From Biol301

• Adapted from Alice's notes.

Contents 1 Ecological Systems 1.1 Hierarchy of Size 1.1.1 Individuals 1.1.2 Population 1.1.3 Communities 1.1.4 Ecosystem 1.1.4.1 Long Term Ecological Research 1.1.5 Biosphere 1.2 Influence of Solar Radiation and Earth orbit on Global Climate Pattern 1.3 Biomes 1.3.1 Deserts 1.3.2 Tropical Rain Forests 1.3.3 Temperate Forest 1.3.4 Boreal 1.3.5 Temperate / Tropical Grasslands 1.3.6 Tundra

Ecological Systems

Hierarchy of Size

• Individual
• Population
• Community
• Ecosystem
• Biosphere
• Experimental studies can be done at all levels except biosphere

Individuals

• Transform energy into biomass
• Converts materials
• Modifies environment and influences resources availability
• Contributes to cycling of energy and nutrients
• Example: plants

Population

• Definition: individuals of the same species living and interbreeding together
• Properties:

1. Census size = births + immigrants - deaths - emigrants

2. Density = (# of individuals / unit area)

• Example: U.S. - coastal / ability to live / originally colonies are most dense areas

3. Age structure = fractions of the population in different age groups

• Tells probability of survival, groth rate, etc.

4. Temporal and Spacial Variation = differences in size and age structure

5. Geographical boundaries are not always obvious

• Exmaple: non-overlapping ranges of different populations of Boreal owls

Communities

• Definition = the interacting population of different species
• Interaction includes
  • competition
  • predator / prey
  • mutualism - both species are benefitting
  • commensalism - only one species gets the benefit, the other is unaffected.
  • parasitism - one species will take over another to reproduce itself

Ecosystem

• Definition: the study of interactions among organisms and their environment
• Biotic iteraction with abiotic

Long Term Ecological Research

• Studies the chesapeake bay over a time scale and spatial scales
• Example: Baltimore ecosystem LTER
  • Hard to do expecially on it
  • Looks at social, economy and ecosystem.

Biosphere

• Global scale
• Observations
  • Organisms are not distributed randomly.
• If earth gets a catastropic jolt and is no longer tilted on its axis the result would be loss of the seasons

Influence of Solar Radiation and Earth orbit on Global Climate Pattern

• The earth's tilt influences the solar radiation.
  • The result is the creation of warm areas, circulationg warm patterns, wind patterns, ocean patterns, counter-clockwise spin, and moderate temperature of contries.
• Clements and Shelford (1939)
  • Found animals and plants show patterns of distrobution and characteristics turned them into type.

Biomes

• Two abiotic factors that determine biome:

1. Rainfall
2. Temperature

• These are so important because they help us determine which species live there.

Deserts

• 20% of earth
• Are dry
• Can be cold or hot
• Can have lots of plants and no plants
• Very little rain
• Cold deserts have shrubs, brush
• Hot deserts - not much vegetation or lots of different plants

Tropical Rain Forests

• Moderate temperatures
• Lots of rain (x > 200 cm/year)
• Poor soil because plants take them up and things get decomposed quickly.
• Canopy - multiple layers
• Flora, fauna - very diverse

Temperate Forest

• Temperature highly variable
• Precipitation - even throughout the year
• Soil - fertile with decaying litter
• Canopy - light penetrates, diversity
• Flora - 3-4 tree species / square Km
  • Trees with broad leaves

Boreal

• Canada / Russia
• North
• Temperature - low in winter
• Precipitation - snow!
• Canapy - low light penetration
• Flora - evergreen mostly
• Short growing season

Temperate / Tropical Grasslands

• Not many trees
• Mostly grass
• Rain - not even across the year; fires

Tundra

• Frozen soil - not many plants
• Mostly shrubs and lichen
• Plants are very dark in pigment because of low temperature
• Very cold climate
• Short growing reproduction time