Topic 12**- Forest community

What’s a community

• Organisms that occupy a common geographical area

• Environment and ecological conditions. Past and Present

• Community as a property of ecosystems

Community→Habitat→Ecosystem

Shawnee Hill

A.) Loess deposits drives community change via variation

B.)West Ill has more Loess than east. Productivity gradient is greater in the west (More loess, the better the plants like the soil quality, moisture, nutrients,etc)

C.)Changes in community composition because of fire suppression. Leading to a mesophycation on once dry sites.

D.) Black oats → Red oaks because of moisture

E.) WHite and black oaks displaced my more mesic species.

Clemensonian View

• Community as one big superorganisms/uniform

• Predictable stages of life

• Climax community was considered stable

Gleason View

• Not superorganisms→Individual species responding in own way

• Variation due to chance and environment

Continuum concept

• Species change gradually across the landscape deepening on the environment

• Continuous change and abrupt chnage are accepted

Ecotones

• Transition zone between two communities

• Abrupt changes in parent material or topography can cause narrow ecotones

• Abrupt-Tepu mountains

• Gradually- Great smoky mountains

• Think about forest grassland vs eastern decidous forest

Mutualisms

Both sides benefits from something

Pollination, seed dispersal, decomposition, protection

Competition

• Two species fighting for the same limiting resource

• One species can block another even if resources isn’t limited

• Will decrease diversity unless weak species shrink niche

Crown Classes

• Species grow, forest structure becomes layered= less light and more competition for resources increase (greater biomass and complex structures)

Niche partitioning

• Minimize comp and Maximize diversity

• Different habitats, food, active, water, etc

Facilitation

• One species helps another w/o mutualism

• Hydraliuc lift- deep roots bring water up, leaks, shallow roots absorb it

• Mycorrhizal networks-fungi on ones roots can move nutrients into another

• Nurse plant- shrubs provide shade/moisture/protection to a seedling

• Kin reconginization

Vertical Structure

• Dominat species can dictate the structure of the rest of the forest. Can keep something from colonizing

Age of the forest

Age of the forest= different processing in maintaingin diversity

Fundamental Niche

• Where a species could live (Capable)

Realized Niche

• Actual habitat

Can’t live somewhere

• Fundamnetal niche. Incapable of survival

Not living somewhere

• Realized nich limitation, something is preventing them from living there

Competitive exclusion principle

• Two species that use the exact same resources cannot coexist, one will win, forcing the other into a reduced realized niche