APES: The Living World

Nitrogen Cycle Steps

Nitrogen Fixation

Ammonification

Nitrification

Denitrification

Human impacts on nitrogen cycle

• excess nitrates

• Burning fossil fuels

• Fertilizer usage

Phosphorus cycle

• doesn’t move through atmosphere

• Mainly in ocean sediments and terrestrial rocks

Human impacts on phosphorus cycle

• phosphate runoff

Sulfur cycle

• in ocean sediments, rock, mineral layers

• Sulfur emitted into the atmosphere (volcanic activity, anesrobic bacteria, hydrogen sulfide, oceanic sea spray, forest fires)

Human impacts on sulfur cycle

• release of sulfur dioxide

Speciation

• formation of new species resulting from selective forces

Geographic isolation

• leads to new species forming

5 types of community interactions

• interspecific competition

• Predation

• Mimicry

• Camouflage

• Chemical warfare

Coevolution types

• parasitism

• Mutualism

• Commensalism

• Amensalism

Resource partitioning example

• insect feeding warblers on spruce trees

Primary succession

Establishment of community from rock

Secondary succession

Soil remains in place and life comes back

Stages of primary succession

1. Exposed rocks

2. Lichens and moss

3. Small herbs

4. Heath may

5. Early teees

6. Late teees

Stages of secondary succession

1. Annual weeds

2. Perennial weeds and grasses

3. Shrubs and small pines

4. Young pine forest

5. Mature forest

Distribution types

• random

• Clumped

• Uniform

Survivorship curve

R-dies fast

K-dies slow