Irrigated urban trees exhibit greater functional trait plasticity compared to natural stand analogs

            Urbanization creates novel ecosystems comprised of species assemblages and environments with no natural analog. Moreover, irrigation can alter plant function compared to non-irrigated systems. However, the irrigations capacity to alter functional trait patterns across multiple species is unknown but may be important for the dynamics of urban ecosystems. We evaluated the hypothesis that urban irrigation influences plasticity in functional traits by measuring carbon-gain and water-use traits of 30 tree species planted in southern California, USA spanning a coastal-to-desert gradient. Tree species respond to irrigation through increasing the carbon-gain trait relationship of leaf nitrogen per specific leaf area compared to their native habitat. Moreover, most species shift to a water-use strategy of greater water loss through stomata when planted in irrigated desert-like environments compared to coastal environments, implying that irrigated species capitalize on increased water...