Soil biota facilitate exotic Acer invasions in Europe and North America
Soil biota facilitate exotic Acer invasions in Europe and North America
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DOI：
10.1890/03-5204
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发表时间：
2004-12-01
影响因子：
5
通讯作者：
Callaway, RM
中科院分区：
文献类型：
--
作者：
Reinhart, KO;Callaway, RM
外来植物成功入侵的主要假设是入侵者已经逃脱了控制它们的专门消费者（敌人释放假设）。然而，很少有研究通过生物地理学实验严格检验这一论断或考虑土壤生物的影响。我们通过比较北美枫树和欧洲枫树在其原生和正常范围内的密度模式，测试了敌人释放假说和互利共生的增强作用。预计逃离天敌的入侵者在标准范围内的密度将高于本地范围。为了确定与土壤生物群的相互作用是否可以解释在田间观察到的种群分布，我们比较了本地和规范范围内与宏碁树和非宏碁树相关的灭菌和非灭菌土壤对温室中幼苗生长的影响。在实地研究中，在规范范围内，从焦点树到最近的宏碁同种的距离比在本地范围内小56-77%。在温室实验中，土壤生物群的影响在槭树的原生范围和正常范围之间也有所不同。相对于绝育对照，与来自本地范围的同种和异种相关的土壤使宏碁幼苗的总生物量和高度的相对变化分别降低了 35% 和 40%。与标准范围内的同种相关的土壤使宏碁幼苗的生物量和高度的相对变化分别降低了112%和64%；但与正常范围内的异种相关的土壤使宏碁幼苗的生物量和高度相对变化分别增加了13%和37%。我们的结果表明，与优势本地物种相关的土壤生物群增强了宏碁的入侵，并且随着宏碁的建立，土壤生物群效应变得更具抑制性。范围之间土壤生物群效应的相对差异支持了释放敌人的假说，但也表明互惠共生在其规范范围内比在其原生范围内对槭树相对更有利。在规范范围内，互利共生可能相对更有利，因为入侵者摆脱了天敌的负面影响，而天敌的负面影响可能会减弱互利共生的积极影响。
The primary hypothesis for successful exotic plant invasions is that the invaders have escaped the specialist consumers that control them (Enemy Release Hypothesis). However, few studies have rigorously tested this assertion with biogeographical experiments or considered the effects of soil organisms. We tested the Enemy Release Hypothesis and the enhanced role of mutualisms by comparing density patterns of the North American Acer negundo and European A. platanoides trees in their native and normative ranges. Invaders that have escaped their natural enemies are predicted to attain greater densities in normative than native ranges. To determine whether interactions with soil biota could explain the population distributions observed in the field, we compared the effects of sterilized and nonsterilized soil associated with Acer and non-Acer trees in native and normative ranges on the growth of seedlings in the greenhouse.In the field study, distances from focal trees to the nearest Acer conspecifics were 56-77% less in their normative ranges than in their native ranges. In the greenhouse experiment, the effect of soil biota also differed between native and normative ranges of Acers. Relative to sterilized controls, soil associated with conspecifics and heterospecifics from the native ranges decreased the total biomass and relative change in height of Acer seedlings by 35% and 40%, respectively. Soil associated with conspecifics in the normative ranges decreased the biomass and relative change in height of Acer seedlings by 112% and 64%, respectively; but the soil associated with heterospecifics in the normative ranges increased biomass and relative change in height of Acer seedlings by 13% and 37%, respectively.Our results suggest that invasion of Acers is enhanced by soil biota associated with dominant native species and that the soil biota effect becomes more inhibitory as the Acers establish. The relative difference in soil biota effects between ranges supports the Enemy Release Hypothesis but also suggests that mutualists are relatively more beneficial to Acers in their normative ranges than in their native ranges. Mutualisms may be relatively more beneficial in normative ranges because the invader has escaped from the negative effect of natural enemies that may attenuate the positive effect of mutualists.