Explaining planted-tree survival and growth in urban neighborhoods: A social-ecological approach to studying recently-planted trees in Indianapolis

This research seeks to answer the question, what factors of the urban social-ecological system predict survival and growth of trees in nonprofit and neighborhood tree-planting projects? The Ostrom social-ecological system framework and Clark and colleagues' model of urban forest sustainability inform our selection of variables in four categories in the social-ecological system; these categories are the trees, the biophysical environment, the community, and management institutions. We use tree inventory methods to collect data on the survival, growth, and the social-ecological growing environment of recently-planted street trees in Indianapolis, IN to answer our research question. We use a probit model to predict tree survival, and a linear regression model to predict tree growth rate. The following variables are positively related to tree success (survival and/or growth): ball-and-burlap or container packaging, a visible root flare, good overall condition rating, the size of the tree-planting project, planting area width, median household income, percent of renter occupied homes, resident tenure, prior tree planting experience, correct mulching, and a collective watering strategy. The following variables are negatively related to tree success: caliper at planting, crown dieback, and lower trunk damage. Additional variables measured have less clear connections to tree success and should be examined further. Given that models including variables from all four categories of the social-ecological system generally outperform models that exclude some components, we recommend that future research on urban tree survival and growth should consider the holistic social-ecological systems context of the urban ecosystem.