Is the modern-day dieback of yellow-cedar unprecedented?
Is the modern-day dieback of yellow-cedar unprecedented?
复制标题
现代黄雪松的枯死是史无前例的吗？
DOI：
10.1139/cjfr-2021-0004
复制
发表时间：
2021
影响因子：
2.2
通讯作者：
Wiesenberg, N.
中科院分区：
文献类型：
--
作者：
Gaglioti, B.V.;Mann, D.H.;Wiles, G.C.;Wiesenberg, N.
在阿拉斯加东南部，许多黄柏(Callitropsis nootkatens(D.Don)Oerst.前D.P.Little；下称“YC”)包含许多站立的、死气沉沉的障碍。基于树木形态的钉龄估计被用来支持这样的解释，即大约1880年之后气候变暖引发了史无前例的YC死亡。在这里，我们提出了新的YC障碍寿命的估计，通过交叉测定61个障碍的形态，表明它们死了很长一段时间。除了四个以外，所有这些障碍都失去了最外层的年轮腐烂，所以我们使用一种新的方法来估计它们死亡的时间，该方法基于在六棵显示部分形成层死亡的活树上测量的木材消融率。结果表明，在因腐烂而失去枝条的YC钉子中，59%的∼钉子(5类钉子)已经存活了200年，有些甚至长达450年(钉子寿命的平均值±SD：233年±92年)。这些发现，以及来自历史照片、树状年代学和已发表文献中的钉痕形态调查的支持证据表明，YC死亡事件也发生在1880年之前和显著的人为变暖开始之前。气候变化在这些早期死亡事件中所起的作用仍有待进一步探讨。
In Southeast Alaska, many stands of yellow-cedar (Callitropsis nootkatensis(D. Don) Oerst. ex D.P. Little; hereinafter “YC”) contain numerous standing, dead snags. Snag-age estimates based on tree morphology have been used to support the interpretation that a warming climate after ca. 1880 has triggered unprecedented YC dieback. Here, we present new estimates of YC snag longevity by cross-dating 61 snags with morphologies that suggest they stood dead for extended periods. All but four of these snags have lost their outermost rings to decay, so we estimate when they died using a new method based on wood-ablation rates measured in six living trees that display partial cambial dieback. The results indicate that ∼59% of YC snags that lost their branches to decay (Class 5 snags) have remained standing for >200 years, and some for as long as 450 years (snag longevity mean ± SD: 233 ± 92 years). These findings, along with supporting evidence from historical photos, dendrochronology, and snag-morphology surveys in the published literature suggest that episodes of YC dieback also occurred before 1880 and before significant anthropogenic warming began. The roles played by climate change in these earlier dieback events remain to be further explored.