Warming makes flowers change dates, or don skates

Blue Fleabane (Erigeron acer) has only moved its flowering date forward around by 3 days in 50 years, and instead the places where it's found in the UK have moved north by around 9 miles. Image credit: Vlad Proklov, used via Flickr Creative Commons licence.

Blue Fleabane (Erigeron acer) has only moved its flowering date forward around by 3 days in 50 years, and instead the places where it’s found in the UK have moved north by around 9 miles. Image credit: Vlad Proklov, used via Flickr Creative Commons licence.

If plants can’t flower earlier to adapt to global warming they’re probably being driven away from where they used to grow, towards cooler places. That’s what new findings on how these responses are linked from Tatsuya Amano at the University of Cambridge and his teammates suggest. “We believe that the link we’ve revealed will help us understand the complex implications of climate change on biodiversity,” Tatsuya told me. “Many studies have relied on models that only consider species’ spatial responses for projecting the impact of climate change on species. We might be able to generate more realistic projections.”

You could think of regular natural events, such as flowering in plants, as being triggered by an alarm clock – another type of dandelion clock, if you like. The study of when those alarms go off is known as phenology. In 2009, Tim Sparks from Coventry University visited Tatsuya, Bill Sutherland and others in Cambridge to give a talk on changes in when these events were happening. He was helped by notes on plant life many people in the UK had jotted down in their spare time, but that data’s inevitable patchiness caused him problems.

Bill and Tatsuya were working on mathematical models that helped fix similar problems in bird count data, and so they offered to help Tim with his work. They were also joined by Richard Smithers, then in charge of the Nature’s Calendar archive run by the UK’s Woodland Trust. He helped them realise the power of this publicly-accessible record of over 250 years’ worth of data on 405 UK species, nearly 400,000 records in all. Using that information, in 2010 the team showed that UK flowers are now blooming earlier in the year than in any 25-year period since 1760.

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Worse extreme temperature effects urge farming precautions

Stanford University's Sharon Gourdji talks about her study on increasing extreme heat during sensitive crop flowering periods. Credit: IOP Publishing, via Creative Commons license, see citation below.

Since 1980, maize and wheat crops in many places have been increasingly exposed to extreme heat during sensitive flowering phases that can damage them and cause harvests to fail. That’s according to scientists at Stanford University, California, who predict that this problem will increase for these crops, and also hit rice. In fact, the area of maize and rice hit by such deadly heat is set to expand more quickly through to the 2050s. “Crop breeders need to think carefully about how to incorporate heat tolerance, particularly during the flowering period, into wheat, maize and rice,” Stanford’s Sharon Gourdji told me.

Our warming climate affects farming in many ways. For example higher temperatures, and the higher CO2 levels that are primarily responsible for them, can speed up the photosynthesis process that makes plants grow. Meanwhile, shifting rainfall patterns are set to have serious impacts on important farming areas. In 2011, Sharon’s teammate David Lobell and other scientists showed that overall crop production growth worldwide has been held back by such changes in the last three decades. But they didn’t discuss how environmental changes might influence future food availability.

“The net impact of all these factors is the golden question, but notoriously difficult to model,” Sharon explained. “Also, the most relevant of these factors, and the associated adaptation measures, differ by location and crop. Therefore most modelling studies to date look at net impacts on just a given region, or type of cropping system.” To make worldwide predictions that could help secure our future food supply, Sharon’s team had to concentrate on a smaller, simpler issue. “We focused on extreme heat during flowering,” Sharon said. “This is one aspect of global environmental change that could be particularly risky for crops regardless of other more gradual changes that are taking place simultaneously.”

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Iconic authors help reveal record early flowering

"When I wrote the following pages, or rather the bulk of them, I lived alone, in the woods, a mile from any neighbor, in a house which I had built myself, on the shore of Walden Pond, in Concord, Massachusetts, and earned my living by the labor of my hands only." Those are the famous opening lines to Henry David Thoreau's Walden. Now, scientists have used Thoreau's notes on his surroundings to show how much earlier global warming has pushed plant flowering. Credit: Tim Hettler, via Flickr

“When I wrote the following pages, or rather the bulk of them, I lived alone, in the woods, a mile from any neighbor, in a house which I had built myself, on the shore of Walden Pond, in Concord, Massachusetts, and earned my living by the labor of my hands only.” Those are the famous opening lines to Henry David Thoreau’s Walden. Now, scientists have used Thoreau’s notes on his surroundings to show how much earlier global warming has pushed plant flowering. Credit: Tim Hettler, via Flickr

Notes from the last 150 years made by two environmental pioneers have helped show that the speed at which global warming is pushing spring events forward is not slowing. Boston University’s Libby Ellwood and her teammates compared flowering times recorded by Henry David Thoreau and Aldo Leopold to spring 2010 and 2012, the warmest and second warmest on record.  “Plants flowered earlier than ever before in these recent record warm years,” Libby told me. That advance is so closely linked to the warming our world’s experiencing, the researchers showed that they can predict flowering time from temperature. This knowledge could help predict climate change’s impact on crops.

“There will likely be winners and losers with climate change,” Libby said. “It is quite possible that some species will be able to use the warmer temperatures and longer growing season to their advantage. The risk for plants that begin growing as soon as the weather is warm though, is that the new spring growth and flowers are susceptible to late season frosts, and this can set back plant growth and reproduction.”

To understand what global warming is doing to other organisms, scientists have to find records about them from times when fossil fuel burning wasn’t as widespread as today. Thoreau and Leopold are best known as authors of books that lay the foundations of modern environmentalism. Both Thoreau’s Walden and Leopold’s A Sand County Almanac, published in 1854 and 1949 respectively, hold powerful ideas on the relationship between humans and nature. But both authors also studied phenology – the cycle of biological events such as plant flowering throughout the year. Read the rest of this entry »

If you question the numbers, ask the plants

The 2012 Plant Hardiness Zone Map unveiled by the US Department of Agriculture this week shows average annual extreme minimum temperatures based on data from 1976-2005.This version is modified to use the same colour code as 1990. See the end of the entry for original image and link to USDA interactive map. Credit: US Department of Agriculture/Friend of the Earth

The 2012 Plant Hardiness Zone Map unveiled by the US Department of Agriculture this week shows average annual extreme minimum temperatures based on data from 1976-2005.This version is modified to use the same colour code as 1990. See the end of the entry for original image and link to USDA interactive map. Credit: US Department of Agriculture/Friend of the Earth

You may have heard of dandelion clocks, but have you ever thought of looking at plants to check the temperature? It may not give you a precise reading, but changes in where plants can live in the US and when they grow in China have clearly demonstrated global warming this month. They reinforce the recently reported worldwide average surface temperature for 2011, providing a real world example of the climate change shown in scientists’ graphs.

Much of the US was one 5°F (2.8°C) half-zone colder in the 1990 Plant Hardiness Zone Map compared to the latest version. Credit: US Department of Agriculture

Much of the US was one 5°F (2.8°C) half-zone colder in the 1990 Plant Hardiness Zone Map compared to the latest version. Credit: US Department of Agriculture

On Wednesday, the US Department of Agriculture (USDA) unveiled its latest map of planting zones, which has been redrawn to reflect warming seen since the last version was published in 1990. The Plant Hardiness Zone Map shows zones representing average annual extreme minimum temperatures. The old map was based on temperatures from 1974-1986, but updating it to include temperatures from 1976-2005 has shifted many zone boundaries. Though that’s in part due to new technology and better weather data, across much of the US the map is one 5°F (2.8°C) half-zone warmer.

And while the USDA says that the map is “not a good instrument” to assess climate change, David Wolfe, professor of plant and soil ecology in Cornell University’s Department of Horticulture says it’s being too cautious. “At a time when the ‘normal’ climate has become a moving target, this revision of the hardiness zone map gives us a clear picture of the ‘new normal,’ and will be an essential tool for gardeners, farmers, and natural resource managers as they begin to cope with rapid climate change,” he told Associated Press reporter Seth Borenstein. Read the rest of this entry »

The hills are alive – with a changing plant mix

This alpine species (Nevadensia purpurea) could disappear from some European mountains in the next few decades Credit: Harald Pauli

This alpine species (Nevadensia purpurea) could disappear from some European mountains in the next few decades Credit: Harald Pauli

Higher temperatures could lead plants living at the top of Europe’s mountains to decline and disappear, as they face greater competition with plants from warmer, lower levels. That’s one finding from surveys of 17 mountain areas conducted by 17 different research teams, co-ordinated by Harald Pauli from the University of Vienna and Austrian Academy of Sciences. Comparing surveys performed in 2008 and 2001 shows that changes are already happening across the continent, and faster than the scientists might have thought. “Alpine vegetation often is given as an example of a highly resilient ecosystem, with slow-growing but long-lived plants that may not see dramatic changes over decades,” Pauli said. “Based on previous studies, we did expect that species composition will change, but not that we would get a significant signal after just 7 years.”

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Climate rhythm shift brings early calving

The Chillingham cattle are said to be the only survivors of the wild herds which once roamed freely through the forests of Great Britain. Credit: Sarah Burthe

The Chillingham cattle are said to be the only survivors of the wild herds which once roamed freely through the forests of Great Britain. Credit: Sarah Burthe

Climate change has caused more of the British wild cattle of Chillingham to be born in winter, when the chance they will survive to reach a year old is lowest. The cattle, which have lived on a 365 acre park since the 13th century, show that climate’s influence on biological event timing could be greater than realised. “The proportion of births in winter was correlated with the timing of the start of the plant growing season in the previous spring, when winter born calves would have been conceived,” explained Sarah Burthe from the UK’s Centre for Ecology and Hydrology. “More calves were born in winter when the plant growing season started early in the previous spring. Although more births are happening now in the winter than they were 60 years ago, winter-born calves do not do very well relative to calves that are born during summer and are more likely to die before they reach the age of one.”

Though Burthe is currently getting up a 3.30am to study birds on the Isle of May in Scotland, the Chillingham cattle’s unique story made studying the recent climate’s impact on them less gruelling for her. As well as reputedly being the only survivors of wild herds that once roamed the land, thanks partly to the encouragement of Charles Darwin information has been collected about them since 1860. The data Burthe and her colleagues used runs back from the modern herd, which numbered 93 cattle in December, to the unusually cold winter of 1947, which only 13 cattle survived. “This study would not have been possible without the amazing data collected by the Chillingham wild cattle association since 1947,” she said. Read the rest of this entry »

Climate change shifts organisms in space and time

Duke University Biologist Bill Morris. Credit: Duke University

Duke University Biologist Bill Morris. Credit: Duke University

As our climate changes, we might expect to see some familiar plants and animals in our local environment replaced by new ones. That’s according to Bill Morris from Duke University in Durham, North Carolina, who recently published work studying shifts in where mountain plants live in top science journal Nature. “Species will likely be found in different places than where they are found now, creating new combinations that did not interact in the recent past,” he told Simple Climate. “What the consequences of these new interactions will be are hard to predict, because it is difficult to study interactions that don’t currently exist.”

Together with Daniel Doak at the University of Wyoming, Morris studied two tundra plant species whose habitat extends south from the Arctic. Higher global temperatures are expected to make conditions for the moss campion and alpine bistort better at the northern end of their geographical ranges. By contrast, at the southern end higher temperatures might be expected cause the plants to decline. Consequently their southern range limit should move northwards, but Morris and Doak found that in fact this had not happened – at least not yet.

Morris explained that the question of whether species’ ranges are spreading, or if it’s more common for the range to stay the same size, but move, remains unanswered. “We have much better evidence that species such as butterflies and birds are shifting toward the poles and to higher elevations, because these species are more often noticed by amateur naturalists, and because they likely move faster than do plants,” he said. “But we do know that many plants in Europe, where historical information about plant distributions is better, have moved to higher elevations over the last century.” Read the rest of this entry »

Climate-driven species creep hangs in the balance

Studies of moss campions in North America have demonstrated that climate change may create tipping points in populations. Credit: Daniel Doak

Studies of moss campions in North America have demonstrated that climate change may create tipping points in populations. Credit: Daniel Doak

There is overwhelming evidence that many species have shifted the geographical ranges they live in over recent decades, with some actually becoming more widespread. However, adverse effects of climate change could still await these species, say University of Wyoming’s Daniel Doak and William Morris at Duke University in Durham, North Carolina.

Their research shows competing influences are holding the southern range limit of two Arctic and alpine plants in place, while warming forces the northern limit further north. However, their temperature-driven spread may ultimately prove short-lived, Doak warns. “Up to a point we may see little effect of warming for many organisms,” he says. “But past a climatic tipping point, the balance of opposing effects of warming will likely cease, leading to subsequent rapid declines in populations.” Read the rest of this entry »

Naturalists show climate effects from beyond the grave

University of East Anglia's Tony Davy. Credit: University of East Anglia

University of East Anglia's Tony Davy. Credit: University of East Anglia

Ecologist Tony Davy has been inspired by the prospect of working with the new information that insect and flower collectors who have long since passed away are providing him. The British researcher has not invented a time machine to recruit their help, or created an army of zombie assistants. Instead, he has shown that museum collections can be used to obtain data about how species have responded in the past to the temperatures they experienced. That data can help us better understand how our environment will be affected by climate change. “It is exciting to be able to use material collected over hundreds of years for an important purpose that collectors could not have imagined at the time,” Davy said.

To test the idea, the University of East Anglia scientist teamed up with compatriots from the University of Sussex, and the UK’s Royal Botanic Gardens in Kew. “It was really a hunch, but we thought there was a good chance that it could work,” Davy told Simple Climate. Together the team compared when early spider orchids preserved in collections called herbaria were in flower against temperature records for those dates. The results showed that the early spider orchids flowered 6 days earlier for every 1ºC rise in average spring temperature. This matched what team member Michael Hutchings had found when he published 30 years of directly measured data on the relationship between early spider orchid flowering and temperature. Read the rest of this entry »

Spider orchid flowering crawls forward with warming

An early spider orchid

An early spider orchid

Despite global warming accelerating since the 1970s, when early spider orchids in the UK flower still varies with temperature in exactly the same way that it has for the past 150 years. By studying preserved plant specimens known as herbaria, researchers from the Universities of East Anglia, Sussex and Kent have found that orchids consistently flower 6 days earlier for every 1ºC rise in average spring temperature. Measurements of how species react to climate changes are rare, and so this first clear demonstration that herbaria can fill these gaps creates a powerful new scientific weapon.

“It is estimated that some 2.5 billion specimens of flora and fauna are held in biological collections worldwide,” the University of East Anglia (UEA)’s Anthony Davy and colleagues wrote in the Journal of Ecology this week. “With appropriate validation, the exploitation of this resource will have increasing relevance and value as we seek to understand and predict the consequences of continuing climate change.” Read the rest of this entry »

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