Ecosystem function of urban plants in response to landscape management

The functional ecology of plants in urban ecosystems is poorly understood relative to natural and agro-ecosystems. Sound management strategies are needed to facilitate sustainable development of urbanized regions. This dissertation examines effects of landscape management on the functional ecology of woody plants in an urban ecosystem at several scales. Landscape management is specifically defined as human alteration of land cover and plant distribution, addition of supplemental water to landscape plants via irrigation, and the removal of plant biomass via pruning. Aspects of plant functional ecology addressed in this dissertation include plant effects on microclimate, carbon sequestration and storage, and water cycling. Socioeconomic land use influenced land and woody plant canopy cover and urban microclimates. The most common land use in the urbanized study area was single family residential (SFR). Woody plant canopy area was the highest in SFR plots, but did not differ significantly from other land uses due to high variance. The greatest disparity in microclimate as a function of land use occurred during pre-dawn summer hours. Agricultural and residential land uses had the highest relative humidities, dew point temperatures, and normalized differential vegetation index (NDVI) with lowest air temperatures (T). Commercial land uses and industrial areas had the highest T and the lowest NDVI. Generally, T negatively correlated to NDVI and atmospheric moisture positively correlated to NDVI. In experimental plots designed to resemble local SFR sites in number and life forms of vegetation present, irrigation rate and pruning regimes influenced plant productivity (PP), average standing canopy leaf area (LA), and irrigation water use efficiency (WUEI). Whole plot PP and LA were higher and WUEI was lower under high irrigation rate as compared to low irrigation rate. Whole plot carbon acquisition and transpiration potentials were influenced by treatment effects on LA. Data indicate that landscape management practices might most influence the plant ecosystem functions examined in this study via changes in vegetation density and LA and that plant distribution, irrigation, and pruning might be modified to optimize plant effects on microclimate and landscape carbon and water dynamics.