Sarah Parsons

Global Change Fellow Alumna | Department of Entomology | North Carolina State University

Spring 2018 Global Change Fellow

Statement of purpose:

Urban trees provide a number of ecosystem services and health benefits to city residents.  Unfortunately, the health of many urban trees is compromised by pests.  A growing body of research is showing that pest growth and development respond positively to rising temperatures.  With rising temperatures and a changing climate our cities and our city trees are particularly vulnerable to damage from pests.  The need for “gathering scientific information and building tools that help [urban] ecosystems adapt to the impacts of changing climate and land use” is more crucial than ever.  Fortunately, new tools, such as landscape design, may hold promise for the future health of our urban trees.

Description of research:

My doctoral research aligns with SECSC’s mission and Science Plan Theme 2: Land Use and Land-Cover Change Projections.   My project directly relates to the project areas of “Consequences of Urbanization and Climate Change on Human and Ecosystem Health.”  My research aims to look at landscape design as a tool to mitigate the negative effects of pests on urban trees in a warming climate. I predict that one special element of landscape design, vegetation complexity, can be manipulated on landscapes around trees to reduce tree pests.  Preliminary analysis of 30 crape myrtles on NC State Campus from 2016-2017 suggests that impervious surface is a strong driver of aphid abundance on crape myrtles and that local vegetation complexity around trees may increase natural enemy abundance.  However, a larger sample size of crape myrtle trees in the greater Raleigh area and in other cities, such as Gainesville, FL, will be essential in determining if this phenomenon is realized across an urban gradient at different latitudes.  I hypothesize that crape myrtle trees surrounded by more vegetation complexity will have fewer tree pests and more natural enemies. My research will test a well-known ecological concept, the Enemies Hypothesis, in a space that has not be thoroughly explored – the city. Ultimately, I hope to establish vegetation complexity thresholds that can be used by designers to mitigate pest damage on street trees in a warming climate.