Ecology Biomes & Populations

 Biome –A large, relatively distinct terrestrial region with characteristic  Climate  Soil  Plants  Animals  Interacting landscapes

Using precipitation and temperature to identify biomes

Significance of precipitation in temperate biomes

The world’s major biomes

 Human effect on biomes –Tundra  Oil exploration and military exercises result in long-lasting damage –Taiga/Boreal forest  Clearcut logging destructive –Temperate and deciduous forests and tropical rain forests  Removed by logging and development

 Aquatic ecosystems –Important environmental factors  Salinity  Amount of dissolved oxygen  Availability of light for photosynthesis

 Aquatic life divided into –Plankton  Free-floating organisms –Nekton  Strongly swimming organisms –Benthos  Bottom-dwelling organisms

Zonation in a large lake

Thermal stratification in a temperate lake

 Marine environments –Intertidal zone  Shoreline between low and high tides –Benthic environment  The ocean floor –Neritic province  Open ocean from shoreline to depth of 200 m –Oceanic province  Ocean deeper than 200 m

Zonation in the ocean

Human effect on water biomes  Eutrophication – water is enriched w/nutrients, usually fertilizers from runoff –Causes increase in organism growth that leads to depleted oxygen

Types of lakes  Which has greater primary productivity?

 Population density –Number of individuals of a species per unit at a given time  Population dispersion (spacing) –Clumped dispersion –Uniform dispersion –Random dispersion

Dispersion of individuals with a population

 Four factors that produce changes in population size –Natality –Mortality –Immigration –Emigration

 Intrinsic rate of increase (r max ) –Maximum rate at which species or population can increase under ideal conditions –Carrying capacity (K) is the largest population that can be maintained  Exponential population growth (J-shaped curve)  Logistic population curve (S- shaped curve)

Exponential population growth

Carrying capacity and logistic population growth

 Density-dependent factors –Regulate population growth by affecting a large proportion of the population as population rises –Examples include predation, disease, and competition  Density-independent factors –Limit population growth but are not influenced by changes in population density –Examples include hurricanes and blizzards

 Survivorship curves –Type I  Mortality is greatest in old age (large mammals) –Type II  Mortality is spread evenly across all ages ( birds, small mammals) –Type III  Mortality is greatest among the young (insects)

Survivorship curves

Age structure diagrams

 Developing countries tend to have people overpopulation that degrades the environment  Developed countries have consumption overpopulation that degrades the environment