Effects of fire on woody vegetation structure in African savanna.
Effects of fire on woody vegetation structure in African savanna.
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火灾对非洲稀树草原木本植被结构的影响。
DOI：
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发表时间：
2010
影响因子：
5
通讯作者：
James Jacobson
中科院分区：
文献类型：
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作者：
I. Smit;G. Asner;N. Govender;T. Kennedy;D. Knapp;James Jacobson
尽管火灾对热带稀树草原的形成具有重要意义，但人们对火灾的频率、季节性和强度如何相互作用影响木本植被结构仍知之甚少，而木本植被结构是热带稀树草原生物多样性的关键决定因素。我们利用新的机载光探测和测距（LiDAR）技术，对最古老的热带草原火灾实验之一的垂直和水平木本植被结构进行了全面分析。我们在南非克鲁格国家公园开发并比较了一系列大型实验烧伤地块的高分辨率木本植被高度表面。54年来，这些7公顷的地块（总面积约1500公顷）在不同的季节和不同的频率遭受火灾，以及非燃烧地区。长期暴露于火中导致木本植被减少至5.0-7.5 m高度，尽管观察到最多减少至4 m。平均火灾强度与木本植被结构变化呈正相关。频繁的火灾比不频繁的火灾更能减少木本植被覆盖，旱季火灾比雨季火灾更能减少木本植被。旱季后期的春季火灾减少的木本植被覆盖最多，而雨季的夏季火灾减少的最少。与开阔的玄武岩景观相比，在树木繁茂的花岗岩景观中，火灾对结构的影响较大，尽管在比例上，树木繁茂的景观比湿润的景观减少得更多。我们发现，火灾频率和火灾季节影响植被三维结构模式，这可能对生物多样性产生级联后果。因此，稀树草原的管理者可以利用火灾的频率和季节来实现特定的植被结构目标。
Despite the importance of fire in shaping savannas, it remains poorly understood how the frequency, seasonality, and intensity of fire interact to influence woody vegetation structure, which is a key determinant of savanna biodiversity. We provide a comprehensive analysis of vertical and horizontal woody vegetation structure across one of the oldest savanna fire experiments, using new airborne Light Detection and Ranging (LiDAR) technology. We developed and compared high-resolution woody vegetation height surfaces for a series of large experimental burn plots in the Kruger National Park, South Africa. These 7-ha plots (total area approximately 1500 ha) have been subjected to fire in different seasons and at different frequencies, as well as no-burn areas, for 54 years. Long-term exposure to fire caused a reduction in woody vegetation up to the 5.0-7.5 m height class, although most reduction was observed up to 4 m. Average fire intensity was positively correlated with changes in woody vegetation structure. More frequent fires reduced woody vegetation cover more than less frequent fires, and dry-season fires reduced woody vegetation more than wet-season fires. Spring fires from the late dry season reduced woody vegetation cover the most, and summer fires from the wet season reduced it the least. Fire had a large effect on structure in the densely wooded granitic landscapes as compared to the more open basaltic landscapes, although proportionally, the woody vegetation was more reduced in the drier than in the wetter landscapes. We show that fire frequency and fire season influence patterns of vegetation three-dimensional structure, which may have cascading consequences for biodiversity. Managers of savannas can therefore use fire frequency and season in concert to achieve specific vegetation structural objectives.