chapter 21 Flashcards
moves many elements through ecosystems.
The hydrologic cycle
closely tied to the movement of energy.
The carbon cycle
cycles through ecosystems in many different forms.
Nitrogen
cycle that moves between land and water
The phosphorus cycle
nutrients regenerate in the soil in what ecosystems
terrestrial ecosystems
The movement of water from the oceans to continents is driven by
the Sun’s energy.
the movement of water through ecosystems and atmosphere; includes evaporation, transpiration, and precipitation.
Hydrologic cycle
97% of water is found in the oceans where is the reamaining water found
the remaining water is in lakes, streams, rivers, wetlands, underground aquifers, and soil
what happens if evaporation doesnt balance the amount of precipitation
all water would accumulate in one part of the cycle
on a global scale where is precipitation greater than evaporation
in terrestrial ecosystems
where is evaporation greater than precipitation
aquatic systems
what happens to excess water that falls on land
it is transported in runoff and groundwater into aquatic systems.
reduces the water that enters the soil and increases runoff.
Creation of impervious surfaces (e.g., roofing, pavement)
roofing, pavement are examples of
impervious surfaces
decreases evapotranspiration and also increases runoff.
Removing plant biomass
examples of removing plant biomass
cutting down a forest
a way humans use water from the ground before it can be replenished
irrigation
may increase temperatures and evaporation rates, leading to an intensity of rain and snowstorms.
Climate change
How might the ocean reduce the effects of fossil fuel combustion on CO2 concentrations in the atmosphere
by absorbing atmospheric CO2
in what habitats is carbon is used for respiration instead of oxygen.
In some O2 -poor habitats (e.g., swamps
has increased to meet energy demands Over the past two centuries
extraction and combustion of fossil fuels (e.g., coal, oil, natural gas)
Combustion of what releases CO2 into the atmosphere?
fossil fuels
greenhouse gas that absorbs infrared radiation.
CO2
exacerbates the problems of excessive greenhouse gases and global warming
Decomposing peat releases methane gas
How might N-fixing bacteria living in symbiosis w/ a plant affect the types of EVRs in which the plant could live
It would allow the plant to live in areas without much nitrogen (i.e. low nitrogen).
the process of converting atmospheric nitrogen (N2) into forms producers can use, including ammonia (NH3) which is rapidly converted into ammonium (NH4+), and nitrate (NO3–).
Nitrogen fixation
occurs in some species of cyanobacteria, free-living species of bacteria (e.g., Azotobacter) and in bacteria that form mutualisms with plants (e.g., Rhizobium).
Nitrogen fixation
requires high amounts of energy, which can be obtained by metabolizing organic matter or from mutualistic partners.
Fixation
occurs when lightning, wildfires, or combustion of fossil fuels provide energy to convert N2 into NO3–.
Abiotic nitrogen fixation
uses high amounts of energy to convert N2 gas into ammonia or nitrates.
Industrial production of N-rich fertilizers
the final process in the nitrogen cycle, which converts ammonium to nitrite, and then from nitrite to nitrate
Nitrification
occurs when primary producers take up NH4+ or NO3– and incorporate it into their tissues; consumers assimilate nitrogen from primary producers or excrete it as waste.
Assimilation
the process of breaking down organic compounds into inorganic compounds.
Mineralization
the process of converting nitrates into nitrogen gas:
Denitrification
under what conditions do bacteria under go denitrification
anaerobic conditions
necessary for breaking down organic matter in oxygen-depleted soils and sediments.
Denitrification
causes nitrogen to leave ecosystems as a gas.
Denitrification
reacts with water to form nitrates, which fall to the ground during precipitation.
Nitric oxide
what effect does precipitation of nitrates have on ecosystems
precipitation of nitrates fertilizes ecosystems, increases productivity, and decreases species richness
what does phosphorous not have in its cycle
a gas phase
what is the only form phophorous can enter the atmosphere
dust
how do animals eliminate excess phosphourous
by excreting urine with PO4^3- or other compiunds that are converted by phosphatizing bacteria
iron binds with sulfur instead of phosphorus, making phosphorus more available under what conditions?
Under low-oxygen conditions
what kind of nutrient is phosphorous in terrestrial and aquatic systems
limiting nutrient
can contribute to algal blooms in aquatic ecosystems.
Phosphorus, in combination with excess nitrates,
an increase in productivity of aquatic ecosystems
Eutrophication
an increase in the productivity of aquatic ecosystems caused by human activities.
Cultural eutrophication
example of humans impact on phosphorous cycling
phosphates from household detergents travelled to natual systems and contributed to eutrophication and dead zones
Why is the weathering of bedrock responsible for such a small fraction of nutrients available to plants?
There is a large distance between bedrock and plant roots.
Nutrient loss from leaching and water transport is balanced by
inputs of nutrients from the air (e.g., nitrogen) and from weathering of bedrock beneath the soil (e.g., phosphorus).
Acids from rainwater and decomposition react with minerals in bedrock to
release elements essential to plant growth.
Weathering rates can be determined by measuring
nutrients entering a system from rainfall and leaving a system by leaching.
an area of land draining into a single stream or river.
watershed
Ecologists often measure rates of nutrient regeneration in a
watershed
primary production relies on regeneration of nutrients from
the break down of detritus.
process that breaks down organic matter into smaller and simpler chemical compounds.
Decomposition
90% of all plant matter produced in a year is not consumed by herbivores, but is ultimately decomposed in what ecosystem
terrestrial ecosystems
removes 10–30% of soluble substances from organic matter; larger organic compounds are left behind
Leaching
plant growth and decomposition in terrestrial systems is influenced by
temperature, pH, and moisture
