Chapter 16Ecosystems 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) Herbivores

(2) Carnivores

(3) Omnivores

(4) 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) Restricted Range and Habitat

(2) Low Biotic Potential

(3) Non-Adaptative Behavior

(4) 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 nutrient-rich soil; frequently saltpan; true xerophytic vegetation --- classes: tropical

temperatecold 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