Identifying Environmental Constraints Affecting Tree Survival and Growth in Rural, Suburban, and Urban Public Settings (NA-98-0328)

This project assesses relationships between tree growth and environmental parameters known to vary across the rural-suburban-urban continuum.

This project was done to assess relationships between tree growth and environmental parameters known to vary across the rural-suburban-urban continuum. For this study, 320 established, healthy, open-crown trees were sampled according to gradients in community population level (0 (rural parks), 500, 5,000 and 50,000) and land use (cityparks, residential, and commercial sites) in 5 Midwestern states. According to population levels, trees in rural parks were older (69 years) and had lower mean growth rates (3.5 mm/yr) than trees in small (51 yrs, 4.6 mm/yr), medium(40 yrs, 4.7 mm/yr), and large towns (39 yrs, 4.6 mm/yr). Across the land use gradient, both mean age and growth rate were lower for trees on commercial sites (24 years and 4.1mm/yr) than for those in city parks (54 yrs, and 5.2mm/yr). The relationships between tree growth rates and several biotic and abiotic variables were also examined.For individual biotic variables, number of other trees within 9 m, and presence of disease, insects, and human-induced injuries were strongly related to tree growth rates. Individual abiotic variables that affected tree growth included bulk density and presence of pavement in proximity to the trees. Values for measured soil properties that increased significantly going from rural to urban and from park to commercial sites included pH. coarse fragment content. and metal content (Pb, Cd, Cu, and Zn). Bulk density increased significantly going from urban to rural sites, and from commercial to park sites, although very few samples had values that are considered limiting to tree growth.

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