At 30° north and south. More species and structurally diverse vegetation than cold deserts. Succulents are common. Many annuals grow after a rainfall. Pollination and fruit dispersal by animals.
What Is a Biome? Chaparral On western sides of continents with cool ocean currents offshore. Winters are cool and wet, summers warm and dry. Adapted to fire. Shrubs and low trees with tough, evergreen leaves. Annuals abundant, supports lots of rodents.
What Is a Biome? Thorn forest and tropical savanna On equatorial sides of hot deserts. Rainfall may be heavy in summer. Small trees may drop leaves in dry winter. Acacia are common. Savannas: grasslands with scattered trees; supports large grazing and browsing mammals and large predators.
What Is a Biome? Tropical deciduous forest Most trees lose leaves during the dry season. Many flower while they are leafless. Most have been cleared for agriculture and cattle grazing.
