Basin-Scale Consequences of Agricultural Land Use on Benthic Light Availability and Primary Production Along a Sixth-Order Temperate River
Basin-Scale Consequences of Agricultural Land Use on Benthic Light Availability and Primary Production Along a Sixth-Order Temperate River
复制标题
流域规模的农业土地利用对六级温带河流沿岸底栖光可用性和初级生产的影响
DOI：
10.1007/s10021-008-9181-9
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发表时间：
2008
期刊：
影响因子：
3.7
通讯作者：
Martin W. Doyle
中科院分区：
文献类型：
--
作者：
Jason P. Julian;Jason P. Julian;Emily H. Stanley;Martin W. Doyle
河流流域是河流生态系统研究和应用的新兴空间尺度。尽管人们对河流景观中的栖息地可用性和营养循环的关注很大，但光的可用性却受到的关注要少得多，而且尚未在流域规模上进行定量评估，尽管它是水生生态系统的主要能源。我们开发了一个流域规模的光可用性模型，耦合容易获得的广泛的空间数据与易于测量的天气数据，使用GIS框架和水力几何的原则。我们用这个模型来（一）量化底栖光的可用性（Ebed）沿着160公里的河流在美国威斯康星州中部，（二）预测总初级生产力（GPP）沿着同一条河，（iii）评估农业土地利用对Ebed和GPP的影响。总体而言，Ebed下降，主要是由于下游方向的浊度增加，并有相当大的局部变化所造成的地形，河岸植被和通道方向的变化。这些Ebed的局部变化导致GPP在短距离内波动很大，在260 m内波动高达2.1 g C m−2 d−1。当在整个河道长度上相加时，现在农业后的GPP（635 kg C d−1）比农业前的GPP（4992 kg C d−1）低约8倍。模型模拟结果表明，农业土地利用可以引起GPP的数量级变化，减少或增加GPP的截面变异性，并显着改变GPP的广泛的空间趋势。我们的流域规模的底栖光可用性模型是一个工具，研究人员可以用来调查光可用性和生态系统过程之间的关系，在广泛的空间尺度，也是一个从业者可以用来更全面的河流生态系统评估。
The emerging spatial scale of interest for fluvial ecosystem studies and applications is the river basin. Although much focus has been directed toward habitat availability and nutrient cycling across the fluvial landscape, light availability has received considerably less attention and has not been assessed quantitatively at the basin-scale despite it being the primary energy source for aquatic ecosystems. We developed a basin-scale light availability model that couples readily available broad spatial data with easily measured synoptic data using a GIS framework and the principles of hydraulic geometry. We used this model to (i) quantify benthic light availability (Ebed) along a 160-km river in central Wisconsin, USA, (ii) predict gross primary production (GPP) along the same river, and (iii) assess the effects of agricultural land use on Ebed and GPP. Overall, Ebed decreased in the downstream direction due primarily to increased turbidity, and there was considerable local variation caused by changes in topography, riparian vegetation, and channel orientation. These local variations in Ebed caused GPP to fluctuate greatly over short distances, as much as 2.1 g C m−2 d−1 over 260 m. When summed over the entire channel length, present-day, post-agricultural GPP (635 kg C d−1) was about eight times lower than estimated pre-agricultural GPP (4992 kg C d−1). Model simulations revealed that agricultural land use can cause an order of magnitude change in GPP, reduce or increase inter-sectional variability in GPP, and significantly alter broad spatial trends in GPP. Our basin-scale benthic light availability model is a tool that researchers can use to investigate relationships between light availability and ecosystem processes at broad spatial scales and also one that practitioners can use for more holistic fluvial ecosystem assessments.