Altered resource availability and the population dynamics of tree species in Amazonian secondary forests
Altered resource availability and the population dynamics of tree species in Amazonian secondary forests
复制标题
亚马逊次生林资源可用性和树种种群动态的改变
DOI：
10.1007/s00442-009-1524-5
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发表时间：
2010
期刊：
影响因子：
2.7
通讯作者：
I. Miranda
中科院分区：
文献类型：
--
作者：
L. Fortini;E. Bruna;D. Zarin;S. S. Vasconcelos;I. Miranda
尽管研究表明，水和养分的有效性对热带森林的多种生态系统过程有很强的影响，但对这些因素对热带树木的人口统计学和种群动态的影响知之甚少。在5年的时间里，我们在旱季灌溉、凋落物清除和控制样地监测了亚马逊地区常见的两种次生林物种——短毛栎（lacistema pubescens）和桃金娘（Myrcia sylvatica）。然后，我们利用矩阵模型和生命表响应实验评估了水和养分有效性改变对人口统计学和动态的影响。我们的研究结果表明，尽管对水和养分有效性进行了长时间的实验操作，但对两种物种的人口统计几乎没有一致的单向处理效果。观察到的处理效果的模式和显著性在很大程度上取决于与降雨模式无关的跨年变率，一旦我们将数据汇集在一起，这种变化就消失了。此外，大多数这些短暂的处理效果对种群增长率的影响很小。我们的研究结果表明，尽管对水分和养分有效性（被认为是热带先锋树种生态的关键因素）进行了主要的实验操作，但自生性光照限制似乎是演替早期/中期树木人口统计学的主要调节因子。事实上，光供应的影响可能完全超过那些被认为影响亚马逊次生林演替发展的其他因素。
Despite research demonstrating that water and nutrient availability exert strong effects on multiple ecosystem processes in tropical forests, little is known about the effect of these factors on the demography and population dynamics of tropical trees. Over the course of 5 years, we monitored two common Amazonian secondary forest species—Lacistema pubescens and Myrcia sylvatica—in dry-season irrigation, litter-removal and control plots. We then evaluated the effects of altered water and nutrient availability on population demography and dynamics using matrix models and life table response experiments. Our results show that despite prolonged experimental manipulation of water and nutrient availability, there were nearly no consistent and unidirectional treatment effects on the demography of either species. The patterns and significance of observed treatment effects were largely dependent on cross-year variability not related to rainfall patterns, and disappeared once we pooled data across years. Furthermore, most of these transient treatment effects had little effect on population growth rates. Our results suggest that despite major experimental manipulations of water and nutrient availability—factors considered critical to the ecology of tropical pioneer tree species—autogenic light limitation appears to be the primary regulator of tree demography at early/mid successional stages. Indeed, the effects of light availability may completely override those of other factors thought to influence the successional development of Amazonian secondary forests.