CNRS and Université Montpellier 2, UMR AMAP, Montpellier, France.
Department of Ecology and Evolutionary Biology, and Natural History Museum and Biodiversity Institute, University of Kansas, Lawrence, USA.
Ann Bot. 2018 Mar 14;121(4):681-689. doi: 10.1093/aob/mcx199.
Investigating the biology of trees that were growing at high latitudes during warmer geological periods is key to understanding the functioning of both past and future forest ecosystems. The aim of this study is to report the first co-occurrence of epicormic shoots and traumatic growth zones in fossil trees from the Triassic of Antarctica and to discuss their biological and environmental implications.
Permineralized woods bearing scars of epicormic shoots were collected from the Triassic Fremouw Formation in Gordon Valley, Central Transantarctic Mountains, Antarctica in 2010. Samples from different portions of three specimens were prepared using standard thin section and hydrofluoric (HF) acid peel techniques, and anatomical details were studied in transmitted light.
The fossil woods represent the outer part of trunks, with at least 40 growth rings that are 0.2-4.8 mm in width. Anatomical comparisons suggest that they represent a new tree taxon for the Triassic of Antarctica. Numerous small epicormic shoots can be seen crossing the wood almost horizontally and are locally branched. Each specimen also contains several occurrences of traumatic growth zones located in the early wood, in the cells produced either at the very start of the growing season or slightly later.
This is the first report of epicormic shoots and traumatic growth zones in the wood of a Triassic tree from Antarctica. Their co-occurrence indicates that these trees from Gordon Valley were subjected to environmental stresses not seen in Triassic trees previously described from this region. This suggests that they had a different biology and/or were growing in a different habitat, which offers a new glimpse into the diversity of high-latitude trees in the Triassic greenhouse climate.
研究在温暖地质时期生长在高纬度地区的树木的生物学特性，是了解过去和未来森林生态系统功能的关键。本研究的目的是报告首例在南极三叠纪化石树木中同时出现的皮孔枝和创伤生长带，并讨论其生物学和环境意义。
2010 年，在南极中横贯南极山脉戈登谷的三叠纪弗罗默夫组中采集到了带有皮孔枝疤痕的矿化木材。使用标准的薄片和氢氟酸（HF）酸蚀剥离技术，对三个标本不同部位的样本进行了处理，并在透射光下研究了解剖学细节。
化石木材代表树干的外部分，至少有 40 个生长轮，宽度为 0.2-4.8 毫米。解剖学比较表明，它们代表了南极三叠纪的一个新的树木分类群。许多小的皮孔枝可以看到几乎水平地穿过木材，并在局部分枝。每个标本还包含几个位于早材中的创伤生长带，这些生长带位于生长季节开始时或稍晚时产生的细胞中。
这是首例在南极三叠纪树木的木材中同时出现皮孔枝和创伤生长带的报告。它们的共同出现表明，这些来自戈登谷的树木受到了该地区以前描述的三叠纪树木所未见的环境压力。这表明它们具有不同的生物学特性，或者生长在不同的生境中，这为三叠纪温室气候中高纬度树木的多样性提供了新的视角。
