Biosphere Flashcards

Question

Describe the Carbon Cycle - also refer to carbon storage e.g. why is the interaction between geological and biological processes so critical in allowing an oxygen-rich atmosphere?

Answer 1

Long-term and short-term; taken in by autotrophs, make compounds for heterotrophs, which then release C through respiration (aerobic), energy for work (photosynthesis). C released through chemical weathering also, buried into ceust through subduction, can be released through volcanism... - For every fixed molecule of CO2, one O2 molecule released but only 700GT of C in atmosphere with 100k O, so NOT ALL CARBON in the BIOSPHERE - Burial/storage in peatlands (coal) and oceans (oil/gas)

Answer 2

Extraction and burning of fossil fuels - gas, oil, coal for industy, power stations, electricity etc. Extracting fossil fuels releases C from sediments to atmosphere Anthropogenic forcing disrupting naturally slow release in LT cycle, increasing by ~100x

Answer 3

Nitrogen = v. complex, many different oxidation states, N2 approx. 78% of atmosphere, not used by plants as easily as C is; a super stable, covalent triple bond which soil microorgs break down, key processes majorly impacted by fertilizers Phosphorus = fewer forms than N or C, mainly phosphate, essential for cell membranes, DNA, RNA, ATP, Slow Cycle (main input is weathering), part transportation by dust e.g. Saharan fertilizing the Amazon (Other key nutrients for life include potassium, sulphur, calcium, magnesium, iron etc.)

Answer 4

Sims: effective at recycling within terrestrial ecosystems, transport to oceans through rivers, LT burial in sediments, added to Earth by fertilizers Diffs: P cycle has no gaseous phase, main geological rock weathering input as opposed to biological N fixation

Answer 5

- Natural C fluxes being enhanced by anthro forcing, to which biosphere reacts, benefiting plants (better growth conditions, more photosynthesis) - Increased N, positive fertilization effect - Contemporary C cycle mitigating impacts at present (ocean and terrestrial storage sinks) - +ve feedback loop = CO2 increases, temp increases, speed of reactions increases, more respiration = more carbon - 1/3rd of C in marine sink, oceans more acidic, reduces their solubility, slowing sinks perhaps?

Answer 6

1. Population - growing, 7 billion in 2011, need food so large areas of land devoted to feeding us (36-40%!), nearly all NPP 'appropriated' for human use, about 1/4 PP of terrestrial biosphere used directly by human kind, loss of pristine land (83% not...), 50% NPP appropriation in Europe - HANPP, Krausmann et al. (2013) 2. Conversion of biomass - masses of land converted by 1980s, agricultrual land, degradation of soils etc. 3. Deforestation - agriculture, large-scale historical loss in Europe/N. America but still huge in the tropics. Since 1970, 1/5 Amazon degraded (700,000km2), discourses and tensions, some UK successful protection methods e.g. SSSI, Green Belt, ASI

Answer 7

1. Island biogeography - fragmentation inreases "islands", increasing extinction and dispersal rates 2. Ecology/extinction - key species depending on others, if lost = cascade of extinctions; 5 previous mass extinction events, 6th is coming? e.g. European Passenger Pigeon extinction of 4M by 19th century 3. Species invasion - habitat ecology changing for a range of reasons like invasive species whether intended or not e.g. 50% Arctic Skua British seabird pop decline as main diet has had to shift to risky pipefish after climate change induced sand eel decline 4. Climate Enveloping Modelling - models to track movement of climate envelopes and predictions of species migration as a result (minimal CC, high dispersal sees 9-13% species extinction by 2050, up to 52% for worst-case scenario) 5. Marine realm - CO2 higher than in last 700k yrs, increasing acidity, carbonates reduced, damaging corals, bleaching

Answer 8

1. Key cycles; N, P and C - excessive N input, acidifcation, acid rain (N oxides dissolve in rain), accumulation of toxic soil compounds, P and N change alters species competition 2. Eutrophication; warmer temp + nutrient abundance = algal bloom - N/P concentrations increasing in freshwater due to leaching of fertilizers (and increased runoff, soil compaction etc.), decomposition of dead plants consumes oxygen, animal species lost

Answer 9

Humans having massive impact on biodiversity - need for land increases resulting in further habitat loss, also climate change threats, altering characteristics and food chains, pollution etc. Solutions - agricultural forms (vertical indoor farms, high density compact cities = sustainable methods with minimal impacts on biodiversity) or initiatives and schemes e.g. UN REDD

Answer 10

Modelling: climate and biodiversity - Different models run with different scenarios and influencing factors e.g. carbon uptake by land surface, NPP increase e.g. IPCC - Difficulties with biodiversity modelling; too many species, so key indicator species targeted - Creation of Living Planet Index that measure trends in key marine, terrestrial and freshwater species - Creation of global maps to show predicted changes e.g. Hoffmann et al. (2010) showing extinction

Answer 11

GPP - Gross Primary Productivity (rate at which plants uptake CO2 & produce carbohydrates through photosynthesis = total photosynthetic flux) NPP - Net Primary Productivity (rate at which plants produce biomass) NEP - Net Ecosystem Productivity NBP - Net Biomass Productivity Autotroph - an organism self-dependent for food (plant) Heterotroph - cannot fix its own C, eats other food

Answer 12

``` NPP = GPP - Ra Rtotal = Ra + Rh NEP = GPP - Rtotal NBP = GPP - Rtotal - disturbance ``` Mg C ha-1 yr-1 = mega grams of carbon per hectare, per year (where Mg means 10^6)

Answer 13

1. DBH; Diameter Biomass at breast Height - forests, biomass about 50% C; cheap, easy 2. Harvest method - litter collected in mesh/plastic; a useful LT method and easy, cheap but neglects roots and uncertainty of upscaling 3. Chamber method - w/infra-red gas analysers placed on ground to measure C fluxes, a dark condition measures only respiration, a light open condition allowing photosynthesis; more sophisticated, detailed, different fluxes, but expensive and small-scale 4. Eddy Covariance Towers - automated, sonic anemometer, 3D wind speeds, large areas e.g. FLUXNET 5. Flask sampling - holding breath, walking into wind, the valve is opened e.g. Mauna Loa Co2 curve diagram data; old and outdated, less accurate but useful in areas with no access to high tech scientific equipment (lack of funding/unobtrusive approach required)