Comparison of nitrogen and phosphorus cycling for five plantation-grown tree species with different leaf longevities

Nitrogen and phosphorus cycling was examined for 28-year-old red oak (Quercus rubra L.), European larch (Larix decidua Miller), white pine (Pinus strobus L.), red pine (Pinus resinosa Ait.) and Norway spruce (Picea abies (L) Karst.) plantations on a similar soil in southwestern Wisconsin. The concentration and content of several soil nutrients differed among the five species but no consistent pattern was observed between deciduous and evergreen species. In general, total N and P content were greatest in the upper 30 cm soil followed by aboveground vegetation and forest floor. Total N and P content in aboveground vegetation was positively correlated with leaf longevity.; Annual aboveground N and P requirement kg/ha/yr) totaled 126 and 13 for red oak, 86 and 9 for European larch, 80 and 9 for white pine, 38 and 6 for red pine, and 81 and 13 for Norway spruce, respectively. In three evergreen species, uptake accounted for 72-74% of the annual N requirement whereas retranslocation accounted for 76-77% of the annual N requirement for two deciduous species. Nitrogen and P use efficiency (ANPP/uptake) was more efficient in deciduous species than evergreen species.; Annual net N mineralization in the top 20 cm of forest floor plus mineral soil differed significantly (p {dollar}<{dollar} 0.05) among the five species and ranged from 53 kg/ha/yr for red oak to 117 kg/ha/yr for European larch. Annual nitrification also differed significantly (p {dollar}<{dollar} 0.05) among species and comprised from 40% for red oak to 95% for European larch of total annual net N mineralized. Annual leaf litterfall N content (kg/ha/yr) over the two years (1988-1989) ranged from 22 for white pine to 53 for Norway spruce but did not explain a significant amount of the observed variation of annual N mineralized among the five species. We speculate that other differences in litter quality may be controlling N mineralization. The results from this common garden experiment demonstrate that differences in N and P cycling among the five species may result from intrinsic characteristics (e.g. leaf longevity) rather than environmental conditions.