The June 2011Massachusetts tornado profoundly altered the landscape over a wide geographic area.

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1 Preliminary Assessment of the Tornado Effects on Residential Street Tree Canopy Cover, Temperature, and Humidity November 2011 USDA Forest Service Northern Research Station TREE CANOPY LOSS IN THE TORNADO IMPACT ZONE WAS EXTENSIVE, WITH MANY LARGE SHADE TREES DESTROYED. The June 2011Massachusetts tornado profoundly altered the landscape over a wide geographic area. On June 1, 2011 a series of tornadoes ripped through Western Massachusetts, and included the second strongest tornado ever recorded in Massachusetts, with wind speeds estimated at 136 to 165 mph, according to the National Weather Service. The most severe tornado was the EF-3, on the Enhanced Fujita Damage Classification Scale, that carved a half-mile-wide path for 39 miles, from Westfield to Charlton, killing three people and injuring 200. In Springfield, the tornados impacted city s South End, Upper Hill, Metro Center, Six Corners, East Forest Park and Sixteen Acres neighborhoods. CANOPY LOSS TREE FAILURE STRUCTURE DAMAGE

2 Tornado Effects on Residential Street Tree Canopy Cover, Temperature, and Humidity: Introduction Introduction Recent modeling studies have reported on the relationships between residential trees and urban micro-climate with subsequent impacts on energy use for heating and cooling (McPherson et al. 1997, Simpson and McPherson 1998, Maco and McPherson 2003, McPherson et al. 2005). However, there are few studies that empirically quantify the relationship between the presence, abundance, and type of residential trees and local micro-climate (Heisler and Brazel 2010). In Sacramento, CA, tree cover density was negatively correlated with local wind speed and with cooling degree APPROXIMATELY 1.4 MILLION POUNDS OF SEQUESTERED CO2 HAS BEEN LOST days (Sailor et al. 1992). In Baltimore, MD, increasing tree cover generally resulted in cooler temperatures during the daylight hours (Heisler et al. 2007). On June 1, 2011, an EF-3 tornado traveled a 39-mile track across southcentral Massachusetts ( jun01_2011_summary.php). The tornado s track crossed the city of Springfield, MA, impacting several neighborhoods and damaging over 480 buildings and 13,000 public trees, with an estimated cost of over $106 million. This event created an opportunity to empirically measure the effects of the loss of neighborhood trees on streetside micro-climate (temperature, relative humidity). We implemented a preliminary study to estimate the impact of the tornado on street trees and micro-climate of the impact zone. CONTEXT IMPACT ZONE TREE LOSS Map 1. New England regional context CANOPY DAMAGE Map 2. Massachusetts map, with Springfield identified in red, and Hampden County noted in pink. CANOPY LOSS

3 Tornado Effects on Residential Street Tree Canopy Cover, Temperature, and Humidity: Study Area and Methods IN THE FIELD ibutton MONITOR STUDY AREA Figure 1. Tornado Impacted (red box) and unaffected (yellow box) neighborhoods and forested Dan Baker Cove Park, East Forest Park, Springfield, MA PLACING MONITOR MONITOR PLACEMENT CANOPY ASSESSMENT Study Area and Methods We measured air temperature and relative humidity in two adjacent residential neighborhoods in the East Forest Park area of Springfield (Fig. 1). Data loggers (ibutton Hydrochrons ) were placed in two blocks of three streets in the tornado damaged area. Matching data loggers were placed in two blocks of the same or paired streets in an unaffected neighborhood just to the south of the tornado track (Fig. 1). A single data logger was placed the forested Dan Baker Cove Park, just north of the tornado damaged area. Data loggers were enclosed in windowscreen envelopes and hung by wires from street signs. Temperature and relative humidity were recorded three times a day; night (0000 hrs), morning (0800 hrs), and afternoon (1600 hrs) for the duration of the preliminary study (30 Aug 26 Sep 2011). Tree canopy cover was measured in the four cardinal directions at each data logger location using a spherical densiometer. Information on the tornado damage to privately-owned residential trees of the study area is being assessed using aerial photographs, which were taken by the Forest Service following the tornado, and i-tree Canopy. Paired, daily mean temperature and relative humidity data were analyzed to assess the effects of the tornado damage to residential trees on streetside micro-climate.

4 Tornado Effects on Residential Street Tree Canopy Cover, Temperature, and Humidity: Results and Discussion Results The tornado nearly eliminated street-side tree canopy cover, from an average of 44% canopy cover in the control, unaffected neighborhood to less than 1% in the tornado impacted neighborhood (Table 1). Daily mean morning and afternoon temperatures were typically greater in the tornado impacted neighborhood than the unaffected neighborhood and forest site, but were similar at night (Fig. 2). Daily afternoon temperatures were intermediate between the tornado impacted neighborhood and forest site in the unaffected neighborhood (Fig. 2). The average morning and afternoon temperature increased between 1-2ºC in the tornado impacted neighborhood, compared to the unaffected neighborhood (Table 1). Night-time temperatures were only slightly less in the tornado impacted neighborhood than the unaffected one (Table 1). Daytime temperatures at the single forest site were cooler than either of the residential sites and nighttime temperatures were similar among all sites (Table 1). Mean daily humidity was similar in the tornado impacted and unaffected neighborhoods, but typically greater in the urban forest (Park) site. Mean percent relative humidity were slightly less in the tornado impacted neighborhood than unaffected neighborhood in the morning and afternoon, and slightly greater in the nighttime (Table 1). Discussion The results of this preliminary study indicate that there is a obvious difference in canopy density and the micro-climate characteristics between the tornado impact zone affected neighborhood and nearby areas that were not affected by the storm event. The noted difference in afternoon daily temperatures between the two areas provides preliminary, quantitative findings that supports the antidotal testimony from residents of the impacted affected area, relative to the increased use of air-conditioning units, personal comfort levels, and an overall increase in energy costs in July and August Further study of this effect of a change in residential micro-climate is necessary to quantify any real relationships between energy costs in 2011, compared to pretornado summer periods and the loss of residential trees and resulting change in micro-climate. Urban Heat Islands Implementation of urban heat island (UHI) mitigation strategies such as increased vegetative cover can reduce the impacts of biophysical hazards in cities, including heat stress related to elevated temperatures, air pollution and associated public health effects. Such strategies also can lower the demand for airconditioning-related energy production. The loss of tree canopy cover following the tornado correlates with comments by residents in the impact zone, who report that the neighborhood lacks any shade and seems hotter and is noisier than in the past. It was noted during the site visits that there is a limited variety of songbirds seen or heard in the tornado impact zone compared to the unaffected neighborhood. It appears that the tornado greatly impacted the street-side tree canopy and micro-climate, the urban bird community, and the overall appeal of tree-lined streets and large residential shade trees. The proposed planting of new trees, which is intended to produce significant benefits over time, provides a unique opportunity to develop a long-term monitoring study within the tornado impact zone. The implementation of a scientific study will provide information, data, and findings from an urban landscape that is undergoing dramatic change, starting from near total tree loss to future recovering of tree canopy cover. The study of past costs and benefits, along with closer examination of micro-climate impacts, and finally, the monitoring of newly planted trees in the impact zone will provide relevant, scientifically-based information for urban foresters, planners and the scientific community. Solecki, et al. 2005

5 IMPACTS Table 1. Mean street-side temperature (ºC) and percent relative humidity (RH) by time of day and mean percent tree canopy cover in tornado impacted and unaffected residential neighborhoods and from a single urban forest site, East Forest Park, Springfield, MA, 30 Aug 26 Sep Figure 2. Daily street-side temperatures (ºC) by time of day, East Forest Park, Springfield, MA, 30 Aug 26 Sep 2011.

6 Literature cited Heisler, Gordon M. and Brazel, Anthony. J The urban physical environment: temperature and urban heat islands. Pgs In: Aitkenhead-Peterson, J. and Volder, A. (Eds.) Urban Ecosystem Ecology. American Society of Agronomy, Agronomy Monograph 55. Heisler, Gordon, Walton, Jeffrey, Yesilonis, Ian, Nowak, David, Pouyat, Richard, Grant, Richard, Grimmond, Sue, Hyde, Karla, and Bacon, Gregory Empirical modeling and mapping of below-canopy air temperatures in Baltimore, MD and vicinity. In: Proceedings of the 7th Urban Environment Symposium. American Meteorlogical Society, San Diego, CA. Maco, Scott E. and McPherson, E. Gregory A practical approach to assessing structure, function, and value of street tree populations in small communities. Journal of Arboriculture 29: McPherson, E. Gregory, Nowak, David, Heisler, Gordon, Grimmond, Sue, Souch, Catherine, Grant, Rich, and Rowntree, Rowan Quantifying urban forest structure, function, and value: the Chicago Urban Forest Climate Project. Urban Ecosystems 1: McPherson, Greg, Simpson, James R., Peper, Paula J., Maco, Scott E., and Xiao, Qingfu Municipal forest benefits and costs in five US cities. Journal of Forestry 103: Sailor, David J., Rainer, Leo, and Akabri, Hashem Measured impact of neighborhood tree cover on microclimate. Pgs In: Proceedings of the 1992 ACEEE Summer Study on Energy Efficiency in Buildings. Volume 9. American Council for an Energy-Efficient Economy. Washington, D.C. Simpson, J.R. and McPherson, E.G Simulation of tree shade impacts on residential energy use for space conditioning in Sacramento. Atmoshpheric Environment 32: Solecki, W.D., Rosenzweig, C., Parshall, L., Pope, G., Clark, M., Cox, J., and Wiencke, M Mitigation of the heat island effect in urban New Jersey. Global Environmental Change, Part B: Environmental Hazards. 6: Project Study Team David V. Bloniarz, Ph.D. Dr. Bloniarz is an Urban Forester with an extensive background in urban forest management and landscape design. Presently Dr. Bloniarz is project coordinator of the USDA Forest Service Northern Research Station s Urban Natural Resources Institute, located at the University of Massachusetts/Amherst. dbloniarz@fs.fed.us Robert T. Brooks, Ph.D. Dr. Brooks studies the ecology of ephemeral or "vernal" pools of northeastern forests. His current research includes study of the effectiveness of Massachusetts forestry Best Management Practices and Conservation Management Practices for vernal pools and and projected climate change effects on the hydrology and ecology of vernal pools. rbrooks@fs.fed.us For more information, contact the UF Forest Service Northern Research Station