Studied by 2 people
ecosystem stability
ability of an ecosystem to maintain it’s structure + function over long periods of time (despite disturbances)
ecological structure
physical + geological structures of the landscape, biodiversity, population size, interactions in the community
ecological function
processes (e.g. water cycling)
requirements for stability
constant energy supply (energy lost at each trophic level) - main source is sunlight
nutrient cycling (logging removes nutrients)
high genetic diversity - enables populations to adapt to changes in the environment by natural selection
tipping point
shift in ecosystem leading to a new equilibrium state
how deforestation can lead to a new equilibrium state
causes a reduction in evapotranspiration and rainfall which could lead to a tipping point where the rainforest cant recover and becomes a savannah
keystone species
species whose activity has a disproportionate effect on the structure of an ecological community - help to maintain biodiversity in an ecosystem
sustainability
use and management of resources allowing full natural replacement of the resources is exploited and full recovery of ecosystems is affected by the attraction and use
if the harvest is equal to (or less) than the growth in population, sustainable use of the resources is possible
max sustainable yield
amount that is removable without depleting the original stock or affecting its’ ability to recover
issues with intensive large scale farming
soil erosion
leaching
fertiliser
agrochemicals
carbon footprint
soil erosion
cause = tillage of soil (prep for crop), lack of crops (no roots to hold soil), wind + water
solution = use cover crops (during winter, etc) to hold soil
leaching
removal of nutrients from soil by percolation of water
cause = removal of plants
solution = improve irrigation or use cover crops
fetiliser
used to replace nutrients
cause = doesn’t improve soil structure, is energy intensive, can lead to eutrophication
solution = reduce leaching, use appropriate amount of fertiliser at right time, use green fertiliser
agrochemicals
artificial fertiliser
cause = monocultures encourage pest/weed problems = increase in the use of pest/herbicides
solution = use organic manure, crop rotations, mixed cropping, biological pest controls
carbon footprint
cause = clearing land, machinery (fossil fuels), etc
eutrophication
enrichment of water with nutrients which stimulates excessive algae growth (e.g. nitrogen and phosphorous)
the decay of dead algae leads to low oxygen conditions and damage to ecosystems
causes of eutrophication
agricultural fertiliser
have high nitrogen/phosphorous contents
leaching - excess fertiliser gets washed out of soil by rain and goes into ponds/rivers)
rivers bring nutrients to oceans
process of eutrophication
increase in concentration of nitrogen/phosphorous in water leads to algae blooming
the algae dies and sinks to the bottom of the lake/pond
accumulation of dead organic matter
increases the activity of decomposers
increased use of oxygen in water by the decomposers for cell respiration increases the biological oxygen demand
leads to a decrease in dissolved oxygen levels in the water
kills fish, shells, other organisms
decrease in light at bottom of lake/pond (dead organic matter build up) = organisms can’t photosynthesise and die
decomposition of dead organisms = release of phosphates and nitrates into water
= positive feedback loop
biological oxygen demand (BOD)
measure of the amount of oxygen required to breakdown organic material (aerobic respiration of microorganisms)
why BOD can increase
more organic waste in water leads to more organisms using waste for cell respiration which leads to an increase in demand for oxygen
impact of eutrophication
cyanobacteria produce toxins that make people sick/die
bioaccumulation
build up of non-biodegradable/slow biodegrading chemicals in body
many toxins are not biodegradable
organisms store the toxins in their fat
over time the concentration of toxins absorbed increases
biomagnification
process whereby concentration of chemicals increases at each trophic level
pollution by DDT
DDT = effective insecticide (very hydrophobic)
is strongly absorbed by soils (half-life average of 15 years)
not soluble in water
uses = WWII control of malaria mosquitoes, control typhus lice, agriculture rids of insects and increases yield
case study DDT
DDT biomagnification = thinning of bird egg shells
eggs crushed during incubation = less chicks hatched = decrease in population
threatened survival of species
macroplastics
larger than 5mm
majority washed into oceans by rivers
ocean current accumulates plastic into large patches
microplastic
smaller than 5mm diameter
degrades leaving toxins in ocean
carbon compounds accumulate on/in plastic with toxic effects when ingested
rewilding
conservation method
allows natural processes in ecosystem to recover
as little human intervention as possible
some intervention is needed
control of invasive species - reintroduce apex predators, distribute seeds, introduce keystone species
rewilding case study
Hinewai reserce
removed alien species (goats, possum, deer)
nurse plants from alien plants
allows native species to re-establish themselves = protection younger seeds
succession
orderly process of change over time in ecosystem
primary succession
starts with formation of soil (volcano, glacier recedes, etc)
soil formed by weathering of rock + decay of dead plants and animals
takes 100s of years
secondary succession
formation of an eco-system with soil present (e.g. after a fire a beaver builds a dam)
os a faster process
stages of primary succession
Bare Rock: The process begins on bare rock after a disturbance (e.g., volcanic eruption).
Pioneer Species: Lichens and mosses colonize the area, breaking down rock into soil.
Soil Formation: As pioneer species die, they contribute organic matter, enriching the soil.
Intermediate Species: Grasses and small plants grow, further improving soil quality.
Shrubs and Young Trees: Larger plants establish, leading to increased biodiversity.
Climax Community: A stable ecosystem forms, often dominated by mature trees, representing the final stage.
arrested succession
community not reaching its expected climate community due to human interference
main gases in climate change
carbon dioxide
methane
the greenhouse effect
long wave radiation - absorbed by greenhouse gas molecules in atmosphere (warms them up)
greenhouse gas molecules emit heat as long wave radiation
earths surface warms up - emits more long wave radiation
= warming up of earths surface and lower atmosphere due to presence of greenhouse gases
enhanced greenhouse gas
increased greenhouse effect due to human activities increasing the concentration of greenhouse gases = climate change
climate
a regions general pattern of weather conditions over a long period of time
determined by the average insolation, precipitation, temperature
weather
short term atmospheric condition
ice core drilling
gas trapped in fossilised ice analysed to determine carbon dioxide concentration
proxy measurement
determining temperature using ratio of carbon dioxide isotopes present in air
albedo
proportion of solar radiation reflected by a particular body or surface
high albedo = clouds, ice, snow
low albedo = water
reduced albedo effect
warm temps =
snow + ice melt
reduced albedo
more absorption solar energy
warmer temp
permafrost
ground that is frozen all year - frozen soil locks lots of carbon dioxide
oceans as a carbon dioxide sink
more co2 diffuses into ocean than out (locked by photosynthesis and phytoplankton)
oceans as a carbon dioxide source
atmospheric temperatures increase lead to ocean temps increasing
warm water holds less co2 = released into atmosphere
thawing of permafrost
temp increases
ground thaws
detritus decomposes
increases release of co2 and methane
temp increase
forest browning
lack of water = reduced photosynthesis
lower primary productivity
less co2 removed from atmosphere
pine needles lose chlorophyll = forest browning
how ocean currents effect the climate
ocean currents - mainly caused by changes in water density due to temp + sailinity
currents distribute heat around globe effecting the climate
nutrient upwelling
deep ocean current forced upwards when they reach a continental shel
brings nutrient rich water to the surface where light can penetrate
carbon fixed by photosynthesis =
high primary productivity
energy enters marine food chains
dead organisms sink to bottom + decompose
upslope range shift
montane species live at specific elevations on the mountain
an increase in altitude leads to an average temperature decrease
climate change increases temp = species move up mountain
leads to interspecific competition
ocean warming
as atmospheric temp increases, ocean temp increases
co2 concentration in atmosphere leads to more diffusing into ocean
coral bleaching
zooxanthellae live inside reef coral tissue (mutualistic relationship)
when coral is under stress it expels the algae which leads to bleaching, starvation, and death
stress triggers = low light (sedimentation), temp increases (kills algae), and ocean acidification (low pH)
relationship between coral and zooxanthellae
algae
photosynthetic = gives coral glucose, amino acids, oxygen
coral
gives protection so algae can be closer to surface of water with more light
ocean acidificaion
increased co2 in atmosphere leads to more diffusing into ocean
co2 reacts with h20 to make carbonic acid
carbonic acid turns into hydrogen and hydrogen carbonate ions
makes pH of water more acidic
increase H+ ions react with CO3(2-)
balances the shift and less available for organisms to build skeletons/shells
increase drop in pH = exisiting shells and skeletons dissolve
afforestation
planting trees where they don’t already grow
peat wetlands
largest terrestrial carbon sink
develop naturally in temperate + boreal ecosystems + tropical
drained and excavated for fuel, fertiliser, and oil
restore them to save the carbon sink function
phenology
study of periodical events synchronized with seasons
photoperiod
number of hours sun is shining and the change in temperature
spruce bark beetles case study
climate changes leads to weaker trees and more beetles
the beetles attack the trees
trees no longer survive due to being weaker and more beetles attacking
habitat
environment in which a species, population, or organism normally lives
geographical location
specific area/region where a species lives
physical location
immediate environment where species lives
adaptations
organisms features aiding in survival by being better suited for the environment
adaptations to grass in sand dunes
rolled leaves = stomata in rolled leaves release less water
stomata in pits = traps water vapour decreasing transpiration
waxy cuticle = reduce water loss
adaptations to trees in mangroves
salt excretion = some parts of plant have salt glands to eliminate salt
tissue partitioning = concentrate soil in designated leaves then drop them (abscission)
pneumatophores = tubes allowing oxygen to reach roots
abiotic features
non-living factors affecting eco-system
examples of abiotic features
water
light
soil
temperature
minerals
biomes
geographical areas with a particular climate and sustain a specific community of flora and fauna
tropical rainforest
hot climate (25-30)
high levels of precipitation
large diversity in species + vegetation
temperate forest
moderate temps
clear seasonal changes
growing period (200 days) during 4-6 frost free months
taiga
cold + icy
small amount precipitation
coniferous trees densely packed
little variation in species
grassland
moderate temps
moderate amount of rainfall
tress/shrubs largely absent
grass is dominant vegetation
tundra
freezing temos
very little precipitation
vegetation is low growing
perennial plants during summer
hot desert
extreme temp conditions
low precipitation
dominant plants species is xenophytes (water conservation)
convergent evolution
different evolutionary lineages developed similar mechanisms due to similar ecological niches
fennec fox adaptations for hot desert
water conservation = kidneys adapted to restrict water loss
temp regulations = dissipates efficiently due to large ears keeping a cool body temo
burrowing = digs extensive burrows making a colder environment to raise young
paws = thick fur to protect from hot sand and aid in digging
nocturnal = avoid extreme heat in day
saguaro cactus case study
photosynthesis = has a special adaptation allowing it to take in co2 at night and store for the next day = minimal water loss
water storage = absorbs and stores large amounts of water to use during drought periods
thick waxy cuticle = reduces water loss through evaporation
spines = modified leaves reducing water loss, providing shade, and protection from herbivores
brown throated sloth adaptations for tropical rainforest
long limbs + strong claws = good for hanging and climbing
slow metabolism = adapted for low energy diet (leaves), slow pace consumes energy when habitat food is nutrient poor + hard to digest
infrequent ground visits = reduces risk of predation
camouflaging fur = can host algae to blend into greenery and hide from predators
scarlet star (flower) adaptations for tropical rainforest
water collection and storage = leaves from central tank storing water. crucial when roots are used for anchorage not water absorption.
brightly coloured bracts = surround small flowers to attract pollinators in dense rainforest
epithytic growth = grows on other plants without parasitising them. allows better light conditions above the forest floor and reduced competition for soil nutrients.
ecological niche
specific role played by a species in its habitat
includes food, where it lives, etc
biotic factor
living things within an ecosystem
examples of biotic factors
plants
bacteria
animals
aerobic
processes or activites requiring presence of oxygen
obligate anaerobes
respire anaerobically and can only survive in absence of oxygen
facultative anaerobes
can respire anaerobically or aerobically depending on oxygen availability
obligate aerobes
resire aerobically and cannot survive in absense of oxygen
autotroph
organisms that can produce their own energy
heterotroph
organisms that cannot produce their own energy
mode of nutrition
method by which an organisms obtains its energy and nutrients
holozoic nutrition
when organisms ingest a variety of organic material, which then undergoes a series of metabolic processes such as internal digestion, absorption, and assimiliation
assimilation
occurs when absorbed products are delivered to specific cells that will use them
mixotrophic nutrition
use both autotrophic and heterotrophic forms of nutrition (mainly occurs in unicellular organisms)
protist
any eukaryotic organism that is not an animal, land plant, or fungus
obligate mixotrophs
obligated to use both auto/heterotrophic means of nutrition to survive.
facultative mixotrophs
can switch between auto/heterotrophic nutrition, but do not depend on any for its survival.
decomposer
organism that breaks down and recycles dead or decaying organic matter
saprotrophs
decomposers releasing digestive enzymes then absorb the external products of digestion
extremophiles
live in extreme hot/cold, salinity, other conditions that are hostile to most other forms of life on earth
photoautotrophs
do a form of photosynthesis using pigments other than chlorophyll and do not generate oxygen
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