Science section 2 Flashcards
Mutualism
a symbiosis in which both partners benefit
Predation
One species uses another species as a resource. This includes herbivory and parasitism.
Competition
occurs when the demand for an ecological resource exceeds its
limited supply, causing organisms to interfere with each other
limiting resource
an environmental resource that
is the primary restriction on the productivity of
autotrophs in an ecosystem
Georgy Gause
led a very famous experiment: begins with two species of bacteria, P. Aurelia and P. Caudatum., and cultivates them in two separate laboratories. When grown separately, both species thrived. However, when Gause put the two species together, P. Aurelia thrived much as it had before while most of the P. Caudatum died off.
community
the populations that live in a certain area. Made up of multiple species
limiting resource
an environmental resource that
is the primary restriction on the productivity of autotrophs in an ecosystem
competitive exclusion principle
If a resource limits the growth and reproduction of multiple species, it cannot be shared: one species will succeed, and
the other will go extinct. This is a principle known as competitive exclusion.
niche
the role of an organism within a community
parasitism
An example of predation, in which animals, plants, fungi, or bacteria feed on or use another organism as a habitat,
causing injury but usually not death
numerical response
when prey density increases, so will predator density
functional response
when prey populations decrease, individual
predators change their behavior and switch from low-density to high-density prey.
food webs
summarizes the species that make up a community and the ways they are linked by various predator-prey interactions to form pathways of energy flow.
keystone species
a dominant species in a
community, usually a predator, with an influence on structure and function that is highly
disproportionate to its biomass
Pisaster star fish
The Pisaster starfish is a key predator that keeps other species in balance. If you remove it from the ecosystem, mussels (specifically, mytilus) end up consuming pretty much everything because there’s no species left to eat them.
In what way are beavers keystone species?
Beavers transform streams into ponds. If you remove them from the ecosystem, pond-animals/plants won’t have anywhere to live.
In what way are mycorrhizal fungi keystone species?
Mycorrhizal fungi live on the roots of many trees. They are critical for the growth process of the tree. If the fungi is removed, many tree habitats are lost.
In what way are old world fruit bats keystone species?
Old world fruit bats are the sole pollinators for hundreds of tropical plant species.
Primary succession
- begins with an event that leaves behind bare rock (e.g. glacial retreat, or volcanic eruption)
- early successional species are usually lichens and mosses. These organisms die and contribute organic matter to the soil
- later successional species are adapted to exploiting open, sunny areas with poor soil nutrients
Secondary succession
- begins on an area of land that is covered with bare soil, usually after an event like a wildfire or hurricane
- after that, it is basically the same process as primary succession
climax forest
outdated term for the plants in the “last” stage of succession. It is now recognized that because natural disturbances are a regular part of most forests, a late-successional stage is always a temporary, rather than a final
phenomenon, so the term climax is no longer used.
decomposers
a heterotroph that feeds on dead organic matter
Where is Organ Cave?
The southern Appalachia of West Virginia
What are the four “full-time residents” of Organ Cave?
A small distant relative of shrimp, crayfish, isopods, and amphipods
How has warming climate impacted organisms in Organ Cave?
Surface waters in the cave became too hot for many organisms during summer, so they became isolated in the consistently cold waters.
What resource do organisms in Organ Cave compete for?
proper sized rocks so they can avoid being washed downstream
Describe the energy flow in Organ Cave.
water flow brings in energy and nutrients, species competition regulates the use of this energy, and water flow takes out unused energy
Laws of thermodynamics
physical principles that govern all transformations of energy
first law of thermodynamics
energy can never be created or destroyed, but it can undergo transformation. The energy content of the universe remains constant
second law of thermodynamics
when energy is transformed, the quantity of energy remains the same, but its ability to do work diminishes
what is the primary source of energy on Earth?
the sun
primary producer
an organism that uses the energy from the Sun to produce usable forms of energy
photosynthesis
the process by which producers use solar energy to convert carbon dioxide and water
into glucose.
equation for photosynthesis
CO2+H2O+energy from the sun —> CH2O+O2
primary productivity
productivity by primary
producers, such as plants or algae; often measured
as biomass accumulated over a unit of time, or
sometimes by the amount of carbon fixed
Gross primary productivity
The total amount of solar energy converted to chemical energy by photosynthesis.
respiration
physiological process that is the opposite of photosynthesis. Cells use carbohydrates and oxygen to create carbon dioxide and water.
Equation for respiration
CH2O+O2—>H2O+energy(heat)+CO2
Net primary productivity
the gross primary productivity minus the energy that is expended during respiration
Net primary productivity equation
NPP=GPP-respiration
Approximately what percent of solar energy is converted to biomass?
1%
What is the average transfer efficiency of energy in an ecosystem?
10% efficiency (so primary consumers will have 10% the energy that primary producers have, etc)
secondary consumers
a carnivore that feeds on
primary consumers (or herbivores)
ecological pyramids
a model of the trophic structure
of an ecosystem, organized with plant productivity
on the bottom, that of herbivores above, and
carnivores above the herbivores
detritivores
organisms that feed on dead organic matter. E.g. bacteria, fungi, dung beetles, and earthworms
ecosystems
a general term used to describe one or more communities that are interacting with their
environment as a defined unit; ecosystems range
from small units occurring in microhabitats to
larger units such as landscapes and seascapes, and
even the biosphere.
what kind of ecosystems have easily defined boundaries?
Caves, as well as many aquatic ecosystems because their boundary is just where land meets water
How do environmental scientists usually define the boundary of ecosystems?
Ecosystem boundaries are often defined based on how Populations of organisms are distributed. However, sometimes boundaries are set according to administrative rather than scientific criteria (e.g. national parks and reserves)
Biotic
the living parts of an ecosystem
Abiotic
non-living parts of an ecosystem, including temperature, water, salinity, soil structure, and mineral nutrients
disturbance
an episode of destruction of some part of a community or ecosystem
perturbation
a much broader term that refers to any kind of change to the norm of an ecosystem
Resilience
the ability of a system to recover from disturbance
Intermediate distribution hypothesis
in ecosystems with no disturbances, competitive exclusion will lead to the dominance of one species. On the other hand, if there is too much disturbance, most species will go extinct. Therefore, an intermediate level of disturbance is ideal
Restoration ecology
activities undertaken by
ecologists to repair ecological damage, such
as establishing vegetation on degraded habitat,
increasing the populations of endangered species,
and decreasing the area of threatened ecosystems
biome
a geographically extensive ecosystem,
occurring throughout the world wherever
environmental conditions are suitable
solar energy flux
Some places on Earth receive more direct sunlight than others
Hadley cell
The air at the equator receives the most direct sunlight out of any location on Earth. This causes it to ascend and release moisture over the equator as it does so. After that, the air is cool and dry because it has lost all its moisture. It descends around 30 N and 30 S, creating desert ecosystems at these latitudes
Coriolis effect
due to the Earth’s constant rotation, winds in the Northern
Hemisphere deflect to the right and those in the
Southern Hemisphere deflect to the left
How do ocean currents affect the distrubution of biomes?
warm currents flowing away from the equator bring heat to northern latitudes. Also, water tends to heat up more slowly in summer and cool off more slowly in winter, helping to moderate the temperature changes of adjacent land masses.
tropical rainforest
Wet and warm
High plant and animal diversity
High productivity
Soil is poor in nutrients
Tropical dry (seasonal) forest
Pronounced dry season
Deciduous trees drop their leaves during the dry season
Basically a less productive and less diverse version of the tropical rainforest
Temperate rainforest
Mild winters
Rainy and foggy
Massive coniferous trees (think of the redwoods)
Mid productivity
Soil is rich in organic matter
Temperate broadleaf forest
Somewhat similar to the temperate seasonal rainforest, but instead of pine trees, we have trees with actual leaves.
Productivity is also mid
Nutrient rich soil (because of all the leaves decomposing)
Low plant and animal diversity
Boreal forest
Coniferous trees
Large mammals
Nutrient poor soil (due to low temperatures and a lack of “leaf litter”)
Dramatic variations in seed production each year, causing dramatic fluctuations in birds and other populations.
Temperate grassland
Not enough precipitation to support a forests
Productivity is about ⅓ of what you would find in a tropical rainforest
Decomposition is slow, so organic matter accumulates, resulting in rich land that can be used for agriculture.
Tropical scrub forest/Savannah
Plant life is limited to scrub vegetation because of limited soil nutrients and a short growing season
Migrating herbivores follow the rain
Fires and grazing keep the region almost bare
Low productivity and species diversity
Desert
Less than 25 cm of rain per year
The key element here is the lack of precipitation, not heat. There are cold deserts (e.g. Antarctica is technically classified as a desert)
Shrubs and grasses
Very low productivity
Animals and vegetation are adapted to the lack of moisture
Mediterranean/chaparral
Woody shrubs and small trees
Vegetation has adapted to conserve moisture with small, waxy leaves
Vegetation is adapted to wildfires with fire-resistant bark
Animal life: jackrabbits, mule deer, kangaroo rats, and several lizards
Tundra
Tundras occur beyond the tree line, or the upper limit of tree growth at high latitudes.
Sedges, lichens, and dwarf trees
Layer of permafrost in the soil is frozen year round
Low productivity
Bird species in the summer, but they migrate south during winter
Rodents are abundant but their populations fluctuate dramatically
Freshwater systems
- Not salty
- Can be flowing (rivers & streams) or standing (lakes and ponds)
transpiration
the evaporation of water from plant leaves (stomata)
evapotranspiration
water losses from a landscape
due to evaporation AND transpiration
Infiltration
the process where rainwater sinks into the soil and percolates downward
groundwater
water stored underground in soil and in rocks
runoff
water that doesn’t sink into the soil – it just flows over the surface of Earth
what is the largest reservoir of water on Earth?
The ocean
what is the main energy source that drives the water cycle?
the sun
Equation for the water cycle/hydrologic cycle
PRECIP = ET + I + RO
*Precip= precipitation
ET= evapotranspiration
I= infiltration
RO= runoff
Mean Residence Time for the ocean (around how many years does water remain in the ocean?)
2,650 years
Mean Residence Time for terrestrial water (around how many years does water remain on terrestrial landscapes?)
403 years
Mean Residence Time for the atmosphere (around how many years does water remain in the atmosphere?)
8 days
carbon fixation
CO2 is pulled out of the atmosphere (by terrestrial plants) and from the ocean (by phytoplankton) via photosynthesis.
Respiration
All living things, including plants and phytoplankton themselves, respirate. In doing so, they release CO2 back into the atmosphere.
Decomposition
Organisms die and the organic carbon that was within them is released to the soil or ocean
Sedimentation
a very small minority of dead organisms don’t decompose before they are buried in sediments. When this happens, the dead organism becomes a fossil. The fossil can later turn to oil, coal, or natural gas, hence why these compounds are called fossil fuels.
Combustion
occurs in forest fires or during the burning of fossil fuels. Chemically, it is an identical process to respiration and decomposition:
CH2O + O2 —> CO2 +H2O + energy
sedimentary rock
rock formed from precipitated
minerals such as calcite, or from lithified particles
weathered and eroded from other rocks
nitrogen fixation
Bacteria and fungi convert atmospheric nitrogen (N2) into another form of nitrogen that is useable by plants — NH4 (ammonium).
Atmospheric nitrogen can also be fixated by lightning strikes and other combustion processes
ammonification
Decomposers convert organic nitrogen into ammonium ions, which can be absorbed by plants
nitrification
ammonium from ammonification is converted to nitrite, and then into nitrate
leaching
an element or molecule is washed out of soil by moving water. This occurs frequently with nitrate
Denitrification
- natural conversion of nitrate to the gas nitrous oxide (N2O), which is emitted to the atmosphere
- Anthropogenic contributions to nitrate leaching can speed up the rate of denitrification, which is problematic because nitrous oxide is a greenhouse gas
Freshwater systems
Aquatic ecosystems that aren’t salty. Can be flowing (rivers & streams) or standing (lakes and ponds)
Marine systems
Aquatic ecosystems that are salty. The main marine system on Earth is the ocean
benthic community
Plants and animals that live near the bottom of an aquatic system
thermoclines
abrupt changes in the temperature of water with depth that prevents the mixing of the layers of water
upwelling
nutrient-rich water from the deep ocean rises up to the surface. Also occurs in coastal areas where nutrients wash in from the land
Marine wetlands
Intertidal areas, aka the area on the shore that is covered at high tide and uncovered at low tide
Estuarine wetlands
where salt water from the ocean meets fresh water from a river
Freshwater wetland
- Includes bogs, marshes, swamps, and peatlands
- Water is at or near the soil surface for most of the year, but never very deep
- Some are highly productive ecosystems and important nesting and feeding points for migratory birds