Input, accumulation, and residence times of carbon, nitrogen, and phosphorus in four Rocky Mountain coniferous forests

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Abstract
Annual aboveground litterfall in forests of Pinuscontorta Loud., Piceaglauca (Moench) Voss, Piceaengelmannii Parry ex Engelm., and Abieslasiocarpa (Hook.) Nutt. in southwestern Alberta ranged from 286 to 321 g•m−2•year−1. The mass of litter accumulated on the forest floors ranged from 6.3 to 11.0 kg•m−2. Residence times of organic matter in the forest floor were 11 years in a 90-year-old P. contorta stand, 16 years in a 120-year-old P. glauca–P. contorta stand, and 23 years in a 350-year-old P. engelmannii–A. lasiocarpa stand. Residence times of litter in the L layer of the forest floor were longer in a recently clearcut area than in the older forests. Residence times of individual nutrients in the forest floors were in the order N > P > C. Litter in the pine forest had lower concentrations of both N and P than did litter in the spruce–pine forest; litter in the spruce–fir forest had relatively high N and low P concentrations. Differences in nutrient concentrations of litter among sites reflected differences in the nutrient-use efficiency of the vegetation, suggesting that the species composition of vegetation is important in determining availability of nutrients in the floor of these forests.