Forest clearance followed by brush control using Tordon 101 (a mixture of picloram and 2,4-dichlorophenoxyacetic acid), caused a decreased thickness of surface organic matter on power line rights-of-way in northern Ontario. The resultant exposure of mineral soil encourages recolonization by tree seedlings. Surface organic matter loss must therefore be controlled to avoid brush-control problems from seeded-in tree species. Erosion is unimportant in removing litter, but decreased net aerial primary production and hastened organic matter decay following spraying are crucial. Organic matter decomposition is increased because soil temperatures rise when the shading plant canopy is killed by the herbicide. The rise in soil temperature is insufficient, however, to entirely account for the hastened decomposition observed. A low-growing, herbicide-resistant, shade-producing, decay-resistant plant canopy is the ideal as a natural or artificial cover crop for transmission corridors. We conclude that Tordon's capacity to push succession back to an early stage is not related solely to its selective toxicity but also to changes in community metabolism.