Decomposition of timothy (Phleum pratense) litter on a reclaimed surface coal mine in Alberta, Canada

Abstract

Three plots differing in the time since their reclamation (7, 3, and 1 years) were selected for a 3-year decomposition study of timothy (Phleum pratense L.) litter on a surface coal mine in Alberta, Canada. A comparison between single and double exponential functions showed that mass losses were best described by double exponential decay functions, which revealed a trend of decreasing mass loss rate of the labile and recalcitrant litter fractions with increasing time following reclamation. This study suggests that abiotic factors control the release of the labile fraction during the initial phase of decomposition, whereas biotic factors control the decomposition of the recalcitrant fraction with minimal influences imposed by the measured microsite parameters. Timothy biomass formed a much larger component of the total biomass on the 7-year plot (39%) than on the 3-year (13%) and 1-year (13%) plots. Reports in the literature indicate that timothy has low nutrient requirements and is tolerant of low soil fertility. The presence of this short-lived perennial at high biomass levels with a relatively small total plant biomass on the 7-year-old plot, along with a relatively low rate of timothy litter decomposition, supports the suggestion that spoil on the oldest plot is deficient in available nutrients.