Ecology Quiz 10 Flashcards
All organisms require
Building blocks of life:
Primary nutrients
Biogeochemistry:
The atmosphere is the ultimate source of
All organisms require specific chemical elements for metabolism and growth, which they absorb from the environment or get in their food.
Building blocks of life: CHNOPS
N and P (primary nutrients)
Biogeochemistry: Study of the physical, chemical, and biological factors that influence movement and transformation of elements.
- is important in determining the availability of nutrients—chemical elements required for metabolism and growth.
Nutrients must be in certain forms for uptake by organisms.
Rates of physical and chemical transformations determine the supply of nutrients.
The atmosphere is the ultimate source of carbon and nitrogen, which must be transformed or fixed by organisms. Carbon is taken up as CO2 by autotrophs through photosynthesis and fixed into organic compounds.
All organisms have similar nutrient requirements, but amounts and specific nutrients vary. Nutrient requirements are reflected in the chemical composition of organisms.
Requirements are related to physiology:
Plants: BLANK is the main component of plant structural compounds; BLANK is largely tied up in enzymes. Relatively BLANK BLANK ratios
Plants and microorganisms take up nutrients in
Animals and microorganisms: have BLANK BLANK ratios than plants.
Herbivores must BLANK BLANK BLANK than carnivores to
Animals mostly get nutrients in food as
Requirements are related to physiology: mode of energy acquisition (autotrophic or heterotrophic), mobility, thermal physiology (endotherm or ectotherm).
Plants: Carbon is the main component of plant structural compounds; nitrogen is largely tied up in enzymes. Relatively high C:N ratios
Plants and microorganisms take up nutrients in simple, soluble forms from the environment.
Animals and microorganisms: have lower C:N ratios than plants.
Herbivores must consume more food than carnivores to get enough nutrients, such as N.
Animals mostly get nutrients in food as large, complex molecules. Some molecules are broken down; others are absorbed intact, such as some amino acids.
All nutrients are ultimately derived from BLANK sources:
abiotic
minerals in rocks (ie., P, K, Mg, Ca)
gasses in the atmosphere (N)
Nutrients may be cycled within an ecosystem, repeatedly passing through organisms and the soil or water.
Phosphorus cycle
Nitrogen cycle
Weathering
Soil
N-fixation
Elements are released from rock minerals by weathering.
Mechanical weathering:
Chemical weathering:
higher vs lower latitudes
Mechanical weathering: Physical breakdown by plant roots, gravity, and expansion and contraction during freeze–thaw and drying– rewetting cycles.
Chemical weathering: chemical reactions release soluble forms of the mineral elements.
Tropical forest soils have experienced high rates of weathering and leaching for a long time and are nutrient poor. Most nutrients in these ecosystems are in the living tree biomass
At higher latitudes, soils have slower leaching rates and are usually richer in mineral nutrients.
Soil is a mix of mineral particles coming from
Soil water contains …. (the soil solution).
Soil properties influence nutrient availability:
Cation exchange capacity:
Parent material:
Soil is a mix of mineral particles coming from parent material, organic matter (mostly decomposing plant matter), water, and organisms.
Soil water contains organic matter, minerals, and gasses (the soil solution).
Texture influences soil water- holding capacity and thus movement of nutrients in the soil solution.
Soils with a high proportion of sand have large spaces between the particles and don’t hold water well. Water drains through quickly.
Cation exchange capacity: related to amount and types of clay particles present.
Parent material: Rock or mineral material that was broken down by weathering to form a soil. Underlying bedrock, Sediment, which can be deposited by glaciers (till), wind (loess), or water (alluvium). Chemistry and structure of the parent material determines the rate of weathering and amount and type of minerals released. Affects soil characteristics such as fertility. Parent material influences abundance, growth, and diversity of plants in an ecosystem.
N-fixation
Nitrogen in the atmosphere is N2, a form that
Nitrogen fixation:
Legume plants provide
Haber–Bosch process
Nitrogen in the atmosphere is N2, a form that can’t be used by most organisms because of the energy required to break the triple bond.
Nitrogen fixation: N2 is converted into a biologically useful form.
Biological N fixation uses the enzyme nitrogenase, which only occurs in certain bacteria. Some N-fixing bacteria are free-living, others are symbionts.
Legume plants provide symbiotic N-fixing rhizobia bacteria with a habitat in special root nodules, and supply them with carbon compounds as an energy source.
The plants get fixed nitrogen in return (N2->NH4 +)
Humans fix atmospheric N2 when they manufacture synthetic fertilizers using the Haber–Bosch process, which uses a lot of energy (from fossil fuels). - altered nitrogen cycle
Nutrient transformations:
Decomposition rates are influenced by climate:
Litter:
Mineralization:
Nutrient transformations: Decomposition - The process by which detritivores break down detritus to obtain energy and nutrients.
Decomposition releases nutrients as simple, soluble organic and inorganic compounds that can be taken up by other organisms.
Decomposition rates are influenced by climate: faster in warm, moist conditions.
Soil moisture influences availability of water and O2 to microorganisms: saturated soils will decrease oxygen and this is done by too much water. Wet soils have low O2 concentrations, which inhibits detritivores.
Dry soils do not have enough water for microorganisms.
Litter: Fresh, undecomposed organic matter on the soil surface.
- Animals such as earthworms, termites, and nematodes consume the litter, breaking it up into progressively finer particles. This fragmentation increases surface area, which facilitates chemical breakdown by microbes
Mineralization: Chemical conversion of organic matter into inorganic nutrients; final step in decomposition.
- Heterotrophic microorganisms release enzymes into the soil that break down organic macromolecules.
Nutrient cycling:
Rate of nutrient cycling depends on the
Nutrients that limit primary production are
Climate also affects cycling rates via influence on metabolic rates of the organisms involved:
Residence times can be used to compare ecosystems. Tropic vs boreal
Nutrient cycling rates are quantified by estimating mean residence time:
Nutrient cycling: Movement of nutrients in ecosystems as they undergo biological, chemical, and physical transformations.
Rate of nutrient cycling depends on the element and location of the cycle.
Nutrients that limit primary production are cycled more rapidly than non limiting nutrients.
Climate also affects cycling rates via influence on metabolic rates of the organisms involved:
Higher temperatures -> faster decomposition rates - faster in tropics
Higher moisture -> faster decomposition rates until the point where soils become waterlogged and anoxic - air important need 02
Residence times can be used to compare ecosystems.
Nutrient pools in tropical forest soils are much smaller and turnover rates much higher than in boreal forests.
Boreal Forest: Decomposition slow bc temperature and climate spend more time in pools
Nutrient cycling rates are quantified by estimating mean residence time—time an average molecule spends in a pool
mean residence time= total pool of element/rate of input
Conservation biology
Biodiversity is declining globally, and Earth’s biota is becoming increasingly
Conservation biology is an integrative discipline that applies the principles of ecology to the conservation of biodiversity
Protecting biodiversity is critical bc we are dependent on ecosystem services and functions
Biodiversity is declining globally, and Earth’s biota is becoming increasingly homogenized(similar)
Ecosystem Service
PROVISIONING:
REGULATING:
CULTURAL:
SUPPORTING:
PROVISIONING: Goods or products produced by ecosystems
REGULATING: Natural processes regulated by ecosystems
CULTURAL: Non-material benefits obtained from ecosystems
SUPPORTING: Functions that maintain all other services - soil
Threats to biodiversity:
- Habitat loss and degradation
- Invasive species
- Overexploitation
- Pollution
- Disease
- Global climate change
- Habitat Loss and Degradation
Habitat degradation:
Habitat loss:
Habitat fragmentation:
Ex:
Habitat degradation: changes that reduce quality of the habitat.
Habitat loss: total conversion of one habitat type into a different type, e.g., forest to farms.
Habitat fragmentation: break up of continuous habitat into habitat patches.
Ex: palm oil
- Invasive species = Declining Biodiversity
Invasive species:
The global movement and introduction of species has greatly increased over the last century.
Invasive species: non-native, anthropogenically introduced species that sustain growing populations and have large effects on communities
The range expansion of some invasive species has coincided with range contraction of many native species.
In many ecosystems, habitat fragmentation is followed by habitat degradation, which increases vulnerability to invasive species.
- Overexploitation
Globally, overexploitation is contributing to imperilment of many species.
The effect of overhunting on tropical forests has removed large vertebrate faunas
Unsustainable Hunting is Defaunating Tropical Forests
Overfishing in the oceans has led to declines in top predators, and other species.
- Pollution
Other anthropogenic factors contribute to declining populations—air and water pollution, climate change, and diseases.
An emerging pollution threat is persistent endocrine-disrupting contaminants (EDCs).
Levels of PCBs and PBDEs were very high in marine mammals in British Columbia (Ross 2006).
