Recent drought stress leads to growth reductions in Larix sibirica in the western Khentey, Mongolia
Recent drought stress leads to growth reductions in Larix sibirica in the western Khentey, Mongolia
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DOI：
10.1111/j.1365-2486.2009.02147.x
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发表时间：
2010-11-01
影响因子：
11.6
通讯作者：
Leuschner, Christoph
中科院分区：
文献类型：
--
作者：
Dulamsuren, Choimaa;Hauck, Markus;Leuschner, Christoph
研究了蒙古北方Khentey西部森林-草原交错带气温和降水的变化趋势，并将其与蒙古最常见树种西伯利亚落叶松（Larix sibirica）的树干生长量和枝梢水分关系联系起来。在过去的47年里，该地区夏季气温显著升高，夏季降水减少。从20世纪40年代以来，> 400株落叶松的树轮宽度序列显示出强烈的年增长率下降。这种下降的开始是独立的树木的年龄，因此，可以归因于在20世纪世纪的日益干旱。在年生长量下降的同时，西伯利亚落叶松的更新也减少了;今天，在西部Khentey山坡上的落叶松林中几乎缺乏更新。在生长季节拍摄水势的测量表现出每日最低水势接近零膨压点的延长期。这些结果表明，干旱胁迫与目前低的年增长率是一致的。森林内部的树木比森林边缘的树木受到更严重的压力，生长更缓慢。这可归因于最近干旱的增加，因为林分密度以及森林内部的树木本身可能适应更潮湿的条件，而森林边缘的树木总是暴露在更极端的小气候中。预计在21世纪，西部Khentey的干旱程度将逐步增加，这表明落叶松林的未来将减少。蒙古森林带大部分地区的干旱预测普遍增加，甚至表明落叶松的超区域下降。
Trends in air temperature and precipitation in the forest-steppe ecotone of the western Khentey, northern Mongolia were studied and related to stem increment and shoot water relations in Mongolia's most common tree species, Siberian larch (Larix sibirica). The area has been subject to a significant increase of summer temperature and a decrease of summer precipitation during the last 47 years. Tree-ring width series from > 400 larch trees show a strongly decreasing annual increment since the 1940s. The onset of this decrease is independent of the age of the trees and, therefore, can be attributed to the increasing aridity in the 20th century. Simultaneously to the declining annual increment, regeneration of Siberian larch decreased as well; today regeneration is virtually lacking in the larch forests on mountain slopes of the western Khentey. Measurements of shoot water potentials during the growing season exhibited daily minimum water potentials close to the point of zero turgor for extended periods. The drought stress indicated by these results is in line with the current low annual increment. Trees in the forest interior were more severely stressed and grow more slowly than trees at the forest line to steppe. This is attributable to the recent increase in aridity, as the stand density and probably also the trees themselves in the forest interior are adapted to moister conditions, whereas the trees at the forest edge have always been exposed to a more extreme microclimate. The progressing increase in aridity during the 21st century that is predicted for the western Khentey, suggests a future decline of larch forests. A widespread increase of aridity predicted for most parts of the Mongolian forest belt, suggests even a supra-regional decline of larch.