Trait hierarchies and intraspecific variability drive competitive interactions in Mediterranean annual plants
Trait hierarchies and intraspecific variability drive competitive interactions in Mediterranean annual plants
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DOI：
10.1111/1365-2745.13248
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发表时间：
2019-09-01
影响因子：
5.5
通讯作者：
Peco, Begona
中科院分区：
文献类型：
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作者：
Carmona, Carlos P.;de Bello, Francesco;Peco, Begona
1.性状的种内和种间差异都可以调节植物之间的相互作用。两种机制被假设来调节这些效应：竞争等级和性状差异，但目前还不清楚每个的流行可能取决于环境条件和种内和种间差异。我们播种六个重复的所有可能的成对组合在8个一年生物种（包括同种竞争和个人没有竞争对手），在两个水平的施肥盆。我们测量了焦点个体的地上和地下特征和总生物量。我们将竞争表示为焦点个体的生物量相对于没有竞争的生物量的减少，并使用定向（层次）或非定向（相异性）性状差异建模竞争，有或没有种内变异性（ITV）。我们发现的证据表明，不同的性状层次结构在不同的施肥条件下运作，但很少支持性状的差异。在两种施肥水平下，竞争对焦点植物的负面影响均随竞争对手的高度增加而增加。此外，在未施肥条件下，植物比叶面积（SLA）和较大的根系经历较少的竞争。将ITV纳入特质层次结构大大提高了我们预测竞争强度的能力。部分原因是ITV减少了竞争层级。合成.我们的研究结果强调了性状在驱动植物间相互作用中的重要性。物种之间的竞争关系取决于性状种内和种间差异与资源可用性之间复杂的相互作用。ITV似乎是一种机制，能够减少性状等级，因此共存植物之间的竞争强度。
1. Both intra- and interspecific differences in traits may modulate interactions between plants. Two mechanisms are hypothesized to regulate these effects: competitive hierarchies and trait dissimilarities, but it is unclear how the prevalence of each might depend on environmental conditions and on intra and interspecific differences.2. We sowed six replicates of all possible pairwise combinations across eight annual species (including conspecific competition and individuals without competitors), in pots under two levels of fertilization. We measured above- and below-ground traits and total biomass of the focal individuals. We expressed competition as the decrease in biomass of focal individuals relative to biomass without competition, and modelled competition using directional (hierarchy) or non-directional (dissimilarity) trait differences, with or without intraspecific variability (ITV).3. We found evidence of different trait hierarchies operating under different fertilization conditions but little support for trait dissimilarities. The negative effect of competition on focal plants increased with the height of the competitors in both of fertilization levels. Further, in unfertilized conditions, plants with lower specific leaf area (SLA) and larger root systems experienced less competition. Including ITV in trait hierarchies substantially improved our ability to predict the intensity of competition. This was partly due to ITV reducing competitive hierarchies.4. Synthesis. Our results underscore the importance of traits in driving interactions among plants. Competitive relationships between species depend on complex interactions between trait intra and interspecific differences and resource availability. ITV appears to be a mechanism capable of reducing trait hierarchies, and hence the intensity of competition between coexisting plants.