OOS 11-4 - Adapting tree ecophysiology methods in support of urban silviculture: insights from Baltimore, MD

Silviculture is a holistic framework for managing forests in rural areas that can also be applied to forests in cities for sustained provision of ecosystem services and benefits to communities. Basic understanding about the physiological performance and characteristics of trees in cities can support the establishment and growth of healthy, high-quality forested areas, and can provide more accurate accounting of ecosystem service provision. Furthermore, “urban silviculture” techniques can be adapted to the diverse needs and values of urban landowners and surrounding communities, in support of “ecology for all.” This talk will present urban tree ecophysiology studies from Baltimore, MD that have adapted some of the most traditional programs of US Forest Service science to urban settings in order to improve assessment and management of urban forests and associated ecosystem services.

A long-term urban experimental forest was established at Stillmeadow PeacePark in order to test the effectiveness of hybrid poplars and willows as “nurse” trees on an ecologically degraded site where native regeneration is challenged by invasive plants, heavy deer browse, and soil disturbance. In addition to testing species and genotypes, the study assesses sapling vs. cutting planting strategies implemented by volunteers and community members. After two years, overall poplar survival and vigor was greater than willow, with differences in height growth by genotype. Survival of potted trees was much greater than that of cuttings planted directly into the ground, and willow cuttings in particular showed greater signs of stress and lower photosynthetic capacity than potted trees. Wood chips had variable impacts on individual tree performance, but did significantly reduce invasive plant cover on the plots.

A lack of information about urban wood properties is a major limitation to accurate characterization of the urban wood resource and associated ecosystems services. To examine potential differences in wood properties between trees grown in forest and urban settings, wood samples from native species were collected from urban trees across varied site types (tree pit, lawn strip, open grown, and forest). Specific gravity of urban wood was also compared to published values from forest-grown trees. Sugar maple, pin oak, and ash tree specific gravity varied significantly by urban planting site type, while red maple did not. Ash trees grown in urban landscaped areas also had higher specific gravity compared to those found in urban forest patches. These results suggest that the use of existing forest-based data may be underestimating urban tree biomass and carbon storage.