Heat and smoke from wildfires influence water temperature and dissolved oxygen levels in headwater streams

IF 1.7 4区 环境科学与生态学 Q3 ECOLOGY
Freshwater Science Pub Date : 2022-09-23 DOI:10.1086/722632
Ashley Sanders, A. A. Coble, Allison G. Swartz, Mark River, P. James, D. Warren
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引用次数: 3

Abstract

Wildfire has become increasingly common and severe in forested landscapes across the western United States. Stream and air temperatures within these landscapes are influenced not only by direct heating during the fire but by shading from heavy smoke. In addition, dissolved oxygen (DO) can be affected by increased ash inputs from fire or reduced primary production under lower light conditions. Because collecting data as the event occurs is challenging, most research exploring fire effects on streams has focused on responses months to years after the event as opposed to during and immediately after the fire. We sought to understand how physical stream parameters change as wildfire burns near streams, how stream temperature responses vary through a stream reach, how parameters respond to shading from pervasive smoke during and shortly after the fire, and how fire severity correlates with observed changes. In this study, we report measurements of light, air temperature, stream temperature, and DO across eleven 2nd- to 4th-order streams in the western Cascade Mountains of Oregon, USA, 1 wk before, during, and 1 wk after an extensive wildfire in 2020. Burning near streams resulted in a brief increase in daily maximum stream temperature of 4.5°C at the most severely burned site but small increases or decreases at less affected sites. Longitudinal replication revealed that temperature responses can be patchy at relatively small scales (∼50 m). DO daily minima decreased by 1.3 to 16.9% saturation on the day of the fire, with the magnitude of effect corresponding to burn severity. Across all 11 sites, riparian and watershed estimates of Rapid Assessment of Vegetation Condition after Wildfire and soil burn severity were better correlated with stream temperature responses to fire than percentage of watershed burned. Smoke effects were pervasive, both spatially and temporally, resulting in decreased light, stream temperature maxima, and diurnal variation in DO. Our results suggest that acute changes to physical stream parameters caused minimal harm to aquatic biota at our sites, and the effects of smoke on physical stream parameters will likely impose larger immediate effects on headwater streams than heating from the fire itself.
野火产生的热量和烟雾影响水源溪流的水温和溶解氧水平
野火在美国西部的森林景观中变得越来越常见和严重。这些景观中的溪流和空气温度不仅受到火灾期间直接加热的影响,还受到浓烟遮蔽的影响。此外,在较低的光照条件下,溶解氧(DO)可能会受到火灾灰烬输入增加或初级生产减少的影响。由于在事件发生时收集数据具有挑战性,大多数探索火灾对溪流影响的研究都集中在事件发生后数月至数年的反应上,而不是在火灾发生期间和之后立即进行。我们试图了解野火在溪流附近燃烧时,物理溪流参数如何变化,溪流温度响应在溪流范围内如何变化,参数如何响应火灾期间和火灾后不久普遍烟雾的遮蔽,以及火灾严重程度如何与观察到的变化相关联。在这项研究中,我们报告了2020年大规模野火发生前、期间和发生后1周,美国俄勒冈州喀斯喀特山脉西部11条二至四级溪流的光照、空气温度、溪流温度和DO测量结果。在溪流附近燃烧,导致燃烧最严重的地点的日最高溪流温度短暂上升4.5°C,但在受影响较小的地点则略有上升或下降。纵向复制显示,在相对较小的尺度(~50米)下,温度反应可能是不稳定的。火灾发生当天,DO日最小值降低了1.3%至16.9%的饱和度,其影响程度与烧伤严重程度相对应。在所有11个地点中,河岸和流域对野火后植被状况快速评估的估计以及土壤烧伤的严重程度与河流温度对火灾的反应的相关性比流域烧伤的百分比更好。烟雾效应在空间和时间上都很普遍,导致光照、溪流温度最高值和DO的日变化减少。我们的研究结果表明,物理溪流参数的急性变化对我们所在地的水生生物群造成的危害最小,烟雾对物理流参数的影响可能会对源头流产生比火灾本身加热更大的直接影响。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Freshwater Science
Freshwater Science ECOLOGY-MARINE & FRESHWATER BIOLOGY
CiteScore
4.10
自引率
0.00%
发文量
49
审稿时长
6-12 weeks
期刊介绍: Freshwater Science (FWS) publishes articles that advance understanding and environmental stewardship of all types of inland aquatic ecosystems (lakes, rivers, streams, reservoirs, subterranean, and estuaries) and ecosystems at the interface between aquatic and terrestrial habitats (wetlands, riparian areas, and floodplains). The journal regularly features papers on a wide range of topics, including physical, chemical, and biological properties of lentic and lotic habitats; ecosystem processes; structure and dynamics of populations, communities, and ecosystems; ecology, systematics, and genetics of freshwater organisms, from bacteria to vertebrates; linkages between freshwater and other ecosystems and between freshwater ecology and other aquatic sciences; bioassessment, conservation, and restoration; environmental management; and new or novel methods for basic or applied research.
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