Schneuwly Dominique M, Stoffel Markus, Bollschweiler Michelle
Department of Geosciences, Geography, University of Fribourg, Chemin du Musée 4, CH-1700 Fribourg, Switzerland.
Tree Physiol. 2009 Feb;29(2):281-9. doi: 10.1093/treephys/tpn026. Epub 2008 Dec 19.
After mechanical wounding, callus tissue and tangential rows of traumatic resin ducts (TRDs) are formed in many conifer species. This reaction can be used to date past events of geomorphic processes such as rockfall, debris flow and snow avalanches. However, only few points are known about the tangential spread or the timing of callus tissue and TRD formation after wounding. We analyzed 19 Larix decidua Mill. (European larch) and eight Picea abies (L.) Karst. (Norway spruce) trees that were severely damaged by rockfall activity, resulting in a total of 111 injuries. Callus tissue appeared sparsely on the cross sections and was detected on only 4.2% of the L. decidua samples and 3.6% of the P. abies samples. In contrast, TRDs were present on all cross sections following wounding and were visible on more than one-third (34% in L. decidua and 36.4% in P. abies) of the circumference where the cambium was not destroyed by the rockfall impact. We observe different reactions in the trees depending on the seasonal timing of wounding. The tangential spread of callus tissue and TRDs was more important if the injury occurred during the growth period than during the dormant season, with the difference between seasons being more pronounced for callus tissue formation than for TRD formation. We observed an intra-annual radial migration of TRDs with increasing tangential distance from the wound in 73.2% of the L. decidua samples and 96.6% of the P. abies samples. The persistence of TRD formation in the years following wounding showed that only L. decidua trees produced TRDs 2 years after wounding (10.5%), whereas P. abies trees produced TRDs 5 years after wounding (> 50%).
在遭受机械损伤后，许多针叶树种会形成愈伤组织和创伤树脂道（TRD）的切向排列。这种反应可用于确定过去诸如落石、泥石流和雪崩等地貌过程事件的时间。然而，关于受伤后愈伤组织和TRD形成的切向扩展或时间，我们所知甚少。我们分析了19棵欧洲落叶松（Larix decidua Mill.）和8棵挪威云杉（Picea abies (L.) Karst.），这些树因落石活动而受到严重损伤，总共造成了111处伤口。愈伤组织在横截面上稀疏出现，仅在4.2%的欧洲落叶松样本和3.6%的挪威云杉样本中被检测到。相比之下，受伤后的所有横截面上都有TRD，并且在形成层未被落石撞击破坏的圆周的三分之一以上（欧洲落叶松中为34%，挪威云杉中为36.4%）可见。我们观察到树木根据受伤的季节时间有不同反应。如果损伤发生在生长季节，愈伤组织和TRD的切向扩展比在休眠季节更显著，季节之间在愈伤组织形成方面的差异比在TRD形成方面更明显。在73.2%的欧洲落叶松样本和96.6%的挪威云杉样本中，我们观察到TRD随着与伤口切向距离的增加而进行年内径向迁移。受伤后数年TRD形成的持续性表明，只有欧洲落叶松在受伤2年后产生TRD（10.5%），而挪威云杉在受伤5年后产生TRD（>50%）。
