Impact of Climate Change

Question 1

Are the impacts of climate change difficult to predict?

Answer 1

YES…

1. Could be catastrophic ‘unlivable earth’
2. Even reduced scenarios involve major changes.
3. Increased temps.
4. Increase storm intensity and frequency.
5. More intense droughts followed by intense rainfall.

Increased pressure of water resources.

Plant selection will need to take account of all extremes.

Emerging pest and disease threats and these will move into traditionally cooler areas as they warm.

Increased fire danger.

Question 2

How is climate change damaging for hort.?

Answer 2

Heavy rains (soil erosion)

Extreme heat/drought soil cracked and soil erosion from wind.

Question 3

How do trees help with climate change?

Answer 3

1. Canopy (shade)
2. Transpiration cools atmosphere.
3. Carbon sequestration.
4. Soil protected
5. Deciduous trees better in fire as more moisture in leaves.
6. Changes in phenology. Plants are blooming earlier.

Platanus species (London Plane Tree) for urban landscapes.

Question 4

Why to not use cultivars?

Answer 4

As pests and disease move they will affect plants. Use diverse varieties of trees rather than cultivar so some will adapt and not get diseasee.

DUTCH ELM
ASH

Question 5

Define phenology

Answer 5

the study of cyclic and seasonal natural phenomena, especially in relation to climate and plant and animal life.

WHEN FLOWERS BLOOM ETC.

Question 6

What is the issue with plants flowering earlier?

Answer 6

As plants bloom earlier, insects may be out of sync which will prevent pollination.

Question 7

Issues with plant selection

Answer 7

1. Survive drought.
2. Survive higher temps and solar radiation. (may be okay in sun now but no so in the future).
3. Temp extremes - plants need to survive colder temps too.
4. Plants need to survive extreme rainfall.
5. Some plants still need watering even when drought tolerant.

Question 8

DRought tolerant vs. low water demand.

Answer 8

1. Don’t always match up - plants can be tolerant but need watering.

Question 9

How to determine what plants?

Answer 9

Look at provenance - where does it come from?

Is it resilient in that climate?

Does that plant survive high temps in summer, low temps in winter and periodic drought.

Central Asia good place to look.

EX: Salvia yangii (able to cope with climate extremes).

Question 10

Issue with invasive species

Answer 10

As temps warm plants that have been OK in the UK may become invasive.

Ex:

Pampas grass and Mimosa (Cortaderia
selloana and Acacia dealbata

Question 11

What causes Cortaderia and Acacia to possibly become invasive?

Answer 11

Most invasive plant problems are not about invading good quality native abitats such as woodland, they’re about disturbed habitats where there has been human impact

understanding of how invasive plants relate to different habitats will be an important
part of future landscape planning. For anybody with a responsibility for land, this
awareness in the future of helping reate strong plant communities that will be resistant to
invasives will be very important.

Question 12

What is the impact of fire?

Answer 12

Woodlands
will recover well from one fire, but not from a second one.

Diff plants have diff vulnerabilities.

EX: Conifers are far
more fire prone than deciduous trees.

Think firewise info…

Question 13

HOw has threat of fire changed?

Answer 13

1. Increasing threat to areas not previously affected.
2. Now a wide range of susceptibility of plants.
3. Conifers worse than deciduous.
4. Proximity of vulnerable plants to buildings.

Question 14

How does climate change affect pests/diseases?

Answer 14

As it gets warmer, pests will migrate to new areas.

Question 15

how to mitigate pests/diseases?

Answer 15

t increased phytosanitary controls at borders will
help. So many of the pests and disease problems that have afflicted particularly tree
species over the last few years can be put down to imported plants or imported plant
products.

Genetic diversity (not cultivars)

ex: Ash dieback and Dutch Elm.

e diversity, there’s a small percentage of ash
trees that seems to be completely invulnerable. They will produce the seed that will allow a
future disease resistant population to develop.

Question 16

What are the implications for planting?

Answer 16

Multiplicity of impacts.

1. GENETIC DIVERSITY (Urban, don’t plant just cultivars.
2. RESILIENCE. plants that can cope with many different extremes.
3. WATER USE. Sustainable is important. Use water butts, green roof, rain gardens etc to conserve water.

palm trees, hibiscus, lavender, grapes and hardy succulents, corn and squash.

gravel garden with plants won’t need as much water.

Question 17

What are the basic things to remember for climate change and hort.

Answer 17

Need to understand range of impacts.

Choose plants for resilience.

Sustainable use of water.

Planting for climate change mitigation (carbon sequestration)

Monitoring new pests, diseases and invasive species.

Question 18

Why are plants so important?

Answer 18

1. More plants, more sequestration.
2. More effectively cool down and shade urban areas.
3. Transpiration cools atmosphere; Trees shade us;

Question 19

What is climate change?

Answer 19

Climate is warming at unprecedented rate because of human activity.

1. Addition of C02 thru fossil fuel burning, which acts as greenhouse gas trapping heat.

Methane from agricultural geared to intensive meat production.

Heat absorbing surfaces such as building and roads.

High altitudes and latitudes are warming more than others.

Prolonged droughts, increased flooding and more extreme weather.

Sea level rising.

Climates changing more rapidly than species can adapt and high risk of extinctions in biodiversity as planet warms.

Question 20

Issues with population and climate change?

Answer 20

Massive population shifts.

Natural habitats forced to live on more marginal land.

Question 21

How will climate change affect plants?

Answer 21

Increased C02 not a problem as will encourage faster growth, however, may be short term BUT limited factors: Drought.

Physical changes may occur in plants: less stomata which impacts growth process and productivity.

Less water flow, less transpiration therefore less cooling impact which limits growth. This will leave more water in the soil which could cause more flooding.

Inc. temp increased growth but limiting factors photosynthetic efficiency declines at a certain point, plants are damaged by heat and solar radiation to the point of dying.

Inc. temps cause resp rates to increase relative to photosynthesis, resulting in no net gain in production of biomass. Plants effectively could then ‘starve’. IF temp increases too much, faster respiration may also tip the balance towards plants becoming a C02 source!

EX: 2003 Europe high temps reduce plant growth by 30%.

Plant events such as buds opening, leaf fall and flowering times are changing. 2.5 days per decade in spring and 2 days delay in autumn.

increased temperatures may slow down dormancy – autumn leaf displays might become duller, but crucially many herbaceous species may not experience cold enough temperatures to trigger dormancy, or they may be triggered into growth early and then suffer a setback with a frost.

Species which need cold to initiate flower bud formation may not be able to do so. A good example is with blackcurrants, which need consistent cold temperatures. steep decline in blackcurrant harvests, fruit quality and juice yields and two traditional varieties are expected to die out within 10 years due to climate change.

Different cultivars of apple require different amounts of cold in winter to
produce to initiate flower buds – so milder winters will change the
geographical range for successful cropping of some traditional apple
cultivars

Question 22

HOw does water stress affect plants?

Answer 22

plants will limit leaf production and leaf
surface area In order to reduce water loss or and/or close its stomata.

decreases the ability of the plant to carry out photosynthesis, with
clear implications for growth and carbon storage, and in extreme cases
normal functioning is impeded so much that death occurs.

short-lived plants like annuals becoming even more short-lived
as they flower and set seed more quickly, greater susceptibility to pests and greater proportion of biomass developed in the roots in order to search for
water

Torrential rainfall increases the risk of flooding or periods of waterlogging.

Question 23

How will high humidity affect plants?

Answer 23

Prolonged periods of high humidity can reduce a plant’s ability to transpire, and there affect the ability of the plant to pull nutrients out of the soil.

Humidity will increase susceptibility to fungal problems.

Question 24

Will climate change affect pests and disease and how?

Answer 24

range of species of both plants and animals becomes more extensive the warmer the climate.

pests/disease and weeds will increase and will have more time to have multiple breeding per year.

Drought will increase plant stress making them more susceptible to fungal and bacterila pathogens.

Question 25

How will climate affect invasive species?

Answer 25

become invasive when they are introduced to ecosystems where they are not native and where there are no predators or diseases which limit their spread or where they have an unfair advantage over local flora

climate warms see more plant species that so far
have been ‘tame’ garden and landscape plants become problematic.

EX: Cortaderia selloana (Pampass grass) and Acacia dealbata both spread so extensively
that they can suppress native species over large areas and form impenetrable vegetation.

Eucalyptus globulus devastating fire potential as well as being an aggressive seeder

Question 26

How will ecosystems be affected?

Answer 26

impact different species differently. If key species are negatively impacted by
stress, their productivity will fall, and therefore their contribution to the
energy balance of the entire system

We depend on natural and semi-natural
ecosystems for many different things: food (as in grazing for livestock), and
‘environmental services): production of oxygen, clearing the air of pollutants, managing the flow of water, etc. Natural ecosystems also make up much of the environment that we enjoy as ‘nature’ and for recreation.

Increased fire risk from drought massive probs for ecosystems. Affects humanity, buildings, wildlife and healthy ecosystem and survival of species.

Question 27

Future invasive plants for britain.

Answer 27

Mimosa, Acacia dealbata, is a serious long-term threat in Britain, It almost totally
annihilates other vegetation.

Question 28

Issues with fire and the ecosystem?

Answer 28

burnt landscapes have a greatly reduced range of species and one skewed
towards the inflammable, such as broom species, Genista and Cytisus spp.

Some species, deciduous hardwoods especially, are
relatively fire-proof; others are practically explosive, such as Eucalyptus spp,
and restios.

short-lived species like yellow-flowered broom (Cytisus sp.), which burn readily but then regenerate rapidly from seed. Major invasive issues.

Question 29

What damage has been done to soil?

Answer 29

1. Agricultural clearing releases high volume of C02.
2. Methane from cows produces greehouse gas.
3. as organic matter
   levels decline, so does soil fertility.
4. , as organic matter
   levels decline, so does soil fertility.

Question 30

Climate Projections:

Answer 30

Global surface temps is projected to continue to rise.

Rate of increase dependent on extent to which C02 and other emissions are restricted.

Yearly variability in rainfall.

Increase in dry spells (most pronounced in So. UK) and esp. over summer months.

Frequency of wet days increase over winter, most pronounced in Northern. UK.

Gardens close to coast or near estuaries may experience more flooding due to tidal surges.

Gardens located upstream will experience an increase in flooding due to more intense and frequent fluvial flooding events.

It is theoretical that in the future, much of the UK could be frost free in some years.

Question 31

Example of plants/gardens to minimize irrigation?

Answer 31

Jo Wakelin garden and Filippi
tends to rely on low growing sub =-shrubs.
Adv: evergreen and look good in winter.
DisAdv: Flowering season may be short.

Question 32

Selecting garden plants for climate resilience and climate change mitigation

Answer 32

1. Look to plants from regions that have experienced extremes: Central Asia.
2. Look at prevenance: where does the plant material we have in cultivation come from?
3. Species with wide ranges will very often have genetically distinct populations, with diff. environmental tolerances. NOT cultivar.

Question 33

How to adapt?

Answer 33

Although frosts may be less prevalent, many borderline hardy plants on heavier soils may die in wet winters. The aim of planting in future may be to have a backbone of ‘resilient’
shrubs which can survive wetter winters and still cope with dry periods in summer.

Mediterranean climate plants such as Lavandula, Cistus and Ceanothus species, which can
tolerate high temperatures and long periods of drought. However many of these are naturally short-lived and some are highly flammable.

Question 34

Best examploe of the ‘perfect’ plant for climate change?

Answer 34

strawberry tree (Arbutus unedo), evergreen, attractive, drought-tolerant, not particularly flammable and capable of rapid regeneration from the base if damaged or burnt.

Question 35

How does this affect garden and landscape design?

Answer 35

cope with torrential rain. Slopes may need to be terraced for soil retention and the reduction of soil erosion. Swales and rain gardens will need to be integratedinto landscapes.

Question 36

How to cope with wind storms?

Answer 36

The trend to smaller and more compact forms of tree - or tree-like shrubs such as standard Photinia x fraseri and Elaeagnus x submacrophylla, which suit the scale of smaller domestic gardens - can only increase

Lg shrubs with good wind resistance: Amelanchier x grandiflora ‘Robin Hill‘ and Cotinus coggygria ‘Royal Purple’ can be used for garden impact in place of larger trees.

Question 37

How to manage water?

Answer 37

heavy rain will increase the likelihood of flooding
from hard landscaped areas, so planting up rain gardens and swales with plants which can tolerate both waterlogging and dry conditions will be helpful. Plants recommended for this will be tough like Iris pseudacorus and Cornus sanguinea and Sambucus nigra cultivars.

Woody plants help manage water: roots take up a large volume of water from the soil, and their canopies intercepts heavy rainstorms allowing the water to filter through the leaves gradually rather than run off from a hard surface. In cities plantings of robust street trees such as Ginkgo
biloba and Zelkova serrata help to manage runoff - small leaves are more effective at the interception of rainfall.

Green roofs with a good depth of substrate (10cms min.) will help to mitigate the impact of periods of heavy rainfall in urban areas.

Question 38

How are the changes in flowering time and seasons impacting insect and bird species?

Answer 38

some insect or bird species have evolved to use specific species as a source of food at one stage in their lives.

flowers that produce pollen at the period at which the hive begins to be active, so if the flowering period starts earlier, this may initially look positive for the bee (more food) but there may be less later on in the season.

birds may depend on a plentiful supply of caterpillars to feed its young but if the trees come into leaf earlier, the breeding cycle of the bird and caterpillar supply may no longer be synchronized.

Question 39

What about currrent planting styles?

Answer 39

Use of bedding plants in decline.

Removal of lawns or accept green in witner/brown summer.

Drought tolerant grass varieties can help, somewhat.

Historic gardens may need to adapt original plantings which can no longer be maintained at the high standard for more drought tolerant species.

Trending already from tradtitional HER Borders to naturalistic perennial plantings.

Question 40

How does plant adaptation aid resilience to climate change?

Answer 40

Leaf adaptations: Hairs, spikes, glauca and smaller leaves.

Root adaptations: storage of water

Question 41

Name and briefly discuss THREE impacts of climate change that will negatively impact plant life in gardens.

Answer 41

a. DROUGHT: Less water will mean less photosynthesis and transpiration. Additionally, If a plant becomes stressed from lack of water it makes it more susceptible to pests and disease. Drought, over time, will force the species to adapt to changes through adaptations to leaves such as hairy leaves, smaller leaves, leaf colour changes to more gray. These adaptations will allow the plant to survive with less water. Examples of plants that have adapted to drought include Lavandula angustifolia. This plant has small grey/blue leaves that are slightly hairy and is well adapted to the Mediterranean climate. (OVER LONG PERIOD OF TIME SO NOT PERTINENT) Noel
b. WATERLOGGING: As the winters may receive more torrential storms there will be more flooding and runoff. If the excess water remains in the soil for more than a few days the oxygen will deplete causing anaerobic conditions. As there is no oxygen in the soil, the roots will become soft and squishy, the soil will smell and the leaves will die. Plants will need to adapt to waterlogging conditions, such as some of the marginal plants Iris pseudacorus.
c. HIGH HUMIDITY: As the air becomes more humid it will be harder for plants to transpire as the relative humidity will be too high for the plant to react. High humidity will slow the growth of the plant. High humidity will also encourage fungal diseases such as downy mildew which will make the leaves to distort and fall off – again reducing the possibility of photosynthesis and transpiration. Vegetables such as Cucumis sativus are affected by downy mildew and may have a reduced crop yield.
d. FIRE: The warmer the temperatures the more chances of wildfires. Wildfires destroy the ecosystem and may provide a perfect haven for invasive plants to take over like Cytisus scoparius or Eucalyptus globulus which easily reseeds.
e. PESTS AND DISEASES: As the area becomes warmer, pests and diseases will spread into the originally cooler areas. As their numbers increase they will reproduce more quickly throughout the year. Plants will be stressed and die due to pests/disease.

MODEL:

Increased heat will damage some plants or make it difficult for them to grow.
Fire will be an increased risk in summer.
There will be different pests and diseases affecting garden plants.

Question 42

Briefly describe what is meant by ‘resilience’ in thinking about selecting plants for climate change.

Answer 42

Resilience is the definition of a plant that can survive the extremes of weather patterns each year.
MODEL:
Resilience refers to the ability of a plant to survive extremes: heat, cold, drought, and to survive from year to year.

Question 43

Why does knowing where a plant comes from help us with plant selection for a more climate change resilient garden?

Answer 43

By knowing the provenance of a plant, you can understand the natural conditions it has grown in and see how it has adapted to that climate. Plants that are native to the Mediterranean will survive well in drought-like conditions. Plants that grow in alpine regions will do well with extreme weather patterns as well. A good area to review would be Central Asia as that area suffers from extreme cold to drought.

MODEL:
Knowing that a plant comes from a region with a climate zone which experiences extremes of temperature would be very useful. On the contrary, being aware of species which come from places that do not generally get extremes should perhaps warn us about too reliant on them in gardens.

Question 44

Name THREE common garden vegetable crops and how they might impacted by climate change?

Answer 44

a. Solanum tuberosum (potatoes): Waterlogging of the soil will rot the stem tubers and reduce the yield. IF a frost comes late, the plants may be damaged.
b. Latuca sativa (lettuce): The intense heat and sun will cause the plant to bolt and eventually the leaves will turn brown and fall. Watering will be necessary and kept in a protected area.
c. Cucumis sativus: (Cucumber): High humidity will cause downy mildew on the leaves and reduce the opportunity for photosynthesis and transpire, therefore reducing crop yield.
d. All spring vegetables could be planted earlier, with the caveat to be aware of a possible late frost.

MODEL:
Potatoes – it may be possible to start growing them earlier in the year,
although they may be more likely to be hit by frost; heat and drought will
bring forward the dates when they might need irrigation.
Cabbages – they will be more likely to be able to kept in active growth in the
winter, but will be more likely to need summer irrigation.
Carrots – autumn sowing might begin to make sense if the winter is mild
enough for them to grow for several months. However in the spring they will
bolt, so they will have to be harvested before this

Question 45

What is meant by phenology? And how might the phenology of garden plants be affected by climate change? What other impacts might there be?

Answer 45

a. Phenology is the study of the periods when plants grow and bloom throughout the year.
b. The phenology of garden plants will change with the climate. As it gets warmer earlier in the year, or possibly reduced number of frost days, plants will bloom earlier. With respect to the Malus spp. they need a certain amount of chill hours, if they don’t get it they won’t bloom. With respect to flowers, the temperatures may increase allowing the flowers to bloom earlier.
c. Plants and pollinators have adapted to the optimum time for growing and hatching. If the plants bloom earlier than the pollinators hatch, it could prove to be devastating to the life cycle of the pollinator.

MODEL:
Phenology is the description and study of when plants grow and develop through the year – the date of leaf opening, flowering, end of year die-back, etc.

With a warmer climate, many species will come into leaf and flower earlier.

This may mean that they get out of step with pollinators. It may also mean
that they are more at risk from late frosts.

Question 46

In planning for climate change it is very important to think about gardens, parks and other planted spaces around where you live. What might have to change?
Imagine you have to make some proposals to gardening colleagues about existing garden or park plantings or features which may no longer be realistic, or even possibly
damaging. Make a list of them, with possible alternatives that will cope better with a changing climate or will help with mitigating climate change.

Answer 46

a. Plant more trees – especially those that can adapt to climate change. Trees have extensive root systems and therefore able to take up large volumes of water in rainstorms, offer shade in the summer and cool the environment through transpiration as well as sequester vast amounts of C02. Suggestions would be Quercus agrifolia (Coast Live Oak) as it is an evergreen, drought and wind tolerant and a ‘fire-safe’ tree. This tree will provide shade, screening, will sequester carbon, and survive wind, drought, water logging and fire. Or possibly the Arbutus unedo (Strawberry tree) as it is drought tolerant and can regenerate quickly if damaged by fire.
b. Remove the lawn: Either plant a meadow or possibly use some of the drought tolerant lawns. Perhaps use ground cover instead, such as Dymondia or Kurapia. Both of these are drought tolerant and evergreen and offer a small amount of carbon sequestration – better than hardscaping!
c. Plant annuals earlier: As the temperatures are warmer earlier, it would be advisable to get annuals in sooner. HOWEVER, it may be better to encourage the staff to use perennials rather than annuals as they are less maintenance, require less water, sequester carbon better and can store nutrients and water in the soil without any further disturbance of the soil (which releases C02 and upsets the microorganisms).
d. Consider reviewing plants: Based on the site location, try to find plants that are already adapted to that future climate of the site. Perhaps look to Central Asia or the Mediterranean for ideas of what will survive. Plants that are sub-shrubs like Lavandula angustifolia or Cistus landanifer are drought tolerant, good for pollinators and can withstand wind. Replace trees and plants that will become difficult to maintain sustainably.
e. Consider a rain garden addition: Incorporate a rain garden in the area where water traditionally pools in the rainy season. Including marginal plants such as Iris pseudacorus or Fagus sylvatica will help to hold the water in the soil.
f. Do not leave bare soil: Be sure to either mulch or fill in blank areas with small plants. The more plants, the more photosynthesis and carbon sequestration.
g. Avoid heavy water requirements: Any plant that needs a lot of water to survive should be removed as this is not sustainable. Replace with drought tolerant grasses or plants such as Nassella tenuissima.
h. Be aware of plants that may become invasive: Try to avoid grasses such as Cortaderia selloana or possibly Cytisus scoparius as it may likely become an invasive plant in Britain as the temperature warms. Use plants that do not reseed as quickly.

MODEL:
Firstly I would worry about trees, species like birches (Betula spp.) that do
best in cool climates. They may need to be replaced with more heat-tolerant
species.
How much open space is there? Warmer summers will mean that both plants
and people will want more shade; there will be a need to plant more heatresistant shade-giving trees, like planes (Platanus species).
Borders with thirstier perennials, often recognised by having large, lush, soft
leaves, may have to change. These species may have to be replaced by more
drought tolerant perennials or sub-shrubs.
How vulnerable to fire are the plants? Recognising species that are fire-prone
will be important, and limiting their use. Plenty of deciduous trees will help
reduce fire risk.
Drier summers may mean reduced flowering at this time. If we want to avoid
using irrigation as much as possible, we will have to re-think traditional
flower-heavy bedding schemes, considering perennials and shrubs with
attractive foliage instead, or which are more likely to flower in dry conditions.