Tree line advance reduces mixing and oxygen concentrations in arctic–alpine lakes through wind sheltering and organic carbon supply
Tree line advance reduces mixing and oxygen concentrations in arctic–alpine lakes through wind sheltering and organic carbon supply
复制标题
林线推进通过避风和有机碳供应减少了北极-高山湖泊的混合和氧气浓度
DOI：
10.1111/gcb.15660
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发表时间：
2021
影响因子：
11.6
通讯作者：
D. Seekell
中科院分区：
文献类型：
--
作者：
M. Klaus;J. Karlsson;D. Seekell
湖底水体缺氧对生态系统健康产生不利影响，包括营养物释放和沉积物中物质减少导致水质下降，以及鱼类生长和繁殖减少。当氧气在有机物分解过程中被消耗时，氧气的补充受到水柱分层的限制。北极高寒湖泊通常混合良好且含氧良好，但这些地区的快速气候变化是流域植被变化的重要驱动因素，可能会影响湖泊的混合和氧动力学。在这里，我们分析了40个瑞典北极高山湖泊的溶解氧浓度和温度分布的高分辨率时间序列。分层持续1 ~ 125天，分层过程中，近底部溶解氧浓度变化幅度为−0.20 ~ +0.15 mg L−1天−1，在最长分层期结束时，最终浓度为1.1 ~ 15.5 mg L−1。结构方程模型表明，岸线植被相对于湖泊面积较高的湖泊具有较高的溶解有机碳浓度和氧气消耗率，但风速较低，分层周期较长，最终具有较低的近底溶解氧浓度。我们使用岸线冠层高度和湖泊面积指数来预测我们研究的湖泊在最长分层期结束时近底部溶解氧浓度的变化（R2 = 0.41）。将这一关系扩大到8392个瑞典北极高山湖泊，结果表明，15%、32%和53%的湖泊近底部溶解氧浓度降至3、5和7 mg L - 1以下，并且这一比例对过去一个世纪观测到的或在全新世（±200米海拔；±0.5°纬度）重建的假设树线移动很敏感（5% - 22%、13% - 45%和29% - 69%）。假设空间-时间替代，我们预测树木线的推进将降低许多北极高山湖泊近底部的溶解氧浓度。
Oxygen depletion in lake bottom waters has adverse impacts on ecosystem health including decreased water quality from release of nutrients and reduced substances from sediments, and the reduction of fish growth and reproduction. Depletion occurs when oxygen is consumed during decomposition of organic matter, and oxygen replenishment is limited by water column stratification. Arctic–alpine lakes are often well mixed and oxygenated, but rapid climate change in these regions is an important driver of shifts in catchment vegetation that could affect the mixing and oxygen dynamics of lakes. Here, we analyze high‐resolution time series of dissolved oxygen concentration and temperature profiles in 40 Swedish arctic–alpine lakes across the tree line ecotone. The lakes stratified for 1−125 days, and during stratification, near‐bottom dissolved oxygen concentrations changed by −0.20 to +0.15 mg L−1 day−1, resulting in final concentrations of 1.1−15.5 mg L−1 at the end of the longest stratification period. Structural equation modeling revealed that lakes with taller shoreline vegetation relative to lake area had higher dissolved organic carbon concentrations and oxygen consumption rates, but also lower wind speeds and longer stratification periods, and ultimately, lower near‐bottom dissolved oxygen concentrations. We use an index of shoreline canopy height and lake area to predict variations among our study lakes in near‐bottom dissolved oxygen concentrations at the end of the longest stratification period (R2 = 0.41). Upscaling this relationship to 8392 Swedish arctic–alpine lakes revealed that near‐bottom dissolved oxygen concentrations drop below 3, 5, and 7 mg L−1 in 15%, 32%, and 53% of the lakes and that this proportion is sensitive (5%−22%, 13%−45%, and 29%−69%) to hypothetical tree line shifts observed in the past century or reconstructed for the Holocene (±200 m elevation; ±0.5° latitude). Assuming space‐for‐time substitution, we predict that tree line advance will decrease near‐bottom dissolved oxygen concentrations in many arctic–alpine lakes.
影响因子：
4.9
作者：
Vonk, J. E.;Tank, S. E.;Wickland, K. P.
通讯作者：
Wickland, K. P.
影响因子：
5.2
作者：
O'Reilly, Catherine M.;Sharma, Sapna;Zhang, Guoqing
通讯作者：
Zhang, Guoqing