Primary Productivity Amount of energy or mass created

during photosynthesis gC/m2/yr or kcal/m2/yr Net Primary Productivity: biomass for

herbivores GPP – CR = NPP

Factors that contribute to its success Nutrients, temperature, sunlight,

moisture

Primary Productivity Factors that contribute to its success Nutrients, temperature, sunlight,

moisture Nutrients as limiting factor

P = freshwater N = terrestrial + marine

Ecosystems are stable, resilient, and resistant

Stable: self perpetuating

Ecosystems are stable, resilient, and resistant

Resilient : repair itself If a tree has been damaged it can

regrow using suckers

Ecosystems are stable, resilient, and resistant Resistant: ability to protect itself

Secondary Succession: soil is there.

Change is natural

Disturbances & the changes they bring about establish community characteristics PRIMARY: NO SOIL SECONDARY: STARTS WITH SOIL

MICROCLIMATELichen are pioneer species

Are major disturbances can be useful

YELLOWSTONE- 1988 700,000 aces burn

for 2 months Changed the

structure of the ecosystem.

Stable ecosystems are resilient to change

DID THE YELLOWSTONE WILDFIRE AFFECT THE ABUNDANCE OR DIVERSITY OF ORGANISMS? HOW DOES THE SELECTIVE PRESSURES CHANGE?

Abundance of shade tolerant species decrease

Abundance of shade intolerant species increased

Diversity remained the same.

Disturbance adapted species:

Prairies Deep roots

Forests Serrotinous cones

Communities in Transition Ecological Succession

Primary Succession - A community begins to develop on a site previously unoccupied by living organisms. Example: A lava flow creates a new land area that is colonized. The first colonists are termed pioneer species.

Secondary Succession - an existing community is disrupted and a new one subsequently develops at the site

Climax community - community that develops last and remains the longest

Disturbances A disturbance is any force that disrupts

established patterns of species diversity and abundance, community structure, or community properties e.g. storms, fires, logging.

Disturbance tends to disrupt the superior competitors the most and allows less competitive species to persist.

Some landscapes never reach a climax community because they are characterized by periodic disturbances (such as wildfires) and are made up of disturbance-adapted species.