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Once the coat around the seed is moistened, the embryo cells expand and burst out in a process called germination. shutterstock/NUM LPPHOTO

This is an article from Curious Kids, a new series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky!

How can a tiny seed actually grow into a huge tree? – Finney, aged 6, from Bairnsdale in rural Victoria.

Tree seeds fall (like the tiny Eucalypt seeds) or helicopter down (like the winged seeds of the Maple) from their parents with a full set of instructions on how to grow.

A single tree may drop hundreds or even many thousands of seeds. Many of these seeds will become snacks for insects or fall where the ground is too hard, too dry, or just not suitable for trees. Some though will fall where the situation is just right!

Just right might mean bare dirt or some nice decayed mulch with enough sunlight.

The seed contains an embryo - a group of cells ready to form roots, a stem and the first leaves. Once the coat around the seed is moistened, the embryo cells expand and burst out in a process called germination.

Time-lapse of seed germination.

First, the roots will develop and push out and down into the soil to make sure the new plant can get water. Then the stem cells stretch up to display the first leaves.

The embryo uses food stored in the seed to power its initial growth until the leaves can start producing food. Small seeds don’t have much stored food so they have to fall in just the right spot to be successful. The parent tree has some ways to improve the chances of its seed finding the right spot, like dropping seeds after a bushfire has made the ground bare and free from other plants that would use all the water and nutrients.

For some plants, a bushfire triggers the release of seeds. Flickr/Tatters, CC BY

Once the roots are in the soil and the first leaves are in the sun, the plant is ready to really start growing.

People stop growing after they’ve become grown-ups but trees just keep getting taller and thicker however long they are alive.

Grass, bamboo and many other plants grow from the bottom up, so if you put a mark on the stem and come back in a little while, that mark will have been pushed further above the ground. But if you put a mark or even nail a board into a tree at one metre above the ground then come back in 10 years, it will still be only one metre above the ground. That’s because trees grow from the outside and the top up.

Some trees can grow to be more than 100 metres tall! Flickr/Andrew Malone, CC BY

The newest and outer shell of a tree contains all the living parts of the wood - the parts that move water up from the roots and food down from the leaves. If trees stop growing these outer, living shells of wood, the whole tree dies.

Some trees can grow to be more than 100 metres tall – that’s as tall as a skyscraper! In fact, humans are now building buildings out of wood that are over 50 metres tall and there are plans to go well beyond that.

The tallest tree currently is over 110 metres tall, and scientists think some trees may have been as much as 150 metres tall.

Trees grow from the top up.

A problem with getting even taller is that trees use water the same as you use blood - to move the nutrients and oxygen and other vital things around our body. But a tall tree has to move it from the roots to the tip of the leaves. For a 100 metre tall tree, that is like 30 flights of stairs. And a big tree could use more than 200 litres of water every day. Imagine carrying 30 buckets of water up 30 flights of stairs every day!

In our tall buildings, we need huge pumps and generators to move the water to the top, but trees just rely on their amazing structure and a little bit of power from the Sun.

Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. They can:

* Email your question to curiouskids@theconversation.edu.au
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Please tell us your name, age, and which city you live in. You can send an audio recording of your question too, if you want. Send as many questions as you like! We won’t be able to answer every question but we will do our best.

Cris Brack does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond the academic appointment above.

Rising temperatures and southerly winds expected to bring toxic air to large parts of England and Wales on Wednesday

The mayor of London, Sadiq Khan, has triggered the capital’s emergency air quality alert as soaring temperatures combined with southerly winds are expected to bring dangerously toxic air to large parts of England and Wales on Wednesday.

The emergency alerts will see warnings displayed at bus stops, on road signs and on the underground.

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Senate inquiry starts as report into political, military and humanitarian risks of climate change across Asia Pacific released

As the Senate launches an inquiry into the national security ramifications of climate change, a new report has warned global warming will cause increasingly regular and severe humanitarian crises across the Asia-Pacific.

Disaster Alley, written by the Breakthrough Centre for Climate Restoration, forecasts climate change could potentially displace tens of millions from swamped cities, drive fragile states to failure, cause intractable political instability, and spark military conflict.

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After a decade of policy backflips and uncertainty, we are now being sold ‘technology neutral’ energy policy. But we need it to be discriminatory – and favour clean power

Ten years ago today Malcolm Turnbull was getting stuck in to a debate in Parliament House with Peter Garrett about climate change.

Climate change, said Turnbull, was “an enormous challenge and probably the biggest one our country faces, the world faces, at the moment.”

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• Oil giants among numerous firms to support conservative group’s plan
• But Greenpeace says: ‘A PR exercise is no cure for decades of deception’

Oil giants ExxonMobil, Shell, BP and Total are among a group of large corporations supporting a plan to tax carbon dioxide emissions in order to address climate change.

The companies have revealed their support for the Climate Leadership Council, a group of senior Republican figures that in February proposed a $40 fee on each ton of CO2 emitted as part of a “free-market, limited government” response to climate change.

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Prof Stephen Hawking has called for leading nations to send astronauts to the Moon by the end of this decade.

After decades in the planning, a space mission to detect gravitational waves finally gets the go-ahead.

• Silent Forest Project map reveals urgent need for conservation protections
• ‘It is terrifying to see the Amazon degraded to this extent,’ scientist says
  

As Brazil’s government steps back from Amazon conservation, the urgent need for stronger protection has been made more apparent by a new data map that highlights the knock-on effect of the forest’s capacity to absorb carbon, regulate temperatures and sustain life.

Related: Wild Amazon faces destruction as Brazil’s farmers and loggers target national park

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As drought grips parts of Kenya, cattle theft has become increasingly violent, with people forced to take refuge from the gun-toting bandits who steal livestock

Rustlers, bandits and gun runners: the gangs vying for cattle in Kenya

All photographs: Will Swanson

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A new survey confirms the use of bicycles as mobility aids and the frustration felt when disabled cyclists are told to dismount

Last week, my charity Wheels for Wellbeing published the results of a national survey of disabled cyclists which is, to our knowledge, the first of its kind. The results largely confirmed our suspicions, including that disabled cyclists – though part of our cycling culture – remain excluded from it in a number of ways.

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A 'thinned' landscape, which provides far from ideal habitat for many species. Author provided

Land clearing is accelerating across eastern Australia, despite our new research providing a clear warning of its impacts on the Great Barrier Reef, regional and global climate, and threatened native wildlife.

Policies in place to control land clearing have been wound back across all Australian states, with major consequences for our natural environment.

One of the recent policy changes made in Queensland and New South Wales has been the introduction of self-assessable codes that allow landholders to clear native vegetation without a permit. These codes are meant to allow small amounts of “low-risk” clearing, so that landholders save time and money and government can focus on regulating activities that have bigger potential impacts on the environment.

However, substantial areas of native forest are set to be cleared in Queensland under the guise of vegetation “thinning”, which is allowed by these self-assessable codes. How did this happen?

Thin on the ground

Thinning involves the selective removal of native trees and shrubs, and is widely used in the grazing industry to improve pasture quality. It has been argued that thinning returns the environment back to its “natural state” and provides better habitat for native wildlife. However, the science supporting this practice is not as clear-cut as it seems.

Vegetation “thickening” is part of a natural, dynamic ecological cycle. Australia’s climate is highly variable, so vegetation tends to grow more in wetter years and then dies off during drought years. These natural cycles of thickening and thinning can span 50 years or more. In most areas of inland eastern Australia, there is little evidence for ongoing vegetation thickening since pastoral settlement.

Thinning of vegetation using tractors, blades and other machinery interrupts this natural cycle, which can make post-drought recovery of native vegetation more difficult. Loss of tree and shrub cover puts native wildlife at much greater risk from introduced predators like cats, and aggressive, “despotic” native birds. Thinning reduces the diversity of wildlife by favouring a few highly dominant species that prefer open vegetation, and reduces the availability of old trees with hollows.

Many native birds and animals can only survive in vegetation that hasn’t been cleared for at least 30 years. So although vegetation of course grows back after clearing, for native wildlife it’s a matter of quality, not just quantity.

Land clearing by stealth?

Thinning codes in Queensland and New South Wales allow landholders to clear vegetation that has thickened beyond its “natural state”. Yet there is little agreement on what the “natural state” is for many native vegetation communities.

Under the Queensland codes, up to 75% of vegetation in an area can be removed without a permit, and in New South Wales thinning can reduce tree density to a level that is too low to support natural ecosystems.

All of this thinning adds up. Since August 2016, the Queensland government has received self-assessable vegetation clearing code notifications totalling more than 260,000 hectares. These areas include habitat for threatened species, and ecosystems that have already been extensively cleared.

It may be that the actual amount of vegetation cleared under thinning codes is less than the notifications suggest. But we will only know for sure when the next report on land clearing is released, and by then it will be too late.

Getting the balance right

Vegetation policy needs to strike a balance between protecting the environment and enabling landholders to manage their businesses efficiently and sustainably. While self-regulation makes sense for some small-scale activities, the current thinning codes allow large areas of vegetation to be removed from high-risk areas without government oversight.

Thinning codes should only allow vegetation to be cleared in areas that are not mapped as habitat for threatened species or ecosystems, and not to an extent where only scattered trees are left standing in a landscape. Stronger regulation is still needed to reduce the rate of land clearing, which in Queensland is now the highest in a decade.

Protecting native vegetation on private land reduces soil erosion and soil salinity, improves water quality, regulates climate, and allows Australia’s unique plants and animals to survive. Landholders who preserve native vegetation alongside farming provide essential services to the Australian community, and should be rewarded. We need long-term incentives to allow landholders to profit from protecting vegetation instead of clearing it.

Our research has shown that Australian governments spend billions of dollars trying to achieve the benefits already provided by native vegetation, through programs such as the Emissions Reduction Fund, the 20 Million Trees program and Reef Rescue. Yet far more damage is inflicted by under-regulated clearing than is “fixed” by these programs.

Imagine what could be achieved if we spent that money more effectively.

April Reside receives funding from NESP Threatened Species Recovery Hub. She sits on the Black-throated Finch Recovery Team and Birdlife Australia's Research and Conservation Committee.

Anita J Cosgrove receives funding from the Australian Research Council. She is a member of the Black-throated Finch Recovery Team, BirdLife Australia and the Australian Conservation Foundation.

Jennifer Lesley Silcock receives funding from the NESP Threatened Species Hub at the University of Queensland.

Leonie Seabrook receives funding from the Australian Research Council.

Megan C Evans receives funding from the National Environmental Research Programme Threatened Species Recovery Hub.

US researchers believe worst event on record is ending but fear coral won’t recover in time before oceans warm again

The worst coral bleaching event in recorded history, which has hit every major coral region on Earth since 2014, appears to be coming to an end, with scientists now worrying how long reefs will have to recover before it happens again.

After analysing satellite and model data, and finding bleaching in the Indian ocean no longer appeared widespread, the US National Oceanographic and Atmospheric Administration (Noaa) has announced the event is no longer occurring on a global scale, and appears to be coming to an end.

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The elephants were killed in the Hwange national park by what has become a common means of poaching

Ten elephants, including a mother and her young calf, have been found poisoned in and around Zimbabwe’s premier game reserve, Hwange national park. Six of the animals died in the south of the park last week; some had their tusks hacked off. The others were found outside the northern sector of the park in state forestry land.

Park rangers responded quickly. A bucket of poison was found near the gruesome scene in the north and three arrests were made over the weekend. One of those arrested was found in possession of ivory.

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Aigas Field Centre, Beauly, Highlands I am struck by the way the willow expresses the richness entailed in a drawn-out death

Just 10 minutes down the valley from this outstanding educational institute is the largest goat willow in Britain. The veteran is tucked away at the roadside amid a line of alders and so sunk in a deep and almost subaquatic gloom that you could easily miss it. A visit also requires a minor girding of loins to brave the midge-laden atmosphere, although meeting the tree on intimate terms is worth any amount of insect nuisance.

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Australians are used to seeing politics switch to vaudeville when it comes to climate policy. This year we’ve been treated to a new farce.

Belectric plans two more small solar farms by end of year after completing first with new, low cost installation system.

Invitation to comment on an application for a developmental wildlife trade operation under part 13A, section 303FN of the EPBC Act. Comments close 21 July 2017.

Turnbull caves in to fossil fuel lobby push for more "continuous power" and asks AEMO to assess needs of the grid. "It would be good to have a state of the art clean coal plant in Australia," he said.

All Ice Energy products now available in Australia exclusively through Apricus.

FELINE HISTORY: A new study on how cats conquered the world - and our hearts - has answered long-standing questions.