North Carolina State University: Stadtbäume können höhere Temperaturen gut verkraften – wenn sie genug Wasser haben

Am 11. März 2018 erschien in der Welt ein Interview mit Gerhard Reese, 36, Umweltpsychologe an der Universität Koblenz-Landau, in dem er das Konzept des moralischen Kontos erläutert:

Klimapsychologie: Sind wir zu dumm für den Klimawandel?

[...]

WELT: Da haben Sie aber auch Klima vernichtet, weil Sie hingeflogen sind.

Reese: Natürlich. Das ist auch Mist. Ich muss zu wissenschaftlichen Konferenzen fliegen und propagiere den Umweltschutz. Das ist tatsächlich problematisch. Wir Psychologen sprechen in dem Zusammenhang vom moralischen Konto: Wenn es gut gefüllt ist, können wir öfter mal über die Stränge schlagen.

[...]

Ein spannendes Konzept: Die “Guten” dürfen die Umwelt stärker verpesten als die vermeintlich “Bösen”, denn sie haben ein gut gefülltes ethisches Umweltkonto. Da haben sich die Aktivisten eine tolle Lösung für ihr Reiseproblem ausgedacht.

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Gefährden steigende Temperaturen unsere Stadtbäume? Diese Frage beantwortete jetzt die North Carolina State University. In einer Pressemitteilung vom 13. März 2018 (via Science Daily) erläuterten die Forscher, dass steigende Temperaturen kein Problem für die Bäume darstellen, solange sie genug Wasser bekommen:

Lack of water is key stressor for urban trees

A study out March 13 [2018] finds that urban trees can survive increased heat and insect pests fairly well — unless they are thirsty. Insufficient water not only harms trees, but allows other problems to have an outsized effect on trees in urban environments.

“We would see some vibrant urban trees covered in scale insects, but we’d also see other clearly stressed and struggling urban trees covered in scale insects,” says Emily Meineke, a postdoctoral researcher at Harvard and first author of a paper on the study. “We wanted to know what allowed some trees to deal with these pests so much more successfully.” “This is important because trees need to grow in order to perform valuable ecosystem services, such as removing pollutants from the air and storing carbon,” says Steve Frank, an associate professor of entomology at North Carolina State University and co-author of the paper.

It’s extremely difficult to design a field study that addresses these questions about the role of various environmental variables, given all of the uncontrolled factors in an urban environment. So the researchers used both field data and controlled laboratory experiments. The researchers collected detailed data on 40 urban willow oaks (Quercus phellos) over the course of two years. The data included temperature, how water-stressed the trees were, and the density of scale insects. Scale insects (Parthenolecanium species) are well-known tree pests. But the researchers also conducted laboratory experiments using willow oak saplings. In these experiments, the researchers manipulated three variables while growing the willow oaks: temperature, water and the presence of scale insects.

The researchers found that higher temperatures could actually have a positive effect on tree growth, as long as the trees had adequate water. And scale insects had little or no adverse effect on the trees if the trees were not water stressed. The researchers also found that water stress limited tree growth all by itself. But the presence of increased heat and/or scale insects, when combined with water stress, had a multiplier effect — curtailing growth far more than water stress or scale insects alone.

“This tells us that management strategies aimed at increasing tree hydration in cities may reduce the adverse effects of all three of these key stressors,” says Meineke, a former Ph.D. student in Frank’s lab. “And that is likely to become increasingly important as water availability, temperature and pest abundance are affected by further urbanization and climate change.” “For example, urban planners could design urban landscapes that retain stormwater in vegetation; invest in hydration strategies, such as appropriate soil quality and soil volume; and plant drought-tolerant tree species and genotypes in the hottest parts of their cities,” Frank says. “Moving forward, we’re very curious about the prevalence of water stress in urban trees globally — and whether this leads to similar problems regarding the impact of tree pests,” Meineke says. “If so, improved tree hydration could become a higher priority for urban forestry management.”

Paper: Emily K. Meineke, Steven D. Frank. Water availability drives urban tree growth responses to herbivory and warming. Journal of Applied Ecology, 2018 DOI: 10.1111/1365-2664.13130

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Wer hätte das gedacht: Auch Fahrradfahren hinterlässt einen CO2-Fußabdruck. Und der kann unter Umständen sogar höher sein, als wenn man dieselbe Strecke mit dem PKW fahren würde. Stimmts? Interessante Thesen auf heritage.org:

Go Green With Gasoline If You’re Going to Consume That Sandwich

Key takeaways:

Researchers at the University of Manchester offer helpful tips on Earth-friendly sandwich making. Among them: Avoid using lettuce, tomatoes, cheese, and meat.

We are told CO2 emissions from the life-cycle process of producing a sandwich is equal to that of driving a car 12 miles.

A bicyclist would need to eat 1.3 sandwiches to go 12 miles. The CO2 footprint of riding a sandwich-fueled bike would be 30 percent higher than driving a car.

Ganzen Artikel hier lesen.