Did thermophilous trees spread into central Europe during the Late Glacial?
Did thermophilous trees spread into central Europe during the Late Glacial?
复制标题
嗜热树木是否在冰期末期传播到中欧？
DOI：
10.1111/nph.14149
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
T. Giesecke
中科院分区：
文献类型：
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作者：
T. Giesecke
推断物种在末次冰盛期（LGM）幸存下来的地方，以及它们从哪里殖民的地区，这些地区随着冰后期气候变暖而变得可用，这与解释植物地理模式和估计植物能够传播的速度有关。后者在关于现代气候变化对物种多样性影响的辩论中很重要，因为未来气候变化的速度可能比植物传播的能力更快（Urban，2015）。Stewart & Lister（2001）认为，喜热类群可能比传统观念更靠北的地方存活下来。这种隐蔽的北方避难所的存在将减少末次大冰期后树木必须传播的距离。来自德国中部51°N的一个地点的栎属和山毛榉属的木炭碎片可以解释为全新世开始之前支持向北的末次大冰期分布的存在（Robin等人，2016年;这一问题的新植物学家，pp。259-268）。另外，罗宾等人（2016）认为，晚冰期的温暖期比目前认为的要长，因此这两种树种可以在晚冰期从更南边的地方到达南部的哈茨山脉。有了这样的关键发现，重要的是要记录它们是真实的，Robin等人（2016）声称已经通过使用三个独立的放射性碳实验室来确定木炭碎片的日期。然而，所有来自喜热树木的前全新世木炭年龄都来自基尔大学（德国）的一个实验室。这个特定的实验室被怀疑在最近几年产生了一些不可靠的日期（Lull等人，虽然我相信作者的木炭鉴定技能，但看到有问题的实际木炭片的照片，而不是从参考收藏中精心准备的照片，表明诊断特征，这将是适当的。当将他们的发现与先前发表的信息进行比较时，Robin等人（2016）在处理文献时表现出粗心，如图1所示。在这里，他们引用了一张来自拉脱维亚的花粉图，其中包含了一些晚冰期时期的栎属花粉粒（Heikeaa等人，2009).栎属花粉分散得很好，因此在当地花粉产量低的地方，在没有树的地区的花粉计数中遇到栎属花粉（Lisitsyna et al.，2011年）。晚冰期湖泊沉积物中花粉的另一个来源是含有较老花粉的土壤的侵蚀。这是Jues湖花粉图中基底样品中水青冈属花粉最可能的情况（Voigt等人，2008年），这是为了支持调查结果。Robin等人（2016年）还列出了一张花粉图，该图很好地代表了晚冰期，距离采样点< 50公里（B€ottger等人，1998年），没有发现单一的水青冈和只有一个单一的栎花粉粒在43个分析样本涵盖新仙女木（YD）和Allerød时期。如果木炭的发现证明了这两种树在晚冰期的传播，那么这些树需要开花才能通过种子产生和传播，而这张花粉图应该显示出证据，但它没有。Robin et al.（2016）引用的所有其他证据都表明栎属的存在是在全新世早期。虽然这些证据比报告的木炭年龄更年轻，但它们确实包含了有趣的发现，如Goslar& Pazdur（1985）的参考。Robin等人（2016）报告的这一参考文献是花粉，实际上是指在波兰中部靠近罗兹的地区发现的放射性碳年代测定的栎属树干（51.73°N，19.38°E -Robin等人（2016）图1中的错误位置），较旧的日期介于10 234和10 523 cal yr BP之间（校准年份在现在之前，现在指的是1950年）。此外，德国橡树年表中最古老的橡树应该是Friedrich等人（2004年）报告的最古老年轮的年龄为10 430 cal yr BP。斯洛伐克南部（北纬47.87°，北方）的花粉和宏体化石证实了在约1000万年前栎属的丰富。11 000 cal yr BP（Jamrichov a等人，2014年），这表明栎属可能在距离该地点不远的YD寒流中幸存下来。过时的水青冈木炭片在几个方面都不合适。研究地点位于哈茨山脉东南边缘，目前太干燥，水青冈无法在森林中占主导地位，晚冰期的干旱可能更严重。栎属在植被中的优势地位反映在7个土坑中栎属木炭的优势地位。其中只有一个坑产生大量的水青冈木炭，而四个坑根本不产生水青冈木炭（Robin等人，2014年）。与粗壮栎相比，森林水青冈对冬季寒冷更敏感，这在其当前分布以及该物种的模拟LGM范围中是可见的（Svenning等人，2008年）。水青冈木炭放射性碳测年结果表明，在12500 cal/yr BP时，有1棵树存活并同化，这一时间点为12500 cal/yr BP。400年进入YD冷却和c.在越来越干燥的条件开始后100年（Rach等人，2014年）。阿尔卑斯山以北没有发现全新世早期的水青冈大型化石（Magri等人，2006年），和最早的花粉值指示其存在日期为C。8200 cal yr BP（Tinner & Lotter，2006）。在中欧花粉图中，水青冈属的扩展通常是在一个长的
Inferringwhere species survived the LastGlacialMaximum (LGM) and from where they colonized areas that became available with post-glacial climate warming is relevant to interpret phylogeographic patterns and to estimate velocities with which plants are able to spread. The latter is important in the debate on the impact of modern climate change on species diversity as the velocity of future climate change may be faster than the ability of plants to spread (Urban, 2015). Stewart & Lister (2001) suggested that thermophilous taxa may have survived the LGMmuch further north than traditionally perceived. The existence of such cryptic northern refugia would reduce the distance over which trees had to spread after theLGM.Charcoal fragments ofQuercus andFagus froma site in central Germany at 51°N dated to before the onset of the Holocene could be interpreted to support the existence of northerly LGM distributions (Robin et al., 2016; this issue of New Phytologist, pp. 259–268). Alternatively, Robin et al. (2016) suggest that warm periods during the Late Glacial were longer than currently considered so that the two tree species could reach the southern Harz Mountains during the Late Glacial from more southerly locations. With critical finds like this, it is important to document that they are genuine andRobin et al. (2016) claim to have established this by using three independent radiocarbon laboratories to date the charcoal fragments. However, all pre-Holocene ages of charcoal from thermophilous trees come from one single laboratory at the University of Kiel (Germany). This particular laboratory is suspected to have produced some unreliable dates in recent years (Lull et al., 2015) so it would have been important to reproduce the critical ages by using a second laboratory.While I trust the charcoal identification skills of the authors, it would have been appropriate to see photographs of the actual charcoal pieces in question, rather than nicely prepared photographs from the reference collection indicating the diagnostic features. When comparing their finds to previously published information, Robin et al. (2016) display carelessness in the treatment of the literature, which is summarized in their Fig. 1. Here they cite a pollen diagram from Latvia containing a few Quercus pollen grains during the Late Glacial (Heikkil€a et al., 2009).Quercus pollen disperses very well and thus where local pollen production is lowQuercus pollen is encountered in pollen counts from regions where the tree is absent (Lisitsyna et al., 2011). Another source of pollen in Late Glacial lake sediments is from the erosion of soil containing older pollen.This is the most likely case for the Fagus pollen in the basal samples in the pollen diagram from Lake Jues (Voigt et al., 2008), which was mentioned in support of the finds. Robin et al. (2016) also list a pollen diagram with a good representation of the Late Glacial, < 50 km from the sample site (B€ottger et al., 1998), with no single find of Fagus and only one single Quercus pollen grain in 43 analyzed samples covering the Younger Dryas (YD) and Allerød periods. If the charcoal finds attest a spread of both trees during the Late Glacial then the trees would need to flower to produce and spread by seed and this pollen diagram should show evidence, which it does not. All other evidence cited by Robin et al. (2016) refers to the earlyHolocene for the presence ofQuercus.While these are younger than the reported charcoal ages, they do contain interesting finds like the reference to Goslar& Pazdur (1985). This reference, reported by Robin et al. (2016) as pollen, actually refers to radiocarbon dated Quercus trunks recovered in central Poland near Lodz (51.73°N, 19.38°E – the wrong location in Fig. 1 of Robin et al. (2016)) with the older date falling between 10 234 and 10 523 cal yr BP (calibrated years before present, with present referring to the year 1950). Also the reference to the oldest oaks in the German oak chronology should have been Friedrich et al. (2004) reporting the age of 10 430 cal yr BP for the oldest ring. The pollen andmacrofossils from southern Slovakia, at 47.87°northern latitude, document indeed the abundance of Quercus at c. 11 000 cal yr BP (Jamrichov a et al., 2014), suggesting that Quercus may have survived the YD cold spell not too far away from that site. The dated Fagus charcoal pieces are out of place in several respects. The location of the study site at the south-eastern edge of the Harz Mountains is currently too dry for Fagus to dominate the forest and drought was likely more severe during the Late Glacial. The current dominance ofQuercus in the vegetation is reflected by the dominance ofQuercus charcoal in the seven soil pits dug at this location. Only one of them yielded a larger amount of Fagus charcoal, while four pits produced no Fagus charcoal at all (Robin et al., 2014). Compared to Quercus robur, Fagus sylvatica is more sensitive to winter cold, which is visible in its current distribution as well as in the simulated LGM ranges of the species (Svenning et al., 2008). The radiocarbon dates of Fagus charcoal suggest that one tree was alive and assimilating by 12 500 cal yr BP which is c. 400 yr into the YD cooling and c. 100 yr after the onset of increasingly drier conditions (Rach et al., 2014). There are no early Holocene macrofossil finds of Fagus north of the Alps (Magri et al., 2006), and the earliest pollen values indicative of its presence date to c. 8200 cal yr BP (Tinner & Lotter, 2006). The expansion of Fagus in central European pollen diagrams is usually preceded by a long
影响因子：
4
作者：
Giesecke;Bennett;Bozilova;Feurdean;Finsinger;Pokorny;Rösch;Seppä;Tonkov;Valsecchi;S Wolters
通讯作者：
S Wolters