Hydrologic and forest management controls on dissolved organic matter characteristics in headwater streams of old-growth forests in the Oregon Cascades
Hydrologic and forest management controls on dissolved organic matter characteristics in headwater streams of old-growth forests in the Oregon Cascades
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DOI：
10.1016/j.foreco.2016.08.029
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发表时间：
2016-11
影响因子：
3.7
通讯作者：
B. S. Lee;K. Lajtha
中科院分区：
文献类型：
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作者：
B. S. Lee;K. Lajtha
溶解有机物（DOM）是连接陆地和水生生态系统的碳循环的重要组成部分。虽然许多因素已被确定为影响DOM通量和不同土地覆盖类型的河流中的生化质量，DOM组成的控制在美国西部的森林河源集水区知之甚少。本研究探讨了位于俄勒冈州小瀑布的H.J.安德鲁斯实验森林流域的水文模式和森林管理历史对流DOM化学的影响。在254 nm（SUVA 254），一般指示芳香性，特定的紫外线吸光度增加，在流在风暴期间增加表层土壤的地平线和垃圾DOM输入。荧光激发和发射矩阵（EEMS）与平行因子分析（PARAFAC）确定了蛋白质样DOM荧光成分以及其他几个与陆生植物材料相关的组件。蛋白质样DOM组分和水文模式，SUVA 254和DOC浓度之间的相关性分析表明，DOM在旱季代表更多的微生物处理的来源，如富含蛋白质，更深的土壤或DOM更大的流中微生物处理，相比，在高流量期间观察到的植物样表层土壤来源。基流指数（基流占总流量的比例）表现出较高的相关性与蛋白质样DOM的相对比例，表明深层土壤水是蛋白质样信号的来源。蛋白质样DOM和腐殖DOM的相对比例也受到粗木质残体（CWD）的丰度的影响，但不是活树生物量，与蛋白质样DOM的比例最高的收获流域低表面活性CWD。这项研究表明，紫外和荧光光谱是一个可行的指纹方法来阐明DOM源在俄勒冈州西部瀑布的原始源头流。
Dissolved organic matter (DOM) is a critical component of the carbon cycle linking terrestrial and aquatic ecosystems. Although many factors have been identified as influencing DOM fluxes and biochemical quality in rivers with varying land cover types, controls on DOM composition in forested headwater catchments of the western U.S. are poorly understood. This study examined the effect of hydrologic patterns and forest management history on stream DOM chemistry at watersheds located in the H.J. Andrews Experimental Forest of the Oregon Cascades. Specific UV absorbance at 254 nm (SUVA254), generally indicative of aromaticity, increased in streams during storms with increasing surficial soil horizon and litter DOM inputs. Fluorescence excitation and emission matrices (EEMs) with Parallel Factor Analysis (PARAFAC) identified a protein-like DOM fluorescent component as well as several other components associated with terrestrial plant material. Correlation analysis between the protein-like DOM component and hydrologic patterns, SUVA254, and DOC concentrations suggest that DOM during dry seasons represents more microbially-processed sources, such as protein-rich, deeper soil or DOM with greater in-stream microbial processing, compared to more plant-like surface soil sources observed during high flow. The base flow index (the proportion of base flow to total flow) showed a high correlation with the relative proportion of protein-like DOM indicating that deep soil water is a source of the protein-like signal. The relative proportions of the protein-like DOM and humic DOM were also influenced by the abundance of coarse woody debris (CWD), but not live tree biomass, with the proportions of protein-like DOM highest in harvested watersheds with low surficial CWD. This study shows UV and fluorescent spectroscopy is a viable finger printing method to elucidate DOM sources in pristine headwater streams at the western Cascades of Oregon.