Holocene vegetation and wildfire disturbance in boreal central Yukon, Canada

IF 2.7 3区地球科学 Q2 ECOLOGY

Arctic Science Pub Date : 2024-05-24 DOI:10.1139/as-2023-0070

K. Brown, P. Jain, Nicholas J.R. Hebda, Nicholas Conder, Richard J. Hebda, Les C. Cwynar

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引用次数: 0

Abstract

Sediment cores were collected from Wrong (WL) and Lenore (LL) lakes in boreal central Yukon Territory, Canada, spanning circa 6000 years. Analyses of pollen, charcoal, magnetic susceptibility, levoglucosan, and down-scaled paleoclimatic data reveal the vegetation history and character/drivers of Holocene fire disturbance. Boreal forest has persisted in the region for millennia, with a regional mid-Holocene expansion of Picea mariana followed by expansion of Pinus contorta in the latest Holocene. The shortest reconstructed fire return intervals (FRI; ca. 110-125 years) occurred in the mid-Holocene, coincident with the development of highly flammable Picea-dominated forest and warm, dry summers that were characterized by elevated JJA Z500 anomalies and associated with an eastward/intense Aleutian Low. In the late-Holocene, FRI increased to ca. 240 years at WL and 280 years LL. Drivers of this change include regional cooling and increased precipitation, with a westward/weaker Aleutian Low position delivering more moisture to interior Yukon. Longer FRIs allowed for greater fuel accumulation between fires, enhancing fire size/severity. While higher fire frequency is noted in the mid-Holocene and increased fire size/severity in the late-Holocene, recent changes in Yukon fire disturbance suggest that the fire regime may soon lie outside the natural range of mid- and late-Holocene variability.

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加拿大育空中部北方全新世植被和野火干扰

沉积物岩芯采集自加拿大育空地区中部北方的 Wrong 湖（WL）和 Lenore 湖（LL），时间跨度约 6000 年。对花粉、木炭、磁感应强度、左旋葡聚糖和缩小比例的古气候数据的分析揭示了全新世火灾扰动的植被历史和特征/驱动因素。该地区的北方森林已经存在了数千年，在全新世中期，该地区的马里亚纳松（Picea mariana）面积扩大，随后在全新世晚期，孔雀松（Pinus contorta）面积扩大。重建的最短火灾重返间隔期（FRI；约 110-125 年）出现在全新世中期，与高易燃性 Picea 主导森林的发展以及温暖干燥的夏季相吻合，这些夏季的特点是 JJA Z500 异常值升高，并与向东/强烈的阿留申低气压相关联。在全新世晚期，FRI 在 WL 增加到约 240 年，在 LL 增加到 280 年。这一变化的驱动因素包括区域降温和降水增加，阿留申低地的西移/减弱为育空内陆提供了更多水汽。较长的 FRI 允许在两次火灾之间积累更多的燃料，从而增加了火灾的规模/严重程度。虽然全新世中期火灾频率较高，全新世晚期火灾规模/严重程度增加，但育空火灾干扰的近期变化表明，火灾机制可能很快就会超出全新世中期和晚期的自然变化范围。

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

Arctic Science Agricultural and Biological Sciences-General Agricultural and Biological Sciences

CiteScore

5.00

自引率

12.10%

发文量

期刊介绍： Arctic Science is an interdisciplinary journal that publishes original peer-reviewed research from all areas of natural science and applied science & engineering related to northern Polar Regions. The focus on basic and applied science includes the traditional knowledge and observations of the indigenous peoples of the region as well as cutting-edge developments in biological, chemical, physical and engineering science in all northern environments. Reports on interdisciplinary research are encouraged. Special issues and sections dealing with important issues in northern polar science are also considered.