By Emily Jack-Scott, Max Piana, Blake Troxel, Colleen Murphy-Dunning, and Mark S. Ashton
New Haven, CT (July 2013) – Existing research demonstrates that community stewardship increases the survival of urban street trees, but there’s a lack of research on how defining characteristics of community groups affect the survival and growth of the trees they plant. A new study looking at greenspace programs in New Haven, CT explores the significance of community group size and type, as well as planting experience and neighborhood dynamics.
The researchers measured 1,393 trees planted from 1995 to 2007, by 134 groups, through the Urban Resources Initiative’s Community Greenspace program in New Haven, CT. They looked specifically at 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).
There was an overall survival rate of 76%. The 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.
In the study conclusions, researchers identify the most interesting findings to include:
- social factors account for a small, albeit significant and important component of urban tree health,
- community group experience, longevity, and size are frequently positively associated with improved tree survival and growth,
- group types were most effective when planting in areas most in line with their focuses, and
- percent homeownership and existing percent canopy cover played a limited role in the survival and growth of community-planted trees.
The most valuable management implication from this study is its insight into just how nuanced social factors affecting street tree survival and growth can be. This study supports existing literature indicating the importance of group experience, longevity, and size, but it also illustrates that no single social factor can guarantee successful stewardship.
Source: “Stewardship Success: How Community Group Dynamics Affect Street Tree Survival and Growth,” Arboriculture & Urban Forestry. July 2013. 39(4): 189–196