I’ve always wondered: are water crystals bad for the environment?

Gardeners use water crystals to drought-proof their plants.
Shutterstock

Michelle Ryan, Western Sydney University

This is an article from I’ve Always Wondered, a series where readers send in questions they’d like an expert to answer. Send your question to alwayswondered@theconversation.edu.au

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Are water crystals bad for the environment? –Terry Gilmour

This is an excellent question, and something an environmentally conscious gardener might wonder. With changing rainfall patterns, drought and an increasing average temperature in Australia many people are looking for ways to save water in their garden, and adding water crystals to your soil appears to be a good solution. But what do we really know about water crystals and are they bad for the environment?

Well, you can put your mind at ease: water crystals are not bad for the environment. In fact, in other forms they are actually used to help protect the environment.

What are water crystals?

Water crystals are tiny super-absorbent polymers (a long chain that’s made up of identical repeating molecules), about the size of a sugar crystal. They are added to potting mix or added to soil in a garden bed to increase the water holding capacity of the soil.

Water crystals act like a sponge, binding water molecules with the molecule chains in the crystals (with what’s technically known as cross-link bonding). This makes the crystal swell, creating a three-dimensional gel network up to 300 times its original size, absorbing water and nutrients.

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Not all community gardens are environmental equals

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Over 5-6 years water crystals slowly degrade, releasing the absorbed water into the root zone of the plant and wetting the soil.

While many water crystals are marketed as water-saving, and many people use them to drought-proof their plants, it’s really important to know that these water crystals don’t actually conserve water. The plants still use the same amount of water, but instead of the water flowing through to the bottom of the pot and into the saucer and evaporating, or through to the bottom of the garden bed, the water crystals hold onto the water in the root zone of the plant. It makes for a more efficient use of the water in the soil.

Gardeners are not always able to frequently water their plants on hot summer days.
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Cross-linked vs linear polymers

To understand where the environmental concerns come from, we have to get a little technical.

The most common type of water crystal on the market is a cross-linked polyacrylamide. Cross-linked polyacrylamides are water absorbent but not water soluble. One of their best-known uses is in disposable nappies.

The environmental concern regarding water crystals comes from people confusing these cross-linked polyacrylamides with non-cross-linked polyacrylamide used by industry. While they are commonly described in the same way, they have a different chemical bonding and properties.

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Non-cross-linked (linear) polyacrylamide is water-soluble. It is currently used in Australian agriculture for improving soil and to help control erosion. It also plays an integral role in aiding flocculation as part of the sewage treatment process.

A 1997 study found when non-cross linked polyacrylamide degrades it creates acrylamide, a suspected carcinogen and neurotoxin.

Obviously this would be very concerning if it also affected water crystals! Acrylamide could leach into the soil and water and be taken up by plants, entering the human food chain. However there’s no proof cross-linked polyacrylamides – which are the water crystals you’d find in a gardening store – behave like this.

It is not clear if water crystals have a negative impact on Australia’s rivers and streams.
Shutterstock

It is also worth noting that further studies, including one published in 2008, found a very small amount (less than 0.5 parts per billion) of acrylamide was released into the environment, which does not cause any environmental concern.

You may also worry water crystals could impact aquatic life if they found their way into rivers and streams. The good news is there’s no reported toxicity or impact on aquatic life from commercially available water crystals (results are more mixed for the water soluble non-cross-linked polyacrylamide, with some studies finding little impact and others showing no toxicity.

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Are common garden chemicals a health risk?

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The other good news is water crystals do not accumulate in the soil or water over the long term. The use of water crystals has no adverse impact on soil microbe populations, which we need for a good healthy soil. If used as directed there is no risk to human health (however, it is always good practice to wear gloves while handling any chemical product).

So environmentally conscious gardeners don’t need to worry about water crystals. They’re great for people who don’t have time to water their pot plants every day in summer. Remember, these crystals do not save water but increase the water holding capacity of the soil, so you still need to water your plants regularly – especially on hot days!

Michelle Ryan, Lecturer – Environmental Health and Management, Western Sydney University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Gardening improves the health of social housing residents and provides a sense of purpose

Gardens bring people together.
Elaine Casap/Unsplash

Tonia Gray, Western Sydney University; Danielle Tracey, Western Sydney University; Kumara Ward, Western Sydney University, and Son Truong, Western Sydney University

Studies indicate spending time in nature brings physical, mental and social benefits. These include stress reduction, improved mood, accelerated healing, attention restoration, productivity and heightened imagination and creativity.

Increased urbanisation has made it more difficult to connect with nature. And members of lower socioeconomic and minority ethnic groups, people over 65 and those living with disability are less likely to visit green spaces. This could be due to inaccessible facilities and safety fears.

A gardening program for disadvantaged groups, running in New South Wales since 1999, has aimed to overcome the inequity in access to green spaces. Called Community Greening, the program has reached almost 100,000 participants and established 627 community and youth-led gardens across the state.

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The science is in: gardening is good for you

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Our independent evaluation explored the program’s impact on new participants and communities in social housing by tracking six new garden sites in 2017. Around 85% of participants told us the program had a positive effect on their health and 91% said it benefited their community. And 73% said they were exercising more and 61% were eating better. One participant said engaging in the program even helped them quit smoking.

These insights have advanced our understanding of how community gardening improves the mental and physical health of Australians living in social housing communities in our cities.

Our study

Trends towards urbanisation and loss of green space have sparked concerns about population health and well-being. This has led to a growing body of research on the impact of community gardens on children and adults.

The Community Greening program is supported by the Royal Botanic Garden Sydney in partnership with Housing New South Wales. Anecdotal feedback gathered by the botanic garden over the past two decades has shown gardening improves well-being and cohesion, fosters a sense of belonging, reduces stress and enhances life skills.

Community Greening provides gardens for people in social housing.

Based on this understanding, Community Greening aims to:

• improve physical and mental health
• reduce anti-social behaviour
• build community cohesion
• tackle economic disadvantage
• promote understanding of native food plants
• conserve the environment
• provide skills training to enable future employment opportunities
• share expert knowledge of the garden.

Our research investigated these outcomes in participants, and whether they changed during the course of the program. We collected data using questionnaires over seven months (before and after participation). We also conducted focus group interviews with participants and open-ended questionnaires with staff working at the community sites.

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Social housing protects against homelessness – but other benefits are less clear

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Of the 23 people who completed both questionnaires before and afterwards, 14 were female and nine were male. They had an average age of 59, ranging from 29-83. Fifteen participants were born in Australia while the rest came from Fiji, Iran, Poland, New Zealand, Philippines, Chile, Afghanistan and Mauritius. One participant identified as an Aboriginal and/or Torres Strait Islander and five people (22%) reported English was not their first language.

Initially, 27% reported they had never gardened prior to the program. At the post-test questionnaire, the frequency of attendance improved for many of them. Over 40% gardened once a week and 22% every day.

Gardening benefits

Overall, we found participants felt a sense of agency, community pride and achievement. The gardening program helped encourage change and community development. Some were happy to learn a new hobby.

Community Greening participants found a lot of benefits to gardening.
Research infographic/Screenshot, Author provided

Gardening also served as an opportunity to socialise with neighbours. In previous years within some social housing communities, it was commonplace for residents to simply stay inside their units without interacting with anyone.

Many participants said they saw a marked improvement in their health and well-being. One participant remarked:

I suffer with a lot of health problems, and a lot of times I’ve been sitting at home, been depressed and not been happy about my illness, and since I’ve become more involved with the garden it helped me to not worry about my health so much like I used to and it actually improved my eating habits. It has changed my life positively. I don’t have time to feel sorry for myself anymore…

Some described the gardening experience as calming and cathartic – especially those who suffered from depression and anxiety. Some spoke of the positive aspect of having something to do each day and their feelings of achievement.

Another participant said:

Going outside gives me not only physical exercise, but it provides a certain amount of joy in that you’re seeing the benefit of your hard work coming through in healthy plants. Whether it’s vegetables or a conifer, you’re seeing it grow and you’re seeing the benefit…

Additional improvements in social health included a genuine enthusiasm for working in a team, with increased co-operation and social cohesion between staff and tenants. The housing managers and social workers work alongside tenants helping to foster trust, co-operation, social collaboration and healthy relationships.

More importantly, this research has provided validation that Community Greening has aligned with contemporary social-housing priorities. These include supporting health and well-being, nurturing a sense of community, enhancing safety and developing a sense of place.

Tonia Gray, Associate Professor, Centre for Educational Research, Western Sydney University; Danielle Tracey, Associate Professor, Adult and Postgraduate Education, Western Sydney University; Kumara Ward, Lecturer, Early Childhood Education, Western Sydney University, and Son Truong, Senior Lecturer, Secondary Education, Western Sydney University

This article was originally published on The Conversation. Read the original article.

Don’t worry, the chance of dying from potting mix is very slim

Potting mix is known to carry harmful bacteria and fungi.
Photo by Markus Spiske on Unsplash

Peter Collignon, Australian National University

Gardening is generally a healthy and pleasurable hobby or occupation. However, any activity carries some risk – and gardening is no exception.

Potting mix is known to carry harmful bacteria and fungi. And there have been reports of deaths from diseases, such as the Legionnaires’ disease (a lung infection), that have been attributed to bacteria in potting mix.

Many bacteria and fungi that can cause infections in people live in soil and water. So it’s not surprising that potting mix can also have in it bacteria and fungi that may on occasion cause harm to people, and in rare cases even kill them. But it’s important to note that, overall, the risk is very low.

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Fertilising more than plants

Potting mix is usually a mixture of inorganic and organic material. It’s also often at a higher temperature compared to soil because of where and how it’s stored, so it retains heat for longer. Bacteria and fungi generally grow better and reach higher numbers when they are in moist and warm environments.

Potting mix is usually warmer than soil, which makes it a better environment for bacteria and fungi to grow.
from shutterstock.com

If bacteria or fungi are already present in low numbers, they can quickly grow to very high numbers in optimal conditions. This includes many bacteria in soil that can cause problems in people – such as strains of nocardia (causes nocardiosis, an infection of the lungs or whole body), legionella (causes Legionnaires’ disease), and clostridium (causes tetanus).

Numerous fungi can also be present in soil and potting mix. In certain areas of the world, soil contains fungi that can invade if inhaled and cause disease. These include the lung infection histoplasmosis, which is caused by a fungus that lives mainly in parts of the United States, but also in some parts of Central and South America, Africa, Asia, and Australia.

Protecting ourselves

The risk to most people of becoming infected with any of these bacterial or fungal diseases is very low. Disease is more likely to be a risk when the micro-organisms are present in very high numbers.

Bacteria or fungi also need to be introduced into our bodies to cause disease. This usually happens through inhalation, where the organisms go into the lungs. It can also occur through the skin, such as with the chronic fungal infection sporotrichosis, also known as “rose gardener’s disease”. If, for any reason, micro-organisms are present in high numbers, then the exposure and risk will be higher.

A fungal infection known as rose gardener’s disease can happen with the organism entering the skin directly through an injury.
from shutterstock.com

There are many things we can do to protect ourselves from introducing bacteria or fungi into our bodies. The most essential is basic hygiene.

If people smoke, eat or drink without first washing their hands, they are at an increased risk of legionella infection from potting mix. This implies direct inhalation isn’t the only way for the bacteria to enter the body, but that oral intake of micro-organisms via contaminated hands is also a risk.

Another added protection measure is wearing gloves. This doesn’t mean you should then not wash your hands before eating. A physical barrier in addition to washing hands obviously provides better protection.

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(At least) five reasons you should wear gardening gloves

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Masks can be worn in high-risk situations, such as when opening a bag of potting mix. Directing the bag away from the gardener when opened, and being in a well-ventilated area, will decrease any inhalation risk.

Signs of infection

People who have a lower immunity, such as those with diseases such as HIV or lymphoma, are more at risk of catching something from potting mix. So it’s even more important they use extra appropriate precautions, including wearing masks when in higher-risk situations.

Simple safety provisions can protect us from harmful bacteria and fungi.
Shutterstock

The symptoms or signs of infection acquired from soil or potting mix depend on where the infection is and what micro-organism is causing it. With potting mix, the main worry is legionella longbeachae. This generally causes a lung infection such as pneumonia.

Symptoms can initially be fever, aches and pains, which are fairly general of illness. But as the infection involves more of the respiratory tract, cough, shortness of breath and/or pain on breathing may develop.

Treatment

While potting-mix-linked legionella infections are uncommon, cases have occurred in countries including Australia, Japan and the US.

So, if people develop symptoms that are ongoing and have had recent exposure to potting mix within the incubation period (two to ten days after exposure), they need to seek medical help and make it clear to that person that they were worried about potting mix being involved.

It’s important to note the potting mix connection because antibiotics needed to kill legionella are different to standard penicillin-like antibiotics often used to treat pneumonia acquired in the community.

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Overall, though, we need to keep these risks in perspective. Millions of people garden and all will be exposed to soil and/or potting mix. Very few of these infections occur in Australia and elsewhere. Fairly simple provisions such as washing hands, wearing gloves and – where necessary – wearing a mask will ensure rates of infection remain low.

Peter Collignon, Professor, infectious diseases and microbiology, Australian National University

This article was originally published on The Conversation. Read the original article.

(At least) five reasons you should wear gardening gloves

Not just to avoid creepy crawlies.
from http://www.shutterstock.com

Mark Blaskovich, The University of Queensland

Gardening is a great way to relax, be one with nature and get your hands dirty. But lurking in that pleasant environment are some nasty bacteria and fungi, with the potential to cause you serious harm. So we need to be vigilant with gardening gloves and other protective wear.

Soils contain all sorts of bacteria and fungi, most of which are beneficial and do helpful things like breaking down organic matter. But just as there are pathogenic bacteria that live on your body amid the useful ones, some microorganisms in soil can cause serious damage when given the opportunity to enter the body. This commonly happens through cuts, scrapes or splinters.

Plants, animal manure, and compost are also sources of bacteria and fungi that can cause infections.

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Read more – The science is in: gardening is good for you

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1. Tetanus

Traditionally, the most common and well-known infection is tetanus, caused by Clostridium tetani, which lives in soil and manure. Infections occur through contamination of cuts and scrapes caused by things in contact with the soil, such as garden tools or rose thorns.

Fortunately, most people have been vaccinated against tetanus, which means even if you are infected, your body is able to fight back against the bacteria to prevent it becoming serious. Symptoms include weakness, stiffness and cramps, with the toxins released leading to muscular paralysis and difficulty chewing and swallowing – hence the common term for tetanus of lockjaw.

2. Sepsis

Bacteria such as Escherichia coli, Salmonella, Campylobacter jejuni, and Listeria monocytogenes are often present in gardens as a result of using cow, horse, chicken or other animal manure. Bacterial infections can lead to sepsis, where the bacteria enter the blood and rapidly grow, causing the body to respond with an inflammatory response that causes septic shock, organ failure, and, if not treated quickly enough, death.

A high-profile case recently occurred in England, where a 43-year-old solicitor and mother of two died five days after scratching her hand while gardening. This hits close to home, as a number of years ago my mother spent ten days in intensive care recovering from severe sepsis, believed to be caused by a splinter from the garden.

3. Legionellosis

Standing pools of water may hold Legionella pneumophila, the bacteria causing Legionnaires’ disease, more commonly known to be associated with outbreaks from contaminated air conditioning systems in buildings.

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Related bacteria, Legionella longbeachae, are found in soil and compost. In 2016 there were 29 confirmed cases of legionellosis in New Zealand, including a Wellington man who picked up the bug from handling potting mix.

Potting mix should be handled with gloves, while wearing a dust mask.
from http://www.shutterstock.com

Another ten cases were reported in Wellington in 2017, again associated with potting soil. In New Zealand and Australia, Legionella longbeachae from potting mix accounts for approximately half of reported cases of Legionnaires’ disease. There were around 400 total cases of Legionellosis in Australia in 2014.

The bacteria is usually inhaled, so wearing a dust mask when handling potting soil and dampening the soil to prevent dust are recommended.

4. Melioidosis

An additional concern for residents of northern Australia is an infection called melioidosis. These bacteria (Burkholderia pseudomallei) live in the soil but end up on the surface and in puddles after rain, entering the body through cuts or grazes, and sometimes through inhalation or drinking groundwater.

Infection causes a range of symptoms, such as cough and difficulty breathing, fever or sporadic fever, confusion, headache, and weight loss, with up to 21 days before these develop.

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In 2012, there were over 50 cases in the Northern Territory leading to three deaths, with another case receiving publicity in 2015. Preventative measures include wearing waterproof boots when walking in mud or puddles, gloves when handling muddy items, and, if you have a weakened immune system, avoiding being outdoors during heavy rain.

5. Rose gardener’s disease

A relatively rare infection is sporotrichosis, “rose gardener’s disease”, caused by a fungus (Sporothrix) that lives in soil and plant matter such as rose bushes and hay. Again, infections through skin cuts are most common, but inhalation can also occur.

Skin infection leads to a small bump up to 12 weeks later, which grows bigger and may develop into an open sore. An outbreak of ten cases was reported in the Northern Territory in 2014.

Aspergillus, usually Aspergillus fumigatus, and Cryptococcus neoformans are other fungi that can cause lung infections when inhaled, usually in people with weakened immune systems. Gardening activities such as turning over moist compost can release spores into the air.

Of course, there are plenty of other dangers in the garden that shouldn’t be ignored, ranging from poisonous spiders, snakes and stinging insects, to hazardous pesticides and fungicides, poisonous plants, and physical injuries from strains, over-exertion, sunburn, allergies, or sharp gardening tools.

So enjoy your time in the garden, but wear gloves and shoes, and a dust mask if handling potting soil or compost. And be aware if you do get a cut or scrape then end up with signs of infection, don’t delay seeing your doctor, and make sure you let them know what you’ve been doing.

Mark Blaskovich, Senior Research Officer, The University of Queensland

This article was originally published on The Conversation. Read the original article.

Five reasons not to spray the bugs in your garden this summer

play4smee/Flickr, CC BY-NC

Lizzy Lowe, Macquarie University; Cameron Webb, University of Sydney, and Kate Umbers, Western Sydney University

The weather is getting warmer, and gardens are coming alive with bees, flies, butterflies, dragonflies, praying mantises, beetles, millipedes, centipedes, and spiders.

For some of us it is exciting to see these strange and wonderful creatures return. For others, it’s a sign to contact the local pest control company or go to the supermarket to stock up on sprays.

But while some bugs do us very few favours – like mozzies, snails and cockroaches – killing all insects and bugs isn’t always necessary or effective. It can also damage ecosystems and our own health.

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There are times when insecticides are needed (especially when pest populations are surging or the risk of disease is high) but you don’t have to reach for the spray every time. Here are five good reasons to avoid pesticides wherever possible, and live and let live.

1. Encourage the bees and butterflies, enjoy more fruits and flowers

Hover fly.
dakluza/flickr

Flowers and fruits are the focal points of even the smallest gardens, and many of our favourites rely on visits from insect pollinators. We all know about the benefits of European honey bees (Apis mellifera), but how about our “home grown” pollinators – our native bees, hover flies, beetles, moths and butterflies. All these species contribute to the pollination of our native plants and fruits and veggies.

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You can encourage these helpful pollinators by growing plants that flower at different times of the year (especially natives) and looking into sugar-water feeders or insect hotels.

2. Delight your decomposers, they’re like mini bulldozers

Slaters improve your soil quality.
Alan Kwok

To break down leaf litter and other organic waste you need decomposers. Worms, beetles and slaters will munch through decaying vegetation, releasing nutrients into the soil that can be used by plants.

The problem is that urban soils are frequently disturbed and can contain high levels of heavy metals that affects decomposer communities. If there are fewer “bugs” in the soil, decomposition is slower – so we need to conserve our underground allies.

You can help them out with compost heaps and worm farms that can be dug into the ground. It’s also good to keep some areas of your lawn un-mowed, and to create areas of leaf litter. Keeping your garden well-watered will also help your underground ecosystems, but be mindful of water restrictions and encouraging mosquitoes.

3. An army of beneficial bugs can eat your pests

Mantises and dragonflies are just some of the hundreds of fascinating and beautiful bugs we are lucky to see around our homes. Many of these wonderful creatures are predators of mozzies, house flies and cockroaches, yet people are using broad-spectrum insecticides which kill these beneficial bugs alongside the pests.

It may sound counterproductive to stop using pesticides in order to control pests around the home, but that’s exactly what organic farmers do. By reducing pesticides you allow populations of natural enemies to thrive.

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Read more: Even ‘environmentally protective’ levels of pesticide devastate insect biodiversity

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Many farmers grow specific plants to encourage beneficial insects, which has been shown to reduce the damage to their crops.

This form of pest control in growing in popularity because spraying can result in insecticide resistance. Fortunately, it’s easy to encourage these bugs: they go where their prey is. If you have a good range of insects in your yard, these helpful predators are probably also present.

Jumping spiders are great at eating flies and other pests.
Craig Franke

4. Your garden will support more wildlife, both big and small

Spraying with broad-spectrum pesticides will kill off more than just insects and spiders – you’re also going after the animals that eat them. The more insects are around, the more birds, mammals, reptiles and frogs will thrive in your backyard.

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Read more: Four unusual Australian animals to spot in your garden before summer is out

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Baiting for snails, for example, will deter the blue-tongue lizards that eat them, so cage your vegetables to protect them instead. Keeping your garden well-watered, and including waterbaths, will also encourage a balanced ecosystem (but change the waterbaths regularly).

5. You and your family be happier and healthier

Engaging with nature increases well-being and stimulates learning in children. Insects are a fantastic way to engage with nature, and where better to do this than in your own back yard! Observing and experimenting on insects is a wonderful teaching tool for everything from life cycles to the scientific method. It will also teach your kids to value nature and live sustainably.

It’s also a hard truth that domestic pesticides present a significant risk of poisoning, especially for small children.

In reality, the risk of exposing your children to the pesticides far outweighs the nuisance of having a few bugs around. Instead, integrated pest management, which combines non-chemical techniques like cleaning of food residues, removal of potential nutrients, and sealing cracks and crevices, is safer for your family and your garden ecosystems.

Think globally, act locally

Your backyard has a surprising impact on the broader health of your neighbourhood, and gardens can make significant contributions to local biodiversity. Insects are an important part of ecosystem conservation, and encouraging them will improve the health of your local environment (and probably your health and well-being too).

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Read more: Conservation efforts must include small animals. After all, they run the world

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In the end, insects and spiders are not out to get you. For the sake of our kids and our environment, you should give them a chance.

Lizzy Lowe, Postdoctoral researcher, Macquarie University; Cameron Webb, Clinical Lecturer and Principal Hospital Scientist, University of Sydney, and Kate Umbers, Lecturer in Zoology, Western Sydney University

This article was originally published on The Conversation. Read the original article.

How do we keep gardening in the face of a changing climate?

Keep the climate in mind when you’re choosing what to plant.
shutterstock

Andrew Lowe, University of Adelaide

Since 1880, the average global temperature has increased by 0.8°℃, with large changes in rainfall redistribution. With these changing conditions upon us, and set to continue, gardeners will have to alter the way they do things.

As climate largely determines the distribution of plants and animals – their “climate envelope” – a rapid shift in these conditions forces wild plants and animals to adapt, migrate or die.

Gardeners face the same changing conditions. If you look at the back of a seed packet, there is often a map showing the regions where these particular plants thrive. But with a rapidly changing climate, these regions are shifting.

In the future we will need to be more thoughtful about what we plant where. This will require more dynamic information and recommendations for gardeners.

The shifting climate

Changes in altitude significantly affect the temperature. As you walk up a hill, for every 100 metres of altitude you gain, the temperature drops by an average of 0.8℃.

Changes in latitude obviously have a bearing on the temperature too. It gets cooler as you move towards the poles and away from the Equator. An accurate rule of thumb is difficult to derive, because of the number of interacting and confounding factors. But generally speaking, a shift of 300 km north or south at sea level equates to roughly a 1℃ reduction in average temperature.

This means that due to warming over the past century or so, Adelaide now experiences the climate previously found in Port Pirie, whereas Sydney’s climate is now roughly what was previously found halfway to Coffs Harbour. The temperature difference is equivalent to a northward shift of approximately 250 km or drop in altitude of 100 m.

At current climate change trajectories, these shifts are set to continue and accelerate.

The plants in your garden might need to change.

Adaptation

Plants are already adapting to the changing climate. We can see that in the hopbush narrowing its leaves and other plants closing their pores. Both are adaptations to warmer, drier climates.

We have also seen some major shifts in the distribution of animal and plant communities over the past 50 years. Some of the most responsive species are small mobile insects like butterflies, but we have also seen changes among plants.

But while entire populations may be migrating or adapting, plants that grow in isolated conditions, such as fragmented bush remnants or even gardens, may not have this option. This problem is perhaps most acute for long-lived species like trees, many of which germinated hundreds of years ago under different climatic conditions. The climate conditions to which these old plants were best adapted have now changed significantly – a “climate lag”.

Using such old trees as a source of seed to grow new plants in the local area can potentially risk establishing maladapted plants. But it’s not just established varieties that run this risk.

The habitat restoration industry has recognised this problem. Many organisations involved in habitat restoration have changed their seed-sourcing policies to mix seeds collected from local sources with those from more distant places. This introduces new adaptations to help cope with current and future conditions, through practices known as composite or climate-adjusted provenancing.

The shifting climate and your garden

Gardeners can typically ameliorate some of the more extreme influences of global warming. They can, for example, provide extra water or shade on extremely hot days. Such strategies can allow plants to thrive in gardens well outside their natural climatic envelope, and have been practised by gardeners around the world for centuries.

But with water bills rising and the need to become more sustainable, we should think more carefully about the seeds and seedlings we plant in our gardens. The climate envelope we mentioned earlier is shifting rapidly.

We will need to start using seeds that are better adapted to cope with warmer and, in many cases, drier conditions. Typically, these plants have thinner leaves or fewer pores. This requires more information on the location and properties of the seeds’ origin, and a more detailed matching of diverse seed sources to planting location.

As the climate changes, we need to be more selective with what we plant.

As the climate continues to change we will also need to introduce species not previously grown in areas, using those that are better adapted to the increasingly changed climatic conditions.
Plenty of tools are now available to help guide seed collection and species selection for planting. These include those offered through the National Climate Change Adaptation Research Facility and the Atlas for Living Australia, for instance.

But these resources are often aimed at expert or scientific audiences and need to be made more accessible for guiding gardening principles and plant selection for the public. The information needs to be intuitive and easy to understand. For example, we should produce lists of species that are likely to decline or benefit under future climate conditions in Australia’s major cities and towns, along with future growing areas suitable for some of our most popular garden species.

This won’t just be useful for a backyard gardener, either. Many exciting new gardening initiatives are being proposed, including rooftop gardens, which promote species conservation, carbon sequestration and heat conservation, and future city designs, which incorporate large-scale plantings and gardens for therapeutic benefits. All of these activities need to take the shifting climate into account, as well as the need to change practices to keep up with it.

Andrew Lowe, Professor of Plant Conservation Biology, University of Adelaide

This article was originally published on The Conversation. Read the original article.