Plants can increase the removal of organic compounds from soil by three basic mechanisms: rhizosphere degradation; uptake, translocation, and volatilization of unmetabolized compounds; and uptake, metabolism or storage. The importance of each of these mechanisms is typically estimated from measurements made on plants in containers in controlled environments or from field studies of single plants and it is necessary to scale this data to the community level. Over the past century physiologists have developed and refined procedures for scaling from measurements made in small chambers to determine mass transport in ecosystems. Here we review procedures and apply the principles to scaling from measurements of volatile and non-volatile contaminants in small chambers to plant communities. Numerical examples from measured literature values are given.