Direct and indirect interactions among plants explain counterintuitive positive drought effects on an eastern Mediterranean shrub species
Direct and indirect interactions among plants explain counterintuitive positive drought effects on an eastern Mediterranean shrub species
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DOI：
10.1111/j.1600-0706.2010.18206.x
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发表时间：
2010-10
期刊：
影响因子：
3.4
通讯作者：
M. Seifan;K. Tielbörger;R. Kadmon
中科院分区：
文献类型：
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作者：
M. Seifan;K. Tielbörger;R. Kadmon
木本植物和草本植物的共存可能是由一组复杂的直接和间接的相互作用，其相对重要性很少评估。我们实验研究了木本物种建立在混合植物群落解开这种生物相互作用的潜在作用和环境变化对它们的影响。在不同的降雨量和光照条件下，结合成年灌木和一年生邻居的存在下的影响，地中海东部常见的灌木物种Sarcopoterium spinosum的幼苗建立进行了研究。我们预测，幼苗将直接受到一年生植物的竞争，增加水的可用性，而成年灌木的直接影响将是积极的，通过改善水分胁迫。间接的影响，预计灌木树冠下，由于减少水的压力和光的可用性为一年生植物和灌木幼苗，这可能会加剧一年生植物和灌木幼苗之间的竞争。为了测试这些预测，我们进行了实地和花园实验中，我们结合操纵灌木和年度存在的操纵水的可用性和光照条件，以模拟灌木冠层的效果。与我们的预测相反，灌木幼苗建立没有促进，但抑制成年灌木，因为光限制。正如预期的那样，一年生植物在潮湿条件下对灌木幼苗有直接的负面影响，在干燥条件下则转为中性或正面影响。因此，灌木和一年生植物之间的相互作用，特别是在干旱年份从竞争中释放，导致干旱对灌木幼苗建立的反直觉的积极影响。我们的研究结果指出，实验研究不同生命形式共存的多维相互作用的重要性，以及在水资源有限的生态系统中，光对成功的作用被低估。
Coexistence of woody and herbaceous plants may be governed by a complex set of direct and indirect interactions, whose relative importance have been rarely assessed. We experimentally studied woody species establishment in a mixed plant community by disentangling the potential role of such biotic interactions and the effect of environmental variations on them. Seedling establishment of the common eastern Mediterranean shrub species Sarcopoterium spinosum was investigated under different rainfall and light conditions, combined with the effect of the presence of adult shrubs and annual neighbors. We predicted that seedlings will be directly affected by competition with annuals with increasing water availability, while direct effects of adult shrubs will be positive via amelioration of water stress. Indirect effects were expected beneath shrub canopies due to reduced water stressed and light availability for both annuals and shrub seedlings, which may intensify competition between annuals and shrub seedlings. To test these predictions we performed field and garden experiments in which we combined manipulation of shrub and annual presence with manipulations of water availability and light conditions to simulate the effect of shrub canopy. In contrast to our prediction, shrub seedling establishment was not facilitated but inhibited by adult shrubs because of light limitation. As expected, annuals had direct negative effects on shrub seedlings under wet conditions, which shifted to neutral or positive effects under dry conditions. Thus, interactions among shrubs and annuals, and in particular the release from competition during drought years, leads to a counterintuitive positive effect of drought on shrub seedling establishment. Our findings point to the importance of experimentally studying multidimensional interactions for coexistence of different life forms and to the underestimated role of light for success in water-limited ecosystems.