Spatial scale mediates the effects of biodiversity on marine primary producers
Spatial scale mediates the effects of biodiversity on marine primary producers
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DOI：
10.1002/ecy.1812/suppinfo
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发表时间：
2017-05-01
期刊：
影响因子：
4.8
通讯作者：
Trussell, Geoffrey C.
中科院分区：
文献类型：
--
作者：
Bracken, Matthew E. S.;Douglass, James G.;Trussell, Geoffrey C.
大多数评估生物多样性对生态系统功能影响的研究都是在单一地点进行的，这限制了我们对在不同空间尺度上测量时多样性与功能关系可能如何变化的理解。我们在美国缅因湾岩石潮间带海岸线沿线三个区域的三个地点进行了物种清除实验，以评估物种丧失对潮间带海藻群落生物量的规模依赖性影响的可能性。我们将每个地点潮间带中部的 50 个地块随机分配给五个处理之一（每个处理 n = 10 个地块）：一个未操作的对照地块、一个包含我们的三种目标海藻物种的混养地块和三个单一栽培地块。我们通过从单一栽培和混养地块中去除所有非目标物种来操纵多样性，然后从混养地块中去除与物种相对丰度成比例的额外生物量，以便每个地点从单一栽培和混养地块中去除的平均数量相等。在最大的空间尺度上，在考虑了区域海藻多样性内的区域和地点之后，所有地点一起考虑对海藻覆盖具有一致的积极影响。多样化的混养地块的覆盖度总是高于海藻组成物种的平均表现所预测的覆盖度，并且通常比表现最好的组成物种的覆盖度还要高。多样性效应在较小的空间尺度上减弱并且变得不太一致，因此在单个地点的尺度上，多样化的混养仅在大约 40% 的时间里表现得比单一栽培的平均水平更好。因此，我们的结果表明，单个地点水平上较弱和/或不一致的生物多样性影响可能会在更大的空间尺度上扩大为更强、更一致的影响。在各个地点进行的生物多样性实验的定量总结并未捕捉到生物多样性影响的空间方面，因此可能低估生物多样性丧失的功能后果。
Most studies evaluating the effects of biodiversity on ecosystem functioning are conducted at a single location, limiting our understanding of how diversity-function relationships may change when measured across different spatial scales. We conducted a species-removal experiment at three sites nested in each of three regions along the rocky intertidal coastline of the Gulf of Maine, USA, to evaluate the potential for scale-dependent effects of species loss on the biomass of intertidal seaweed assemblages. We randomly assigned 50 plots in the mid-intertidal zone at each site to one of five treatments (n = 10 plots each): an unmanipulated control, a polyculture plot that contained our three target seaweed species, and three monoculture plots. We manipulated diversity by removing all non-target species from monoculture and polyculture plots, then removing additional biomass from polyculture plots, proportionate to species' relative abundances, so that the average amount removed from monoculture and polyculture plots was equivalent at each site. At the largest spatial scale, all sites considered together, after accounting for region and site nested within region seaweed diversity had consistent, positive effects on seaweed cover. Diverse polyculture plots always had higher cover than was predicted by the average performance of the component seaweed species and usually had higher cover than even the best-performing component species. Diversity effects weakened and became less consistent at smaller spatial scales, so that at the scale of individual sites, diverse polycultures only performed better than the average of monocultures similar to 40% of the time. Hence, our results indicate that weak and/or inconsistent biodiversity effects at the level of individual sites may scale up to stronger, more consistent effects at larger spatial scales. Quantitative summaries of biodiversity experiments conducted at the scale of individual sites do not capture this spatial aspect of biodiversity effects and may therefore underestimate the functional consequences of biodiversity loss.