The transformation of urban forests from “frill” to “high-performance biotechnology” is driven by several factors. Environmental policies provide incentives for tree planting and stewardship projects that reduce air pollutants (i.e., carbon dioxide, ozone), conserve energy, and control stormwater. Residents are increasingly willing to pay a premium for “green products” and their values will shape the sustainable attributes of future urban forests. Demographic trends such as increasing age and ethnic diversity of urban populations are changing the fabric of our communities. Together, these forces are creating a new canvas on which to weave green infrastructure.
Central to the design of high-performance urban forests are three questions:
- What are key attributes that influence the performance of individual trees as design elements?
- What are limitations to the success of large-scale tree projects?
- How can ecologists contribute to the design and management of high-performance urban forests?
Results/Conclusions
Tree Performance Attributes – Key features linked to performance are tree size, species, and location. Size, particularly leaf and stem surface area, is directly linked to many ecosystem services. The physiology and architecture of different tree species influences their performance. For instance, foliation period, crown density, and biogenic volatile organic compounds (BVOC) emission rates influence tree effects on air quality. Tree location can influence its health, growth, and longevity, as well as its capacity to directly shade a building or filter airborne particulates.
Limitations to Performance – Achieving high levels of tree survival, growth, and longevity is a challenge to the success of large-scale tree planting projects. Threats include pests/disease, drought, storms, vandalism, and land disturbance. Potential adverse impacts of trees can be a deterrent to large-scale projects. Because trees are relatively costly to plant and maintain, it is important to identify strategies that reduce long-term costs without sacrificing performance.
Contributions from Ecologists –Ecologists are well-equipped to lead the study, planning, and implementation of tree projects. Their expertise is needed to better understand the full scope of inputs and outputs, from nursery production to tree removal and biomass utilization. Ecologists can contribute to a more complete accounting of ecosystem services that includes food production/community gardens, insect and wildlife habitat, and ecological literacy. Their knowledge is needed to determine desirable levels of species and age diversity, as well as effects of climate change on growing environments. Monitoring is an essential component of the high-performance urban forest, and an area where ecologists can make important contributions.
