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 Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.

nachricht 100 % Organic Farming in Bhutan – a Realistic Target?
15.06.2018 | Humboldt-Universität zu Berlin

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: Temperature-controlled fiber-optic light source with liquid core

In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.

Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...

Im Focus: Overdosing on Calcium

Nano crystals impact stem cell fate during bone formation

Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Graphene assembled film shows higher thermal conductivity than graphite film

22.06.2018 | Materials Sciences

Fast rising bedrock below West Antarctica reveals an extremely fluid Earth mantle

22.06.2018 | Earth Sciences

Zebrafish's near 360 degree UV-vision knocks stripes off Google Street View

22.06.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>