Testing non-equilibrium theories in savannas: 1400 years of vegetation change in Tsavo National Park, Kenya
Testing non-equilibrium theories in savannas: 1400 years of vegetation change in Tsavo National Park, Kenya
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DOI：
10.1016/j.ecocom.2004.06.001
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发表时间：
2004-12-04
影响因子：
3.5
通讯作者：
Gillson, Lindsey
中科院分区：
文献类型：
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作者：
Gillson, Lindsey
人们对稀树草原中的非平衡过程知之甚少，因为关于树木丰度在很长一段时间内如何变化的数据很少。在这里，我分析了来自肯尼亚察沃国家公园坎德里沼泽的花粉化石和木炭，以调查过去 1400 年植被变化的模式。我将结果与循环模型、相变模型和随机非平衡模型的预测进行了比较。花粉数据的傅里叶分析提供了树木丰度周期性变化的证据，周期为 250-500 年，但花粉数据还表明，正如阶段和过渡模型预测的那样，坎德里沼泽周围的植被仍处于长期林地阶段，从公元 770-1520 年左右。此外，结果提供了树木/草丰度短期变化的证据，可能反映了树木/草丰度的随机变化。 降雨。木炭数据表明植被变化与火灾历史之间存在联系，这可能是通过降雨变化对草本层中可燃生物量积累的影响来调节的。还有证据表明，过去 1400 年来曾发生过两次极端火灾。结果表明，在局部尺度上，坎德里沼泽附近的植被主要受到局部扰动的影响，而不是气候变化或牛瘟疫情的影响，需要周期性、阶段和过渡以及随机模型的元素才能充分理解观测到的植被变化模式。 (C) 2004 Elsevier BX 保留所有权利。
Non-equilibrium processes in savannas are poorly understood because little data is available on how tree abundance has changed over long periods of time. Here I analyse fossil pollen and charcoal from Kanderi Swamp in Tsavo National Park, Kenya in order to investigate patterns of vegetation change over the past 1400 years. I compare the results with the predictions of cyclical, phase and transition and stochastic non-equilibrium models. Fourier analysis of the pollen data provides evidence of cyclical changes in tree abundance with a periodicity of 250-500 years, but the pollen data also suggests that the vegetation surrounding Kanderi swamp remained in a prolonged woodland phase, as predicted by phase and transition models, from approximately 770-1520 A.D. In addition, the results provided evidence of much shorter term changes in tree/grass abundance, perhaps reflecting stochastic variations in rainfall. The charcoal data suggests a link between vegetation change and fire history, possibly mediated through the effects of rainfall variation on the accumulation of combustible biomass in the herb layer. There was also evidence of extreme fires occurring twice in the past 1400 years. The results suggest that at the local scale, the vegetation near Kanderi Swamp has been mainly influenced by localised disturbance, rather than climatic shifts or the Rinderpest epidemic, and that elements of cyclical, phase and transition and stochastic models are needed in order to fully understand the observed pattern of vegetation change. (C) 2004 Elsevier BX All rights reserved.