Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The science behind why leaves change colour in the Autumn

05.10.2004


Autumn is marked out by spectacular changes in leaf colour as the greens of summer change into the yellows and reds of autumn. In parts of North American whole tourist industries are based on this change, but why do leaves turn these bright colours before falling off the trees?

New work by Dr Dave Wilkinson (an ecologist in the School of Biological and Earth Sciences at Liverpool John Moores University) and his colleague Martin Schaefer (University of Freiburg, Germany), published in Trends in Ecology and Evolution, has added new twists to this autumnal story.

Most biology textbooks, if they mention autumn colour at all, are likely to say that it is the accidental by-product of the death of the leaves. For over one hundred years some biologists have wondered if there may be more to it than accident, but until recently the ‘accidental’ explanation has gone relatively unchallenged.



The autumn leaf story was reinvigorated by the late WD Hamilton (one of the greatest evolutionary theorists of the twentieth century) and two of his former students. They suggested that autumn colour was actually a signal of tree health designed to tell insect pests that they would be better off going elsewhere to attack a less healthy tree. Their idea was that only a healthy tree would have really bright autumn colours. Over the last five years several scientists (including Dr Wilkinson) have published research articles discussing the merits of this new idea.

In their new paper Drs Wilkinson and Schaefer review many recent studies on the chemistry of autumn leaves which strongly suggest that Hamilton’s imaginative idea is wrong.

There is now good evidence to suggest that these colours have evolved to help plants remove important chemicals from their leaves, for reuse next year. The autumn pigments do this by helping the plant continue to use the sun’s energy during the period at the end of the leaf’s life, so providing the energy needed to extract chemical nutrients before leaf fall.

Dr Wilkinson explained: “Contrary to what many people assume, photosynthesis does not stop once leaves change from green to red, and in the autumn, plants can be subjected to a potentially destructive combination of low temperatures and high light levels. The red and yellow pigments act like sunscreen, protecting the plants from the effects of chemicals produced by light acting on the contents of the dying leaf and may actually help plants photosynthesise better at lower temperatures.” Although Dr Wilkinson thinks Hamilton’s idea is wrong he points out that that doesn’t make it a failure.

He continued: “One of the important roles of new theories in science is to force people to think in new ways and to draw attention to overlooked phenomena in need of explanation. Like many biologists, before Hamilton’s theory it had never occurred to me to think hard about autumn leaf colour. The idea that these brief annual shows of colour may have good biochemical explanations, rather than being just an accident, makes them even more extraordinary to look at”.

Shonagh Wilkie | alfa
Further information:
http://www.livjm.ac.uk

More articles from Ecology, The Environment and Conservation:

nachricht Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel

nachricht Removing fossil fuel subsidies will not reduce CO2 emissions as much as hoped
08.02.2018 | International Institute for Applied Systems Analysis (IIASA)

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

Im Focus: Basel researchers succeed in cultivating cartilage from stem cells

Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.

Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Structured light and nanomaterials open new ways to tailor light at the nanoscale

23.04.2018 | Physics and Astronomy

On the shape of the 'petal' for the dissipation curve

23.04.2018 | Physics and Astronomy

Clean and Efficient – Fraunhofer ISE Presents Hydrogen Technologies at the HANNOVER MESSE 2018

23.04.2018 | Trade Fair News

VideoLinks
Science & Research
Overview of more VideoLinks >>>