Effects of the herbicides glyphosate, 2,4,5-trichlorophenoxyacetic acid, and 2,4-dichlorophenoxyacetic acid on forest litter decomposition

Laboratory studies with two leaf litter and one forest floor substrate showed that the herbicides 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), a 50:50 mixture of these, and glyphosate all had toxic thresholds at which they reduced decomposition. However, in all cases, the thresholds were > 50 times higher than residue concentrations that occur in the field after silvicultural herbicide treatments. In a field study at one site, no measurable 1-year postspray effects on litter decomposition were found among treatment plots sprayed at 0.0, 3.4 or 6.7 kg 2,4,5-T/ha.

MASS LOSS IN A FORESTED BOG: RELATION TO HUMMOCK AND HOLLOW MICRORELIEF

The importance of microrelief in relation to mass loss was studied in a Minnesota ombrotrophic forested peatland. Litter and paper strips placed in hummocks for 1 yr lost significantly more mass (two and three times, respectively) than similar material placed in hollows. Less favorable environmental conditions for decomposition, especially lower temperature, reduced decomposition in the hollows. Key words: Peatlands, ombrotrophic, decomposition, Histosols