Three-dimensional light structure of an upland Quercus stand post-tornado disturbance
Three-dimensional light structure of an upland Quercus stand post-tornado disturbance
复制标题
龙卷风扰动后高地栎林的三维光结构
DOI：
10.1007/s11676-019-00907-y
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发表时间：
2019
影响因子：
3
通讯作者：
D. Dey
中科院分区：
文献类型：
--
作者：
Kevin G. Willson;L. Cox;J. Hart;D. Dey
光照是森林植物群落中最常见的限制因子，影响着郁闭林分的物种组成、林分结构和林分生产力。在封闭的树冠下，林分垂直光结构相对简单，因为大部分光被上层树木捕获。然而，风干扰事件创建从本地到景观尺度的树冠开口，增加林下光强度和垂直光结构的复杂性。我们研究了EF-1龙卷风对水平和垂直（即三维）光结构的影响，以确定光结构如何随着干扰程度的增加而变化。我们使用两层方法收集森林地面以上4.67 m和1.37 m处的光合光子通量密度，以构建跨冠层干扰严重程度梯度的三维光结构，看看光强度是否随着龙卷风破坏的增加而变化。结果表明，增加冠层干扰更接近龙卷风的轨迹增加光穿透和光结构异质性在较低的森林层。增加光照强度与树苗密度增加，更随机地分布在整个情节和转移光捕获更高的立场结构。光透过上层是最强烈的相关性降低干密度在两个最重要的树种（基于相对优势和相对密度）的立场，栎alba L。（r =-0.31）和Ostrya virginiana（Mill.）K. Koch（r =-0.27，p < 0.01），并表明林下光穿透受这两个物种的影响最大。随着管理人员对自然干扰的造林条目图案越来越感兴趣，他们必须了解自然干扰事件后发生的残留林分和光照结构。通过提供量化干扰后光结构的空间光数据，管理人员可以使用这些结果来改善长期管理所需的规划。这项研究还提供了与人为干扰的中层，可能提供有用的比较，自然类似物为未来的造林考虑。
Light is the most common limiting factor in forest plant communities, influencing species composition, stand structure, and stand productivity in closed canopy stands. Stand vertical light structure is relatively simple under a closed canopy because most light is captured by overstory trees. However, wind disturbance events create canopy openings from local to landscape scales that increase understory light intensity and vertical light structural complexity. We studied the effects of an EF-1 tornado on horizontal and vertical (i.e. three-dimensional) light structure within a Quercus stand to determine how light structure changed with increasing disturbance severity. We used a two-tiered method to collect photosynthetic photon flux density at 4.67 m and 1.37 m above the forest floor to construct three-dimensional light structure across a canopy disturbance severity gradient to see if light intensity varied with increasing tornado damage. Results indicate that increased canopy disturbance closer to the tornado track increased light penetration and light structure heterogeneity at lower forest strata. Increased light intensity correlated with increased sapling density that was more randomly distributed across the plot and had shifted light capture higher in the stand structure. Light penetration through the overstory was most strongly correlated with decreased stem density in the two most important tree species (based on relative dominance and relative density) in the stand, Quercus alba L. (r = − 0.31) and Ostrya virginiana (Mill.) K. Koch (r = − 0.27, p < 0.01), and indicated that understory light penetration was most affected by these two species. As managers are increasingly interested in patterning silvicultural entries on natural disturbances, they must understand residual stand and light structures that occur after natural disturbance events. By providing spatial light data that quantifies light structure post-disturbance, managers can use these results to improve planning required for long-term management. The study also provides comparisons with anthropogenic disturbances to the midstory that may offer useful comparisons to natural analogs for future silvicultural consideration.