Hixon Center for Urban Ecology

Prospect, CT, United States

Hixon Center for Urban Ecology

Prospect, CT, United States
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Locke D.H.,Clark University | Han S.,University of Nebraska at Omaha | Kondo M.C.,U.S. Department of Agriculture | Murphy-Dunning C.,Hixon Center for Urban Ecology | And 2 more authors.
Landscape and Urban Planning | Year: 2017

For some volunteers, neighborhood safety is one of the reasons for becoming involved in community greening. For example, many volunteers of the Community Greenspace program at the Urban Resources Initiative in New Haven, Connecticut believe that there is a potential reduction in crime from community greening activities, even though it is not an explicit goal of the program. These types of community-led interventions are distinct from both existing tree canopy and large-scale municipally led initiatives. These types of interventions remain understudied with respect to the potential for reducing crime. We therefore used a quasi-experimental difference-in-differences (DID) approach to test whether more than a decade of street tree planting (1996–2007) in New Haven had an effect on crime levels at planting sites (n = 300) compared to control sites that received no Community Greenspace-planted trees (n = 893). We examined violent, property, and misdemeanor crimes (comprised of vandalism, prostitution, and narcotics crimes) individually and jointly to test for crime-type specific effects, while controlling for sociodemographic factors and spatio-temporal trends. In general, we found a null relationship between trees planted and crime on block faces per year at the p < 0.05 level. Increases in crime were not observed on treatment sites. We discuss implications for tree inventories and monitoring, study design, and techniques to assess impacts of tree planting efforts. © 2017 Elsevier B.V.

Jack-Scott E.,Hixon Center for Urban Ecology | Piana M.,Hixon Center for Urban Ecology | Troxel B.,Hixon Center for Urban Ecology | Murphy-Dunning C.,Hixon Center for Urban Ecology
Arboriculture and Urban Forestry | Year: 2013

Over the last two decades, there has been a substantial increase in street tree plantings across the United States. Many cities have set ambitious planting goals, relying on volunteer community groups to meet them. Existing research demonstrates that community stewardship increases the survival of urban street trees. There is a lack of research, however, on how defining characteristics of community groups affect the survival and growth of the trees they plant. This study explores the significance of community group size (# participants), type (apartment, block watch, church, concerned neighbors, park, public housing, school, and social service), planting longevity (# years active), experience level (# trees planted), and neighborhood (geo-political boundaries). Measured for this study were 1393 trees planted from 1995 to 2007, by 134 groups, through the Urban Resources Initiative's Community Greenspace program in New Haven, Connecticut, U.S. There was an overall survival rate of 76%. Highest survival and growth was found among trees planted by groups with more planting experience, greater longevity, and more participants. Higher tree survival and growth was observed when trees were planted by groups working in line with their mission (e.g., park groups in parks). Lowest survival and growth was found among yard trees planted by public housing groups. Existing canopy cover and neighborhood percent homeownership had little effect on survival or growth. This research can offer guidance for city managers by suggesting which planting groups require particular assistance in conducting successful, lasting street tree plantings. © 2013 International Society of Arboriculture.

Troxel B.,Hixon Center for Urban Ecology | Piana M.,Hixon Center for Urban Ecology | Murphy-Dunning C.,Hixon Center for Urban Ecology
Urban Forestry and Urban Greening | Year: 2013

Knowledge of allometric equations can enable urban forest managers to meet desired economic, social, and ecological goals. However, there remains limited regional data on young tree growth within the urban landscape. The objective of this study is to address this research gap and examine interactions between age, bole size and crown dimensions of young urban trees in New Haven, CT, USA to identify allometric relationships and generate predictive growth equations useful for the region. This study examines the 10 most common species from a census of 1474 community planted trees (ages 4-16). Regressions were applied to relate diameter at breast height (dbh), age (years since transplanting), tree height, crown diameter and crown volume. Across all ten species each allometric relationship was statistically (p<0.001) significant at an α-level of 0.05. Consistently, shade trees demonstrated stronger relationships than ornamental trees. Crown diameter and dbh displayed the strongest fit with eight of the ten species having an R2>0.70. Crown volume exhibited a good fit for each of the shade tree species (R2>0.85), while the coefficients of determination for the ornamentals varied (0.380.66). Allometric relationships can be used to develop spacing guidelines for commonly planted urban trees. These correlations will better equip forest managers to predict the growth of urban trees, thereby improving the management and maintenance of New England's urban forests. © 2013 Elsevier GmbH.

Locke D.H.,Clark University | Roman L.A.,U.S. Department of Agriculture | Murphy-Dunning C.,Hixon Center for Urban Ecology
Arboriculture and Urban Forestry | Year: 2015

Many cities are making substantial capital investments in urban tree planting. Residents play active and diverse roles in enhancing and protecting the urban forest, and are therefore critical to many municipal-level policy objectives. The way residents perceive and value the urban forest can have implications for achieving urban forestry goals through residents and volunteers. However, urban residents are not a monolithic block or homogenous category; instead, they have diverse opinions, needs, and constraints. Moreover, relatively little is known about how residents hear about available resources, such as free trees, and decide to 'opt-in' to tree planting initiatives, choosing to plant and maintain trees on or near their properties. The focus of this study was to address three questions about participation in a request-driven program that provides free street trees to residents of New Haven, Connecticut, U.S.: 1) Who requests trees through this program? 2) How did the requesters hear about this program? 3) Why did residents request free street trees? Survey respondents were primarily long-term residents of New Haven; mostly learned about the opportunity from their neighbors; and requested a street tree to replace a removed tree, because they value the aesthetics, and to a lesser extent the environmental benefits. Future research should systematically investigate differences between participants and non-participants in local tree planting initiatives, exploring possible trends across cities and programs. Such studies would identify opportunities and barriers to engaging private residents in efforts aimed at increasing canopy. © 2015 International Society of Arboriculture.

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