Lundström Tor, Jonas Tobias, Stöckli Veronika, Ammann Walter
WSL, Swiss Federal Institute for Snow and Avalanche Research SLF, CH-7260 Davos, Switzerland.
Tree Physiol. 2007 Sep;27(9):1217-27. doi: 10.1093/treephys/27.9.1217.
Eighty-four mature Norway spruce (Picea abies L. Karst), silver fir (Abies alba Mill) and Scots pine (Pinus sylvestris L.) trees were winched over to determine the maximum resistive turning moment (M(a)) of the root-soil system, the root-soil plate geometry, the azimuthal orientation of root growth, and the occurrence of root rot. The calculation of M(a), based on digital image tracking of stem deflection, accounted not only for the force application and its changing geometry, but also for the weight of the overhanging tree, representing up to 42% of M(a). Root rot reduced M(a) significantly and was detected in 25% of the Norway spruce and 5% of the silver fir trees. Excluding trees with root rot, differences in M(a) between species were small and insignificant. About 75% of the variance in M(a) could be explained by one of the four variables--tree mass, stem mass, stem diameter at breast height squared times tree height, and stem diameter at breast height squared. Among the seven allometric variables assessed above ground, stem diameter at breast height best described the root-soil plate dimensions, but the correlations were weak and the differences between species were insignificant. The shape of the root-soil plate was well described by a depth-dependent taper model with an elliptical cross section. Roots displayed a preferred azimuthal orientation of growth in the axis of prevailing winds, and the direction of frequent weak winds matched the orientation of growth better than that of rare strong winds. The lack of difference in anchorage parameters among species probably reflects the similar belowground growth conditions of the mature trees.
为了确定根 - 土系统的最大抵抗转矩（M(a)）、根 - 土板的几何形状、根系生长的方位取向以及根腐病的发生情况，对84棵成熟的挪威云杉（Picea abies L. Karst）、银枞（Abies alba Mill）和苏格兰松（Pinus sylvestris L.）进行了绞拉试验。基于树干挠度的数字图像跟踪计算M(a)，不仅考虑了力的施加及其变化的几何形状，还考虑了悬垂树木的重量，其重量占M(a)的比例高达42%。根腐病显著降低了M(a)，在25%的挪威云杉和5%的银枞中检测到根腐病。排除有根腐病的树木后，不同树种之间M(a)的差异很小且不显著。M(a)约75%的方差可以由四个变量之一来解释——树木质量、树干质量、胸径平方乘以树高以及胸径平方。在上述评估的七个地上异速生长变量中，胸径最能描述根 - 土板的尺寸，但相关性较弱，不同树种之间的差异不显著。根 - 土板的形状可以用一个具有椭圆形横截面的深度相关锥度模型很好地描述。根系在盛行风方向上表现出优先的方位生长取向，频繁微风的方向比罕见强风的方向更符合生长取向。不同树种在锚固参数上缺乏差异可能反映了成熟树木相似的地下生长条件。
