Basic Ecology

Study of the interactions among ecosystem residents and their environment

Residents……individuals…populations…communities

Ecology – the basics

Niche……the role or function of a population within its ecosystem

Study of the interactions among ecosystem residents and their environment

Ecology – the basics

Abiotic components……air…water…soil…temperature

Habitat……the local environment of a population, biotic and abiotic

Fundamental concerns:

…flows through ecosystems; not recycled

Ecology – the basics

Fixed by producers, harvested by consumers & detritivores

Used for respiration, tissue maintenance & reproduction

Some is lost with each transformation

Transformed, stored and transferred

The trophic pyramid of a terrestrial ecosystem

1-10% energy transformation

efficiencies

Fundamental concerns:

Ecology – the basics

…cycles within ecosystems.

Assembled by producers, harvested by consumers, reused by producers

Reservoirs: GTTransfers: GT/yr

Compartments: GT Transfers: GT/yr

Compartments: MTTransfers: MT/yr

Compartments: MTTransfers: MT/yr

A Food Web (Trophic Web) illustrates energy and nutrient transactions in an ecosystem

Ecosystems are dependent on their primary producers

soil nutrients

Limits to Primary Production

Light

Water

Nutrients

Temperature

On land, the most favorable combination of these assets is found in tropical rainforests

!!Tropical rainforest litter residence time is very low!!

Essentia

lly

free r

esource

s

The effect of climate on organic decomposition

temperate forest floor tropical rainforest floor

over comparable time periods

GPP – R = NPP

Gross Primary Production – Respiration = Net Primary Production

NPP is higher in tropical

rainforests than other forest ecosystems

Energy Budget

Energy available for consumer trophic levels depends on…

…NPP*efficiency of transfer(s) (5-20%)* assimilation efficiency(ies)

= assimilated/ingested

…depends on type of ingested material

e.g. wood: 15%; seeds/animal tissues: 90%

Energy Budget

Consumer production…

=assimilated energy – respiration – excretion

Net Production Efficiency = production/assimilation

…depends on the animal

bird: 1%; sedentary cold-blooded: 75%

O (organic) Horizon

A Horizon

Zone of Leaching

B Horizon

Zone of Accumulation

C Horizon

Partially decomposed parent material

Soils develop from above and below

organic

mineral

provide primary producers with…

…water

…mineral nutrients

…anchorage

Soils

Soil Texture Classification

Soil particle size classes

<0.002 mm clay0.002-0.05 mm silt0.05-2 mm sand

% c

lay %

silt

% sand

Some Soil Properties Influenced by Soil TextureTexture Class

Soil Property Sand Silt Loam Clay

Aeration excellent good poor

Drainage excellent good poor

Tillage easy moderate difficult

Spring Warming rapid moderate slow

Water holding low moderate high

Cation Exchange low moderate high

Soil Weathering in Tropical Rainforests

Laterization

–wet warm climates

– clay particles broken down

– silica leached downward

– iron & aluminum oxides retained

– low nutrient holding capacity

– low organic content