Effects of hurricane canopy gaps on longleaf pine and upland oak sapling growth
Effects of hurricane canopy gaps on longleaf pine and upland oak sapling growth
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飓风冠层间隙对长叶松和陆地栎树苗生长的影响
DOI：
10.1016/j.foreco.2022.120684
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发表时间：
2023
影响因子：
3.7
通讯作者：
Sharma, Ajay
中科院分区：
文献类型：
--
作者：
Pope, Cody A.;Cannon, Jeffery B.;Bigelow, Seth W.;Sharma, Ajay
长叶松林和林地是一个具有重要生态意义的生态系统，曾经主导着美国东南部的大部分地区。众所周知，频繁的火灾是这些系统中森林动态的驱动因素，但人们对风扰动如何重组植物群落知之甚少。为了更好地了解飓风影响如何改变次生长叶松林地的动态，我们研究了美国乔治亚州西南部飓风迈克尔（2018 年）后三种竞争性高地树种（沼泽松、镰形栎、玛格丽塔栎）树苗的生长反应。我们使用最大似然法将树苗的高度和径向生长建模为特定物种的光可用性米氏函数，并使用模型比较方法检查了树苗大小、土壤持水能力和年降水量的影响。高度和径向生长的最佳模型包括物种特定的生长速率、树苗大小的幂函数以及 2 年滞后降水的影响。总的来说，我们发现所有物种的身高增长率都随着辐照度的增加而增加，但所有物种的身高增长率在低辐照度下都接近。径向生长率也随着辐照度的增加而增加，并且物种间的差异更加明显。长叶松和南方红橡的径向生长对增加的辐照度反应最为强烈。我们的研究结果表明，飓风带来的光照增加对改变树苗的生长动态有直接影响。此外，由于茎半径是地表火灾中生存的有力预测因素，飓风损害也可能通过改变未来火灾中的生存而对树苗动态产生间接影响。我们的结果表明，飓风可以加强长叶松的主导地位，并可能在稳定群落结构方面发挥作用。了解风和火灾等常见干扰的影响（无论是一起还是单独）可以揭示塑造易发生火灾的生态系统的结构和功能的重要机制。
Longleaf pine forests and woodlands are an ecologically important ecosystem that once dominated much of the southeastern U.S. Frequent fire is well-known to be a driver of forest dynamics in these systems, but far less is known about how wind disturbance may reorganize plant communities. To gain a better understanding of how hurricane impacts may alter dynamics in a second-growth longleaf pine woodland, we investigated growth response of saplings from three competing upland species (Pinus palustris, Quercus falcata, Q. margaretta) following Hurricane Michael (2018) in southwest Georgia, United States. We used maximum likelihood to model height and radial growth of saplings as species-specific Michaelis-Menten functions of light availability and examined the effect of sapling size, soil water holding capacity, and annual precipitation using a model comparison approach. The best model for both height and radial growth included species-specific growth rates, a power function for sapling size, and an effect of 2-year lagged precipitation. Overall, we found that height growth rate increased with irradiance for all species, but asymptotic height growth rate for all species was approached at low irradiance. Rates of radial growth also increased with irradiance and were more strongly differentiated among species. Radial growth in longleaf pine and southern red oak responded most strongly to increasing irradiance. Our findings suggest that increases in light availability from hurricanes has direct effects on altering growth dynamics of saplings. Further, because stem radius is a strong predictor of survival from surface fires, hurricane damage may also have an indirect effect on sapling dynamics, by altering survival in future fires. Our results suggest that hurricanes can reinforce the dominance of longleaf pine and potentially play a role in stabilizing community structure. Understanding the effects of common disturbances like wind and fire—together and individually—can reveal important mechanisms that shape the structure and function of fire-prone ecosystems.