climate change 3 Flashcards
ecosystem process: photosynthesis; carbon sequestration; NPP FACE simulation experiments (19 cards)
quick fun respiration fact
respiration degrades energy rich compounds
productivity units
grams of biomass per year and hectare or
g C year-1 m-1
GPP
gross primary productivity
carbon fixed in photosynthesis
NPP
net primary productivity
GPP- plant respiration
net ecosystem productivity
NPP- heterotroph respiration (animals, decomposers)
npp is high in tropical rainforests and ocean
the effect of CO2 enrichment on C3 plants
CO2 is accumulating in the atmosphere faster than any other time in history
CO2 enrichment stimulates photosynthesis, therefore enhanced photosynthesis
high CO2 can lower long term photosynthesis due to low nutrients e.g. N
carbohydrate accumulation in leaves can repress genes for photosynthetic proteins
this feedback system maintains C:N ballance
the effect of CO2 enrichment on C3 plants: nitrogen limitation
during CO2 enrichment, the rate of N uptake from soils is not equal to photosynthesis and carbon sequestration
thus, C:N ratio increases and progressive nitrogen deficit (particularly in the leaves)
high C:N ratio also lowers soil and litter quality
study on effect of C enrichment on N
2014 study by Loladze
plant foods are increasingly carbon rich but lo in other nutrient’s e.g. K, N, P, Fe
another study shows plants have lower levels of protein
ecosystem processes which effect carbon and nitrogen stores
ecosystem carbon
carbon stocks (pools, resevoirs) amount of carbon at a particular time (or ecosystem component)
soil carbon
biomass carbon
flows (fluxes, rates) movement of carbon within or in and out of the ecosystem
NPP, GPP, NEP
time component
Eddy flux towers
monitoring system
monitor flows of water and carbon dioxide across ecosystems
found high in trees
carbon stock assesement
allometry: weighing mass of an organism or organism parts
forestry economics
provide important habitats and ecosystem services
an important oxygen source
a natural carbon sink
commercial timber products
area for recreation
forestry economics: timber
not just concerned with timber production, it also includes the environmental amenities provided
timber is a renewable resource
best time for timber to be harvested, to what degree timber production should be emphasised
multiple outputs, both positive and negative, from forestry externalities makes it distinctive from other renewable sources
free-air CO2 enrichment (FACE)
FACE facilities were developed across the world to grow plants in the field with controlled high CO2 levels under full open air conditions
used in agriculture fields to measure CO2
measures CO2 with a base rate of 505ppm because this is the simulated global climate conditions by the end of the century
can also change, temperature, add in gasses or change other conditions
studies from FACE shows crops grow better at high CO2, especially legumes
can result in deficiency and C4 plants don’t benefit much from high CO2
Key results from the first 6 years of elevated CO2 enrichment at BIFoR FACE
bellow ground
+40% increase in fine roots
+ 39% increase in root carbon exudation
+36% root nitrogen uptake
+20% faster nitrogen supply
not yet a nitrogen deficit but there are lower nutrients and protein in the plants
Key results from the first 6 years of elevated CO2 enrichment at BIFoR FACE above ground
+23% inc in CO2 uptake
increased leaf mass
+28 increase in trunk growth
+9.5% increase in litterfall
effect of climate change in Amazon
increased daytime maximum temperature and night time minimum temperature have grown - more variable conditions
heatwaves in the Amazon
Eddie flux tower in Brazil Amazon shows climate change
not all tree crowns are the same temperature, difference between species
some plant species regulate temperature by staying above air temperature
conclusions part 1
most plants grow better with elevated carbon dioxide but can cause limitations on other nutrients e.g. nitrogen
nature-based solutions to climate change require forests and grasslands assimilate extra carbon and store it in soils
however, plant seeds may become more nutrient poor especially in poor soils
conclusion part 2: tropical forests
tropical forest are experiencing unprecedented high-temperature conditions due to climate change that could limit photosynthesis
the trees in the hottest Amazonian forest site are already sensitive and experiencing temperatures too close to their high-temperature sensitivity threshold
