Detecting dynamics and variations of crown asymmetry induced by natural gaps in a temperate secondary forest using terrestrial laser scanning
Detecting dynamics and variations of crown asymmetry induced by natural gaps in a temperate secondary forest using terrestrial laser scanning
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使用地面激光扫描检测温带次生林中自然间隙引起的树冠不对称的动态和变化
DOI：
10.1016/j.foreco.2020.118289
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发表时间：
2020-10
影响因子：
3.7
通讯作者：
Wang G. Geoff
中科院分区：
文献类型：
--
作者：
Lu Deliang;Zhu Jiaojun;Wu Danni;Chen Qingda;Yu Yue;Wang Jing;Zhu Chunyu;Liu Huaqi;Gao Tian;Wang G. Geoff
林窗的形成和关闭在森林演替过程中起着重要作用。大多数研究集中在林隙内的更新，但对林隙周围冠层树木的生长动态（即，间隙边界树），这限制了我们对间隙填充过程的理解。利用陆地激光扫描（TLS）技术，对6种不同木材密度的林冠树种在幼龄林隙（15 a）、老龄林隙（32 a）和郁闭林分（CK）中的树冠不对称性进行了定量研究。扩展林隙面积为166.8 ~ 408.1 m2，平均271.5 m2。每个间隙边界树被分成两个部分，即，一部分面向差距（FG），另一部分面向森林内部（FF）。冠长、冠投影面积和冠体积的比值（FG/FF）分别代表一维、二维和三维树冠不对称性。结果表明，90%的林窗边缘树的冠幅与林窗边缘树的冠幅之比平均为1.58。对于郁闭林分中的树木，虽然树冠不对称性在不同方向上随机发生，且变异较大，但平均比率接近1.00。然而，林隙的差距年龄和林隙边界树的位置（即，差距的北、东、南、西4个方向）对树冠不对称性的影响不显著，这可能是由于林隙形成时间长，树冠不对称性的差异就消失了。树冠不对称性表现出种间差异，并与木材密度呈正相关，这表明具有较高木材密度的树种如色木槭（0.61 g cm−3）可以支撑更不对称的树冠，并且具有比其他树种如胡桃楸（0.45 g cm−3）更高的不对称树冠阈值。冠不对称性在不同尺寸之间有相似的结果。我们的研究结果表明，一般冠不对称的间隙边界树木可能会增加抢购和连根拔起的风险，在风和雪的干扰。虽然基于林隙的造林广泛应用于森林管理，但应考虑其他做法，如间伐或选择性采伐，以创造更多的空间，减轻因林隙形成而引起的树冠不对称。
Gap formation and closure play important roles in forest succession. Most studies focused on regeneration within gaps, but less is known about the growth dynamics of canopy trees surrounding the gaps (i.e., gap border trees), which limits our understanding of the gap-filling process. In this study, terrestrial laser scanning (TLS) was used to quantify the crown asymmetry of six canopy tree species with different wood densities among young gaps (15a), old gaps (32a), and closed forest stands (CK). The size of expanded gaps ranged from 166.8 to 408.1 m2with an average of 271.5 m2. Each gap border tree was separated into two parts, i.e., one part facing the gap (FG) and the other facing the forest interior (FF). The ratios (FG/FF) of crown length, crown projected area, and crown volume of these two parts were calculated to represent one-, two-, and three-dimensional crown asymmetry, respectively. We found that 90% gap border trees had asymmetric crown toward gaps with an average ratio of 1.58. For trees in the closed forest stands, although crown asymmetry occurred randomly in different directions and had a large variation, the average ratio was close to 1.00. However, the gap age and the location of gap border tree (i.e., north, east, south, and west of the gap) did not show significant influences on the crown asymmetry because differences of crown asymmetry probably disappeared after the long period of gap formation. The crown asymmetry exhibited inter-specific variations and was positively correlated with wood density, which indicated that tree species with a higher wood density such asAcer mono(0.61 g cm−3) could support a more asymmetric crown and have a higher asymmetric crown threshold than others such asJuglans mandshurica(0.45 g cm−3). Crown asymmetry had similar results among different dimensions. Our findings indicated that the general crown asymmetry of gap border trees might increase snapping and uprooting risks during wind and snow disturbances. Although gap-based silviculture is widely applied in forest management, additional practices such as thinning or selective harvesting should be considered to create more space and alleviate an asymmetric crown induced by gap formation.
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影响因子：
2.2
作者：
K. Lertzman;C. Krebs
通讯作者：
K. Lertzman;C. Krebs
影响因子：
4.8
作者：
T. Young;S. Hubbell
通讯作者：
T. Young;S. Hubbell
影响因子：
1.8
作者：
Jiaojun Zhu;Xiufen Li;Z. Liu;W. Cao;Y. Gonda;T. Matsuzaki
通讯作者：
Jiaojun Zhu;Xiufen Li;Z. Liu;W. Cao;Y. Gonda;T. Matsuzaki
影响因子：
4.8
作者：
Jones, CG;Lawton, JH;Shachak, M
通讯作者：
Shachak, M
影响因子：
1.5
作者：
Jiaojun Zhu;Zhihong Mao;Lile Hu;Jinxin Zhang
通讯作者：
Jiaojun Zhu;Zhihong Mao;Lile Hu;Jinxin Zhang