St Clair Samuel B, Lynch Jonathan P
Intercollegiate Graduate Program in Ecological and Molecular Plant Physiology, The Pennsylvania State University, 102 Tyson Building, University Park, PA 16802, USA.
Tree Physiol. 2005 Jan;25(1):85-92. doi: 10.1093/treephys/25.1.85.
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.
包括锰（Mn）超积累在内的叶片养分失衡，与生长在酸性森林土壤上的敏感树种健康状况下降的症状相关。本研究的目的是：（1）比较生长在酸性森林土壤上的六种落叶树种（糖枫（Acer saccharum Marsh.）、红枫（Acer rubrum L.）、红橡树（Quercus rubra L.）、白橡树（Quercus alba L.）、黑樱桃（Prunus serotina Ehrh.）和白蜡树（Fraxinus americana L.））和三种常绿树种（铁杉（Tsuga canadensis L.）、白松（Pinus strobus L.）和白云杉（Picea glauca (Moench) Voss.））的叶片养分积累模式；（2）研究叶片物候以及区分常绿和落叶树种的其他特征如何影响叶片锰积累速率和对过量锰的敏感性。对于第一个目标，采集了宾夕法尼亚州阿勒格尼高原五个酸性、非冰川化野外地点的幼苗叶片样本，并分析了叶片元素浓度。在第二项研究中，我们研究了砂培中暴露于过量锰的幼苗的生长和光合反应。在野外样本中，落叶中的锰超积累到浓度，比常绿针叶中的浓度高出两倍多。在树种中，根据生长和光合测量，糖枫对过量锰最敏感。红枫和红橡树的光合作用对过量锰也敏感，而白橡树、黑樱桃、白蜡树和三种常绿树种对过量锰具有耐受性。在这九个树种中，光合相对速率与叶片锰浓度呈负相关，这表明对锰的光合敏感性是其在幼苗叶片中积累速率的函数。
