© 2005 Heron Publishing—Victoria, Canada
Element accumulation patterns of deciduous and evergreen tree seedlings on acid soils: implications for sensitivity to manganese
toxicity
Samuel B. St.Clair (1) and Jonathan P. Lynch (1, 2, 3)
1. Intercollegiate Graduate Program in Ecological and Molecular Plant Physiology, The Pennsylvania State University, 102 Tyson
Building, University Park, PA 16802, USA / 2. Department of Horticulture, The Pennsylvania State University, 221 Tyson Building, University Park, PA 16802, USA / 3. Corresponding author (jpl4@psu.edu) / Received May 26, 2004; accepted July 18, 2004; published online November 1, 2004
Summary
Foliar nutrient imbalances, including the hyperaccumulation of manganese (Mn), are correlated with symptoms of declining health
in sensitive tree species growing on acidic forest soils. The objectives of this study were to: (1) compare foliar nutrient
accumulation patterns of six deciduous (sugar maple (Acer saccharum Marsh.), red maple (Acer rubrum L.), red oak (Quercus rubra L.), white oak (Quercus alba L.), black cherry (Prunus serotina Ehrh.) and white ash (Fraxinus americana L.)) and three evergreen (eastern hemlock (Tsuga canadensis L.), white pine (Pinus strobus L.) and white spruce (Picea glauca (Moench) Voss.)) tree species growing on acidic forest soils; and (2) examine how leaf phenology and other traits that distinguish
evergreen and deciduous tree species influence foliar Mn accumulation rates and sensitivity to excess Mn. For the first objective,
leaf samples of seedlings from five acidic, non-glaciated field sites on Pennsylvania’s Allegheny Plateau were collected and
analyzed for leaf element concentrations. In a second study, we examined growth and photosynthetic responses of seedlings
exposed to excess Mn in sand culture. In field samples, Mn in deciduous foliage hyperaccumulated to concentrations more than
twice as high as those found in evergreen needles. Among species, sugar maple was the most sensitive to excess Mn based on
growth and photosynthetic measurements. Photosynthesis in red maple and red oak was also sensitive to excess Mn, whereas white
oak, black cherry, white ash and the three evergreen species were tolerant of excess Mn. Among the nine species, relative
rates of photosynthesis were negatively correlated with foliar Mn concentrations, suggesting that photosynthetic sensitivity
to Mn is a function of its rate of accumulation in seedling foliage.
Keywords:
ash, cherry, chlorophyll, fluorescence, hemlock, maple, nutrition, oak, photosynthesis, pine, spruce.
