DIVERSITY ENHANCES COVER AND STABILITY OF SEAWEED ASSEMBLAGES: THE ROLE OF HETEROGENEITY AND TIME.
DIVERSITY ENHANCES COVER AND STABILITY OF SEAWEED ASSEMBLAGES: THE ROLE OF HETEROGENEITY AND TIME.
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多样性增强了海藻群落的覆盖度和稳定性：异质性和时间的作用。
DOI：
10.1890/07-1873.1
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发表时间：
2008
期刊：
影响因子：
4.8
通讯作者：
Amber I. Szoboszlai
中科院分区：
文献类型：
--
作者：
J. Stachowicz;M. Graham;M. E. Bracken;Amber I. Szoboszlai
关于植物多样性对生态系统过程的影响的机制，以及模式是否超越研究系统仍然难以捉摸。许多陆地植物多样性操作发现，植物生物量随着多样性的增加而增加，但大多数海洋研究发现，海藻多样性对生产者生物量或生产几乎没有影响。然而，在实验方法（现场与围隔）和持续时间（年与周）公布的陆地和海洋实验之间的差异混淆了这些差异的解释，以应对不断变化的多样性。我们在美国加州中部的潮间带岩礁上进行了为期三年的海藻多样性实地调查，以研究多样性对海藻覆盖的影响。我们发现，多样性增加了藻类覆盖率，减少了相对于单一栽培的自由空间的可用性，但这种效果需要9个月才能实现。此外，不同的组合并没有一贯超过表现最好的单作，直到18个月后，实验开始，这表明多样性的影响随着时间的推移而加强。总体而言，多样性的影响始终强于单个物种，而不是归因于任何特定物种的影响（抽样效应），因为（1）多元文化最终实现了更高的覆盖率，甚至比表现最好的单一文化和（2）单一文化很少有很大的不同，排除了强大的抽样效应。相反，机制，如促进和差异化使用的微生境在异质环境中可能会导致较高的复盖率在多元文化。我们的研究结果对比与其他海藻的短期实验，但与陆地植物的长期实验相似，这表明实验设计和方法，而不是海洋和陆地生态系统之间的固有差异，系统之间的对比反应。我们认为，在现场进行的实验，并为更长的时间，允许表现出更多的潜在机制的过度在不同的社区，增加观察到强大的多样性效应的可能性。
Generalizations regarding the mechanisms underlying the effects of plant diversity on ecosystem processes, and whether the patterns transcend study systems remain elusive. Many terrestrial plant diversity manipulations have found that plant biomass increases with diversity, but most marine studies find little or no effect of seaweed diversity on producer biomass or production. However, differences in experimental approach (field vs. mesocosm) and duration (years vs. weeks) between published terrestrial and marine experiments confound the interpretation of these differences in response to changing diversity. We conducted a three-year field manipulation of seaweed diversity on intertidal rocky reefs in central California, USA, to examine the effect of diversity on seaweed cover. We found that diversity increased standing algal cover and decreased the availability of free space relative to monocultures, but this effect took nine months to materialize. Furthermore, diverse assemblages did not consistently exceed the best performing monocultures until 18 months after the experiment was initiated, suggesting that the effect of diversity strengthens over time. Overall, diversity's effect was consistently stronger than that of individual species and not attributable to the influence of any particular species (sampling effect) because (1) polycultures eventually achieved higher cover than even the best performing monoculture and (2) monocultures rarely differed much, precluding a strong sampling effect. Instead, mechanisms such as facilitation and differential use of microhabitats in a heterogeneous environment likely caused the higher cover in polycultures. Our findings contrast with short-term experiments with other seaweeds but are similar to longer-term experiments with terrestrial plants, suggesting that experimental design and approach, rather than inherent differences between marine and terrestrial ecosystems, underlie contrasting responses among systems. We argue that experiments conducted in the field, and for a greater length of time, allow for the manifestation of a greater number of potential mechanisms of overyielding in diverse communities, increasing the likelihood of observing a strong diversity effect.