Arroyo Antonio I, Pueyo Yolanda, Saiz Hugo, Alados Concepción L
Instituto Pirenaico de Ecología (CSIC) Av. Montañana 1005 P.O. Box 13.034 50080 Zaragoza Spain.
UMR 6553 Ecobio CNRS - University of Rennes 1 Av. du General Leclerc 35042 Rennes Cedex France.
Ecol Evol. 2015 Oct 28;5(22):5305-5317. doi: 10.1002/ece3.1770. eCollection 2015 Nov.
Plant-plant interactions are among the fundamental processes that shape structure and functioning of arid and semi-arid plant communities. Despite the large amount of studies that have assessed the relationship between plant-plant interactions (i.e., facilitation and competition) and diversity, often researchers forget a third kind of interaction, known as allelopathy. We examined the effect of plant-plant interactions of three dominant species: the perennial grass , the allelopathic dwarf shrub , and the nurse shrub on plant diversity and species composition in a semi-arid ecosystem in NE Spain. Specifically, we quantified the interaction outcome (IO) based on species co-occurrence, we analyzed diversity by calculation of the individual species-area relationship (ISAR), and compositional changes by calculation of the Chao-Jaccard similarity index. We found that had more positive IO values than , and had values between them. and acted as diversity repellers, whereas acted as a diversity accumulator. As aridity increased, transitioned from diversity repeller to neutral and transitioned from neutral to diversity accumulator, while remained as diversity repeller. had more perennial grass species in its local neighborhood than expected by the null model, suggesting some tolerance of this group to its "chemical neighbor". Consequently, species that coexist with were very similar among different individuals. Our findings highlight the role of the nurse shrub as ecosystem engineer, creating and maintaining patches of diversity, as well as the complex mechanism that an allelopathic plant may have on diversity and species assemblage. Further research is needed to determine the relative importance of allelopathy and competition in the overall interference of allelopathic plants.
植物与植物之间的相互作用是塑造干旱和半干旱植物群落结构与功能的基本过程之一。尽管已有大量研究评估了植物与植物之间的相互作用（即促进作用和竞争作用）与多样性之间的关系，但研究人员常常忽略了第三种相互作用，即化感作用。我们研究了三种优势物种——多年生草本植物、化感矮灌木和护土灌木——之间的植物与植物相互作用对西班牙东北部一个半干旱生态系统中植物多样性和物种组成的影响。具体而言，我们基于物种共现情况量化了相互作用结果（IO），通过计算单个物种-面积关系（ISAR）分析了多样性，并通过计算Chao-Jaccard相似性指数分析了组成变化。我们发现，[物种名称1]的IO值比[物种名称2]更具正向性，[物种名称3]的值则介于两者之间。[物种名称1]和[物种名称2]起到了多样性排斥者的作用，而[物种名称3]起到了多样性积累者的作用。随着干旱程度的增加，[物种名称1]从多样性排斥者转变为中性，[物种名称3]从中性转变为多样性积累者，而[物种名称2]则仍为多样性排斥者。[物种名称3]在其局部邻域内的多年生草本物种比空模型预期的更多，这表明该类群对其“化学邻居”具有一定的耐受性。因此，与[物种名称3]共存的物种在不同的[物种名称3]个体之间非常相似。我们的研究结果突出了护土灌木[物种名称3]作为生态系统工程师的作用，它创造并维持了多样性斑块，以及化感植物可能对多样性和物种组合产生的复杂机制。需要进一步的研究来确定化感作用和竞争在化感植物总体干扰中的相对重要性。
