A New Architectural Perspective on Wind Damage in a Natural Forest
A New Architectural Perspective on Wind Damage in a Natural Forest
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DOI：
10.3389/ffgc.2018.00013
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发表时间：
2019-01-07
影响因子：
3.2
通讯作者：
Malhi, Yadvinder
中科院分区：
文献类型：
--
作者：
Jackson, Tobias;Shenkin, Alexander;Malhi, Yadvinder
风害是温带和热带地区森林结构、生态和碳循环的重要驱动力，但大多数关于风害的文献都集中在针叶林种植园。以前在阔叶林的研究一直受到缺乏树木结构数据的限制，这一问题有可能通过地面激光扫描（TLS）来克服。在这里，我们采用新的方法来估计的临界风速，树木将打破在温带，落叶林阴谋Wytham伍兹，英国，使用现场数据和有限元分析相结合。白蜡树（Fraxinus excelsior）的临界风速往往低于梧桐树（Acer pseudoplatanus），而英国橡树（Quercus robur）的机械强度最高。临界风速（CWS）的这种差异是由树木的大小和结构，而不是材料特性驱动的。我们观察到CWS和增长率之间的权衡，无论是在物种内和跨物种。我们估计的临界风速从现场数据是在夏季低于冬季，强调春季和秋季过渡期的重要性。在我们研究的三个物种中，那些临界风速较低的物种在秋季早些时候落叶，这表明落叶的时间可能是在选择压力下，以尽量减少冬季风暴对树木造成损害的风险。这些结果是试验性的，但也是有趣和直观的。
Wind damage is a significant driver of forest structure, ecology and carbon cycling in both temperate and tropical regions, but most of the literature on wind damage focusses on conifer plantations. Previous studies in broadleaf forests have been limited by a lack of data on tree architecture, a problem that is potentially overcome by terrestrial laser scanning (TLS). Here we apply novel approaches to estimate the critical wind speeds at which trees will break in a temperate, deciduous forest plot in Wytham Woods, UK, using a combination of field data and finite element analysis. Ash trees (Fraxinus excelsior) tend to have lower critical wind speeds than sycamores (Acer pseudoplatanus), while English oak (Quercus robur) are the most mechanically robust. This difference in critical wind speed (CWS) is driven by tree size and architecture, rather than material properties. We observe a trade-off between CWS and growth rate, both within and across species. Our estimates of critical wind speeds from field data are lower in summer than in winter, emphasizing the importance of the spring and autumn transition periods. Of the three species we studied, those with lower critical wind speeds drop their leaves earlier in autumn, suggesting that the timing of leaf shedding may be under selection pressure to minimize risk of tree damage from winter storms. These results are tentative, but also intriguing and intuitive.