Lecture 10: Climate change impacts on terrestrial ecosystems Flashcards
IPCC synthesis report 2014
shows impacts CC has on worlds ecosystems
- more current
impacts of CC on ecosystems: migration
= polewards (north) migration of species 6.1km advance per decade i.e butterfly spp
impacts of CC on ecosystems: changes in time of biological events
changes in the timing of spring events
- 2.3 days earlier per decade
effects of CC on natural systems paper =
Parmesan & Yohe 2003
woody plant invasion into open ecosystems =
- shrubification
- 1987 - 2013 Alaska
- arctic greening
impacts of GC on the worlds ecosystems:
1) Drought-related fires in tropical forests
2) woody plant encroachment in savannas
3) forest dieback during hot droughts
4) resistance to CC in grasslands
Fires in tropical forests: droughts during El Nino events __ Tropical carbon sinks
WEAKEN
El Nino and La Nina
- -El Nino = warming seas every few years
- - La Nina = cooler sea temps
Fires in tropical forests: fires were __ in pre-industrial period
rare 1/2 per 1000 years
Fires in tropical forests: trees adaption
not adapted, so when do burn its detrimental
Fires in tropical forests: fires have increased because
- forest clearance for agriculture and timber
- peat drainage
fires in tropical forests: example –> 97-98 El Nino
- drought
- fires across 16 million ha of tropical forest in Southeast Asia & Latin America
- CO2 emissions = half global fossil-fuel emissions
fires are linked to ___ events
severe drought events
rainfall has become more ___ and ___ across the tropics
more seasonal and unpredictable
– amazonia experiencing intense wet & dry years
woody plant encroachment in savannas: What does this mean?
woody trees enter open canopies
- replacement of grass w trees/bushes
- common in South African savannas, happens across continents
woody plant encroachment in savannas: happens to a greater extent where?
in wetter places!
savanna tree density is controlled by
fire & herbivores
- – grow fast enough (tall) to avoid burning & eating
- trees grow tall, grass is outcompeted, shaded
- fires more important in wet (more rain, more grass, more fuel)
woody plant encroachment in savannas: is rising CO2 helping trees to escape fire?
- tree growth & root storage depend on atmospheric CO2
- CO2 fertilises CO2, grow faster and escape
- disturbance accounts for some trends also, not just CO2
woody plant encroachment in savannas: why do we care? Good CO2 sink?
- livelihoods in savannas
- pasture for grazing domestic animals (lose cattle)
- firewood harvesting + charcoal = POSITIVE
- charismatic animals bring tourism revenue
afforestation of grassy ecosystems with exotic trees can ___ carbon stock & water
- degrade underground carbon stocks
- compromise water resources (use up water, issue)
Forest dieback during hot droughts: probability of heatwaves ___ in some locations
doubled
– greater frequency of HW in Europe, Asia and Australia
Forest dieback during hot droughts: drought trend predictions
hard to predict
hot droughts=
atmospheric dries out
Forest dieback during hot droughts: greater vulnerability to drought in a hotter world =
1) droughts eventually will occur everywhere
2) warming produces hotter droughts
3) atmospheric moisture demand increases non-linearly w temperature
4) mortality can occur faster in hotter drought
resistance to climate change in grassland ecosystems: Buxton Climate Change Impacts Laboratory . What do they do?
BCCIL
- winter warming
- summer watering
- summer drought
since 1993 26 years
resistance to climate change in grassland ecosystems: BCCIL: CC impacts buffered by
1) functional diversity among species
2) functional diversity within species
resistance to climate change in grassland ecosystems: BCCIL: CC impacts buffered by: functional diversity AMONG species
- those that are taller, high photosynthesis and tough leaves respond strongly to winter warming
- resource-conservative species with high tissue construction costs respond better to summer drought
