UC Riverside

Urban vegetation represents a novel ecosystem where classical theories of vegetation ecology interact with systems of management and control not found in wildland areas. These interactions provide unique circumstances to test classical ecological constructs of how vegetation responds to climate while under the influence of urban actors. Cities can be hotter than their rural counterparts, include a diverse array of vegetation, and are directly and inadvertently treated with additional water and nitrogen resources. All these factors make urban regions novel common gardens to examine vegetation ecology. Furthermore, understanding the nexus of urbanization, vegetation, and climate will aid in quantifying ecosystem services as well as provide insight into how a diverse array of vegetation responds to multiple stressors. The research contained within this dissertation aims to explore how the dynamics of cities influence vegetation responses to extreme climates. To capture the many possible interactions, I explore urban vegetation ecology at multiple levels of organization, including the organismal, community, and ecosystem scale. Moreover, these studies examine both within the city and across city dynamics, comparing cities from different regional climates. I use a combination of ecophysiological traits, community diversity sampling, and remote sensor networks to understand the interactions of cities, climate, and plant-based ecosystem services. Overall, I find that the abundance of water resources in arid cities causes urban trees to decouple their carbon and water-use strategies and that decoupling is increased in desert climates. When comparing plant communities in parks in mesic and arid cities, taxonomic diversity was strongly driven by climate, but aspects of functional diversity were more determined by management practice. Across cities, the ecosystem service of vegetation-derived nocturnal cooling was tightly correlated to atmospheric aridity, highlighting the relationship between transpiration and ecosystem services. Taken together this dissertation connects how increases in water availability can result in shifts in plant function, community diversity, and resulting plant-derived ecosystem services