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Morani A.,CNR Institute of Agro-environmental and Forest Biology | Nowak D.,U.S. Department of Agriculture | Hirabayashi S.,Davey Institute | Guidolotti G.,CNR Institute of Agro-environmental and Forest Biology | And 6 more authors.
Environmental Pollution | Year: 2014

Ozone flux estimates from the i-Tree model were compared with ozone flux measurements using the Eddy Covariance technique in a periurban Mediterranean forest near Rome (Castelporziano). For the first time i-Tree model outputs were compared with field measurements in relation to dry deposition estimates. Results showed generally a good agreement between predicted and measured ozone fluxes (least sum square = 5.6 e-4) especially when cumulative values over the whole measurement campaign are considered. However at daily and hourly time-step some overestimations were observed in estimated values especially in hot dry periods. The use of different m values in the Ball-Berry formula in the different periods, produced the best fit between predicted and measured ozone fluxes. This suggests that a variable value for the coefficient m accounting for water availability may be appropriate to improve model estimates for Mediterranean and drought prone regions. © 2014 Elsevier Ltd. All rights reserved. Source

Nowak D.J.,U.S. Department of Agriculture | Hoehn R.E.,U.S. Department of Agriculture | Bodine A.R.,Davey Institute | Greenfield E.J.,U.S. Department of Agriculture | O'Neil-Dunne J.,University of Vermont
Urban Ecosystems | Year: 2013

The tree population within the City of Syracuse was assessed using a random sampling of plots in 1999, 2001 and 2009 to determine how the population and the ecosystem services these trees provide have changed over time. Ecosystem services and values for carbon sequestration, air pollution removal and changes in building energy use were derived using the i-Tree Eco model. In addition, photo interpretation of aerial images was used to determine changes in tree cover between the mid-1990s and 2009. Between the mid-1990s and 2003, tree cover in Syracuse exhibited a decline from 27.5 to 25.9 %, but subsequently increased to 26.9 % by 2009. The total tree population exhibited a similar pattern, dropping from 881,000 trees in 1999 to 862,000 in 2001, and then increasing to 1,087,000 trees in 2009. Most of this increase in the urban tree population is due to invasive or pioneer trees species, particularly Rhamnus cathartica, which has more than tripled in population between 2001 and 2009. Insects such as gypsy moth and emerald ash borer pose a substantial risk to altering future urban forest composition. The annual ecosystem services provided by the urban forest in relation to carbon sequestration, air pollution removal and reduction in building energy use are estimated at about $2.4 million per year. An improved understanding of urban forests and how they are changing can facilitate better management plans to sustain ecosystem services and desired forest structure for future generations. © 2013 Springer Science+Business Media New York (outside the USA). Source

Persad A.B.,Davey Institute | Tobin P.C.,U.S. Department of Agriculture | Tobin P.C.,University of Washington
Arboriculture and Urban Forestry | Year: 2015

The emerald ash borer (EAB), first discovered in North America in Michigan in 2002, continues to expand its distributional range. Early detection of EAB remains a major caveat in efforts to implement proactive management strategies. Past reports have shown that ash trees infested with EAB have an increased risk of branch failure and other symptoms associated with tree decline. Therefore, early detection efforts could be improved if a suite of tree symptoms - prior to visible signs of EAB infestation - can be identified. Researchers initiated a four-year study in Ohio, U.S. (2009-2012) to investigate and document symptoms associated with the EAB-ash tree complex in urban sites. The prior history of EAB at the study sites ranged from ash trees with no visible evidence of infestation to those that were infested for more than two years. In trees shown to be recently colonized by EAB, visible signs of infestation, such as adult emergence holes, presence of EAB galleries, bark loss, and canopy loss were not always apparent. However, in EAB-positive trees, there was a significant tendency for the presence of cracks in scaffold branches, branch fractures within the upper canopy, and branch fractures specifically located closer to the union with the stem as opposed to at the branch tip or at the branch's center of gravity. This study highlights tree symptoms associated with the initial colonization of EAB when host trees are still apparently healthy, which could greatly facilitate future detection efforts for EAB. ©2015 International Society of Arboriculture Source

Persad A.B.,Davey Institute | Siefer J.,Davey Institute | Kirby S.,Davey Tree Experts | Rocha O.J.,Kent State University | And 3 more authors.
Arboriculture and Urban Forestry | Year: 2013

Emerald ash borer (EAB), an invasive insect borer on ash trees, currently occurs in the Untied States and Canada. In many regions, large populations of ash trees are affected with many trees exhibiting partial to full canopy dieback. Several cases exist in northwest Ohio, U.S., where EAB infested ash branches or stems fail prematurely during deadwood pruning or whole tree removal. This study was initiated to resolve the effects of EAB on the material properties of ash branches and stems. Visually non-infested ash trees and trees with recent and advanced EAB activity were examined. The data from static loading tests on primary branches indicate that maximum bending stress at failure was not significantly lower in EAB infested trees compared to non-infested trees. Examination of the fracture zone, however, revealed that wood moisture was significantly lower and more cracking was observed in wood sections of branches taken from EAB infested trees. During static loading, branch failure at the union occurred only in the EAB infested trees. In a wood resistance evaluation of infested and non-infested ash stems, significantly lower resistance was observed in advanced EAB infested ash stems when drilled at the base compared to drill sites 1 m above. This was not observed at similar drill site heights in the visually non-infested ash stems. These data may help identify risk elements associated with structural and material degradation of ash wood as early as one to two years after infestation by EAB. © 2013 International Society of Arboriculture. Source

Nowak D.J.,U.S. Department of Agriculture | Hirabayashi S.,Davey Institute | Bodine A.,Davey Institute | Greenfield E.,U.S. Department of Agriculture
Environmental Pollution | Year: 2014

Trees remove air pollution by the interception of particulate matter on plant surfaces and the absorption of gaseous pollutants through the leaf stomata. However, the magnitude and value of the effects of trees and forests on air quality and human health across the United States remains unknown. Computer simulations with local environmental data reveal that trees and forests in the conterminous United States removed 17.4 million tonnes (t) of air pollution in 2010 (range: 9.0-23.2 million t), with human health effects valued at 6.8 billion U.S. dollars (range: $1.5-13.0 billion). This pollution removal equated to an average air quality improvement of less than one percent. Most of the pollution removal occurred in rural areas, while most of the health impacts and values were within urban areas. Health impacts included the avoidance of more than 850 incidences of human mortality and 670,000 incidences of acute respiratory symptoms. © Published by Elsevier Ltd. Source

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