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78 terms

Community and Ecosystems Ecology

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Community
an association of pops of different species interacting with one another in the same location, habitat or environment.
defining feature of communities
species composition (richness) and diversity (evenness).
defining feature of communities
the kinds of interactions between community members
defining feature of communities
abiotic interactions between climate, topography and habitat, and their affects on community members
defining feature of communities
the availability of food and resources
defining feature of communities
the adaptations or ecological roles (niche) of community members.
defining feature of communities
ongoing trends, changes, or dynamics impacting community structure.
ecological niche
the specific role that each species plays in its community, including its habitat resource requirements (food, nutrients, energy, shelter) and the kinds of interactions with other species.
Producers (autotrophs)
organisms that produce the food or chemical energy that sustains the community. includes photoautotrophs and chemoautotrophs.
Consumers (heterotrophs)
organisms that feed on other members of the community to obtain their energy and resources.
herbivore
consumer that only eats plants
detritivores
consumer feeding on decayed particles of organic matter
carnivores
consumer that eats meat
Competition
interaction occurs between members of one or more species utilizing the same resources (e.g. light, space, nutrients, etc) of a given habitat which are in limited supply.
Competition
most common interaction between members of a community
Competition
does not occur when resources are abundant
Competition
always has neg effects (suppressed growth) on both species
Competitive exclusion principle
document by G.F Gause studies of two species--paramecium---which formulates ___ ____ _____ that no two species can indefinitely occupy the same niche at the same time.
Succession
the gradual and orderly process of change in an ecosystem brought about by the progressive replacement of one community by another until a stable (climax) community is established. (get pioneer species--most plants are going to be annuals)
Annual
plants that produce a lot of seeds, seeds dispersed, germinate, plant grows for one cycle, then parent plant dies back. Next group of plants referred to as perrenials (persist from one year to the next)
Perrenials
plants that persist from one year to the next.
Climax species
trees
Primary succession
succession that occurs in newly exposed or created barren habitats that have no prior history of plant or animal life
Secondary succession
succession that occurs in disturbed habitats where plant and animal communities previously existed.
Bare-rock succession
watering and soil formation are critical; pioneer species include bacteria, algae, lichens, mosses; accumulation of dust and organic mater contribute to soil developmen; progressive habitat modification or improvement allows new successional species to invade and take over; may take ~1000 years.
Bare-rock succession
islands of Hawaii were created by this
lichens, mosses, algae, bacteria
first things to grow in bare-rock succession
stone crops
primitive vascular plants that appear to grow on stones--actually grows on poor soil (no water in rock--so dry out but rehydrate during next available rainfall)
lichens and algae
provide nitrogen to the rock area in rock-barren succession
Agricultural land succession
soil is already formed; seeds of many pioneer species are already present in the soil, others invade; pioneers include weedy annuals, then weedy perennials.
Relay Floristics Models
groups of species migrate to habitat at the same time, then occupy and modify habitat for the next association; the same climax community is eventually established; aka the facilittation model
Initial floristic composition model
almost all species are randomly present at abandonment; abundance depends on how fast they mature and reproduce; slower, long-lived species eventually dominate; aka the "tolerance model"
ecosystem
a dynamic, often changing web of interactions between all the living (biotic) species or components of a specific habitat, including their interactions with the non-living (abiotic) physical components of the environment associated with that habitat.
Biotic components
producers, consumers, decomposers, detritivores
Abiotic components
climate conditions (temp, rain, seasons, etc.), resource pools.
Omnivores
bears, turtles are both
detritivores
part of food chain, feeding on reminents of organic matter (earthworm, etc)
decomposers
breakdown organic matter after detritivores got to it; break down the last of it and release minerals
energy flow
flows through ecosystem in every possible way; law of thermodynamics says no ___ ____ is not 100%
energy flow
is directional (into, through and out of the ecosystem).
chemical flow
is cyclical (remaining within an ecosystem).
sun
source of energy in all ecosystems--captured by plants which is reflected back by water, clouds, etc. 20% absorbed by the atmosphere. Rest of it used to heat the land/water.
Carbon
an important chemical that cycles in the atmosphere
Biogeochemical cycles
a pathway (or process) by which nutrients (or chemicals) and abiotic (lithosphere, atmospher and hydrosphere) components (or compartments) of an ecosystem.
energy flow
this flow is often modeled after carbon flow. Once Photosynthesis occurs, we have something to estimate ___ ____ in the ecosystem.
Hydrologic Cycle
Balanced by P = E + T + R + I (Evaporation + Transpiration + Runoff + Infiltration)
Hydrologic Cycle
a major driving force for nutrient cycling.
20 barrels
amount of water transpired in an oak forest--removes moisture from soil and moves back to the atmosphere--cools the leaves
6%
soil percolation in the oak forest hydrologic cycle
Potometer
how botanists measure the amount of moisture in a plant; uses standard inverted pipettes (equilibrium stuff that measures mm increments).
potometer
in oak trees, they measure transpiration by making a huge cut in the tree and making a giant ____. Build scaffolding around it to support tree. put a huge vessel beneath it and pour water continuously.
quantify moisture evaporated by trees
reasons for measuring moisture in a forest
clear cutting
way of quantifying the amount of moisture in the trees
potometer
device plant ecologists use to measure transpiration in cut plant parts. (DOES NOT MEASURE EVAPO-TRANSPIRATION)
biomass
reduced carbon that measures energy.
Carbon Cycle
the cycle of CO2 through the atmosphere; use biomass to measure reduced carbon that measures energy
Sediments and rocks (carbonate ions--limestone)
the largest amount of carbon reserve on Earth.
Limestone (carbonate ion), fossil fuels (coal, oil)
the forms of the largest amount of carbon reserve on Earth.
Bicarbonate ion
main form of carbon in the oceans on Earth.
bicarbonate ion
main for of carbon in the soil on Earth.
Photosynthesis
creates the greatest flux of carbon on earth. 120 tons move from atmosphere to plants.
Cellular respiration
represents the same amount of carbon (60 gigatons each) back to the atmosphere that photosynthesis takes away (120)
global warming/greenhouse effect
increase in CO2 in the atmosphere causes _____.
greenhouse effect
CO2 levels arising steadily and, thus, causing global warming.
infrared wavelengths
wavelengths that cannot pass through glass.
Nitrogen Cycle
cycle of nitrogen throughout the ecosystem.
atmosphere
has the largest reservoir of nitrogen (78% nitrogen)
sediments
second largest reservoir of nitrogen on Earth.
Soil
third and biggest jump in amount of reservoir percentage reserve on Earth.
Terrestrial biomass
35 billion metric tons for nitrogen reserve
marine biomass
0.37 billions of metric tons of nitrogen reserve on Earth.
N2 fixation
microbial--(4N2+6H20-->4NH3) how atmospheric nitrogen gets introduced into the ecosystem in bacteria and animals; chemical (N2+3H2-->2NH3)--requires high temp and pressure--convert nitrogen and hydrogen into ammonia--processed for fertilizer.
Nitrification
conversion of ammonia or ammonium to nitrate. Plants prefer nitrate--biological activity to convert this--two step reaction. Step 1: (2NH4 + 3O2 --> 2NO2 + 4H + 2H2O); Step 2 (2NO2 + O2 -->2NO3)
Uptake and Assimilation
(NH4 + NO3-->amino acids)
Denitrification
NO3-->N2 (and other N gases) via obligate anaerobic bacteria.
Ammonification
conversion of already reduced ammonia (nitrogen) in form of amino acids back to ammonium-->ammonium plus one charge easily coverts to ammonia gas.
N Deficiency in corn
corn is one of the most nitrogen intensive crops we have typically in form of nitrate; patches of yellow in the crop is due to ___.
nitrate
plants love this chemical