| Description |
Urbanization impacts both energy and water cycles through transformation of land cover and surface properties affecting water infiltration and runoff, soil evaporation, albedo, heat capacity, and consequently soil moisture and plant water use. Although urban water systems are highly engineered, the precise routes of water travel and storage and their impact on microclimate are still uncertain. Using micrometeorological data from urban parks and residential neighborhoods, I evaluate the effect of surface geometry, land cover composition, and vegetation type on spatial and temporal variation in temperature and humidity in the Salt Lake Valley of Utah, USA. Additionally, using stable isotopes of urban water sources and soil water, I evaluated the spatiotemporal dynamics of tree water sources in managed urban parks in the semiarid Salt Lake Valley. I found that vegetation composition and surface geometry influence the heterogeneity and magnitude of air temperature and humidity, with different effects at different times of the day. Turfgrass and tree cover have similar effects during the day, while increased turfgrass cover is associated to decreased nighttime temperatures. I also found that in urban managed parks not only irrigation but also winter snowmelt contributed to the composition of soil moisture and tree transpiration even in the summer months. Thus, presence of winter snowmelt in late summer in this seasonally dry ecosystem provides evidence for an ecohydrological partitioning of soil water sources. Based on my results, urban heat island mitigation should consider both the unequal daily impacts of tree canopy cover during the day and night and the high water demands of turfgrass. Thus, developing urban tree management practices to attain climate mitigation should consider the impact of irrigation practices, water mobility and availability, and seasonal patterns of precipitation. |
