Distribution and cycling of nutrients in an aspen-mixed-hardwood- Spodosol ecosystem in northern Wisconsin.

J. Pastor, J. G. Bockheim

Research output: Contribution to journalArticlepeer-review

80 Scopus citations


In overstory aspen and understory sugar maple, stand biomass and net primary production (NPP) were 198 Mg/ha and 12.5 Mg.ha-1yr-1, respectively. Overstory quaking aspen Populus tremuloides comprised 60% of the biomass and 50% of the NPP, and understory sugar maple Acer saccharum comprised 24 and 25% of these values, respectively. The total soil N pool and extractable soil P and Mg pools were larger than the respective vegetation nutrient pools. Nutrient cycling within this ecosystem is characterized by large uptake rates, retention of 40-60% of nutrient uptake in perennial tissues, and leaching losses of <3 kg.ha-1yr-1 for each nutrient. Between 22-40% of total stand nutrient uptake is retained in perennial tissues of quaking aspen and 4-20% in perennial tissues of sugar maple. Aspen was more effective than maple in retaining nutrients because a larger proportion of its production was perennial tissues with higher nutrient concentrations. Because nutrient-rich leaves constituted a smaller proportion of aspen's production compared with sugar maple's, aspen used nutrient more efficiently in production of dry matter. Translocation of nutrients out of leaves back into perennial tissues was an important retention mechanism for N, P and K; was less important for S, Mg and Fe; and did not occur for Ca and Zn. Aspen translocated proportionally more of most nutrients out of green leaves than did sugar maple, but differences between the species were often small. Uptake as rainwater passed through the canopy and immobilization within the A1 horizon of the soil were additional retention mechanisms for NH4-N and NO3-N. A fragipan at the base of the rooting zone also showed leaching losses.-from Authors

Original languageEnglish (US)
Pages (from-to)339-353
Number of pages15
Issue number2
StatePublished - 1984


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