How trees thrive in a dry climate: diurnal and seasonal hydrology and water relations in a riparian cottonwood grove.

In semi-arid ecoregions, trees are restricted to river valley floodplains where river water supplements the limited precipitation. To characterize the associated diurnal and seasonal dynamics in hydrology and water relations, we studied narrowleaf cottonwoods (Populus angustifolia) along a prairie river in Canada. From June through August, the shallow soil moisture was depleted but moisture remained higher above the alluvial groundwater table, which dropped to 2.

A prescription for drug-free rivers: uptake of pharmaceuticals by a widespread streamside willow.

Following human excretion and limited removal with wastewater treatment, pharmaceuticals are accumulating in rivers worldwide. These chemicals can challenge the health of fish and aquatic organisms and since rivers provide drinking water sources, there is concern for cumulative exposure to humans. In this study, we discovered that sandbar willow (Salix exigua), a predominant riparian shrub along streams throughout North America, has the capacity to quickly remove pharmaceuticals from aqueous solutions.