NRES 151 Exam 1

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Biotic Factors Influencing Succession

(Living) Producers: get energy from sun, turns to glucose Consumers: opposite

Abiotic Factors Influencing Succession

(Non-Living) Mineral soil, water, temp, essential elements, disturbances (frequency/severity)

Dynamic Equilibrium

A state of balance between continuing processes

3 Topography Factors Influencing Soil Development

Altitude- water runs downhill Slope- soil erosion Aspect- orientation to sun

Inputs

Amount of substance entering ecosystem

Outputs

Amount of substance leaving ecosystem

Storage

Amount of substance retained in ecosystem

Steps to convert organic N to inorganic N

Bacteria eat organic N, Nematodes eat bacteria, excess N excreted as inorganic N

Factors relating to energy transfer and EE Cycling

Biological Diversity, temperature, water

3 Changes in ecosystems as they mature

Biomass increase Species richness increase (# species) Species diversity increase (# species & distribution)

CEC

Cation Exchange Efficiency: a measure of the soils ability to hold & supply essential elements. Increases with OM content, clay content, increased pH

Allogenic Changes

Caused by external factors unrelated to plant community (soil erosion, herbivory)

Autogenic Changes

Caused by organisms occupying the site (organic matter, soil pH)

Ecosystem Development

Changes over time in plant and animal communities under constraints & influences of abiotic enviornment

Ecosystem Replacement/Species Replacement

Competition, structure, growth form, etc. all change over time

How primary minerals influence soil fertility

Weathering of primary minerals releases EEs into soil. Through weathering, soil is able to retain greater amounts of EEs. Fertility increases

Primary Succession

Ecosystem development in the absence of biological legacy

Secondary Succession

Ecosystem development with biological legacy where soil stays in tact following a disturbance

Gleason's Succession Model

Ecosystem structure produced by changing interactions in environment, changes in populations of species, disturbances. Climax communities= RARE, little predictability

Laws of Thermodynamics

Energy/Heat always moves from higher to lower Energy can't be created or destroyed- just transferred Energy disperses (entropy) As temps. reach absolute zero, dispersal of energy is 0

Calculate Transfer Efficiency

Exploitation x Assimilation

Pools

Form of storage compartment within system

Liebig's Law of the Minimum

Growth is not controlled by the total resources available, but rather by the scarcest resource that is required for growth

3 Criteria for Essential Elements

If not present, organism dies element directly involved in metabolic process Can't be replaced by another element

How cycling of high demand (macro-elements) controls primary production

If the cycle is slow or disrupted there will be less primary production

How Increased Biodiversity influences Efficiency

Increases number of organisms occupying an area Increases types of organisms occupying an area Increase in number and type= Greater Utilization

How CO2 contributes to Greenhouse Effect

It traps radiation (heat) and does not allow it to escape back into space, the earth becomes warmer

Major disturbance

Large impact, ecosystem function & composition altered

Minor disturbance

Little impact, ecosystem function largely unaltered

Distribution & sources of EE in highly weathered, very old soils

Low fertility Low CEC Phosphorus Retention Majority of EEs in standing vegetation Demand of EEs met by cycling

Flux

New loss/gain from inputs & outputs

Element that commonly limits primary production

Nitrogen

Physical Weathering

No change in chemical makeup of material being weathered, increase surface area

Where majority of Carbon resides in most terrestrial Ecosystems

Organic Matter, only a function of the carbon used for growth

How pH influences activity of fungi

Populations and activity decline at high pH levels

How pH influences activity of bacteria

Populations and activity decline at low pH levels

Where Essential Elements Come From

Primary minerals weathering Accumulation & Decomposition of organic matter Atmospheric Decomposition

5 Factors influencing ecosystem recovery after disturbance

Regeneration Germination of pre-existing seed bank Sprouting Migration into area from neighboring ecosystem Resource availability

Turnover Time

Relationship between inputs & outputs

Chemical Weathering

Results in EE being released, changes in chemical makeup of materials being weathered

5 Characteristics of Species establishing on Disturbed Sites

Small size of organism Low energy requirements Many offspring produced Early maturity Individuals only reproduce once

What causes late stage communities to be more effective?

Species richness increase Energy transfer= more efficient Nutrient cycling= more efficient

Clement's Succession Model

Succession= ordered progression from 1 state to another. End state= stable community (stable, balanced, persistent, not very diverse)

2 Climate Factors influencing Soil Development

Temperature (Increase= Increase in weathering) Moisture (Increase= Increase in weathering)

Succession

The changes in community composition and associated processes following a disturbance

How pH influences EE availability/solubility

The lower the pH more soluble the soil is, the more available EEs are

How Biodiversity influences N use efficiency

The more biodiversity, the more ways N can be recycled and more sources of N, so less unused N

Assimilation Efficiency

The percentage of captured solar energy that is digested at the next trophic level

Exploitation

The percentage of energy from a primary producer that is consumed over a given period of time

Changes in soil over time

They get deeper (more) Increase in clay content CEC Increase pH decrease Organic Matter Increase Water holding capacity Increase Horizons develop

Model that Describes Litter Decomposition

Tree= Accumulation of EEs Leaf litter contains carbon & EEs Bacteria eat leaf litter Nematodes eat bacteria & release excess EE Plants take in EE & capture C from atmosphere

Sources of N

Weathering of parent material


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