Plant Responses to Climate Change

Question 1

What two climate impacts due to climate change will most likely impact plants?

Answer 1

• Global mean surface temperature projected to rise <3.1 °C by the end of the century
• Associated with changes in precipitation

Question 2

Rising temperature affects growth patterns in plants
How?

Answer 2

• Stalks become longer
• Leaves shrink
• Grow further away from other plants (plants become unsupported and unstable/breakages + weakness)
• Air composition may affect development of allergens and poisonous plants

Question 3

How has climate change led to changes in the flowering periods?

Answer 3

• Temp increases = flowering earlier in the season
• Reduced ability to withstand the entire season
• Decreased precipitation = flowering later in the seasons

Question 4

What is the suggested general trend concerning plant growing season and global warming

Answer 4

• Planet warms = longer growing season = more precipitation
• Vegetation has longer to consume water = soil drying
• Soil depleted of nutrients

Question 5

Why is it hard to predict with certainity the effects of climate change on plant growth?

Answer 5

• Some plants lacking neighbours maybe more affected
• Local adaptations of plants species
• Ecotype-specific responses to precipitation

Question 6

Why can changes in global temperature affect photosynthesis

Answer 6

• In most plants, photosynthetic capacity will be low under extreme hot and cold conditions and highests under intermediate conditions
• Due to changes in activity of photosynthetic components or enzymee/proteins will denature
• Sometimes if the changes are slow plants do somethimes have the ability to adapt (not-linear)

Question 7

Heat stress can affect what two things with plants?

Answer 7

• Carbon metabolism (photosynthesis, enzyme activity, chlorophyll content)
• Reproduction (flowering time, pollen viability, pollen tube growth, ovule number)
• Affect are age dependent though and can affect crop yeild!

Question 8

Plants are more sensitive to temperature changes during which time of day?

Answer 8

• Temperature changes at night time
• Due to increase respiration, resulting in a loss of carbon

Question 9

Why can the response to heat stress in plants vary?

Answer 9

• Dependent on location
• And different environmental signals
• Changes in phenology (earlier budding/flowers)
• Impact on pest, diseases and pollinators
• Urban-rural phenology (urban heat island effect)

Question 10

What two biological pathways does rubisco cataylse?

Answer 10

• Calvin cycle
• Photorespiration

Question 11

Why is there a balance between the two biological pathways with rising CO₂ and temperature?

Answer 11

Increased CO₂ = redcution in oxygenation reaction of Rubisco
BUT
Increased Temperature = increased oxygenation
(results in loss of fixed carbon)

Question 12

Why is the effect of precipitation increases due to anthropogenic global warming produce a non-linear response on plants?

Answer 12

• Dependent on plant age
• Geography and land relief
• Soil quality and features

Question 13

What is the tradeoff of gas exchange in plants?
How is this affected by high temp and low water supply in the soil?

Answer 13

During gas exchange at the stomata, water vapor is lost through transpiration
BUT under high temp and low water supply, the plant will close stomata to conserve water supply
This will result in less photosynthesis

Question 14

If the water balance coefficient is low (negative), what effect does this have on photosynthesis?

Answer 14

Photosynthesis is limited by water availability

Question 15

If the water balance coefficient is high (positive) what effect might this have on photosynthesis?

Answer 15

Photosynthesis may be limited by other climatic variables (not water)

Question 16

High latitudes have plentiful ….. but low …… and …….. which restricts photosynthesis

Answer 16

plentiful water but low light and temperature

Question 17

List some extreme weather events?

Answer 17

• Heat waves/cold snaps
• Heavy rainfall/floods/snowfall/hail storms
• High wind/tornados
• Drought
• Cyclones/hurricanes
• Storm surges

Question 18

How have humans affected extreme events?

Answer 18

70% (of 405) extreme events were made worse through human-caused climate change

Question 19

Why do humans exacerbated extreme weather events?

Answer 19

• Land use change
• Local biogeographical features (deforestation, overgrazing and continous cropping)

Question 20

What effect does the removal of vegetation have?

Answer 20

• Removal of vegetation increases rainwater runoff and the risk of mudslides
• Can lead to: soil erosion, land degradation, species loss, food shortage and mortality
• Can also impact weather patterns, strengthens sea breezes and brings rain clounds inland, resulting in more rainfall and flash floods

Question 21

CO₂ concentrations do not only control how many stomat are open and closed but also….

Answer 21

How many stomta a plant may have in total
(leaf temperature can also have a similar affect)

Question 22

What two global cycles can plants affect?

Answer 22

• The water cycle
• global energy cycle

Question 23

What is the difference between the natural water cycle and the urban water cycle?

Answer 23

• changing land use will also effect the water cycle
• Where rather than water being uptake by vegetation, it instead is removed through runoff
• (climate change predictions do not necessarily take account of land use either)

Question 24

How would a precipitation deficit affect global water cycles

Answer 24

• Would result in critical soil moisture deficits
• This would resultantly affect streamflow and groundwater deficits
• Knock on affects of soil moisture/surface water and groundwater storage
• As well as evaportranspiration

Question 25

In a future climate scenario, where rising CO₂ and soil water and runoff increase, how does this happen?

Answer 25

* High CO₂ results in more closed plant stomata * Results in decreased transpiration and hence increasing soil and water runoff

Question 26

In a future scenario, where there is high CO₂ and decreasing soil water and runoff, how does this occur?

Answer 26

* Longer and warmer growing season * AND CO₂ fertilisation increases ecosystem water demands, resulting in more stomata open * Therefore higher evapotranspiration

Question 27

The distance and the shape of tree rings can?

Answer 27

inform us about what the climate was like due the trees growing season

Question 28

Pollen can be used as a proxy for climate reconstruction How?

Answer 28

Because the patterns of vegetation which can be reconstructed from the pollen can inform us about the state of the climate

Question 29

How can plant fossils be used to reconstruct past CO₂ levels?

Answer 29

Through measuring the number of fossilised stomata on the plants, which will reflect the levels of past CO₂

Question 30

Climate and precipitation levels will affect

Answer 30

The global distribution of biomes

Question 31

What are some patterns in terms of geography which are expected to be seen with future global climate change?

Answer 31

* Increasing desertification * Large areas of uninhabitable land * Sea rise - loss of land including islands

Question 32

How does climate change lead to forest degradation?

Answer 32

* The forest through degradation, will lose its ability to generate its own rainfall thereby preventing the rainforest ecosystems * Rise in temp corresponds with a 10-20% reduction in rainfall * And an increase in forest fires

Question 33

How does removing forest affect temperatures?

Answer 33

* Removing forest results in a decrease in aldeo and hence higher temperatures?

Question 34

What is the major cause of deforestation?

Answer 34

Agriculture is the major cause of deforestation

Question 35

Who depends on rainforests?

Answer 35

* 1.2 billion people in the world rely on tropical rainforests for survival * Tropical rainforests are home to nearly 30 million species of plant and animals (2019 - 1m species face extinction)

Question 36

Agriculture is responsible for x% of greenhouse gas emissions?

Answer 36

13% - due to plant being carbon stores (whole food system 35% man-made GHG emissions)

Question 37

What agricultural activities contribute to GHG emissions?

Answer 37

* Land use changes (clearing) * Farmland management activities (Plowing fields/fertilisers) * fossil fuels from tractors/harvesters * Raising livestock

Question 38

What are some 'positives' seen from rising temperatures on agriculture?

Answer 38

* Increased length of growing season * Increased carbon dioxide = reduced photorespiration

Question 39

What are some negatives seen from rising temperatures on agriculture?

Answer 39

* Altered pests and diseases * Increased extreme weather events * More droughts and flooding

Question 40

What affect will climate change have on pests and dieases?

Answer 40

* Increase in temperature = migration of pest to N-latitudes * Rise in pest related damages * Insects are ectotherms - increasing temperature will mean they require more food * Many pests and diseases spread through wind or rain and changes in weather conditions will alter dispersion

Question 41

What is the difference between heat avoidance or tolerance

Answer 41

Avoidance: transpirational cooling, stomatal closure, leaf orientation, early maturation Tolerance: altered transcripts, free radical scavengers, alternation in membrane lipids, heat shock proteins, osmoprotectants

Question 42

Many adaptation in plants due to climate change can occur through changes in .............

Answer 42

Ecosystem services These can directly impact the response to climate change

Question 43

Conversion from pasture/grassland to agroforestry can affect soil organic carbon levels how?

Answer 43

Conversion from pasture/grassland to agroforestry can increase soil organic carbon content by 10%

Question 44

How do tree canopies of agroforestry affect evapotranspiration in soils

Answer 44

Tree canopies of agroforestry systems can reduce evaporation of soil water by 41% and transpiration by 32%

Question 45

Why might you add trees to a place which suffers from frequent extreme events

Answer 45

* Increasing tree density can help buffer against extreme events * Reduce surface runoff, and increased water-holding capacity reduces flood risk * Reduces landslide risk as land is more stabilised * Trees can serve as windbreaks