Latest news with #trees
Yahoo
16 minutes ago
- Science
- Yahoo
Could trees know when the summer solstice is?
This article was originally featured on The Conversation. People have been celebrating the summer solstice with elaborate rituals since prehistoric times. But humans aren't the only species to take mark June 21 as a special time. Studies are showing the summer solstice is an important cue for plants too. Recent studies, including one of my own, have proposed that trees may use the longest day of the year as a key marker for their growth and reproductive cycles. The solstice seems to act like a calendar reminder for trees. For example, at the solstice, trees growing in cold places slow down the creation of new wood cells and focus their energy on finishing already formed but still incomplete cells. This ensures trees have time to complete cell construction before winter hits. Incomplete cells are damaged by freezing winter temperatures, rendering them useless for water transport the following year. Along similar lines, trees use the solstice to fine-tune the 'winding down', or senescence, of their leaves in preparation for autumn. Senescence allows the tree to reabsorb critical nutrients from the leaves before they fall. This process is timed to balance missing out on sunlight from 'winding down' too early, against leaving it too late and losing nutrients if still-green leaves are killed by autumn frosts. Satellite observations of forests, and controlled experiments in greenhouses, reveal that warmer temperatures immediately prior to the solstice cause the onset of leaf browning to start earlier that autumn. In contrast, warmer temperatures just after the solstice slow down the senescence process. This means a longer transition period from green to fully brown leaves. This fine-tuning enables trees to extend the period of photosynthesis in years when temperatures stay warmer for longer, so they don't miss out on these favourable conditions. But not all scientists are convinced. From an evolutionary perspective, the solstice may not be the best seasonal marker for timing these transitions. For example, in forests in the far north, leaves do not appear until early June, only days before the solstice, and the growing season can extend late into October. In these forests, using the solstice to initiate the winding down process makes little sense for trees that have only just started growing for the year. Nevertheless, there is more consensus about plants using the solstice to synchronise reproduction. In many plants, especially trees from the temperate mid-latitudes, the number of seeds they produce varies dramatically year on year, known as masting. A large European beech tree can produce hundreds of thousands of seeds in a bumper year (a 'mast event') and forgo reproduction altogether in other years. Beech trees vary their annual seed production in step, often on a continental scale. They do this to increase the efficiency of their reproduction. A small moth, Cydia fagiglandana, lays its eggs in beech flowers. When the grubs hatch, they eat and destroy the developing seeds. Cycles of famine and bumper years help protect their seeds from these moths. UK beech trees typically lose less than 5% of their seeds to Cydia because the cycles starve the moths into low numbers ready for masting years. But when trees are out of sync, seed loss can increase to over 40%. For decades we have known that beech mast events happen in the year after a warm summer. These warmer temperatures trigger an increase in the formation of flower buds. More flower buds usually lead to a greater crop of seeds that autumn. Scientists have long puzzled over how beech trees across Europe seem to use the same seasonal window to control mast events. Their seed production is determined by temperatures in late June and early July, irrespective of where they grow in Europe. But how can a beech tree know the date? In my team's 2024 study, we showed that they use the solstice as a seasonal marker. As soon as the days start to shorten after the solstice, beech trees across Europe seem to simultaneously sense the temperature. Anywhere temperatures are above average in the weeks following the solstice can expect to have a mast event the next year. Weather conditions in the weeks before the solstice, by contrast, seem to be irrelevant. As seen on weather maps, warm and cool spells tend to occur simultaneously over large areas. This allows beech trees to maximise the synchrony of their reproduction, whether that is investing in a mast year (warm temperatures), or forgoing reproduction for a year (low temperatures). Using a fixed marker like the solstice is the key to achieving this synchrony, and the benefits that come from it. The evidence for this phenomenon has come from observations across dozens of forests across Europe. However, my research group is collaborating with about a dozen other groups in Europe to test this effect by manipulating the temperature of beech branches before and after the solstice at different sites. Ongoing research I am involved with seems to show flowering genes are activated at the summer solstice. Also, studies into the circadian rhythms of plants show they have mechanisms in their molecules that allow them to detect and respond to tiny changes in day length. This is the basis for that extraordinary scale of synchronised reproduction. If the weather is warm over the next month or so, then there is a good chance that beech trees in your local area will have heavy seed crops next autumn. What's more, trees across the UK and into northern and central Europe will probably be doing the same.
Yahoo
9 hours ago
- Science
- Yahoo
Why the summer solstice is a ‘celestial starting gun' for trees
For millennia, the summer solstice has marked a pivotal moment in the human calendar – a turning point steeped in mythology, when the oak king is said to yield to the holly king, and the days begin to shorten. Now, science is increasingly revealing that trees really do respond to this celestial shift, with changes in their growth and reproductive strategies occuring immediately after the calendar's longest day. A study gives fresh insights into why this happens, with implications for how forests might adapt to changing climates. Although it has long been known that plants use daylight to cue seasonal activities such as leaf growth, botanists have recently begun to question whether the summer solstice itself, which occurs between 20 and 22 June in the northern hemisphere, could act as a celestial 'starting gun' for certain events. Last year, researchers led by Prof Michał Bogdziewicz at Adam Mickiewicz University in Poland discovered that, regardless of where in Europe beech trees live, they abruptly open a temperature-sensing window on the solstice, using it to decide how many seeds to manufacture the following year. If it is warm in the days after the solstice, they will produce more flower buds the following spring, leading to a bumper crop of beech nuts in the autumn. But if it's cool they might produce none – a phenomenon known as masting. 'The window of temperature sensitivity opens at the solstice and remains open for about 30 to 40 days. There is no other phenomenon that could so tightly anchor beech trees all across Europe at exactly the same time,' Bogdziewicz said. Swiss researchers also recently discovered that trees in temperate horthern hemisphere forests seemingly switch their growth strategy at around the solstice: warm temperatures before this date accelerate the ageing of their leaves, whereas warm temperatures after it slow down this process. This means it takes longer for their leaves to turn brown in the autumn, maximising their ability to photosynthesise and grow when conditions are favourable. The latest study, published in Proceedings of the National Academy of Sciences, provides a fresh insight into the relationship between trees and the summer solstice. Dr Victor Van der Meersch and Dr Elizabeth Wolkovich at the University of British Columbia in Vancouver, Canada, analysed 1,000 years of temperature records across Europe and North America, combining them with future climate projections. Their findings suggest that trees reach their thermal optimum – the temperature range where their physiological processes hum most efficiently – around the summer solstice. Remarkably, this peak has remained stable across centuries. 'In Spain the optimal period is slightly earlier, and in Scandinavia it is slightly later – on average across Europe and North America, the summer solstice seems to be an optimal time for plants to make decisions,' Van der Meersch said. 'This was quite surprising because the warmest days are usually in July or August – they are not around the summer solstice.' If the solstice consistently coincides with peak growing conditions, it could make evolutionary sense for plants to use it as a cue – especially since this thermal sweet spot appears to have held steady across time. 'Plants are always trying to find a balance between risk and opportunities,' Van der Meersch explained. 'The further they go into the growing season, the easier it is for them to know if it's a good growing year or a bad one – but there's also less time left to use this information.' The solstice seems to represent a critical juncture in this decision-making process. 'It makes sense for them to switch between one growth strategy or another at this time.' However, the question of whether they are sensing the change in day length, or a coincidental sweet spot in temperature, remains open. While researchers like Bogdziewicz are exploring how trees detect changes in day length at around the solstice, Van der Meersch thinks temperature may be playing a larger role than previously appreciated. 'Rather than sensing the solstice, perhaps what really matters are the temperature accumulation patterns at around this time,' he said. However, because there is a strong correlation between temperature and day length, 'we need a lot more research to disentangle these complex signals',' he added. 'It is also possible that they rely on a combination of both summer solstice and thermal cues to optimise growth and reproductive timing.' Understanding the mechanism is important, because it could have implications for how forests adapt to the climate crisis. 'If plants are using warmth signals rather than day length this might be a good thing, because they could have a better ability to adapt to local environmental conditions,' Van der Meersch said. 'If they are relying on day length, the solstice will always be fixed to around 21 June, so there is less flexibility.'
The Guardian
12 hours ago
- Science
- The Guardian
Why the summer solstice is a ‘celestial starting gun' for trees
For millennia, the summer solstice has marked a pivotal moment in the human calendar – a turning point steeped in mythology, when the oak king is said to yield to the holly king, and the days begin to shorten. Now, science is increasingly revealing that trees really do respond to this celestial shift, with changes in their growth and reproductive strategies occuring immediately after the calendar's longest day. A study gives fresh insights into why this happens, with implications for how forests might adapt to changing climates. Although it has long been known that plants use daylight to cue seasonal activities such as leaf growth, botanists have recently begun to question whether the summer solstice itself, which occurs between 20 and 22 June in the northern hemisphere, could act as a celestial 'starting gun' for certain events. Last year, researchers led by Prof Michał Bogdziewicz at Adam Mickiewicz University in Poland discovered that, regardless of where in Europe beech trees live, they abruptly open a temperature-sensing window on the solstice, using it to decide how many seeds to manufacture the following year. If it is warm in the days after the solstice, they will produce more flower buds the following spring, leading to a bumper crop of beech nuts in the autumn. But if it's cool they might produce none – a phenomenon known as masting. 'The window of temperature sensitivity opens at the solstice and remains open for about 30 to 40 days. There is no other phenomenon that could so tightly anchor beech trees all across Europe at exactly the same time,' Bogdziewicz said. Swiss researchers also recently discovered that trees in temperate horthern hemisphere forests seemingly switch their growth strategy at around the solstice: warm temperatures before this date accelerate the ageing of their leaves, whereas warm temperatures after it slow down this process. This means it takes longer for their leaves to turn brown in the autumn, maximising their ability to photosynthesise and grow when conditions are favourable. The latest study, published in Proceedings of the National Academy of Sciences, provides a fresh insight into the relationship between trees and the summer solstice. Dr Victor Van der Meersch and Dr Elizabeth Wolkovich at the University of British Columbia in Vancouver, Canada, analysed 1,000 years of temperature records across Europe and North America, combining them with future climate projections. Their findings suggest that trees reach their thermal optimum – the temperature range where their physiological processes hum most efficiently – around the summer solstice. Remarkably, this peak has remained stable across centuries. 'In Spain the optimal period is slightly earlier, and in Scandinavia it is slightly later – on average across Europe and North America, the summer solstice seems to be an optimal time for plants to make decisions,' Van der Meersch said. 'This was quite surprising because the warmest days are usually in July or August – they are not around the summer solstice.' If the solstice consistently coincides with peak growing conditions, it could make evolutionary sense for plants to use it as a cue – especially since this thermal sweet spot appears to have held steady across time. 'Plants are always trying to find a balance between risk and opportunities,' Van der Meersch explained. 'The further they go into the growing season, the easier it is for them to know if it's a good growing year or a bad one – but there's also less time left to use this information.' The solstice seems to represent a critical juncture in this decision-making process. 'It makes sense for them to switch between one growth strategy or another at this time.' Sign up to Down to Earth The planet's most important stories. Get all the week's environment news - the good, the bad and the essential after newsletter promotion However, the question of whether they are sensing the change in day length, or a coincidental sweet spot in temperature, remains open. While researchers like Bogdziewicz are exploring how trees detect changes in day length at around the solstice, Van der Meersch thinks temperature may be playing a larger role than previously appreciated. 'Rather than sensing the solstice, perhaps what really matters are the temperature accumulation patterns at around this time,' he said. However, because there is a strong correlation between temperature and day length, 'we need a lot more research to disentangle these complex signals',' he added. 'It is also possible that they rely on a combination of both summer solstice and thermal cues to optimise growth and reproductive timing.' Understanding the mechanism is important, because it could have implications for how forests adapt to the climate crisis. 'If plants are using warmth signals rather than day length this might be a good thing, because they could have a better ability to adapt to local environmental conditions,' Van der Meersch said. 'If they are relying on day length, the solstice will always be fixed to around 21 June, so there is less flexibility.'
BBC News
12-06-2025
- Health
- BBC News
Hay fever 2025: What is it and how can you treat the symptoms?
The official start of summer is just around the corner. The weather is feeling warmer and lots of plants are in bloom. This also means that there is more pollen in the air. With pollen comes hay fever, an allergic reaction to pollen, which can mean a runny nose and itchy eyes for many to the Met Office, the UK's national weather service, pollen levels will be high in many areas of the UK over the next five days, with differences depending on where you what exactly is hay fever and what are the ways we can improve symptoms? Read on to find out. What is the pollen count? People with hay fever can check how high the levels of pollen in the air are by watching special weather well as telling you about the weather, presenters can also give a pollen count, to warn people when the levels are Met Office record the pollen count for five days ahead across the whole of the the next five days they have predicted that in some areas the pollen will be high, and in some it could be very high. However, this does vary depending on where you live, so it is important to check the information for your local area. What is hay fever? Hay fever is an allergy. People who have it are allergic to is a type of fine powder which is released by lots of different plants and are three different types of pollen - tree pollen, grass pollen and weed are lots of proteins in pollen which can cause your nose, eyes and throat to become swollen or irritated if you are allergic to you have hay fever you might suffer from an itchy throat, itchy eyes, a runny nose, or sneezing. All of these are signs of your body is trying to protect itself by getting rid of the pollen. Who is likely to get hay fever? Hay fever is one of the most common allergies in the UK, affecting about 13 million can get it at any age, although it usually starts when you are everyone has hay fever, but it is more common in people whose family members already have it or if you have fever is also more common in people with other can be affected by different types of pollen as example, there is a lot of tree pollen in the spring, grass pollen in the summer and weed pollen in the autumn. Tips for dealing with hay fever symptoms Although there is no cure for hay fever, people who have it can manage the symptoms in many different tips include:Wearing sunglasses to help stop as much pollen getting into your freshly cut clothes if you have been spending too long outside in the early evening when the pollen count can be windows at night-time.
Yahoo
31-05-2025
- Health
- Yahoo
Trees can help detect volcano eruptions: Study
(NewsNation) — A recent study says trees may now be able to help detect when a volcano is about to erupt. The study by NASA and the Smithsonian Institution, looking at carbon dioxide levels around Mount Etna in Italy, compared data from sensors around the volcano with satellite imagery and discovered a strong relationship between more carbon dioxide and greener trees. 'There are plenty of satellites we can use to do this kind of analysis,' said Nicole Guinn, a volcanologist at the University of Houston. Dozens sickened in expanding salmonella outbreak linked to recalled cucumbers Across the course of two years, Guinn and a group of researchers found 16 clear spikes in carbon dioxide and the NDVI, matching magma movements underground. The patterns of the spikes were even observed farther away from faults in the mountain. When volcanoes become more active and near eruption, they push magma up closer to the surface while also releasing increased levels of carbon monoxide. The carbon monoxide boosts the health of the surrounding trees and makes the leaves greener. Copyright 2025 Nexstar Media, Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.
