Månad: augusti 2019

How climate change and a tiny beetle destroy German forests

Publicerat i Climate ChangeLämna en kommentar

Image: Forest in the German Harz Mountains that has been damaged by the bark beetle.

At the moment the news talk a lot about of the wildfires in the Amazon and the Arctic. But climate change and human activity also pose other dangers to forests, as can be seen in Germany.

During this summer family and friends had told me quite a bit about the extreme heat wave and drought in Germany. I had also heard through the news that German forests were suffering as a consequence.

However, none of this prepared me for what I saw when visiting my family home in the Harz Mountains in the middle of Germany.

As long as I can remember, the area around my home town has been covered in dense spruce forests. Much of my childhood was spent roaming these forests, looking for interesting animals and playing with friends.

When we approached my home by car at the end of August it was very clear, that this vast coniferous forest is sick. Like in the image above, many trees had lost their needles and large proportions of the forest had been felled leaving empty, moon-like landscapes.

You might think that the trees are only dying because they do not get enough water, but it is not as simple as that. Yes, the drought and hot temperatures limit the trees water supply. Nevertheless, the coniferous trees are still able to get enough water for their basic functions like photosynthesis. But the lack of water damages the spruce’s ability to defend against pests like the bark beetle.

The bark beetle is a tiny insect measuring about 6 mm (0.25 inch) that reproduces inside tree bark. The male and female drill into a tree to build a chamber for their eggs. After hatching the larvae bore away from the egg chamber feeding on the inner bark. This harms the part of the wood which transports water and food. In addition, the plant’s ability to form fresh bark is decreased. As a consequence, the tree will slowly die.

Like our skin the bark of a tree keeps out diseases and parasites. The normal response to a bark beetle attack is the secretion of tree sap to suffocate the beetles and their larvae. But in the event of extreme drought and heat, the trees cannot produce enough sap. Like the human immune system, the tree’s defenses do not work well under extreme stress.

The bark beetle has always been a pest in the Harz Mountains, my home area. One reason for this is that the trees are grown as a monoculture that mainly includes spruce. Deciduous trees are much more resilient towards the bark beetle and can form a natural barrier when planted in between spruces. Unfortunately, the forest is cultivated and managed by the timber industry which is only interested in the fast-growing spruce.

Despite the old monoculture problem, the current explosion of beetle infections is unprecedented and a consequence of climate change. Summers have continuously gotten hotter. During this year’s July heatwave even the – normally chillier – Harz Mountains reported temperatures above 35 degrees Celsius over several days and many new temperature records. At the same time the amount of rainfall in summer has decreased. Also, warmer temperatures allow more bark beetles to survive the winters.

The sad part of this story is that the National Park in the Harz Mountains is most severely affected. The park was founded in the early 1990s on former timber industry lands, covered with spruce monocultures. The aim was to let the land develop naturally into a mixed forest over many years. Now climate change and the bark beetle seem to be speeding up this process by destroying most of the spruce trees.

While the timber industry removes damaged wood to prevent healthy trees from getting infected, this cannot be done in a National Park where nature must be left to its own devices. As a result, the areas containing sick and dead trees are much larger in the National Park compared to the timber forests. This development could be a chance for deciduous trees to colonize the National Park faster forming a natural, mixed forest.

The future of the timber industry forest is not as clear. It is obvious that spruce monocultures will not survive the changes that global warming brings for much longer. There are now discussions in Germany to introduce foreign tree species that can cope better with heat and drought to replace the spruce. Maybe some forestry commissions will even move towards more natural mixed forests.

Looking at the dead trees and moon-like landscapes right now, I am wondering if this area will ever regain its former beauty. I cannot help but ask if my own children will ever see the vast forests of my own youth here. You do not need wildfires to destroy large amounts of forest. The trees in Germany are being destroyed by climate change and a tiny beetle.

I believe that the Harz Mountains and other German forests will eventually recover, the National Park by slowly developing into a natural, mixed forest and the timber forests possibly by introducing foreign tree species. But there is a chance that the spruce trees, that have been so iconic for German forests over centuries, could be gone.

Women in Science: Rosalind Franklin and the DNA Structure

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Image credit: MRC Laboratory of Molecular Biology – From the personal collection of Jenifer Glynn. 1955. CC BY-SA 4.0.

One of the most important researchers involved in discovering the structure of DNA (deoxyribonucleic acid) would have celebrated their 99th birthday on July 25 this year. No – it is not James Watson or Francis Crick. It is Rosalind Franklin, a brilliant chemist, whose contribution to the discovery of DNA’s structure has gone largely unrecognized.

Rosalind Elsie Franklin was born 1920 in London. Aged only 15 she decided she wanted to be a scientist. Her father discouraged her scientific interest knowing that at the time such a career choice would be very difficult for women. Nevertheless, in 1938 Franklin enrolled at the University of Cambridge to study Chemistry.

After graduating in 1941 Franklin was awarded a research scholarship to complete a PhD. However, this work was cut short by the start of World War II. The young researcher gave up her scholarship in order to work for the British Coal Utilisation Research Association, where she investigated ways to use coal and carbon in the war effort. Fortunately, she could adopt this research into her doctoral thesis and received a PhD from the University of Cambridge in 1945.

In 1947 Franklin went to Paris, where she worked with Jacque Méring, an expert in X-ray crystallography. X-ray crystallography or X-ray diffraction is a technique that uses X-rays to determine the arrangement of atoms in a material. It is still widely used today in scientific research.

Her time in France not only taught Franklin the technique of X-ray crystallography, but also how to tackle scientific challenges. She would later need both skills to discover the structure of DNA.

So, why did people bother to figure out the structure of DNA? DNA or deoxyribonucleic acid is the genetic material inside your cells. DNA is like a blueprint or building plan for your body. It basically tells the cells of your body what to do. Almost all organisms store this building plan as DNA in their cells.

In 1951 Rosalind Franklin returned to Britain joining King’s College in London. There she started applying her knowledge about X-ray crystallography to study DNA. Franklin’s biggest contributions in the hunt for the DNA structure was finding the density of DNA and the insight that DNA forms a helix. A helix is a structure that looks like a cork screw or a wound staircase.

Franklin did not know that she was in a race with two other scientists from the University of Cambridge, James Watson and Francis Crick. Even worse was that Franklin’s colleague at King’s College Maurice Wilkins had developed a friendship with Watson and Crick. Without Franklin’s knowledge or permission Wilkins passed on her results to Watson and Crick.

Finally, Watson and Crick combined Franklin’s findings and her X-ray diffraction images of DNA with their own research. Again, this was all done with neither Franklin’s knowledge nor her permission. In April 1953, together with Wilkins, they announced that the structure of DNA was a double helix, or in other words a wound ladder. The race was over.

Soon after Franklin took a position at Birkbeck College, London, where she continued to work on coal and DNA. In addition, she started to determine the structure of viruses, which Franklin herself saw as her biggest success. Rosalind Franklin died of cancer in April 1958, aged only 37. She never knew of the contribution she had made to discover the structure of DNA.

James Watson, Francis Crick and Maurice Wilkins were awarded the Nobel prize in Medicine for the discovery of the structure of DNA in 1962.

When discussing why Franklin did not receive the Nobel prize, the first argument is always that she died it was awarded in 1962. It is true that the Nobel prize is only awarded to people who are alive. However, in my opinion it is very unlikely that Franklin would have received the prize even if she had been alive in 1962.

There are two reasons for this. The first is that Watson, Crick and Wilkins never mentioned Franklin’s results in their publications despite having used them for their own work. In fact, Franklin never knew herself how much she had contributed to their model.

The second is that at the time women were just not well regarded in Science. When Franklin died in 1962 only three women had ever won the Nobel prize, Marie Curie, Irene Joliot-Curie and Gerty Cori. In addition, she had to battle the sexism in Science in her everyday life by protesting her lower pay and lack of promotion compared to her male colleagues.