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American elms tested for city life – Boston University News Service – Boston, Massachusetts

Boston, Massachusetts 2020-11-22 09:00:00 –

Lillian Eden
BU news service

Field trials to test the spirit of American elm in the city have entered its first growth phase. This is the culmination of decades of research aimed at restoring elm to urban spaces and forests throughout the United States.

American elm was once the most popular urban tree in the United States and provided deep shade and cooling due to its high height and dense canopy. In the 1930s, they wilted due to Dutch elm disease and began to turn yellow. DED is caused by a fungus carried by native and invasive elm beetles that sneak into the bark of trees, both alive and dead, and spread the disease.

Some trees survived, and over the years, scientists cloned them and tested and mated them to create genetically diverse elm populations. Trees have already been reintroduced into natural forest habitats, but elm has never been tested this way in the city.

“I think the level of resistance we have achieved is probably sufficient to restore wild species. We still don’t know if it’s sufficient for the urban environment,” said the floodplain of the environmental nonprofit The Nature Conservancy. Ecology and conservation researcher Christian Marks, who is involved in a project working on forest research in Japan, said.

Elms are fast-growing, native, provide vast cool shades and connect the streets of the city to larger ecosystems. This is an advantage that cannot be easily reproduced. Elm alien species do not grow very large or have a low canopy density and are not very palatable to native insect populations. At least historically, it has been a valuable asset to urban forests, coupled with resistance to harsh urban life.

In a 1900 illustrated book before the arrival of Dutch elm disease, American elm was described as “one of the most spectacular of all American trees.”Images from the Biodiversity Heritage Library / Smithsonian Library

In a new study, part of a large, long-term project by the U.S. Department of Forestry, researchers plant DED-resistant Nile clones in a variety of urban conditions, from quiet city parks in Columbus, Ohio to harsh sidewalks. I did. Newark, Delaware; and Philadelphia.

Cornelia Pinchot, a research ecologist at the US Department of Forestry, who oversees Ohio’s experiments, said: For example, roadside trees have no protection from other trees and can be exposed to excessive salt and heat reflections on pavement and concrete.

A total of 135 elms, excluding a few that didn’t become “leaves” this spring, are doing well, according to Pinshaw. They were planted last fall with the help of volunteers, but researchers aren’t sure if the trees are sufficiently DED resistant for years to come.

“If you want to see the ultimate success of roadside trees, you won’t get the answer for 30 years. Unless they all die in the first year, and you have your answer,” Pinshaw jokes. Said. “It’s just a tree, you know, it’s slow.”

Danielle Mikolajewski, a graduate student at the University of Delaware, is studying what happens to trees in the first year as part of her master’s degree. She didn’t check the trees much this spring due to coronavirus restrictions, but she didn’t see much anyway.

“These trees look almost like big sticks, like branches stuck in the ground,” she said. “The two dead ones look like two long rods without leaves, but the remaining ones now have leaves.”

Mikolajewski examines how the tree reacts to where it was planted. She records how much the trees grow, their stress levels, and whether they are absorbing soil nutrients.

“Who cares if they are resistant to Dutch elm disease if they don’t grow up?” She said. “We did our best to plant them as much as possible. Otherwise, it’s like letting us run the course naturally.”

Maintaining the trees that researchers are working on to maintain consistent management is very easy, including mulching, watering, and pruning to prevent weed growth.

Results may be slow, but the inherited nature of the study is similar to the inherited nature of the tree itself, which is as part of the cityscape as buildings and monuments.

“This is a long process with many experiments, and the study was started by long scientists after retiring decades ago,” Marks said. “And each scientist has made some progress through his career towards the ultimate goal of species recovery.”

This article was originally published by the National Association of Science Writers

American elms tested for city life – Boston University News Service Source link American elms tested for city life – Boston University News Service

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