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Keep your tree’s ‘air-con’ running in the heat with regular watering

16th Jul 2022

Nature has long inspired artists and engineers. When an innovation closely copies the functioning of a plant or animal, it’s called biomimetic. Biomimetic fabrics that copy the way trees take up water and let it evaporate to keep them cool remind us how important it is to keep watering newly planted trees in hot weather.

As we experience a much-reported heatwave, this clever wicking material sounds like a good idea. It’s designed to efficiently let perspiration dry off from clothes, keeping the wearer dry and cool. Moisture can only travel one way through the fabric before rapidly evaporating, taking heat with it. This occurs through capillary force – the same process a plant uses to draw up water from the ground.

To make the process fast, several layers are necessary to draw moisture out – but dense fabric can also hold heat. To overcome this problem, inventors have looked to the way trees stay cool. After all, trees have optimised the way they use water as ‘air-con’ over the course of millions of years of evolution. What they noticed was that plant pores get smaller and smaller towards the surface, which maximises capillary force, meanwhile the network of leaf veins also contributes to heat transfer from the surface. Transpiration-inspired textiles work on the same principles, with a multi-layer structure and inter-fibre channels that transport moisture one-way, away from skin.

Remember to keep watering newly planted trees

If you have recently planted a tree (especially in the last 12 months), you will probably be nurturing it according to our aftercare guidelines. But we urge you during hot spells to ramp up the watering.

At the nursery, potted trees are on a drip irrigation system, so their growing media never dries out. Dried out roots are lethal! Once planted, roots will grow into the surrounding soil and eventually cover enough area to support the whole tree with all the water it needs (generally speaking), but in the first few growing seasons you must generously water the tree in the root zone to make sure it thrives.

Trees are constantly taking up water, not only to transport nutrients from the soil, but also the keep cool. Similarly to humans, they like a certain operating temperature, and will do what they can to maintain their cool when things get overly warm. They can’t take off clothes or move into the shade – it’s all about transpiration. That is, when it gets hot, they will move more water up to the leaf surface to allow it to evaporate heat. So they need more water to carry out this function.

That said, trees can also close stomata to slow down transpiration if there’s not much water to be had and they want to conserve what they have within them. You can see where this goes… if there’s no water, and it’s hot, they just won’t be able to carry out their essential functions. This leads first to failure to thrive, then dying leaves, then twig die-back, and so forth.

Do not let your tree dry out! Keep it running on a full tank of water, so it doesn’t have to shut down any of its air-con, and it will continue to thrive in the summer months.

  • Watering in the morning or evening is best
  • Apply a bucket (10 litres) per 15L potted tree and more for larger trees, every day in hot weather
  • Mulch with 5cm of chipped bark or other material to conserve soil moisture and keep weeds down.

 

Other tree-inspired tech

We couldn’t resist looking up a few other tree-inspired technologies…

Artificial evaporators, based on tree transpiration, can capture hazardous substances in soil – for example removing water containing heavy metal particles.

Artificial photosynthesis systems, whose physical form is based on trees, have been suggested as one method to remove carbon dioxide from the air – and may potentially turn it into sustainable fuel.

Responsive building facades that copy trees to provide a dynamic ‘skin’ that responds to changing patterns of daylight, keeping occupants comfortable through reducing glare and heat. For example, the slatted wood panels on Melbourne’s City Council House 2 (completed in 2006) diffuse light entering the building, inspired by the way trees face their leaves towards the sun. Flexible shading with semi-transparent materials also saves on energy that would otherwise be needed for air conditioning, while ensuring that there is ample natural light. Complex, multi-layered configurations using adjustable, curved forms inspired by tree canopies, have been suggested for climate-adapted buildings.

The retractable roof of Shanghai’s Qizhong Stadium, meanwhile, is based on a magnolia flower and effectively allows the venue to host events indoors or outdoors.

The physical qualities of tree tissues have attracted attention in engineering, for example tree branches have been studied to provide clues useful for strengthening joints in aircraft, and composite ceramics and other materials that are less brittle than traditional forms have been developed using insights from wood.

Synthetic materials that can heal themselves following damage have also been thought up, through mimicking the function of proteins that help trees to carry this out. Latex, for example, is exuded by the rubber tree (Hevea brasiliensis) when the tree is damaged, which releases proteins that close wounds.

Quite fascinating also are tree-climbing robots that can harvest coconuts and gather biological specimens high up in trees!

 

Read more about watering:

Watering trees, shrubs and hedges

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