CITY TREES VERSUS COUNTRY COUSINS. Dug up after a growing season in two kinds of air pollution, cottonwood trees show the retardant effects of ozone. From left, five city trees from the Bronx, where nitric-oxide pollution reduced the ozone exposure period; Cornell ecologist Jillian Gregg; and five country trees that grew in a high ozone rural environment in Riverhead, Long Island. Photo provided by Jilian Gregg. Copyright © Cornell University
NOT SO LUCKY. Examining tree growth in New York City, Cornell ecologist Jillian Gregg says low-ozone "footprints" in urban areas occur because high nitric-oxide concentrations scavenge ozone from the urban atmosphere. But rural areas arent so "lucky". These same nitric oxide compounds are one of the primary precursors that react to form high ozone concentrations that are blown to rural environments. Once there, nitric oxide is very low in concentration so ozone remains in the atmosphere for a longer period. While individual one-hour peak ozone concentrations are often higher in urban environments, the extended exposure period outside the urban center cause some rural trees to grow only half as fast as their city cousins. Photo provided by Jillian Gregg.Copyright © Cornell University
A tree grows in Brooklyn -- despite big-city air pollutants. Meanwhile, identical trees planted downwind of city pollution grow only half as well -- a surprising finding that ecologists at Cornell University and the Institute of Ecosystem Studies (IES) reported in the current issue of Nature (July 10, 2003). They attribute the effect to an atmospheric-chemistry "footprint" that favors city trees.
"I know this sounds counterintuitive but it’s true. City-grown pollution -- and ozone in particular -- is tougher on country trees," says Jillian W. Gregg, lead author of the Nature cover article, "Urbanization effects on tree growth in the vicinity of New York City." Other authors of the Nature report are Clive G. Jones, an ecologist at the Institute of Ecosystem Studies in Millbrook, N.Y., where some of the field studies were conducted, and Todd E. Dawson, professor of integrative biology at the University of California, Berkeley, and a professor at Cornell when the study began.
Gregg was a joint Cornell/IES graduate student, pursuing a Ph.D. in ecology, when she started planting identical clones of cottonwood trees (also known as poplars, or by the scientific name Populus deltoides ) in and around New York City. Test sites included the New York Botanical Garden and the Hunts Point water works in the Bronx; a Consolidated Edison fuel depot in Astoria, Queens; as well as Long Island’s Brookhaven National Laboratory in Upton; Eisenhower Park in Hempstead; and the Cornell Horticultural Research Laboratory in Riverhead. About 50 miles north of Manhattan, in the Hudson River valley, she also planted cottonwood clones at the Millbrook institute.
Roger Segelken | Cornell University
Urban growth causes more biodiversity loss outside of cities
10.12.2019 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig
Wie ganze Ökosysteme langfristig auf die Erderwärmung reagieren
10.12.2019 | Universität Wien
Vaccinia viruses serve as a vaccine against human smallpox and as the basis of new cancer therapies. Two studies now provide fascinating insights into their unusual propagation strategy at the atomic level.
For viruses to multiply, they usually need the support of the cells they infect. In many cases, only in their host’s nucleus can they find the machines,...
More than one hundred and fifty years have passed since the publication of James Clerk Maxwell's "A Dynamical Theory of the Electromagnetic Field" (1865). What would our lives be without this publication?
It is difficult to imagine, as this treatise revolutionized our fundamental understanding of electric fields, magnetic fields, and light. The twenty original...
In a joint experimental and theoretical work performed at the Heidelberg Max Planck Institute for Nuclear Physics, an international team of physicists detected for the first time an orbital crossing in the highly charged ion Pr⁹⁺. Optical spectra were recorded employing an electron beam ion trap and analysed with the aid of atomic structure calculations. A proposed nHz-wide transition has been identified and its energy was determined with high precision. Theory predicts a very high sensitivity to new physics and extremely low susceptibility to external perturbations for this “clock line” making it a unique candidate for proposed precision studies.
Laser spectroscopy of neutral atoms and singly charged ions has reached astonishing precision by merit of a chain of technological advances during the past...
The ability to investigate the dynamics of single particle at the nano-scale and femtosecond level remained an unfathomed dream for years. It was not until the dawn of the 21st century that nanotechnology and femtoscience gradually merged together and the first ultrafast microscopy of individual quantum dots (QDs) and molecules was accomplished.
Ultrafast microscopy studies entirely rely on detecting nanoparticles or single molecules with luminescence techniques, which require efficient emitters to...
Graphene, a two-dimensional structure made of carbon, is a material with excellent mechanical, electronic and optical properties. However, it did not seem suitable for magnetic applications. Together with international partners, Empa researchers have now succeeded in synthesizing a unique nanographene predicted in the 1970s, which conclusively demonstrates that carbon in very specific forms has magnetic properties that could permit future spintronic applications. The results have just been published in the renowned journal Nature Nanotechnology.
Depending on the shape and orientation of their edges, graphene nanostructures (also known as nanographenes) can have very different properties – for example,...
03.12.2019 | Event News
15.11.2019 | Event News
15.11.2019 | Event News
13.12.2019 | Physics and Astronomy
13.12.2019 | Physics and Astronomy
13.12.2019 | Materials Sciences