Phytomanagement of Contaminated Sites Using Poplars and Willows

Poplars and willows find widespread use for the phytomanagement of contaminated sites. We review the processes involved in poplar and willow phytomanagement with the aim of elucidating knowledge gaps and fertile areas for future research. Poplars and willows are fast-growing tree species reduce contaminant mobility by their high water use and stabilisation of the contaminated substrate. Root exudates and microorganisms associated with the rhizosphere of these trees promote the degradation of some organic contaminants. Some clones accumulate of toxic trace elements, such as Cd, thereby facilitating their entry into the food chain. Phytomanagement using poplars and willows can result in biomass products, such as timber, bioenergy, essential oils, organic mulches, and stock fodder. These offset the cost of the operation. There is great potential to improve the performance of phytomanagement systems using these species by exploiting their natural genetic variation and microbiological symbionts. A key unknown is the response of deep-rooted poplars to heterogeneities in soil, which may promote or reduce contaminant mobility.

Keywords: Avoidance, biomass products, clonal variation, dairy effluent, deep-rooted species, endophytic bacteria, evapotranspiration, food chain, genetic variation, groundwater, landfill, leaching, merA or merB genes, phytomanagement, phytostablilization, poplars, Salix purpurea, Salix viminilis, trace elements, willows.