Text

theses

Urbanization transforms ecological systems, altering soils, hydrology, climate, species pools, and landscape patterns. Municipalities are turning to ecological restoration of urban forests to provide essential ecosystem services. This dissertation examines long-term effects of ecological restoration of forest patches invaded by woody invasive plants within urban park natural areas in New York City, New York, USA. I compared invaded sites where restoration was initiated 15-20 years prior with similarly invaded urban park forests that had not been restored. Significantly lower invasive species abundance, more complex vertical forest structure, and greater native tree recruitment indicated that invasive species removal followed by planting resulted in divergent successional trajectories and achievement of the central goals of the restoration. However, regenerating species indicated novel future assemblages, and restored sites varied in degree of reinvasion. To examine sources of this variability and test the importance of management effort to success of ecological restoration in urban forest remnants, I compared plant communities, management records, indicators of disturbance, and site characteristics among and between restored and unrestored invaded patches and a less-disturbed urban forest remnant. Differences among restored plant communities were associated with total restoration effort and with soil surfaces impacted by urban conditions, indicating the importance of urban context and ongoing management effort to outcomes of ecological restoration in urban areas. To examine these soil effects and to test whether impacts of urbanization on soils affect long-term outcomes of ecological restoration in urban forest patches, I compared plant community composition of restored, unrestored and less-disturbed sites with soil physical and chemical characteristics and urban soil classification maps. No single soil impact dominated effects on plant community composition, but all sites were impacted by anthropogenic factors known to reduce plant growth, change distributions of soil biota, and alter nutrient cycles. I present an urban perspective on the use of succession theory in ecological restoration and introduce adaptive successional phasing as a tool, emphasizing site-specificity, long-term processes, and the importance of the urban environment’s effects on soils, species pools and disturbance regimes, and suggest that native species persisting and thriving in cities should be used in urban ecological restoration.

ETD_4756

Ph.D.

Includes bibliographical references

Includes vita

by Lea R. Johnson

http://hdl.rutgers.edu/1782.1/rucore10001600001.ETD.000068890

doi:10.7282/T3GQ6WB6

ETD doctoral

The author owns the copyright to this work.