Article
How Climate Change Affects Plants in Urban Environments and Us
Urban vegetation is affected by climate change (credit: Tricky_Shark on Shutterstock)
In my book "A Guide to a Healthier Planet", I have explained why spending time in nature is beneficial for our health (Chapter 13): it reduces harm, restores capacities, and builds capacities by influencing biophysical processes. These beneficial effects happen even when we experience nature in urban areas, even though urban areas are known for a lot fewer plants and animals than rural areas. For example, plants improve mental and physical health by reducing anxiety, depression, blood pressure, etc. That is why caring well for these plants is very important for residents.
Unfortunately, with climate change progressing, the health of many of these plants and animals is at risk. For example, in chapter 16 of the same book, I explain how urbanization impacts pollinator behavior in urban areas. But also plants are affected because climate change is causing various biotic and abiotic stresses. Biotic stress is caused by attacks of living organisms including pests, weeds, and harmful microorganisms. Abiotic stress is caused by harsh conditions and damage caused by non-living factors, such as rising temperatures and carbon dioxide (CO2) concentrations, and increase or decrease in rainfall. Many plant species are struggling to adapt to these increasing number of stress factors, especially in urban environments.
Difference between biotic and abiotic stress (credit: BigBearCamera on Shutterstock)
The higher number of stress factors hinders plant growth and survival. Also, as our climate is complex and dynamic, and environmental changes due to climate change impact both biotic and abiotic stress factors, plants have to deal with constantly changing circumstances. This is how climate change impacts plants in urban environments and us:
Drought
The first way climate change impacts urban plants is through droughts. A drought is an unusually long period of low rainfall that leads to water shortage. This water shortage has a large impact on soil, animals, and plants. It does not only lead to smaller yields and less food to eat, but it also affects urban vegetation. This is for example because:
- the composition of plants that make up urban forests changes
- plants' growth changes as their growth phases shorten
- plants can turn less CO2 into energy
- stomata function less well so that plants can use water less efficiently. Stomata are small pores in leaves that allow the exchange of gases
- more oxidative stress damages the plants. Oxidative stress is an imbalance between the amount of toxic molecules in cells and tissue, and the ability to detoxify these molecules
Urban tree affected by drought (credit: OksBut on Shutterstock)
Higher temperatures
The second way climate change impacts urban plants is through higher temperatures. Higher temperatures are caused by increasing global temperatures, more frequent heatwaves, and heat islands. A heat island is an area that is a lot warmer than the surrounding area. This higher temperature is possible because infrastructure such as buildings and roads absorb and re-emit heat more than vegetation does. This affects vegetation for example because:
- heat stress decreases plants' growth rates and changes metabolic regulation. Metabolic regulation involves regulating the chemical processes within cells
- heat stress reduces chlorophyll, the pigment responsible for making plants look green and for photosynthesis, which involves turning CO2 from the atmosphere, water, and sunlight into oxygen and nutrients
- heat stress causes more phenolic compounds to be produced, which are molecules that harm cells
- heat stress can cause reactive oxygen species to be generated. Reactive oxygen species are highly reactive molecules causing oxidative stress
- more frequent heatwaves limit plants' development more than the temperature during the heatwave
Heat islands in red during a heat wave in India (credit: "ASA's ECOSTRESS Detects 'Heat Islands' in Extreme Indian Heat Wave" by NASA/JPL-Caltech is licensed under CC0 1.0 public domain)
Higher salt concentration
The third way climate change impacts urban plants is through high salt concentrations. Salt concentrations increase in the soil when water evaporates and when urban coasts are flooded with seawater. This increased salinity impairs plants' growth and disrupts other processes in plants, for example:
- higher salt concentrations disrupt osmotic functions. Osmosis is the movement of water molecules from a solution with a high concentration to a solution with a lower concentration of water molecules. The two solutions are separated by a membrane that lets water molecules pass but prevents salt molecules from passing. This means that osmotic functions in plants involve regulating the balance between concentrations in cells, which is crucial for processes such as growth and taking up nutrients.
Osmosis involves water molecules passing a membrane from an area of lower solute concentration to an area of higher solute concentration. The solute concentration, indicated by the red circles, is in this case salt (credit: petrroudny43 on Shuttersto
- high salt concentrations can in some plants prevent salt ions from moving from the roots to the part above the ground. An ion is an atom or molecule with a positive or negative electric charge because it lost or gained one or more electrons. Plants need these ions to make osmosis possible, absorb water, and keep a healthy pressure from within cells so that the plants remain rigid. A lack of healthy pressure is also the reason why the leaves of our plants at home droop when we haven't watered them enough.
Impact on us
The impact of climate change on urban plants through droughts, higher temperatures, and higher salinity affects us as well. This is because urban plants are very important for our well-being, both physically and mentally.
Plants in urban areas benefit us physically, for example, because urban plants:
- remove air pollutants, which means they improve air quality in urban areas
- create cool areas in hot cities
- trigger us to spend more time on outdoor sports, which is good for our physical well-being
- provide food in urban gardens and on green roofs
Green roof (credit: Hana Kolarova on Shutterstock)
Plants in urban areas benefit us mentally, for example, because urban plants:
- inspire us to spend more time on outdoor sports, which is not only good for our physical well-being but also our mental health
- make us feel calmer and more at ease as it is more pleasant to look at plants than at a blank wall
- allow us to feel more relaxed and refreshed by allowing us to focus our attention away from everyday tasks and demands
Conclusion and how we can take action
As climate change affects plants through droughts, higher temperatures, and higher salinity, and this in turn affects us, it is important to protect urban vegetation. Here are practical ideas of what you and I can do to limit the impact of climate change on urban vegetation:
- Selecting and growing more resilient and climate-resistant plants
- Contributing to limiting climate change (further reading: Part I Climate change of "A Guide to a Healthier Planet")
- Using biostimulants to increase the stress resistance of plants. Biostimulants stimulate natural processes in plants and help them use nutrients in their surroundings that can without this help not be used to make them more resistant to abiotic stress
- Replacing a paved area with plants to limit the development of heat island and cool the area down
- Using mulch instead of pavement stones to define a path in your garden
- Making your roof a green roof
- Growing plants on your balcony
- Creating green walls to provide shadow and limit the heat uptake of buildings such as your house
Which one of these can you implement in your daily life? And do you have further ideas of what you and I could do? Thank you in advance for putting them into practice and sharing them in a comment to this question to inspire all of us.
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Did you enjoy this article? Then I'm sure you'll love my book "A Guide to A Healthier Planet" as well. Check it out at:
A Guide to a Healthier Planet
This book focuses on closing the gap between scientific insights on pressing environmental issues that do not often reach the general public.
https://www.sustainabledecisions.eu/guide-to-a-healthier-planet
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About the author
Dr. Erlijn van Genuchten is a an internationally recognized environmental sustainability expert. She is a science communicator, helping scientists in the fields of nature and sustainability increase the outreach of their results and allowing us all to put scientific insights into practice and contribute to a sustainable future. Erlijn has inspired thousands of people around the world - for example - by supporting the United Nations with her expertise, her book "A Guide to A Healthier Planet" published by Springer Nature, her YouTube channel Xplore Nature, and her posts on social media. Website: https://www.sustainableDecisions.eu
Credit
This article is based on:
Image: Heat islands in red during a heat wave in India (credit: “ASA's ECOSTRESS Detects ‘Heat Islands' in Extreme Indian Heat Wave” by NASA/JPL-Caltech is licensed under CC0 1.0 public domain)
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5 w
Love the ideas for taking action ✊ Planting more trees, using biostimulants, even green roofs!
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5 w
After reading this I am going to grow even more plants on my balcony! 🌿🌻
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5 w
Understanding the impact of climate change on urban plant life is crucial for our well-being.
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5 w
Thanks for sharing, It's clear nature or even viewing scenes of nature reduces anger, fear,stress and increases pleasant feelings.
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6 w
This is very interesting, thanks for sharing! The impact of climate change on plants is largely talked about but always concerns crops and agriculture. But this sheds light on something else as well: how can we regreen cities to mitigate climate change when trees and plants die from it?