Establishment and growth of oak (Quercus alba, Quercus prinus) seedlings in burned and fire-excluded upland forests on the Cumberland Plateau
Establishment and growth of oak (Quercus alba, Quercus prinus) seedlings in burned and fire-excluded upland forests on the Cumberland Plateau
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DOI：
10.1016/j.foreco.2010.05.005
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发表时间：
2010-07
影响因子：
3.7
通讯作者：
J. Royse;M. Arthur;A. Schörgendorfer;D. Loftis
中科院分区：
文献类型：
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作者：
J. Royse;M. Arthur;A. Schörgendorfer;D. Loftis
在广泛的生态系统中，已经记录了橡树（栎属）再生的反复问题。在美国中部和阿巴拉契亚硬木地区以橡树为主的森林中，缺乏竞争性的橡树再生在一定程度上与这些景观的灭火有关，整个地区的管理者都在使用规定的火灾来解决这一问题。为了研究火灾对橡树再生的影响，研究人员通常依赖于现有幼苗的库存或种群研究。这些研究是有价值的，但不允许检查火灾在促进橡树桅杆事件产生的新橡树幼苗的建立和生长中的作用。在本研究中，白栎（Quercus alba）和栗子栎（Quercus prinus）橡实杆作物在景观尺度规定火灾试验的第三年（2005年秋季）偶然发生。在肯塔基州东部坎伯兰高原上，研究了新苗的建立、存活率、幼苗高度和幼苗直径。处理方法为排除火源、单次火烧（2003年1次烧）和多次火烧（2003年、2004年和2006年橡果落果后3次烧），均在晚春进行。尽管火灾发生在橡子落地后，但新建立的栗子和白栎幼苗的初始密度在不同处理之间具有统计学上的相似性（P=0.42）。除板栗栎外，其他样地栎基面积对幼苗密度均有显著的预测作用（R2=0.12 ~ 0.46）。3次烧伤处理的凋落物深度比1次和不着火处理的凋落物深度小，而两种烧伤处理的冠层开度都比不着火处理的大。与燃烧地点相比，不着火地点的幼苗死亡率普遍较高，尤其是白栎。初生凋落物深度和开放天空显著预测了栎树幼苗前两个生长季的死亡率，凋落物深度越大，开放天空百分比越低，死亡率越高。在第三个生长季，所有测量的变量都不能预测板栗栎幼苗的成活率；对于白栎而言，开放天空的百分比仍然是死亡率的重要预测指标。初期，未着火地点的幼苗高度相近，但直径较小；三个生长期后，不同处理的幼苗高度和直径差异不大。我们的研究结果表明，规定的火灾在建立森林地面和光照条件方面可能起着潜在的作用，这些条件可能会提高新橡树发芽的成功率，尽管不同物种之间的不同反应可能表明需要针对单个橡树物种进行目标管理。
Recurrent problems with regeneration of oaks (Quercus spp.) have been documented across a wide range of ecosystems. In oak-dominated forests of the central and Appalachian hardwood regions of the United States, a lack of competitive oak regeneration has been tied, in part, to fire suppression in these landscapes, and managers throughout the region are using prescribed fire to address this concern. To examine fire effects on oak regeneration, researchers have generally relied on inventories or population studies of existing seedlings. These studies are valuable but do not permit examination of the role of fire in enhancing the establishment and growth of new oak seedlings stemming from oak mast events. In this study, white (Quercus alba) and chestnut oak (Quercus prinus) acorn mast crops serendipitously occurred in year three (fall 2005) of a landscape-scale prescribed fire experiment. We examined establishment, survival, height and diameter of new seedlings on sites on the Cumberland Plateau in eastern Kentucky. Treatments were fire exclusion, a single prescribed fire (1x-burn; 2003), and repeated prescribed fire (3x-burn; 2003, 2004, and after acorn drop in 2006), all conducted in late spring. Initial densities of newly established chestnut and white oak seedlings were statistically similar across treatments (P=0.42), despite fires on the 3x-burn site having occurred after acorns were on the ground. Oak seedling density was significantly predicted by oak basal area on all sites (R2=0.12–0.46), except for chestnut oak on fire-excluded sites (R2=0.04). Litter depth was less on 3x-burn sites compared to 1x-burn and fire-excluded sites, whereas canopy openness was greater on both burn treatments compared to fire-excluded sites. Seedling mortality was generally higher on fire-excluded sites compared to burn sites, especially for white oak. Oak seedling mortality in the first two growing seasons was significantly predicted by initial litter depth and open sky, with greater litter depth and lower percent open sky leading to higher mortality. In the third growing season none of the measured variables predicted chestnut oak seedling survival; for white oak, percent open sky remained a significant predictor of mortality. Initially, seedlings on the fire-excluded sites had similar height but smaller diameter; after three growing seasons there were few differences in seedling height or diameter among treatments. Our findings suggest a potential role for prescribed fire in establishing forest floor and light conditions that may enhance the success of new oak germinants, although different responses among species may suggest the need to target management for individual oak species.