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BIOB50 - LEC 4 - JAN 17 - DONE.docx

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Marc Cadotte

BIOB50 – LEC 4 Species Ranges:  Envi determines species  We know what species are there  When species appear outside of its range – we’re very interested Eg. Grey Owl - Normally extends to northern but also in southern Ontario (1x) Eg. Arctic Bird - Willow tarmagan bird  Ecology is derived from energy = currency by which org interact  Whether they are competing for resources  Predator prey organisms (consuming another)  Parasites – steal nrg It’s all about energy  Most organisms its from sunlight  Earth is bomboarded with energy – but small proportion ends up in biomass of plants (1%)  And into herbivores – a small amt of biomass - (10%) then to others and others  Energy is important b/c quickly drops off to amt of total energy available  If nrg transfer efficient – should see plant grows leaves it’s eaten right away  Nrg is limited especially for top predator – so how they find nrg is important to their survival  Also why we don’t see top top top predators (min nrg available to sustain population) Sources of Energy  Autotrophs – either thru photo or chem.  Mainly from photo however  Take c02 and water and turning into sugar 02 Figure 19.3 – G. Tansley 1935  Fixed by autotrophs into chem. Nrg avail to other org  1935 – 1st time to view a system this way : pond  all the mutual interactions are possible b/c of input of solar radiation  arrows being energy flow (going in 1 direction)  interconnected species b/c of flow of energy Primary Production  nrg rep by carbon is currency to measure productivity  movement of carbon is our energy currency BIOB50 – LEC 4  measure amt of carbon moved to sys by measuring primary productivity ( how much carbon are autotrophs fixing to turn into biomass - is made into sugar) – think as the GDP of economy – how much resource available  GPP – total C fixed by autotroph in ecosystem  Depends on climate (rainfall, moisture, temp) as well as LAI – how much ground is covered by leaves? LAI  Varies among biomes – Arctic - 0.1 – only 10% covered by leaves (10% of area is photosyn)  12 in boreal – 12 layers of 100% leaf cover  LAI = 1 means that 100% of ground is covered by leaves  Another layer on top of that making larger than 1  Benefit of multiple layers – single layer can’t capture all solar radiation Diminishing returns  additional layers can capture more energy – but not as equally efficient  Layer 15 (top layer) – moving thru day getting to…  going to mid day – uptake of C is high = 1.2 g/m2/hour  down to leaf layer 1 – only taking a small amt of C at that same time  top layers are beneficial more than bottom layers  can calculate things like:  how much leaves respire ? – what is optimal leaf layers to have?  At some point these lower layers will respire more than c02 they take up – net waste  What is net c02 uptake by diff leaf layers – the yellow line is the graph – linear inc w/ layer inc – more layers – more net c02 uptake Prim prod  How much c02 taken up by plants?  NPP = GPP(total C taken up by plants) – respiration (plants need to grow and reproduce too)  What is nrg left over for storage in biomass? – storage of C  At night plants don’t photosyn – but produce c02 as they respire  Storage is the one available for all the other organisms Remote sensing of terrestrial NPP (how to measure?)  Hi rates in warm regions  Low rates in cold regions Prim Production  Conceptually, we mean the whole plants. BIOB50 – LEC 4  What happens below ground? – hard to measure C stored below ground  Also – roots live and die fast – turnover quickly- always giving fraction of NPP below ground  may also release C into soil – transferring C  microorganisms below ground are getting fed as well Minirhizotrons – scanner in soil to estimate how much C being stored below ground – important for some habitat Figure 19.5 - % of plants net primary productivity  What is % of plants NPP is allocated below ground - Almost 70% of NPP is below ground for grasslands  Vast grassland – you just see 30% of plant biomass – 70% is underground Prim prod – measuring  Harvest plant – cut and weigh C – but impractical for large diverse ecosystem (but good for smaller scale)  Solution: measure chlorophyll concentration  Using satellite imaging  Take pictures w/ diff filters – 2 aspects interested in is  Visible light (seen with eye)  And near infrared light radiance  Calculate the NDVI NDVI – more absorption/more chlorophyll – more NDVI  Healthy tree – photosynthesizing – very little visble light is reflected around 8%only 8 % is being reflected – lot of visible light is absorbed into plantation (lots of chrylophyll)  Vs autumn – not photosyn anymore – more visib
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