ECO EXAM 3

what determines the number of trophic levels?

- Amount of energy entering via primary production (more production = more level

- Frequency of disturbance

- Ecosystem size: Large ecosystems = large populations have more habitat heterogeneity, and have higher species diversity

what does allochthonous mean (give example)

- external energy inputs

- EX: bear brook in New Hampshire receives 99.8% of its energy as allochthonous inputs

what does autochthonous mean (give example too)

- energy produced by autotrophs within the system

- EX: nearby mirror lakes autochthonous accounts for almost 80% of the energy budget

what does a trophic pyramid show?

Trophic pyramid portrays the relative amounts of energy or biomass in each trophic level

Trophic levels definition

- groups of species that have similar ways of obtaining energy

trophic levels (list and define them)

• Primary producers—autotrophs

• Primary consumers—herbivores

• Secondary consumers—carnivores

• Tertiary consumers—carnivores

Trophic cascade:

- A carnivore eats an herbivore (a direct negative effect on the herbivore).

- The decrease in herbivore abundance has a positive effect on a primary producer.

- number of urchins directly affects number of otters and indirectly affects the number of orcas (and vice versa)

species diversity is a combination of... ?

richness and evenness

species richness is...?

number of species in a community

species evenness...?

relative abundances compared with one another

relative abundance suggests?

- what species interactions might be occurring

species composition: comparing communities diversity and species

two communities can have the same amount of diversity but totally different species

what is succession

- change in species composition in communities over time

- ex. mt st helens

agents of change vary in...?

(there are 2, give examples)

- frequency (tornado)

- intensity (mt st helens)

what scales does stability depend on

- spatial

- temporal

what is regime shift?

a community changes too much and is unable to return to its original state (ball rolls too far)

tipping point: what do ball and valley represent

Valleys represent different community states, a ball represents a community

describe tipping point in terms of ball and valley

- The ball can move from one valley to another, depending on presence or

absence of strongly interacting species

- the ball can move too far and be unable to move back

what is biogeography

- The study of ecological patterns of species composition and diversity across geographic locations

- It's the study of why organisms exist where they exist

what are spatial scales?

- Pattern of composition and diversity at higher levels determines pattern at lower levels

- organization hierarchy (next question)

spatial scales: organizational hierarchy

- Global

- Regional

- Landscape

- Local

plate tectonics: how are mid ocean ridges formed?

molten rock flows from the seams between plates and then cools, creating new crust and forcing the plates to move apart

plate tectonics: what is the process of mid ocean ridges forming called?

seafloor spreading

what is continental drift?

plates (sections of earth's crust) move or drift through the action of currents generated deep within the molten rock mantel

factors affecting species richness?

- immigration

- emigration

- extinction

- dispersal rates

- dispersal distance

- ease of dispersal

- habitat fragmentation

what is a biofuel

liquid or gas made from plant material

ex. corn / ethanol

what is resource mediation

if disturbance, stress, or predation keeps the dominant competitor from reaching carrying capacity, competitive exclusion cannot occur, and coexistence will be maintained

- for example, prairies without disturbance have less species diversity because the dominant species is able to exclude others

examples of what can species diversity control

- community function

- plant productivity

- soil fertility

- water quality

services provided to humans by community function (examples)

- food

- fuel

- water purification

- O2 and CO2 exchange

- protection from catastrophic events like flooding

deep sea life: explain how chemotrophs can live in the deep sea

Chemotrophs in the deep sea surround thermal vents and absorb the chemicals from them to create organic carbon allowing ecosystems to survive where there is no sunlight: ex. Tube worm

deep sea life: how does upwelling affect life

When deep sea organisms die they become nutrients that upwelling brings to the surface

what does the term ecosystem refer to?

all the components of an ecological system, biotic and abiotic, that influence the flow of energy and elements

ecosystem integrates which sciences?

ecology, geochemistry, hydrology, and atmospheric science

what is primary production?

chemical energy generated by autotrophs during photosynthesis and chemosynthesis

trophic level is determined by?

distance to autotroph

what is gross primary production (GPP)

total amount of carbon fixed by autotrophs

GPP determines three things

- carbon budget

- carbon cycle

- ecosystem health

plants use half their GPP for?

cellular respiration // biosynthesis and cellular maintenance (this is the cost of plant to stay alive)

what is net primary production (NPP)

- amount of energy captured by autotrophs that results in an increase in biomass // energy= available for plant growth and consumption

- stored carbon in an ecosystem

- ultimate source of energy in an ecosystem

NPP formula

NPP = GPP - respiration

plants allocate NPP to?

growing different tissues in order to respond to their environment

what controls NPP

Temperature

Precipitation (good until overwatering)

Climate

NPP example of grass

grasslands allocate more NPP to roots bc of lack of nutrient soil and water

terrestrial NPP

- controlled by nitrogen

- associated with leaf area index and growing season

aquatic NPP (marine)

- controlled by nitrogen / iron

- associated w/ nutrient inputs

aquatic NPP (lake/stream)

- controlled by phosphorous

- associated w/ nutrient inputs

Net secondary production (NSP)

- Energy derived from consuming organic compounds produced by autotrophs

- makes up a small portion of NPP

NSP: what are the heterotrophs (examples)

archaea, bacteria, fungi, some plants, animals

what are carnivores?

consume other animals

what are omnivores

consume plants and animals

formula for net secondary production

NSP = Ingestion - Respiration - Egestion

NSP in organisms depends on two things

food and physiology

trade off of endotherms: NSP: respiration and growth

endotherms have high respiration rates so they cannot allocate as much energy for growth

what are omnivores? (give example)

- feed at multiple trophic levels

- ex coyotes

(relative abundance): in a community with low species evenness, the dominant species has what effect on the other species

- negative effect (this is the two mushroom pictures)

- experiments with adding or removing species are relevant

species composition (define, why is it important)

- identity of species in a community

- critical to understanding community structure

dominant / foundational species (define, effects and reason for those effects)

- most abundant species

- large effects on other species

- effect species diversity

- bc of considerable abundance or biomass (oak trees)

what do ecosystem engineers do?

create, modify, or maintain habitat for themselves and others

- ex. beavers building dams

Why do keystone species matter?

- have strong effects because of their role in a community

- their effects have larger role than their biomass or abundance

- ex. (otters)

mt st helens example: (what happened, what was the result in terms of organisms)

- St. Helens erupts

- Disturbance left almost no organic matter (disturbance)

- Gradually plant species moved in and made the non organic matter livable again (grasses break up lava rock, then trees can start growing, the organisms can start living there again)

what is disturbance

Events that injure or kill some individuals and create opportunities for other individuals

what is stress

Abiotic factors that reduce growth, reproduction, or survival of individuals

abiotic agents of change (there are two)

- disturbances

- stress

succession: what is the pioneer stage? (example organisms?)

- first stage in primary succession

- prepare environment for later species by breaking down rocks and enriching soil when they die

- is dominated by lichens, mosses, horsetails, willows, and cottonwoods

what is primary succession

Colonization of habitats devoid of life (e.g., volcanic rock).

Secondary succession:

Reestablishment of a community in which some, but not all, Organisms have been destroyed.

what does alternative stable states mean

Sometimes different communities develop in the same area under similar environmental conditions

what is stability?

ability of an community to return to its original state after a disturbance

stability: relationship between richness and stability

positive (both go up or both go down)

stability: what is tipping point?

point where a community is disturbed too much and cannot return to its original state

big ideas of psalm 104

- God created an Earth that He actively takes care of

- Earth's ecosystems and life is complex and details

- God made uplift

- We should praise God for his incredible creation

- Water = life

amazon rainforest

- species used in medicine and research

- high species diversity

habitat fragmentation causes

- Deforestation

- construction

- logging

- small populations

results of habitat fragmentation

- less species diversity

- edge effect (edge of forest degraded over time)

- loss of forest overall

forest harvesting vs sustainable forest management

quick gain vs long return

continental drift: what is subduction zone (and draw it)

one plate is forced downward under another plate, resulting in earthquakes, volcanic activity, and mountain range formation

continental drift: what is a fault? (and draw it)

formed when plates slide past each other

what is the theory of Pangea?

all of Earth's land masses made up one large continent

what is equilibrium theory in island biogeography?

- number of species on an island depends on the balance between immigration or dispersal rates and extinction rates

- island size = extinction rates

- distance to mainland = immigration rates

species richness: high specialization = ?

high richness

species richness: low competition = ?

high richness

what does carbon neutral mean

amount of CO2 produced by burning them is equal to the amount taken up by the plants from which they are made

ethics of biodiversity

- Some (Alex Epstein) believe fossil fuels are good for and necessary to the environment

- others believe other forms of energy need to be developed in order to combat climate change and global warming.

what is the land trade off for biofuels

land can be used for fuel or food

what is resource partitioning

competing species are more likely to coexist if they use resources in different ways

what is the base of all food chains?

primary production

high temperature and precipitation has what effect on NPP

- higher NPP (until it hits a certain point)

- ex tropical rainforest

what are herbivores

consume plants / algae (some matter used for respiration, and some egested)

What are detrivores?

consume dead organic matter

What is egestion?

removal of undigested waste

define trophic efficiency

- Percentage of production transferred from one trophic level to the next

- amount of energy at one trophic level divided by the amount of energy at the trophic level immediately below it

what is consumption efficiency

Proportion of available energy that is ingested (total energy): Assimilation + Production

what is assimilation efficiency

Proportion of ingested food that is assimilated (what the animal uses itself)

What is production efficiency

Proportion of assimilated food that goes into new consumer biomass (passes on): only a fraction of energy consumed can pass to the next trophic level

is consumption efficiency higher in aquatic or terrestrial ecosystems

aquatic

is consumption efficiency higher for carnivores or herbivores?

carnivores

describe assimilation efficiency in endotherms vs ectotherms

Endotherms digest food more completely than ectotherms and thus have higher assimilation efficiencies

what does trophic cascade refer to? (define and example)

- Series of trophic interactions that change biomass and species composition

- Ex. increase in orcas = decrease in otters = increase in urchins

how do omnivores affect trophic cascade?

they act as buffers

trophic cascade: what is bottom up control

Resources that limit NPP determine energy flow through an ecosystem