Long Robert P, Horsley Stephen B, Hallett Richard A, Bailey Scott W
U.S. Forest Service, Northern Research Station, Delaware, Ohio 43015, USA.
Ecol Appl. 2009 Sep;19(6):1454-66. doi: 10.1890/08-1535.1.
Sugar maple, Acer saccharum, decline disease is incited by multiple disturbance factors when imbalanced calcium (Ca), magnesium (Mg), and manganese (Mn) act as predisposing stressors. Our objective in this study was to determine whether factors affecting sugar maple health also affect growth as estimated by basal area increment (BAI). We used 76 northern hardwood stands in northern Pennsylvania, New York, Vermont, and New Hampshire, USA, and found that sugar maple growth was positively related to foliar concentrations of Ca and Mg and stand level estimates of sugar maple crown health during a high stress period from 1987 to 1996. Foliar nutrient threshold values for Ca, Mg, and Mn were used to analyze long-term BAI trends from 1937 to 1996. Significant (P < or = 0.05) nutrient threshold-by-time interactions indicate changing growth in relation to nutrition during this period. Healthy sugar maples sampled in the 1990s had decreased growth in the 1970s, 10-20 years in advance of the 1980s and 1990s decline episode in Pennsylvania. Even apparently healthy stands that had no defoliation, but had below-threshold amounts of Ca or Mg and above-threshold Mn (from foliage samples taken in the mid 1990s), had decreasing growth by the 1970s. Co-occurring black cherry, Prunus serotina, in a subset of the Pennsylvania and New York stands, showed opposite growth responses with greater growth in stands with below-threshold Ca and Mg compared with above-threshold stands. Sugar maple growing on sites with the highest concentrations of foliar Ca and Mg show a general increase in growth from 1937 to 1996 while other stands with lower Ca and Mg concentrations show a stable or decreasing growth trend. We conclude that acid deposition induced changes in soil nutrient status that crossed a threshold necessary to sustain sugar maple growth during the 1970s on some sites. While nutrition of these elements has not been considered in forest management decisions, our research shows species specific responses to Ca and Mg that may reduce health and growth of sugar maple or change species composition, if not addressed.
糖枫（Acer saccharum）衰退病是由多种干扰因素引发的，当钙（Ca）、镁（Mg）和锰（Mn）失衡作为诱发应激源时。我们在本研究中的目标是确定影响糖枫健康的因素是否也会影响以断面积生长量（BAI）估算的生长情况。我们在美国宾夕法尼亚州北部、纽约州、佛蒙特州和新罕布什尔州使用了76个北方硬木林分，发现糖枫生长与叶片中Ca和Mg的浓度以及1987年至1996年高压力时期糖枫树冠健康状况的林分水平估算值呈正相关。利用Ca、Mg和Mn的叶片养分阈值来分析1937年至1996年的长期BAI趋势。显著的（P≤0.05）养分阈值与时间的相互作用表明在此期间生长与营养状况的变化有关。20世纪90年代采样的健康糖枫在20世纪70年代生长量下降，比宾夕法尼亚州20世纪80年代和90年代衰退事件提前10 - 20年。即使是那些没有落叶、但Ca或Mg含量低于阈值且Mn含量高于阈值（从20世纪90年代中期采集的叶片样本来看）的明显健康林分，到20世纪70年代生长量也在下降。在宾夕法尼亚州和纽约州部分林分中同时存在的黑樱桃（Prunus serotina）表现出相反的生长反应，与Ca和Mg含量高于阈值的林分相比，在Ca和Mg含量低于阈值的林分中生长量更大。生长在叶片Ca和Mg浓度最高的立地上的糖枫从1937年到1996年生长量总体呈增加趋势，而其他Ca和Mg浓度较低的林分生长量呈稳定或下降趋势。我们得出结论，酸沉降导致土壤养分状况发生变化，在20世纪70年代，某些立地上这种变化超过了维持糖枫生长所需的阈值。虽然在森林管理决策中尚未考虑这些元素的营养状况，但我们的研究表明，如果不加以解决，糖枫对Ca和Mg的物种特异性反应可能会降低其健康状况和生长量，或改变物种组成。
