Pueyo Y, Kéfi S, Díaz-Sierra R, Alados C L, Rietkerk M
Instituto Pirenaico de Ecología CSIC, Avda. Montañana 1005, PO Box 13034, 50080 Zaragoza, Spain.
Theor Popul Biol. 2010 Dec;78(4):289-97. doi: 10.1016/j.tpb.2010.09.001. Epub 2010 Sep 25.
The dynamics of semi-arid plant communities are determined by the interplay between competition and facilitation among plants. The sign and strength of these biotic interactions depend on plant traits. However, the relationships between plant traits and biotic interactions, and the consequences for plant communities are still poorly understood. Our objective here was to investigate, with a modelling approach, the role of plant reproductive traits on biotic interactions, and the consequences for processes such as plant succession and invasion. The dynamics of two plant types were modelled with a spatially-explicit integrodifferential model: (1) a plant with seed dispersal (colonizer of bare soil) and (2) a plant with local vegetative propagation (local competitor). Both plant types were involved in facilitation due to a local positive feedback between vegetation biomass and soil water availability, which promoted establishment and growth. Plants in the system also competed for limited water. The efficiency in water acquisition (dependent on reproductive and growth plant traits) determined which plant type dominated the community at the steady state. Facilitative interactions between plant types also played an important role in the community dynamics, promoting establishment in the driest conditions and recovery from low biomass. Plants with vegetative propagation took advantage of the ability of seed dispersers to establish on bare soil from a low initial biomass. Seed dispersers were good invaders, maintained high biomass at intermediate and high rainfall and showed a high ability in taking profit from the positive feedback originated by plants with vegetative propagation under the driest conditions. However, seed dispersers lost competitiveness with an increasing investment in fecundity. All together, our results showed that reproductive plant traits can affect the balance between facilitative and competitive interactions. Understanding this effect of plant traits on biotic interactions provides insights in processes such as plant succession and shrub encroachment.
半干旱地区植物群落的动态变化取决于植物之间竞争与促进作用的相互影响。这些生物相互作用的正负及强度取决于植物的特性。然而，植物特性与生物相互作用之间的关系以及对植物群落的影响仍知之甚少。我们在此的目标是通过建模方法研究植物繁殖特性在生物相互作用中的作用，以及对植物演替和入侵等过程的影响。我们用一个空间明确的积分微分模型模拟了两种植物类型的动态变化：（1）具有种子传播能力的植物（裸土定居者）和（2）具有局部营养繁殖能力的植物（本地竞争者）。由于植被生物量与土壤水分有效性之间存在局部正反馈，两种植物类型都参与了促进作用，这促进了植物的定居和生长。系统中的植物也会争夺有限的水分。水分获取效率（取决于植物的繁殖和生长特性）决定了在稳态下哪种植物类型主导群落。植物类型之间的促进性相互作用在群落动态中也起着重要作用，促进了在最干旱条件下的定居以及从低生物量状态的恢复。具有营养繁殖能力的植物利用种子传播者从低初始生物量在裸土上定居的能力。种子传播者是很好的入侵者，在中等和高降雨量条件下保持高生物量，并且在最干旱条件下具有利用营养繁殖植物产生的正反馈的高能力。然而，随着繁殖投入的增加，种子传播者的竞争力会下降。总之，我们的结果表明，植物繁殖特性会影响促进性和竞争性相互作用之间的平衡。了解植物特性对生物相互作用的这种影响有助于深入理解植物演替和灌木入侵等过程。
