Ecology Exam 3 Data

Ecosystem

an entity bound in space and time made up of a set of interacting elements that may be biological, physical, or chemical

Sir Arthur Tansley

Though the organism may claim our primary interest ... we cannot separate them from their special environment, with which they form one physical system

Energy flow

transformation and storage of energy (i.e., the tracking of C-C bonds)

Material (nutrient) cycling

transformation, storage, reuse, and movement of materials (C,H,N,O,P,S, etc.) (nutrients in ecosystems)

Structure

the distribution and abundance of materials within an ecosystem

Standing stock

(kg/m2), animal-like materials, element of structure

Standing crop

(kg/m2), plant-like materials, element of structure

Organic matter (OM)

living or dead material generated by biota (composed mainly of CHNOPS)

Function

rates of processes occurring within ecosystems that influence the distribution and abundance of energy and materials

Metabolism

all biotically driven anabolic and catabolic chemical reactions within an ecosystem (mg C/m2/d, mgO2/m2/d, kg OM/ha/yr)

Primary production

rate of carbon fixation by autotrophic organisms

Respiration (R)

rate of biological oxidation of organic matter, amount of energy lost due to biological oxidation of organic matter

Gross primary production (GPP or PG)

the amount of energy fixed as carbon per unit time

Net primary production (NPP)/net ecosystem production (NEP)

amount of carbon fixed as biomass per unit time (i.e., after loss due to respiration is included)

Relationship of GPP, R, and NPP/NEP

GPP = NPP + R or GPP = NEP - R

Predictors of NEP

Temperature and moisture

Predicting NPP across a tropical to arctic gradient

actual evapotranspiration (AET) = total amount of water that is evaporated through plants during a year (mm H2O/yr)

NPP across various systems within a similar biome have features:

heat content is relatively similar and rates of NPP are driven water availability

With a given water availability, primary production variation is related to...

...nutrient abundance

Forest NPP is limited by...

...nitrogen availability

Freshwater systems are limited by...

...phosphrous availability

Ocean productivity is limited by...

...N, P, Si, and Fe

Order of biome NPP rates (highest to lowest)

Estuaries/Swamps/Tropic Rain Forest, Temperate Forest, Deserts, Open Ocean

Order of biome NPP amounts (highest to lowest)

Open Ocean (32%), Tropic Forests (29%), Temperate Forests (14%)

Trophic level

a collection of biota at the same level of energy exchange as measured by the number of steps of energy assimilation starting with primary production

Trophic transfer causes the loss of...

...energy via respiration

Lindeman Ratio

10% of production at one trophic level becomes production at the next

Each step of trophic interaction adds...

...OM to the detrital pool

Decomposition

breakdown of organic matter including physical reduction in size and biotic oxidation of carbon

Nutrient

elements required by organisms for development, maintenance, and reproduction

Mineralization

conversion of nutrients from organic to inorganic form

Decomposition Intrinsic factors

Features internal to OM influence rates and processes of decomposition e.g., lignin, toughness, internal nutrients (C:N), species (higher N is more tough)

Decomposition Extrinsic factors

External environmental features influence rates of decomposition e.g., precipitation, nutrients, temperature,

Biogeochemistry

The study how the basic chemical conditions of the Earth are affected by the existence of life.

Nutrient Pool

The amount of a particular nutrient stored in a portion, or compartment, of an ecosystem

Nutrient Flux

An areal rate of nutrient transformation or translocation

Nutrient source

A portion of the biosphere where a particular nutrient is released more rapidly than it is consumed

Nutrient sink

A portion of the biosphere where a particular nutrient is consumed more rapidly than it is released

Highest-demand nutrients

nitrogen and phosphorus

Biological Roles of P

nucleic acids, nucleotides, membranes, apatite (bones)

Sedimentary Pools

igneous and sedimentary rocks containing P. Largely found in N. Africa, Russia, the US, and China. Vital in sedimentary cycle

Apatite rock weathering...

...releases P, source in the global P cycle

The soil pool of P is large but...

...largely unavailable, seeing accumulations due to agriculture (the "P bomb")

The oceanic pool of P is large but...

...very diluted

The main flux in the global P cycle is...

...river transport of P, usually in particulate form

Primary limiting factor in primary production is...

...the P cycle contained in freshwater

Biological roles of N

amino acids, proteins, enzymes, excretory forms (ammonotelism-aquatics, ureotelism-mammals, amphibians, sharks, uricotelism-birds, reptiles, insects)

Largest pool in N cycle

Atmospheric N2 (4 * 10^9 Tg)

Division of N in the Surface Ocean

Plankton and fish (470 Tg) and dissolved N2 (2.2*10^7 Tg)

All sources of nitrogen (highest to lowest)

Atmosphere N2, Ocean sediment, Surface Ocean, Soils, Plants

Reactive Nitrogen (NR)

Forms of N that cycle readily among living entities

Nitrogen fixation (N-fixation)

Rate of conversion of N2 gas to a biologically available form, often found on the earth's surface

Denitrification

Rate of converting nitrate (NO3-) into N2 gas via anaerobic respiration

Non-reactive (inert) N

Atmospheric N2

Biological N-fixation

Rate of biological conversion of N2 gas to Norg

Autotrophic biological N-fixation

The use of light energy for N2 reduction to form internal organic N.

Bluegreen bacteria

autotrophic N-fixers that can from Harmful Algal Blooms (HABs)

Heterotrophic biological N-fixation

The use of existing organic C to fuel N2 reduction to organic N

Root nodules in some plants...

(e.g., legumes) house heterotrophic symbiotic bacteria that carry out heterotrophic N-fixation.

Industrial N-fixation

Rate of the industrial synthesis of ammonia (NH3 = NR) from nitrogen (N2) and hydrogen (H2), known as the Haber-Bosch process.

Human industrial and agricultural N-fixations has...

...doubled the rate of input to the reactive N pool, while rates of removal from denitrification have remained constant. Reactive nitrogen pool has increased in size

Glacier Bay (Vancouver and Muir)

Muir Glacier visible reduction in size over the course of a century, leaving behind newly uncovered surfaces

Glacier National Park (Fagre)

USGS analysis has shown massive glacial retreat in the park since the 1960s

Succession

gradual change in the structure and functioning of plant and animal communities following disturbance

Pioneer community

early successional colonists capable of establishing populations on newly exposed area shortly after disturbance

Primary succession

succession occurring on substrates not significantly modified by organisms (starting from scratch, no seed bank)

Secondary succession

succession that occurs in areas where disturbance has removed the community but not destroyed the soil

Climax community

a community whose composition remains stable until again influenced by disturbance

Glacier Bay Succession

shows the changes of primary plant succession over 1000 years, understood due to the gradual retreat of the glaciers

GB PPS 0-20 Years

bluegreen crusts, lichens, liverworts, horsetail, willows

GB PPS 30-50 Years

Dryas shrubs (N-fixing, mat-like dwarf shrub)

GB PPS 50-100 Years

alder trees (w/ nitrogen fixing symbionts), grow thicker as Dryas dies back

GB PPS 100-200 Years

Spruce stands

GB PPS 1000+ Years

Muskegs (peatland)

Space for time substitution

An approach that uses different locations to represent different stages of succession based upon the age of individual positions in space. The influence of time is inferred from spatial comparison among sites with different time since disturbance.

Primary succession species richness plateaus around...

...1500 years post disturbance

Secondary succession happens...

...with similar trends to primary succession, but on a quicker timescale, as resident biota still exists to initiate growth and repopulation

Plants and Old-field Succession

instances of plants recovering from agriculture, same shape of richness increases but at a quicker rate due to secondary succession

Animals in old fields and secondary succession...

...mirror and follow the richness and influences of vegetation trends, similar species richness trends at a similar rate

Ecosystem succession

changes in ecosystem structure and function following disturbance

Succession increases...

...soil depth/development, soil OM, moisture, N

Succession decreases...

...bulk density, pH, P

Hardwood Watershed Disturbance (Bormann and Likens)

pair watershed approach, 60-year-old forest was clear cut after several years of observation, succession was repressed with herbicides (disturbance)

When ecosystems are disturbed...

...they lose nutrients through their waterways (nitrate accumulation increased 10x) because no vegetation is present to use the nutrients

During succession...

...primary production increases, and nutrient loss declines (nitrate back to baseline after 4 years, Ca and K still high after 7)

Disturbance Related Mortality...

...changes the relative abundance of dead organic matter and the balance of production and respiration

Desert Stream flash floods (secondary succession)...

...experiences increases biomass accumulation and increased GPP:R ratios post-flood (more autotrophic driven)

Gross primary productivity

The rate at which producers in an ecosystem capture energy

Net primary productivity

The energy captured by producers in an ecosystem minus the energy producers respire

GPP - R = ...

NPP and NEP

Regarding NEP of PNW forests, older forests have an NEP close to...

...0 due to Metabolic Steady State, may be slightly autotrophic to allow growth

Disturbance creates...

...patches that are at different ages (seral stages) and they act differently

Recently disturbed forests have an NEP...

...much less than 0 (respiration is much greater than GPP, source, heterotrophic)

Young but developing forests have an NEP...

... much greater than 0 (GPP is greater than respiration, sink, autotrophic)

Global change

Planetary-scale alterations to the Earth system

Earth system

The integrated pools and processes linking the atmosphere, hydrosphere, geosphere, and biosphere

Dominant sources of global change

Habitat loss, Invasive species, Pollution, Climate change, Disease

Global warming

Observed century-scale rise in the average temperature of the Earth's climate system and its related effects

Fossil fuel

Carbon containing substances generated by geologic and biological processes used by man as an energy source

Greenhouse effect

The process by which radiation from a planet's atmosphere warms the planet's surface to a temperature above what it would be without its atmosphere (radiatively-active gases = RAGs)