Amount and reactivity of dissolved organic matter export are affected by land cover change from old‐growth to second‐growth forests in headwater ecosystems
Amount and reactivity of dissolved organic matter export are affected by land cover change from old‐growth to second‐growth forests in headwater ecosystems
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溶解性有机物输出量和反应性受到水源生态系统中从老林到次生林土地覆盖变化的影响
DOI：
10.1002/hyp.14343
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发表时间：
2021
影响因子：
3.2
通讯作者：
Rhoades, Charles C.
中科院分区：
文献类型：
--
作者：
Fegel, Timothy S.;Boot, Claudia M.;Covino, Timothy P.;Elder, Kelly;Hall, Edward K.;Starr, Banning;Stegen, James;Rhoades, Charles C.
美国西部的水源森林生态系统产生了北美河流中运输的溶解有机物(DOM)的很大一部分。改变森林结构和物种组成的土地覆盖变化会影响转移到水生生态系统的DOM的数量和组成。砍伐每年影响北美约1%的森林面积，使大多数西部森林处于不同的再生阶段，古老森林的总面积正在减少。这种普遍的管理做法对分水岭碳循环的影响尚不清楚。我们研究了从老混交林到以樟子松为主的次生林的土地覆盖变化对坡面DOM出口的特征和反应性的影响。我们评估了在美国科罗拉多州中北部的弗雷泽实验森林的3年时间里(2016-2018)，从凋落物渗滤液中输入的DOM和从沟渠山坡底部收集的DOM的出口。侧向潜流排干老林和次生林的溶解有机碳和总溶解氮较高。荧光光谱分析表明，老生林输出的DOM具有更多的异质性和芳香性，而蛋白质类、微生物加工的DOM组分在次生林中更为普遍。生物需氧量分析表明，与次生林相比，老生林凋落物渗滤液和地下输出物中DOM的微生物代谢率要低得多。原生林和次生林混杂在受管理的生态系统中，我们的研究结果表明，土地覆盖从针叶树种的混合到黑松优势种的变化影响了DOM的输入，从而增加了DOM从陆地生态系统转移到水生生态系统的反应性。
Headwater forest ecosystems of the western USA generate a large portion of the dissolved organic matter (DOM) transported in streams across North America. Land cover changes that alter forest structure and species composition affect the quantity and composition of DOM transferred to aquatic ecosystems. Clear‐cut harvesting affects ~1% of the forest area of North America annually, leaving most western forests in varying stages of regrowth and the total area of old‐growth forest is decreasing. The consequences of this widespread management practice on watershed carbon cycling remain unknown. We investigated the role of land cover change, because of clear‐cut harvesting, from mixed‐species old‐growth to lodgepole pine‐dominated second‐growth forest on the character and reactivity of hillslope DOM exports. We evaluated inputs of DOM from litter leachates and export of DOM collected at the base of trenched hillslopes during a 3‐year period (2016–2018) at the Fraser Experimental Forest in north‐central Colorado, USA. Dissolved organic carbon and total dissolved nitrogen were higher in lateral subsurface flow draining old‐ versus second‐growth forest. Fluorescence spectroscopy showed that the DOM exported from the old‐growth forest was more heterogeneous and aromatic and that proteinaceous, microbially processed DOM components were more prevalent in the second‐growth forest. Biological oxygen demand assays revealed much lower microbial metabolism of DOM in litter leachate and subsurface exports from the old‐growth forest relative to second growth. Old‐growth and second‐growth forests are co‐mingled in managed ecosystems, and our findings demonstrate that land cover change from a mixture of conifer species to lodgepole pine dominance influences DOM inputs that can increase the reactivity of DOM transferred from terrestrial to aquatic ecosystems.
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影响因子：
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作者：
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DOI：
--
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期刊：
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期刊：
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