Optical properties of dissolved organic matter in throughfall and stemflow vary across tree species and season in a temperate headwater forest
Optical properties of dissolved organic matter in throughfall and stemflow vary across tree species and season in a temperate headwater forest
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DOI：
10.1007/s10533-022-00985-x
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发表时间：
2022-10
期刊：
影响因子：
4
通讯作者：
K. Ryan;T. Adler;A. Chalmers;J. Perdrial;S. Sebestyen;J. Shanley;Aron Stubbins
中科院分区：
文献类型：
--
作者：
K. Ryan;T. Adler;A. Chalmers;J. Perdrial;S. Sebestyen;J. Shanley;Aron Stubbins
树木衍生的溶解有机质（DOM）构成了森林流域内重要的碳通量。很少有研究评估树衍生DOM的光学性质。为了进一步了解树源DOM质量的控制因素，我们测量了美国佛蒙特州温带落叶林中夏秋季17次降雨事件的透水和茎流中DOM的光学性质、溶解有机碳（DOC）和钙浓度。滴流和茎流中的DOC和钙通量平均富集于降雨入射通量的4 ~ 70倍。利用吸光度和荧光光谱建立了一个多路模型来进一步表征DOM的光学性质。通流比茎流含有更高百分比的蛋白质样DOM荧光，而茎流则具有更高百分比的腐殖质样DOM荧光。黄桦（Betula alleghaniensis）茎流DOM吸收光谱斜率显著高于糖槭（Acer saccharum）茎流。DOM光学指标不受降雨量的影响，但随着秋季叶片衰老，透光中蛋白样荧光百分比增加。考虑到树木来源的DOM通量对接收土壤和下游生态系统的潜在影响，未来的DOM传输和土壤生物地球化学建模应反映不同树种和季节的透雨和茎流中不同DOM质量的影响。
Tree-derived dissolved organic matter (DOM) comprises a significant carbon flux within forested watersheds. Few studies have assessed the optical properties of tree-derived DOM. To increase understanding of the factors controlling tree-derived DOM quality, we measured DOM optical properties, dissolved organic carbon (DOC) and calcium concentrations in throughfall and stemflow for 17 individual rain events during summer and fall in a temperate deciduous forest in Vermont, United States. DOC and calcium fluxes in throughfall and stemflow were enriched on average 4 to 70 times incident fluxes in rain. A multiway model was developed using absorbance and fluorescence spectroscopy to further characterize DOM optical properties. Throughfall contained a higher percentage of protein-like DOM fluorescence than stemflow while stemflow was characterized by a higher percentage of humic-like DOM fluorescence. DOM absorbance spectral slopes in yellow birch (Betula alleghaniensis) stemflow were significantly higher than in sugar maple (Acer saccharum) stemflow. DOM optical metrics were not influenced by rainfall volume, but percent protein-like fluorescence increased in throughfall during autumn when leaves senesced. Given the potential influence of tree-derived DOM fluxes on receiving soils and downstream ecosystems, future modeling of DOM transport and soil biogeochemistry should represent the influence of differing DOM quality in throughfall and stemflow across tree species and seasons.