Changing drivers of species dominance during tropical forest succession
Changing drivers of species dominance during tropical forest succession
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DOI：
10.1111/1365-2435.12240
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发表时间：
2014-08-01
影响因子：
5.2
通讯作者：
Bongers, Frans
中科院分区：
文献类型：
--
作者：
Lohbeck, Madelon;Poorter, Lourens;Bongers, Frans
1. 确定性理论预测，基于生态位差异，通过植物功能适应，本地群落从区域物种库中聚集起来。我们测试了功能性状是否也可以解释共同发生的物种间的物种优势模式。我们预测，沿着次级演替的梯度，物种优势的主要驱动因素从相对苛刻（干燥和炎热）的早期演替条件下的环境过滤，到后期演替条件下（光照有限时）竞争相互作用的增加和相似性的限制。本文利用峰度(K)对墨西哥恰帕斯高多样性热带雨林次生林群落功能性状分布进行了分析。林龄在1 ~ 25年之间，利用与植物碳、水、热平衡相关的8个叶片功能性状。我们基于物种优势度和物种存在度计算功能性状分布，其中性状值以物种相对基底面积加权，所有物种计数一次。随后通过基于物种优势度的峰度除以基于物种存在度的峰度来计算“K-ratio”。如果k比高，优势物种功能相似，我们将其解释为环境驱动的功能趋同，使物种成为优势物种。如果k比很小，优势物种是现有物种的一个功能不同的子集，我们将其解释为竞争性驱动的功能分化，使物种成为优势物种。我们发现，在演替早期，优势种代表了具有相似特征的物种的一个功能狭窄的子集，而在演替后期，优势种越来越多地代表了存在的物种的一个广泛子集。这一趋势在反映光合性能和光捕获的性状中被发现，并表明随着演替对光的竞争增加。没有发现抵抗食草动物的性状的趋势，这表明食草动物的压力没有演替变化。合成。这是第一个研究表明，物种优势的驱动因素沿着二级演替的梯度变化。在我们评估的早期演替时间窗内，环境过滤作为驱动力的重要性迅速消失，生态位划分对物种优势的重要性开始显现。
1. Deterministic theories predict that local communities assemble from a regional species pool based on niche differences, thus by plant functional adaptations. We tested whether functional traits can also explain patterns in species dominance among the suite of co-occurring species.2. We predicted that along a gradient of secondary succession, the main driver of species dominance changes from environmental filtering in the relatively harsh (dry and hot) early successional conditions, towards increased competitive interactions and limiting similarity in later successional conditions (when light is limited).3. We used the Kurtosis (K) (a measure of peakedness) of the functional trait distribution of secondary forest communities in high-diversity tropical rain forest in Chiapas, Mexico. The forests ranged 1-25 years in age, and we used eight functional leaf traits related to a plants' carbon, water and heat balance. We calculated the functional trait distribution based on species dominance, where trait values were weighted by species' relative basal area, as well as based on species presence, all species counting once. 'K-ratio' was subsequently computed by dividing kurtosis based on species dominance by kurtosis based on species presence. If the K-ratio is high, the dominant species are functionally similar and we interpreted this as environmentally driven functional convergence allowing species to become dominant. If the K-ratio is small, dominant species are a functionally dissimilar subset of the species present and we interpreted this as competitively driven functional divergence allowing species to become dominant.4. We found that in early succession, dominant species represent a functionally narrow subset of species with similar traits, and in late succession, dominant species increasingly represent a wide subset of the species present. This trend was found for traits that reflect photosynthetic performance and light capture, and indicates increased competition for light with succession. No trend was found for traits that indicate defence against herbivory, suggesting no successional changes in herbivore pressure.5. Synthesis. This is one of the first studies showing that drivers of species dominance change along a gradient of secondary succession. During the early successional time window we evaluated, the importance of environmental filtering as a driving force fades away rapidly, and the importance of niche partitioning for species dominance starts to emerge.