Light as a first‐order control on ecosystem structure in a temperate stream
Light as a first‐order control on ecosystem structure in a temperate stream
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DOI：
10.1002/eco.144
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发表时间：
2011-05
期刊：
影响因子：
2.6
通讯作者：
J. P. Julian;Sarah Z. Seegert;S. Powers;E. Stanley;M. Doyle
中科院分区：
文献类型：
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作者：
J. P. Julian;Sarah Z. Seegert;S. Powers;E. Stanley;M. Doyle
生态水文学中一个新出现的问题是光在河流生态系统动力学中的作用。在这里，我们调查光合有效辐射（PAR）如何影响水文地貌和水地球化学的二阶温带流与不同的河岸社区从严重阴影的森林部分到无阴影的草地部分。首先，将河流PAR与沿着1·2 km河段的沉水水生植物分布进行比较。分析了水生植物对水深、沉积物粒径、沉积物体积、有机质积累和营养盐吸收的影响。与有森林的地点相比，无森林的地点有三倍多的底栖PAR，这导致了大型植物生物量的四倍。非森林地区生物量的增加增加了水深、沉积物积累和可溶性活性磷（SRP）的吸收。床沉积物的大小和OM之间没有显着差异的森林和非森林的网站。最后，我们使用上述关系来估计完全森林覆盖河段和非森林覆盖河段之间的地球化学差异。与森林覆盖河段相比，非森林覆盖河段的河床沉积物几乎是前者的两倍，而SRP则是前者的四倍多。因此，河岸条件的变化可能会产生一个级联，通过该级联，阴影驱动流栖息地的变化，这反过来又驱动水文地貌和地球化学循环的变化。版权所有© 2010约翰威利父子有限公司.
An emerging issue in ecohydrology is the role of light in fluvial ecosystem dynamics. Here, we investigate how photosynthetically active radiation (PAR) influences the hydrogeomorphology and biogeochemistry of a second‐order temperate stream with varying riparian communities from heavily shaded forest sections to unshaded grass sections. First, in‐stream PAR was compared to submerged aquatic macrophyte distributions along a 1·2‐km reach. The effects of macrophytes on water depth, sediment size, sediment volume, organic matter (OM) accumulation and nutrient uptake were then analysed. Compared with forested sites, non‐forested sites had three times more benthic PAR, which resulted in a quadrupling of macrophyte biomass. This greater biomass at non‐forested sites increased water depth, sediment accumulation and the uptake of soluble reactive phosphorous (SRP). Bed sediment size and OM were not significantly different between forested and non‐forested sites. Finally, we used the above relations to estimate biogeochemical differences between a completely forested reach and a non‐forested reach. Compared with a forested reach, the non‐forested reach accumulated almost twice as much bed sediment and retained more than four times as much SRP. Thus, changes in riparian conditions may create a cascade through which shading drives changes in stream habitat, which in turn drives changes in hydrogeomorphology and biogeochemical cycles. Copyright © 2010 John Wiley & Sons, Ltd.