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Transcript
Chapter 16 Ecosystems and Biomes Biogeography Biogeography studies the ecology of a spatial location across time Ecology examines the interaction of a location’s abiotic (non-living) and biotic (living) components [an open system] Ecology was coined/started about 100 years ago by Ellen Swallow at M.I.T. Biotic structure can be hypothesized as a hierarchy of complexity and energy demand within an even greater hierarchy of living and non-living elements of scientific study Ecology Studies Living / Non-Living Feedback Among Organisms Species Populations Communities Ecosystems Ecosphere (Biosphere) Laws of the Biosphere (1) Law of Production - Biotic Potential [BP] - carrying capacity (2) Law of Adaptation - Darwin’s Natural Selection (3) Law of Fertility - progression of producer-consumer-decomposer Laws of the Biosphere, cont (4) Law of Succession - orderly and progressive sequence of vegetation introduction into newly created or recently modified landscapes - progression to climax vegetation Laws of the Biosphere, cont (5) Law of Control - Limiting Factor Principle - Environmental Resistance [ER] --- density dependent (ex:disease; parasites) --- density independent (ex: climate; soil; human activity; catastrophe) ----- predation Connections: Energy Flow, Matter Cycling and Gravity Life on Earth is dependent on three connected factors: (1) One-way flow of high-quality (useable) energy from the sun (recognizing existence of chemosynthesis) (2) Cycling of matter and energy by living organisms through ecosystems (3) Gravity – constrains atmosphere and creates downward movement of matter / energy cycles (ex: rock cycle; gaseous cycle; biochemical cycle) Carbon and Oxygen Cycles Figure 16.8 The Nitrogen Cycle Figure 16.9 The Sun: Source of Energy for Life Sun supplies radiant energy, visible light, energy for photosynthesis … primary productivity or biomass (C/sq. m/yr) [6H2O+6CO2+energy --- C6H12O6+6O2]; factor behind unequal heating that creates temperature zones and winds --- 72% hydrogen; 28% helium --- an immense fusion reactor The Sun: Source of Energy for Life - A tiny percentage of solar ejected solar energy reaches the Earth [.0000001%] --- 34% of this insolation is reflected by the atmosphere; remaining 66% warms the atmosphere/Earth surface - Most of this energy will inturn become long wave infrared radiation to heat the atmosphere – natural greenhouse effect Functional Format: Chains/Webs (1) Abiotic (including Law of Tolerance/range of tolerance) (2) Autotrophs --- net primary productivity terrestrials: insolation; soil moisture and nutrients; atmospheric CO2 / O2 / O3; plant age/species; etc marine: water depth; turbidity; nutrient load; pollution; etc Functional Format: Chains/Webs, cont (3) Heterotrophs (secondary productivity) (1) (2) (3) (4) Herbivores Carnivores Omnivores Detritivores Functional Format: Chains/Webs (4) Decomposers Ecological Pyramids - pyramid of organism numbers - biomass pyramid - productivity A species occupies a habitat and operates within an ecological niche (niche) - by niche, a species can be classified as a specialist or a generalist And within an ecosystem will develop biotic associations between plant and animal communities Species in an Ecosystem (1) Native Species (2) Alien (or Immigrant) Species (3) Indicator Species (4) Keystone Species Traits of Vulnerable Species (1) (2) (3) (4) Restricted Range and Habitat Low Biotic Potential Non-Adaptative Behavior Specialized Diet Classification of Terrestrial Ecosystems (1) Forest- moderate-to-high annual precipitation; tree and smaller mass vegetation patterns --- classes: tropical rainforest tropical deciduous tropical shrub temperate deciduous evergreen coniferous Restatement of Table 16.2, p. 542 Classification of Terrestrial Ecosystems, cont (2) Grasslands – average annual precipitation patterns sufficient to support grass/shrub vegetation; drought may be common; vegetation bordering on xerophytic --- classes: tropical temperate arctic tundra Classification of Terrestrial Ecosystems, cont (3) Deserts and semi-deserts- locations where evaporation exceeds precipitation; annual average precipitation < 10”; often nutrientrich soil; frequently saltpan; true xerophytic vegetation --- classes: tropical temperate cold semi-desert Classification of Marine Ecosystems Why are the oceans important? (1) the Earth surface is approximately 72% water (2) Their role in: hydrologic cycle; distribution of solar energy; CO2 sink; generation of pressure systems; food source; habitat; minerals; pollution dispersion; etc Classification of Marine Ecosystems, cont Ocean Zones Oceans have two major life zones (1) Coastal - relatively warm; nutrient rich; high-water mark to continental shelf; <10% of ocean area, contains 90% of marine species; high net primary productivity per unit of area (1) Coastal, cont --- coral reefs – most threatened ecosystem in coastal zone We’ve mentioned: --- estuaries --- coastal wetlands --- beaches – barrier and rocky --- barrier islands (2) Open Ocean-vast area of Earth oceans; only about 10% of marine species inhabit; average net primary productivity per unit is low -comprised by three vertical zones --- euphotic --- bathyl --- abyssal