Meeting Abstract

S2.7  Sunday, Jan. 4 11:30  Species introductions and their cascading impacts on native biotic interactions in desert riparian ecosystems HULTINE, Kevin / R*; BEAN, Dan / W; DUDLEY, Tom / L; GEHRING, Catherine / A; Desert Botanical Garden; Palisade Insectory, Colorado Department of Agriculture; Univ. of California, Santa Barbara; Northern Arizona University khultine@dbg.org http://www.dbg.org/research-conservation/research-conservation-staff/plant-physiologist-ecophysiologist

Desert riparian ecosystems of North America are hot spots of biodiversity that support many sensitive species, and are in a region experiencing some of the highest rates of climate change (CC) in North America. Populus fremontii is a foundation species of this critical habitat, but is threatened by CC and by non-native Tamarix, both of which can disrupt the mutualism between P. fremontii and root-associated fungi (RAF). The specialist herbivore (Diorhabda spp.) introduced for biocontrol of Tamarix is altering the relationship between this shrub and its environment. Diorhabda feeds exclusively on Tamarix foliage, resulting in varying rates of dieback and mortality depending on resource availability and genetic variation in resource allocation. Likewise, mortality varies with latitude owing to phenological asynchrony caused by varying developmental cues; Tamarix responds to temperature and Diorhabda responds to photoperiod. We anticipate that 1) defoliation by Diorhabda will reduce the negative impact of Tamarix on P. fremontii / RAF associations, 2) certain P. fremontii genotypes will respond more favorably to Tamarix dieback and mortality than others due to selection pressures to cope with competition, stress and altered RAF communities, and 3) Spatial variability in climate change will modify the capacity for Tamarix to survive episodic defoliation by Diorhabda thereby altering the complex interaction between Tamarix and P. fremontii and its associated RAF communities.