theme B - climate change impacts on ecosystems Flashcards
what are the main components of the earths system
atmosphere
hydrosphere
biosphere
geosphere
anthrosphere
- material moves between these reservoirs at different rates - if the rate changes then the volume of the reservoirs change
the atmosphere components and layers
troposphere
stratosphere
mesosphere
thermosphere
exosphere
78% N
21% O
trace gases
definition, structure and energy flow in the biosphere
- it encompasses the earths life zone, comprising of all living organisms and organic matter that has not decomposed
- follows a hierarchical structure (food chain) where all life depends on primary producers
- energy and mass is transferred between trophic levels in the food chain
definition and components of the hydrosphere
- encompasses all the water on our planet
- water vapour and clouds, cryosphere, salt water
definition and components of the geosphere
- comprises of all the solid earth, continental and oceanic crust and earths interior layers
- composed of rocks and minerals
- lithosphere - outermost part of the geosphere
definition and significance of the anthrosphere
- represents the human component of the earth system and its interactions with the environment
is earth an open or closed system
nearly a closed system beacuse:
- energy is the only thing that can enter and leave (apart from hydrogen and helium)
- matter cannot enter or leave (except from meteoroids and comets but very rare)
implications of earth being a closed system
- finite resources - therefore they must be managed responsibly
- zero waste principle - cannot just throw things away as waste accumulates affecting the entire system
- interconnected impacts - changes in one part of the system have a ripple effect
how do we study complex systems
- identify the components of the system and how they interact
- determine the residence time
- identify feedback loops
- computer models are usually used
what is a reservoir
amount of material of interest in a given form
what is a flux
amount of material added to a source or removed from a sink in a given period of time
what is residence time
the time it would take to empty or fill the reservoir
RT= amount in reservoir/ total sources/sinks
how do clouds affect the climate
- currently have a net cooling effect but may change in the future depending on what cloud type is dominant
- high clouds absorb more radiation = warmer
- low clouds absorb less radiation = cooler
environmental consequences of intensive irrigation in the Aral sea
- irrigation began in 1960 significantly altering the water flow
- inflow had decreased to 5KM3 per year
- tenfold increase in salt concentration
- local groundwater contamination
- toxic dust storms (due to lake bed drying)
energy sources in the earths system
- solar radiation
- geothermal heat
methods of energy transfer in the earths system
- radiation
- convection
- conduction
the water cycle
residence time of 9-2.7 million years
shapes the biosphere
factors that control plant distribution
- climate
- physiographic
- edaphic
where is the Bellis perennis (daisy) found
- cosmopolitan spices
- present all over Uk as well adapted to lots of differnet conditions
where is sea sandwort found
distributed around coasts in maritime conditions
- can cope with diff temps and rain conditions
how does climate control plant distribution
- control global and regional patterns
- local and microclimates can be distinguished
- have the biggest control at the biggest scale
how do physiographic factors control plant distribution
- determined by landforms
- altitude important - lapse rate (-6.5 for each 1000 increase)
- aspect (direction of slope) important as influence the amount of irradiance plants receive
how do edaphic factors control plant distribution
factors associated with soil
- rooting medium
- source of water
- source of nutrients
- provides both conditions and resources
what are (plant) resources
- commodities that are consumed by plants
- are essential to growth - prevents them from getting outcompeted
- excess resources is sometimes detrimental - supra optimal
what are (plant) conditions
- environmental variables to which plants respond
- help regulate the availability of resources
what scale is pH measured in
negative logarithmic
- pH 4 has 10x more H+ ions compared to pH 5
what is species richness and how is it measured
- grimes humpback curve shows maximum SR
- measure of how much biomass an area of ground produces and how many different species present
how does biomass relate to species richness
- high biomass = low biodiversity - because it must be a nutrient rich environment so aggressive plants competitively exclude other species
- low biomass = low biodiveristy - conditions must be harsh so only a few species can survive
relationship between pH and species richness
low pH soils are invariably species poor - fewer species are adapted to grow in acidic soils compared to neutral or calcareous soils - know as reservoir effect
- soil pH important beacuse it influences the availability of nutrients and potential toxic ions
external influences in natural climate variation
- changes in the amount of particles in the atmosphere from volcanic eruptions - haze effect
- sun spot cycle - variations in the suns energy over a 11 year cycle
interneral infleucens in natrual climate variation
- el nino
- North Atlantic oscillation
- north Atlantic ocean circulation/gulf stream
what is the north Atlantic oscillation
in postive phase there is high pressure in the subtropical high and low pressure in the icelandic low - this creates a higher pressure gradient along the atlantic than normal - draws more storms and moistrue to norther europe and cold dry werather to canada (negative phase opposite)
what is the gulf stream
warm water rises in the carribbean some of this water evaoporates meaning it has a higher salt concentration - this water is then denser so sinks into the ocean collum - conveyor belt of water bring warm water to northern Europe
- it is reducing due to the increased input of freshwater due to melting icecaps - dilutes to salt
how do models uncertainty change with scale
there is greater uncertainty at smaller scales as there is limited data
how does the IPCC climate prediction model change
5 different scenarios created depending on different factors
range from increase of 8.5 to decrease of 2
how do plants cope with climate change
migrate, adapt, die
- due to a climatic envelope plants can only occupy a certain area as they have limited tolerance ti climatic variable - plants may move to stay in this envelope
- die if plant cant evolve in time
how could plants adapt to climate change
2 methods
- plasticity - an organisms ability to change its form or function within itself
e.g. if it in a drought plant will allocate more resources to growing roots to enable it to get more water - evolution - will struggle to keep place with rapid climate change as is a slow process
latitudinal migration
- movement N or S
- data collected from 750 species in different taxonomical groups
- average shift of 17Km per decade
- done so plants stay in their climatic envelope
- protected areas may struggle as plant cannot migrate sufficiently - only 8% good for next 100 years
what is climate velocity
plants
the speed the plants need to move to keep up with the pace of climate change
- mountaneous areas have the lowest CV as they dont have to move far to get into cooler conditions
- in flat areas plants may need to mouve up to 7m/y (andes ) which is too fast
why is drought a problem for forest mortality
as it takes a long times for forests to recover but can die very quickly
- severe but short term - only less adapted forests die
- prolonged medium intensity- all forests die
how do extreme droughts kill forests
by hydraulic and symplastic failure
- as the trees try to transpire without water they get cavitation in the xyxle due to the increased pressure - this stops the process of transpiration happening
- is the drought is long laster the trees cant photosynthesise properly - this means it will enter a carbon deficit and the tree will slowly starve to death which is a very long process
importance of rainfall in xeric habitats
- low water so plant is normally in stress conditions
- if less frequent rainfall events plant will be taken out of drough conditions into ideal soil mositrue - habitat will become less stressed - positive impact
importance of rainfall in hydric habitats
large gap between rainfall events will allow the soil to become drier - ideal soil moisture will be reached
Konza Prairie rainfall experiment and theory
stress environments will become less stressed when there is bigger rainfall events with bigger gaps but unstressed environment will become more stressed
plant growth in a higher co2 world scenario
- more co2= more photosynthesis
- rubisco more efficient with greater co2 levels - less photorespiration
- leaves can have less open stomata = more water efficiency
- does not causes increased growth because there are other limiting factors
FACE experiment’s
free air co2 enrichment
- average crop yield was 17% (lower than what was estimated)
- wheat and rice did not respond to elevated co2
where will there be increased carbon sequestration with increasing co2 levels
- 12% biomass increase (global average)
- largest increase of 13% in forest systems
- productive systems are more responsive
- largest absolute increase in TRF
why might increased C storage be less than FACE suggests
as leaf photosynthesis increases but biomass does not - therefore mature forests may not increase C storage significantly
effects of elevated co2 on different grasslands
- limestone
- eco2 significantly increases plant biomass
- P in plant and microbes not changes - Acidic
- eco2 significantly reduces plant biomass
- eco2 causes microbes to get more of P therefore there is less for the plants to use to grow - planst cannot cope iwth increased competition
land and ocean sinks with increasing co2
- as co2 increases land and ocean absorb more
- places a limit on cc
- proportionally less co2 is absorbed than released
- capacity of land and ocean will reach a limiting point
how is the impacts of climate change studied
– monitoring populations or ecosystems over time
- site comparisons to compare pristine sites (not common)
- predict impacts of future change through manipulation experiments and gradient studies
how has UK animals abundance changed over time
19% decline in abundance since 1970
recent trend - stronger gains for winners and bigger losses for losers - big divide
priority species
37% decline since 1970
since 2010 reduced decline - conservation working?
simulations of climate change impacts - Buxton and Wytham
studied the ability of the plant community to maintain comosition and biomass and there rate of recovery - resistance and resiliance
Buxton (derby) vs wytham (oxford)
- W in early succession so community is more dynamic and prone to change
- therefore species here will respond more rapidly to CC
- B is an infertile systems so opportunities of new speices are rare - it also has a local variation in soil moisture and nutrinets so the systens accomodates unique species that would be lost from a more homogenous environmnet
- is a more mature less fertile community so responds slower to CC
what are tensioned landscapes
issue of space occupancy
is a major barrier to change
distrubance may trigger a sudden shift which is an opportunity for new species establishment = tension
most important envrionmental changes
land use
climate change
nitrogen deposition
water security conflict
conflict - human demand for freshwater vs biodiveristy in water system
80% of world population has a high level of threat for water security
0.16% earths surface unthreatened
biodiveristy threat
wealthy nations invest into ensuring water security but same effort does not go into protecting biodiveristy as it is not a human need
65% ecosystem has high levels of incident biodiveristy threat
land use pressure on local species richness
- most ecosystems have declining species richness
- more human intervention = greater decline
- 14% global loss of SR
- 31% loss of SR in worst hit areas
examples of positive environmental change to species richness
- mountain summits show increasing SR (up to 5x)
- this is beacuse conditions are less harsh so less well adapted species can not survive
- also due to species migrating to stay in their climatic envelope
climate change in Arctic
warming 4x faster than the global average due to polar amplification
sea ice decline at 12.5% per decade
what is polar amplification
- snow and ice melt = less albedo and more energy absorbed
- more of the extra trapped energy goes into warming instead of evaporation
- altercations to ocean and atmospheric circulation
- the atmospheric layer in shallower in the artic so more easily warms
- as sea ice reatreats, solar heat is more easily transfered to the atmsosphere from the oceans as they are warmer
how is permafrost changing
- covers 24% of land in NH
- stores carbon as peat and methane
- stores double the amount of carbon than is currently in the atmosphere
Arctic Greening
warmer summers and longer snow free durations each year
- increase plant growth
- ecpansion of more productive plansts - stratification
- increased in C sequestered by greening tundra
ecological consequences of sea ice decline
early ice retreat = altered timing of zooplankton = less food for seabirds and mammals
warmer arctic = sub artic marine birds moving north = ice associaed birds in decline as more competition for resources
anthropogenic atmospheric N deposition
- wet deposition in rain
- dry deposition as gas or aerosols
oxidised and reduced forms of atmospheric N
oxidised
- wet - nitrate
- dry - nitrous oxide
reduced
- wet - ammonium
- dry - ammonia
anthropogenic sourced of N
- ff combustion (NO)
- agriculture (NH) - especially ammonia from livestock manure
factors affecting deposition of N
- distance from sources
- less important for NO as has long distance dispersal
- important for NH since deposition is close to source - surface roughness
- deposition velocities faster on rougher surfaces - rainfall
- more rainfall = more wet deposition
- seeder feeder effect
what is the seeder feeder effect
when aerosols are activated into droplets at cloud base from an orographic feeder cloud
where are there high and low rates of N deposition in the UK
high rates in
- upland areas (seeder feeder)
- areas near major industrial centres and farms
- forests (high surface roughness)
- Peak district and Pennines (industrial activity, rain and seeder feeder)
low rates in
- Scotland - remote from emissions sources more significant than influence of rain and seeder feeder
mechanisms of N deposition as an ecological effect
- eutrophication
- soil acidification
- secondary stress of plants
- direct toxicity to plants
why is eutrophication (N) an ecological threat
- N accumulation in soils allows expansion of nitrophillous species
- can result in competitive exclusion leading to reduced biodversity
why is soil acidification (N) an ecological effect
- can reduce plant health and productivity
- alter community composition and cause decline in species richness
how does N deposition cause secondary stress of plants
- greater herbivory
- reduced resistance to pathogen attack
- increased susceptibility to drought
how does eutrophication lead to competitive exclusion
- fast growing N loving species outcompete others
e.g. Dutch Chalk
- causes species richness to decline
evidence for decline in grassland diversity across UK
areas of contrasting N depositions were surveyed
- average deposition in the UK recued species richness by 4-5 species
how is N deposition an increasing global issue
- estimated to be 2 fold greater in 2050 than 1990
- 3rd greatest threat to global biodiversity
- industrialisation of developing countries means more N emissions
world biodiversity hotspots
cover only 2.5% of the earths terrestrial area but contain 50% of the worlds vascular species and 43% of all terrestrial vertebrate species
- many of these location are in developing countries that are undergoing industrialisation - threat
how is N deposition changing in biodiversity hotspots
Average N deposition in hotspots was 50% higher than the global average in the mid-1990s.
Projected to more than double by 2050.
33 out of 34 hotspots will experience increased N deposition by 2050.
17 hotspots may have 10-100% of their area receiving over 15 kg N/ha/yr, exceeding critical loads for many European ecosystems.
4 hotspots predicted to have average deposition exceeding 20 kg N/ha/yr.
research need in biodiveristy hotspots
-Assess the sensitivity of hotspot vegetation to N deposition.
-Conduct empirical studies in tropical and subtropical ecosystems.
-Improve regional and local N deposition mapping.
-Develop better regional models to refine deposition estimates.
major classes of marine life
- benthic - on epifauna or in infauna on the seabed - invertebrates or algae
- demersal - associated with the seabed
- pelagic - in the water column
- macroalgae - need to be attached to the sea floor and also have light (restricted to coastal areas as shallow seabed)
phytoplankton
- overcome coastal dependence be being single cells and floating
- found throughout the oceans (not homogenously)
- responsible for 50% of oxygen production
measurement methods in the ocean
NASAs MODIS 0 measured chl everyday over the entire planet
in situ - Argo network which is a series of floating buoys
how has the two ocean layers dilemma been overcome
light at the top nutrients at the bottom - life would not be able to survive
- mixing of surface water by wind
- Coriolis effect
- surface currents and tides
- localised upwelling of nutrient rich waters
how are the seas divided up
- into ocean basins horizontally then seas
- vertically by depth
- biologically by productivity
- biogeographically by species composition (ecosystems, biomes)
- politically (EEZs, fishing areas)
major depth zones in the ocean
- epipelagic/euphotic zone (50-200m) - light enough for photosynthesis
- mesopelagic/dysphoric zone (-1000m)- enough light for animals not plants
- bathypelagic/aphotic zone (-6000m) - no light 3/4 of the ocean (abyssal plain)
- hadal zone (>6000m) - ocean trenches
Longhursts biogeographic definition for marine ecosystems
oceans are divided into 4 pelagic biomes based on the physical forces regulating the distribution of phytoplankton
- polar biome, westerlies biome, trade winds biome and coastal boundary’s zone biome
- each biome occurs in every major ocean basin
- ocean basins are then divided into 54 biogeographical provinces
Longhurst pros and cons
- concentrates on the planktonic ecosystems and the physical oceanographic processes driving it
- very useful for large scale studies
- does not properly cover significant marine ecosystems and taxa that are of interest to people
MEOW biogeographic definition of marine ecosystems
(marine ecoregions of the world)
- motivated by conservation concerns
- coastal and shelf areas only as they have the highest biodiveristy and highest human pressures
- strong biogeographic basis - taxonomical configuration, evolutionary histroy and patterns of dispersal and isolation
- has a hirearchial structure
- is a combination of data and expert opinion
what are ocean realms
- 12 large regions with internally consistent biotas at higher taxonomical levels
- high levels of endemism
- driven by water temperature, isolation and depth
what are ocean provinces
- 62 large areas defined by distinct biotas that have some cohesion over evolutionary
time - some levels of endemism (particularly among species)
- driven by distinct abiotic boundary features (geomorphological, hydrological or geochemical
what are ocean ecoregions
- 232 areas of homogenous species composition clearly distinct from adjacent species
- biogeographically driven by iscolation, upwelling, nutrient inputs or temperature
- ecologically cohesive
- endemism is not a key determinant
what is endemism
distribution of a taxon
MEOW pros and cons
- designed to be pragmatic and relevant to management and conservation
- only consider a minority a marine taxa
- most of the world oceans are not covered by this scheme
properties of water
- liquidity - molecules stick together via weak H bonds
- high heat capacity
- dense - support for animals
what does salt do to water
- freezing point lowers
- density increases
- saltier water sinks
what is thermohaline circulation
cold water sinks near poles and moves equatorward through the deep ocean - tropical water is lifted, mixed and welled towards the surface - at the surface its heated and moved towards the poles
ocean atmosphere interactions
and impacts
- gas exchange at interface
- heat exchange
- changes in atmospheric co2 impacts primary productivity and ocean chemistry as different amounts of C get dissolved
- turnover between 500-1000y
carbon in the deep ocean
- 6x C in sea than atmosphere
- C delivered by marine or biological carbon pump
- key processes involved C - photosynthesis of phytoplankton and fixation into calcium carbon for shells
- marine organisms sinks to ocean floor after death - stay here for a long time and make ff
what happens to co2 in the sea
- either exchange with the atmosphere or taken up by photoautotrophs
- combines with water to from carbonic acid
what has caused ocean acidification and what is it
more co2 in the atmosphere:
- increased conc. of dissolved co2
- increased concentration of hydrogen ions
- increased concentration of bicarbonate ions
- decreased concentration of carbonate ions
- this all results in a decrease in pH
what is the heat capacity of the oceans
- 93% of heat generated by anthropogenic sources has been absorbed by ocean
- thermohaline circulation distributes this heat spatially
- sea temp changes very slowly
how does CC affect the sea
- ocean acidification
- warmer
- holds less oxygen - deoxygenation in deep seas
- less buoyant
- sea ice melts - slower thermohaline circulation
- rise in sea level - melting ice caps and thermal expansion
- changing patterns of ocean circulation
prediction of future UK seas
- average increased temp of 0.25-0.4 per decade
- bottom waters will become unsaturated in more soluble form of calcium carbonate - hard for marine organisms
- episodic undersaturation events will occur
- 2100 there will be 4% decline in oxygen
- sea level rise by 0.5m
- changed timing of thermal stratification
- decreased salinity
- increased coastal erosion
- increased storms
- seasonal ice freeze
- weakening of Atlantic meridian overturning circulation
impacts of cc on marine life
- migrate to different location within their thermal limits
- die (if cant migrate or food source dies)
- calcification will be harder
- deoxygenation will be harder
impacts on humans from oceans changing due to cc
- food production from fisheries and aquaculture will change
- prevalence of harmful species (toxic agal blooms)
- coastal communities will experience increased flooding and more serve storms
what makes a soil healthy
physical, chemical and biological components
- nutrient capacity
- N
- soil structure
soil and ecosystem service provision
- foundation of the terrestrial ecosystem
- globally soils are degraded - have cost the UK £1.3 billion (due to loss of organic matter)
- 33% of the worlds arable topsoils has been lost to erosion over the last 40 years
- erosion rates from ploughed fields is 10-100x greater than rates of soil formation - removal of nutrients and release of co2
what factors affect soil infiltration
- soil structure - good structure = more pore species, lots of organic matter, greater soil invertebrates and microbes
- vegetation - different vegetation has different effects on soil structure and quality
- soil compaction - loss of pore spaces from the soil
clay soil and infiltration
- slow
- holds the greatest amount of water but much is held too tightly for plant use
loam soil and infiltration
- moderate speed
- holds the highest proportion of plant available water
sand soil and infiltration
- very fast speed
- holds the least amount of water
