future forests Flashcards
(132 cards)
1
Q
LEC 1
Tree
A
prernnial plant with elongated stem (trunk) supporting branches and leaves
2
Q
LEC 1
Forest
A
: large area dominated by trees, offering biodiversity, ecosystem services, and climate regulation
3
Q
LEC 1
Deforestation
A
: Europe; 84% to 34% forest over last 2000 years (wood, beef, soy, palm oil (UN FAO)
4
Q
LEC 1
TREE RINGS:
A
made up of xylem, vascular cambium , phloem. Cells from cambium producing cells differentiate (cells pushed out to yxlem and phloem, can see this progression. Reflect seasonal growth patterns and environmental conditions
5
Q
LEC 1
XYLEM TRANSPORT:
A
water roots->leaves, has rings to prevent collapse (suction)
6
Q
LEC 1
How does water move up xylem?
1) ROOT PRESSSURE
A
osmotic pressure in roots forces water up xylem, caused by accumularion of solutes in the stele, role of casparian strip (lignified radial walls, sleeves of membrane in middle of root, can be substantial. GUTTATION – a consequence of root pressure, plants secrete water drops
7
Q
LEC 1
How does water move up xylem?
2) CAPILLARITY:
A
capillary tension, pressure (motor of transpiration)
8
Q
LEC 1
How does water move up xylem?
3) TRANSPIRATION
A
needs column of water that connects leaves to roots
9
Q
LEC 1
How does water move up xylem?
COHESION TENSION THEORY
A
- Evaporation 2. Capillary tension 3. Cohesion
10
Q
LEC 1
Water patterns change:
A
more CO2, how much water can they loose to take in more CO2, balance, photosynthesis and transpiration compromise
11
Q
LEC 1
TOO DRY?:
A
too much evapotranspiration; pressure much higher, column can snap, xylem cavitation stops transport (surface tension stronger than evaporation pull), no backflow into soil, some roots have cavitation fuses (loss of conductivity shows an increase in snapping of xylem vessels
12
Q
LEC 1
AT NIGHT
A
- At night, stomata shut, root pressure flushes out xylem, forces bubbles out, xylem functional again
13
Q
LEC 1
research shows cavitation is…
A
greater when conditions for transpiration are better (sallelo et al)
14
Q
LEC 1
Experiment to induce stress:
A
- Trees have different results, loss of conductivity varies between species
- Leads to different distribution of trees (smaller vessels can maintain integrity under low WP)
- Differences in xylem structure between gymnosperms and angiosperms affect vulnerability to cavitation and hydraulic conductivity (angiosperms appear to be more vulnerable to cavitation than gymnosperms NOT ABSOLUTE)
15
Q
LEC 1
PORES
A
: pores between adjacent vessels increase hydraulic conductivity
- Pores allow cavitation to spread through xylem, in gymnosperms valves prevent cavitation spreading through all xylem
- DIAGRAM
16
Q
LEC 2: CLIMATE CHANGE AND FOREST MORTALITY
CLIMATE CHANGE AND EXTREME EVENTS:
A
Greenhouse effect -> co2 increase from 320ppm in 60s to 420ppm now (our world in data)
2024 warmest year on record (our world in data) 1st year 1.5C above pre-industrial levels
17
Q
LEC 2: CLIMATE CHANGE AND FOREST MORTALITY
HIGHER TEMPS:
A
induces higher demand for evapotranspiration and enhance drought, intensity, duration and frequency of drought and heat stress events, increasing (2 months of drought per year n amazon)
18
Q
LEC 2: CLIMATE CHANGE AND FOREST MORTALITY
What drives forest mortality?
A
EXTREME WEATHER EVENTS DRIVR FOREST MORTALITY GLOBALLY (Hammond 2022)
19
Q
LEC 2: CLIMATE CHANGE AND FOREST MORTALITY
DROUGHT-INDUCED EMBOLISM:
A
key mechanism driving forest mortality
Water rootshoots via xylem (under -ve pressure). When drought stress increases tension in water column rises, molecules of water can break and create embolism, if embolism spread can lead to blockage and hydraulic failure.
20
Q
LEC 2: CLIMATE CHANGE AND FOREST MORTALITY
DROUGHT-INDUCED EMBOLISM:
- Zaccaro+Groover, 2019
A
inter-vessel and inter-tracheary pits allow lateral movement between cells
21
Q
LEC 2: CLIMATE CHANGE AND FOREST MORTALITY
DROUGHT-INDUCED EMBOLISM:
pit membrane
A
- PIT MEMBRANE: stops air from an embolised vessel from entering adjacent vessel, as water stress increases pressure inside vessels decreases (while embolised vessel remains at atmospheric pressure) difference in pressure between moth sides of pit membrane becomes large enough to force an air bubble through a pore embolism spreads
22
Q
LEC 2: CLIMATE CHANGE AND FOREST MORTALITY
DROUGHT-INDUCED EMBOLISM:
greater connectivity…
A
- Greater connectivity between vessel elements allows for rapid spread of embolism,
- VULNERABILITY CURVE; 80% of vessels embolised = point of no return
23
Q
LEC 2: CLIMATE CHANGE AND FOREST MORTALITY
DROUGHT VULNERABILITY:
species
A
Juniper very resistant; Pueraria very sensitive
24
Q
LEC 2: CLIMATE CHANGE AND FOREST MORTALITY
DROUGHT VULNERABILITY: assess hydraulic safety margins?
A
Can use WP50 measurements to assess hydraulic safety margins: BUG DIFFERENCE BETWEEN ANGIOSPERMS (lower hydraulic activity margin) AND GYMNOSPERMS
25
LEC 2: CLIMATE CHANGE AND FOREST MORTALITY
DROUGHT VULNERABILITY:
Nolan 2021 – AUSTRALIA
AUSTRALIA; new S wales, data can tell us how much stress a tree experienced at a time if death (thresholds), reveals water use strategies
26
LEC 2: CLIMATE CHANGE AND FOREST MORTALITY
STRATEGIES
stomata
: stomata close to preserve integrity of water column (stops photosynthesis and carbon assimilation) (pegureo-pina et al 2009)
27
LEC 2: CLIMATE CHANGE AND FOREST MORTALITY
STRATEGIES
Drought tolerance
tolerance to low WP, damage and has cell protection
28
LEC 2: CLIMATE CHANGE AND FOREST MORTALITY
STRATEGIES
Drought escape
vegetative dormancy, short lifespan
29
LEC 2: CLIMATE CHANGE AND FOREST MORTALITY
STRATEGIES
Drought avoidance
- Water spender: extensive root systems, high hydraulic conductivity, high gs. Max
- Water saver: small leaves, low hydraulic conductivity, low gs.max, low stomatal density, trichomes, waxes, rapid stomatal closure.
30
LEC 2: CLIMATE CHANGE AND FOREST MORTALITY
STRATEGIES
The diversity of these strategies is important for mixed forest ecosystems, it allows for positive interaction – resource partitioning = less competition and facilitation (e.g. hydraulic redistribution) (Grosslord 2018)
31
LEC 2: CLIMATE CHANGE AND FOREST MORTALITY
HEAT STRESS AND VPD:
Higher temps the vapour pressure deficit increases (atmospheric moisture demand increases).
32
LEC 2: CLIMATE CHANGE AND FOREST MORTALITY
VPD and temp increases globally with...
climate change, higher evaporative demand and heat stress for many forest ecosystems (Fang 2022). HEAT DOME (E.G. NW US 2021) large scale leaf scorching
33
LEC 2: CLIMATE CHANGE AND FOREST MORTALITY
LEAF THERMOREGULATION:
: canopies/leaf can regulate their temp via dissipation of 1)latent heat flux = transpiration; 2) sensible heat flux = air flow convection.
34
LEC 2: CLIMATE CHANGE AND FOREST MORTALITY
LEAF THERMOREGULATION:
Smiaj 2023
rates of transpiration varies within and between canopies, depends on level of exposure to environmental factors (humidity, air temp).
35
LEC 2: CLIMATE CHANGE AND FOREST MORTALITY
LEAF THERMOREGULATION:
Smiaj 2023
age
Age matters (young leads less protection + scorch faster).
36
LEC 2: CLIMATE CHANGE AND FOREST MORTALITY
LEAF THERMOREGULATION:
Smiaj 2023
soil moisture
When temp increases or soil moisture too extreme triggers stomatal closure and reduced evaporative cooling.
37
LEC 2: CLIMATE CHANGE AND FOREST MORTALITY
LEAF THERMOREGULATION:
Smiaj 2023
canopy architectural traits
Canopy architectural traits and forest characteristics play role in determining temp. since they affect temp regulation via convective heat exchange by directly influencing aerodynamics.
38
LEC 2: CLIMATE CHANGE AND FOREST MORTALITY
LEAF THERMOREGULATION:
stresses too intense?
If stresses too intense, canopy will surpass air temp, when leaf temp. reaches threshold, induces tissue death.
- Understanding leaf thermal thresholds could help with model prediction accuracy
39
Lec 5: PALAEONTOLOGY
The time domain
geological time divided into periods based on changes in characteristics in the rock record (oldest living tree dates back 45000 years)
40
Lec 5: PALAEONTOLOGY
How many times did trees evolve
relationships from living plants using molecular evidence shows >3 origins – 1) monilophytes (spore bearing, seed free plants ‘ferns’) 2) gymnosperms 3) angiosperms. BUT molecular evidence (DNA, RNA) not currently attainable from fossils > approx. 1 mil years old
41
Lec 5: PALAEONTOLOGY
EVIDENCE FROM FOSSIL RECORD
: first 130 million years of trees of tree evolution, multiple tree origins
42
Lec 5: PALAEONTOLOGY
EARLIEST FORESTS:
: fossil forests from SW England, NY USA, giant ferns, limited diversity (trees from a single genus with small species diversity), simple ecosystem, lasts 10Ma bedore other plant groups evolved trees (Davies 2023)
43
Lec 5: PALAEONTOLOGY
EARLIEST COMPLEX FOREST ECOSYSTEMS
carboniferous lowland equatorial forests (approx. 340-300Ma), ecologically diverse, extended over vast tracts of low and mid palaeo-latitudes for approx. 40Ma, massive carbon burial (coal resource), died out during regional warming and climatic drying at end of Carboniferous associated with the Pangeo super continent.
44
Lec 5: PALAEONTOLOGY
ATMOSPHERIC CONSEQUENCES OF EVO OF TREES
massive drop in co2, rise in O2 (terrestrialisation), middle Devonian evolution and spread of trees massive contributor. CO2 taken in to increase biomass through photosynthesis, high O2 supports animal respiration +wildfire (over 20%)
45
Lec 5: PALAEONTOLOGY
CONSEQUENCES OF EVO OF TREES
increased plant size requires increase root size and deeper penetration, greater water uptake, increased biological weathering (breaking down crystalline rock into mud), increased biomass into geosphere (carbon storage), reduced physical erosion (alego+scheckler 1998)
46
Lec 5: PALAEONTOLOGY
COEVOLUTION OF PLANTS AND SEDIMENTARY ENVIRONMENTS
decrease in coarse and increase in fine sediment (biological weathering); braided to meandering rivers (vegetation stages); increased carbon burial as coals and charcoal
47
Lec 5: PALAEONTOLOGY
plants have shaped...
TERRESTRIAL ECOSYSTEMS (davis + Gibling 2020)
48
Lec 5: PALAEONTOLOGY
EVOLUTION OF EARLIEST RAINFORESTS
(Wilson 2015): carboniferous medulloslaes seed fern medulosa, Tree 1-5m high, megaphyllous leaves, large seeds (11cm); biochemically models of transpiration rates on anatomically preserved fossils; physical properties of fossil tissues based on properties of water conducting cells + stomata efficient of living plants.
49
Lec 5: PALAEONTOLOGY
EARLIEST RAIN FORESTS
(Wilson 2015): water transport exceed living gymnosperms and many angiosperms; high evapotranspiration rate (increases humitidy, cloud cover+precipitation); modified environment to its living preferences and supports earliest rainforest during the paleozoic.
50
Lec 5: PALAEONTOLOGY
EVOLUTION OF UPLAND AND SEASONALLY DRY FORESTS
(DiMichele 2020): carboniferous (~330-350 Ma) evolution of gymnosperm dominated forest in upland, floras rarely preserved; dominated by conifers and cycads.
51
Lec 5: PALAEONTOLOGY
DEFINING UPLAND:
plants in upland setting more resistant to climate change
52
Lec 5: PALAEONTOLOGY
HYPERTHERMAL CLIMATES
sudden warming of planet on geological time scale (no robust definition), more in recent earth history.
53
Lec 5: PALAEONTOLOGY
HYPERTHERMAL CLIMATES
primary causes
: large igneous provinces, massive scale volcanism, massive release of GHGs, temporal correlation with mass extinctions (not all)
54
Lec 5: PALAEONTOLOGY
PERMIAN-TRIASSIC MASS EXTINCTION:
~252Ma, highest extinction+deforestation (reset >150mil years of terrestrialization) (Xu, Hilton in prog); mass loss of global biodiversity, stress gradual increase before catastrophic loss (well discussed in research) linked to increasing hot temp
55
Lec 5: PALAEONTOLOGY
PERMIAN-TRIASSIC MASS EXTINCTION
N. china
su, Tang, Hilton 2022) – ecological variation (lowland+wetland extinct), uplands (conifer+gymnosperm) dominated vegetation, costal systems conduits for recovery. VEGETATION COMES BACK V. DIFFERENT.
56
Lec 5: PALAEONTOLOGY
PERMIAN-TRIASSIC MASS EXTINCTION:
S. China
(Shu, Yu, Hilton in press) – extinction of lineages of trees (climax wetland Gigantopteris forest ecosystem), recovery >5Ma
57
Lec 5: PALAEONTOLOGY
PERMIAN-TRIASSIC MASS EXTINCTION:
OZONE ROLE IN PTME
(benca, 2018): experments show that increases in UVB=pollen malformation and sterility, high levels of malformalities at PTME interval, similarity, infers damage/loss of atmospheric ozone layer at +after PTME
58
Lec 5: PALAEONTOLOGY
PERMIAN-TRIASSIC MASS EXTINCTION:
EARTH SYSTEM MODELLING
(Xu, Hilton, in review): SCION model, early Triassic super-greenhouse climate driven by vegetation collapse (lethally hot temps caused by plant deforestation 65% productivity loss, terrestrial carbon burial loss, increase palaeo-CO2: trees and forests central to recovery of biomass (decrease pCO2, increase C storage), 10 mil years after PTMA started to get coal again
59
Lec 5: PALAEONTOLOGY
PERMIAN-TRIASSIC MASS EXTINCTION:
FOSTER 1998 quote
“INDEED THE EARTH IS RESPONDING IN SUCH A SIMILAR MANNAR TO ANTHROPOGENIC GHG EMISSION”
Biota can adapt, migrate or die when climate changes
Onset of current crisis much faster, at least x10 faster than any deep time hypothermal event.
60
Lec 6: EARTH MODEL SYSTEMS
Land carbon sink
most important carbon feedback cycle (coupling of carbon, water and nutrient cycling), environ stress may limit land carbon sink (eps. Mature forests)
61
Lec 6: EARTH MODEL SYSTEMS
risen in co2
driven by fossil fuel+land use change (9:1), EMISSION AVOIDED MORE IMPORTANT (Le Quere 2018)
62
Lec 6: EARTH MODEL SYSTEMS
uncertainities
Strong uncertain links between land C sink and climate and CO2. Land C sink 10x more uncertain over land than ocean (values ranging 0.2-1.4) – could close these uncertainties with FACE)
63
Lec 6: EARTH MODEL SYSTEMS
Terrestrial ecosystems have absorbed approximately...
32% of the anthropogenic emissions of carbon dioxide (CO2) since preindustrial time (he, 2014) other effects forests have – non-GHGs, albedo take into account
64
Lec 6: EARTH MODEL SYSTEMS
comprehensive simulation used to understand+predict how Earth’s climate and ecosystems respons to natural and human influences. Integrates physical, chemical, and biological processes across atmosphere, ocean, land and biosphere. Including feedbacks (carbon cycling, nutrient flow, vegetation dynamics).
65
Lec 6: EARTH MODEL SYSTEMS
essential for...
forecasting future climate scenarios, testing hypotheses, informing policy (esp. when direct measurement is not possible over large areas or future time periods.
66
Lec 6: EARTH MODEL SYSTEMS
simplification?
trying to capture all natural and industrial processes, have to make simplification, any lateral connection via freshwater movement through land
67
Lec 6: EARTH MODEL SYSTEMS
why do we need?
cant measure everywhere (allows for estimates where we are not measuring), cant measure future, estimate impact of change (adaptations), provide evidence for policy, understand which processes control climate (local/global), test new elements of our understanding of chemistry/physics
68
Lec 6: EARTH MODEL SYSTEMS
why do we need? - SURPLUS
- Helps us understand system; allows us to draw conclusions we could not otherwise draw. SURPLUS (McMullin 1967)
69
Lec 6: EARTH MODEL SYSTEMS
AI IMPACTS
rarely improves; models performing well for wrong reasons, overlooks problems of equifinality and parameter
70
Lec 6: EARTH MODEL SYSTEMS
MEASURMENT ENOUGH TO INFORM MODEL
red green amber assessment (Medlyn 2015), green (FACE allowed discrimination), amber (additional data needed to discriminate among model assumptions), red (FACE data missing or wrong)
71
Lec 6: EARTH MODEL SYSTEMS
BIFoR FACE
(MacKenzie 2020): whole ecosystem patches of N. temperate forests to CO2 +150ppm, built into existing forests, have to measure for a long time (complex system, play out)
72
Lec 6: EARTH MODEL SYSTEMS
BIFoR FACE
ELEVATED CO2 results in
increased photosynthetic rates, thicker leaves, more N resorption, enhanced root exudates that stimulate soil N recycling
73
Lec 6: EARTH MODEL SYSTEMS
BIFoR FACE
Mackenzie stats:
photosynthesis
20% more photosynthesis
74
Lec 6: EARTH MODEL SYSTEMS
BIFoR FACE
Mackenzie stats:
stomatal conductance
% lower stomatal conductance
75
Lec 6: EARTH MODEL SYSTEMS
BIFoR FACE
Mackenzie stats:
green leaves
20% thicker green leaves
76
Lec 6: EARTH MODEL SYSTEMS
BIFoR FACE
Mackenzie stats:
Nitrogen
15% more N reabsorbed
77
Lec 6: EARTH MODEL SYSTEMS
BIFoR FACE
Mackenzie stats:
exudate
40% more exudate from roots
78
Lec 6: EARTH MODEL SYSTEMS
BIFoR FACE
FOREST PRODUCIVITY AND CARBON CAPTURE
(norby 2024): increased under eCO2, variability due to biotic (insect outbreaks) and abiotic (heat, drought) stressors, limits predictability
79
Lec 6: EARTH MODEL SYSTEMS
BIFoR FACE
FOREST PRODUCIVITY AND CARBON CAPTURE
stats
Pollen mineral mismatch (Filipiak 2024), 33% less protein in acorns (Foyer 2015), seedlings bigger but more susceptible to powdery mildew (mayorai 2023) effecting subsequent generations
80
Lec 6: EARTH MODEL SYSTEMS
BIFoR FACE
FOREST PRODUCIVITY AND CARBON CAPTURE
elevated productivity depends on...
- Long term sustainability of elevated productivity depnds on continued nutrient avaliabilty (eps N).
81
Lec 6: EARTH MODEL SYSTEMS
BIFoR FACE
half time results
20% increase in C flowing into forest (6yrs), 10% increase in dry matter (wood), thicker+denser leaves (N-poor litter), faster more efficient recycling of N to sustain growth, interannual variability (long term steady state?)
82
Lec 6: EARTH MODEL SYSTEMS
TOTAL FOREST IMPACT ON CLIMATE =
TREE CARBON + SOIL CARBON + METHANE + ALBEDO
83
Lec 6: EARTH MODEL SYSTEMS
BIFoR more to do?
include eating and rotting (NPPNEP), tie togther C, N, P and H2O, interannual variability (e.g. NAO), biotic stresses (e.g. mildew, AOD), 7yrs15yrs (acute vs chronic)
84
lec 4: TREES UNDER DROUGHT
tree metabolism
photo synthesis
respiration
water +nutrient transport
defence
85
lec 4: TREES UNDER DROUGHT
tree metabolism
- secondary metabolites
hormones
vitamins
alkaliods
lignans
85
lec 4: TREES UNDER DROUGHT
tree metabolism
- primary metabolites
carbs
lipids
proteins
nucleic acids
86
lec 4: TREES UNDER DROUGHT
drought as stress
period of water stress
(frequency, intensity, soil retention capacity, previous water stress)
87
lec 4: TREES UNDER DROUGHT
drought as stress
2 contrasting strategies
dying from thirst (desiccation)
- hydraulic failure
dying from famine (starvation)
- carbon starvation
88
lec 4: TREES UNDER DROUGHT
drought as stress
other strategies
deep root systems (LT)
hybrid strategies
89
lec 4: TREES UNDER DROUGHT
effects of drought
photosynthesis reduced to save water
growth/reproduction reduced or stopped to save energy
respiration; trying to maintain basal levels for defence
water/nutrition; trying to work
defense; hormones (ABA), calcium signalling, osmoregulators, antioxidants (redox activity), waxes
90
lec 4: TREES UNDER DROUGHT
water perception and pathway signalling
ABA
Abscisic acid
drought response hormone that regulates stomatal closure and gene expression
91
lec 4: TREES UNDER DROUGHT
water perception and pathway signalling
ROS
reactive oxygen species
secondary messenger in drought stress signalling but can also cause oxidative stress is not controlled
92
lec 4: TREES UNDER DROUGHT
water perception and pathway signalling
Ca2+
calcium ions
act as intracellular messengers activating stress response genes
93
lec 4: TREES UNDER DROUGHT
response to drought:
physiology
osmotic adjustment, retain water on cell (osmoregulators)
root growth, gather water
leaf adaptations, reduce water loses, stomata closure, waxy thick leaves
94
lec 4: TREES UNDER DROUGHT
response to drought:
biochem
ABA-mediated stomata closure
- ABA binds to receptors in guard cells -> ion efflux -> closure
osmolyte regulation
cuticular wax and suberin deposition
lignin deposition
aquaporins regulation
95
lec 4: TREES UNDER DROUGHT
consequences of drought
- water shortage on cells
biochemical pathways compromised
Rubisco and TCA cycle
96
lec 4: TREES UNDER DROUGHT
Consequences of drought
- redox activity
redox activity increases
toxic for plant cells = cell death
damage of cell structures
difficult to revive once accumulated
damage to protein damage in DNA
97
lec 4: TREES UNDER DROUGHT
protection against oxidative damage
ROS detoxifiers
superoxide dismutase (SOD)
catalase (CAT)
peroxidases (POD)
98
lec 4: TREES UNDER DROUGHT
protection against oxidative damage
natural antioxidants
flavonoids and phenolic compounds to capture -OH groups
99
lec 4: TREES UNDER DROUGHT
protection against oxidative damage
protein protectors/stabalisers
heat shock proteins (HSPs) to prevent denaturation, the loss of functionality
100
lec 4: TREES UNDER DROUGHT
molecular adaptations
drought stress triggers extensive changes in gene expression
101
lec 4: TREES UNDER DROUGHT
molecular adaptations
activate drought tolerant genes
by dehydration responsive element binding (DREB) TFs
102
lec 4: TREES UNDER DROUGHT
molecular adaptations
protect cellular structures from desiccation
using late embryogenesis abundant (LEA) proteins
103
lec 4: TREES UNDER DROUGHT
molecular adaptations
epigenetic modifications
DNA methylation and histone modifications regulate long-term drought responses
104
lec 4: TREES UNDER DROUGHT
long term effects and ecological implications
lower tree vitality, increaes susceptibilty to pests/pathogens
forest dieback directly or indirectly related to drought
increased vulnerability to wildfires (waxes and resins)
reduced biodiversity (only resistant/tolerant)
reduced carbon sequestration and climate change exacerbation
105
lec 4: TREES UNDER DROUGHT
Future direction of bimolecular studies
Genetic modification for drought tolerance
CRISPR-based editing to enhance drought resistance genes
106
lec 4: TREES UNDER DROUGHT
Future direction of bimolecular studies
forest management strategies
selecting tree species with natural drought resilience for reforestation projects
107
lec 4: TREES UNDER DROUGHT
Future direction of bimolecular studies
climate change adaptations
understanding long term drough effects on tree epigenetics and stress memory
108
lec 4: TREES UNDER DROUGHT
Future direction of bimolecular studies
biotechnology applications
developing bioengineered solutions such as drought resistant rootstocks for agricultural and forestry use
109
lec 4: LECTURERS RESEARCH
young seedling tolerance
seedling stages specially at germination points are extremely susceptible to stress
proteome and transcription profiling
redox activity tested
LEA, HSP, and catalse levels were highly impacted
110
lec 4: LECTURERS RESEARCH
maternal inheritance and transgeneration tolerance
intra and inter specific study
experiment will well irrigated verus drought to test off spring drought tolerance
physiological and proteomic analysis conducted on seedlings during drought
metabolic analysis and NIRS on acorns
111
lec 4: LECTURERS RESEARCH
epigenetic changes between dry and wet locations
global changes no discriminant, implies more massive genetic differences
some patterns associated to provenances differences
112
lec 4: LECTURERS RESEARCH
plants vaccine and induced resistance
Looking at defence mechanisms, there are alternatives to boost natural resistance
plant compounds can trigger mechanisms to react faster and stronger by priming of defense
hormone ABA and no-proteic amino acids can increase drough resistance, reducing mortality rates
113
lec 3: APPLICATION OF STABLE ISOTOPES IN TREE RINGS
hockey stick graphs
(mann + bradely 1999)
based on huge data sets of trees
scientistics showed impacts of climate change of trees
often with trees not large amount of data (tropics high diversity and difficult to get replication)
114
lec 3: APPLICATION OF STABLE ISOTOPES IN TREE RINGS
Adv of using stable isotopes
more direct assessments of plant biochem and ecophysiology
more direct assessment of past climate variability (hydrological studies)
require less replication, esp. useful for remote or igh diversity ecosystems
115
lec 3: APPLICATION OF STABLE ISOTOPES IN TREE RINGS
basic concepts in stable isotope science
(aston 1921 mass spec methods)
atoms with same proton but different mass no. which do not decay and dont emit any radiation (different rates of reaction)
isotopic ratio = i heavy / i light
116
lec 3: APPLICATION OF STABLE ISOTOPES IN TREE RINGS
basic concepts in stable isotope science
isotopic discrimination
used for biochem reaction involving enzymes (photosynthesis)
how much difference in delta following a series of reactions
only used when fractionation unknown
117
lec 3: APPLICATION OF STABLE ISOTOPES IN TREE RINGS
basic concepts in stable isotope science
fractionation factor
empirically derived and used to predict how much fractionation can be expected in a specific reaction (e.g.liquid vapour interface)
equilibrium: more even
kinetic: to one side (important in e.g. wind removing water vapour)
118
lec 3: APPLICATION OF STABLE ISOTOPES IN TREE RINGS
CRITICAL ISSUE: co2 fertilisation effects on plant water use efficiency and consequences for hydrological cycle
STOMATA
specialised leaf structures that allow stomata to close in response to co2, solar radiation, hyrdrological stress
increased co2 allows stomata to close for longer,
longer stomata closure reduces evaportranspiration leading to increased intrinsic water use efficiency (iWUE)
increased iWUE leads to elevated 13C in plant tissue (tree rings)
119
lec 3: APPLICATION OF STABLE ISOTOPES IN TREE RINGS
CRITICAL ISSUE: co2 fertilisation effects on plant water use efficiency and consequences for hydrological cycle
iWUE
iWUE = assimilation / stomatal conductance
increasing iWUE measured through carbon isotopes in tree rings across globe
benefits: possibly increase carbon assimilation
negatives: possibly reducing rainfall recycling
120
lec 3: APPLICATION OF STABLE ISOTOPES IN TREE RINGS
uncertainties:
response by vary...
with climate conditions (adams 2019)
121
lec 3: APPLICATION OF STABLE ISOTOPES IN TREE RINGS
uncertainties:
response may not be...
that strong in humid conditions where rainfall recycling is more important
122
lec 3: APPLICATION OF STABLE ISOTOPES IN TREE RINGS
uncertainties:
current measurments for very...
few species considering the high diversity in tropics (~40 species)
(Van der sleen 2015)
123
lec 3: APPLICATION OF STABLE ISOTOPES IN TREE RINGS
uncertainties:
many uncertainities regarding...
differences between various species functional types (Van der sleen 2015)
124
lec 3: APPLICATION OF STABLE ISOTOPES IN TREE RINGS
uncertainties:
real magintude of responses still...
highly inaccurate due to unaccounted for ontogeny effects (Brienen 2017)
125
lec 3: APPLICATION OF STABLE ISOTOPES IN TREE RINGS
uncertainties:
effects of co2 conc and temp on...
leaf (mesophyll) tissue conductance to co2 (Busch 2020)
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how we get to isotopes
tree ring sampling and preparation for isotope analysis
cellulose samplers
elements analyser
isotope mass spectrometer
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additional applications
1) identifying protein responses in...
water uptake by tree species
oxygen isotopes in water used by trees indicated depth of water uptake from soil
(Schwendenmann et al. 2010).
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additional applications
2) placing present climate change into historical perspective
for climate change research
Climatic information in oxygen isotopes from rain water
- Condensation temperature in the tropics
- Humidity and large-scale rainfall amounts in
the tropics
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summary
stable isotopes offer...
efficient methods of using trees rings as recorder of plant physiology and environmental variability
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lec 3: APPLICATION OF STABLE ISOTOPES IN TREE RINGS
summary
carbon isotopes in trees rings have been...
central in research in assessing effectos of CO2 on tree physiology and associated forest feedback in the land atmosphere interface
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lec 3: APPLICATION OF STABLE ISOTOPES IN TREE RINGS
summary
oxygen isotpoes offer...
additional routes for exploring past climate in remote regions where there is a lack of climate information or for plaeoclimate reconstructions
