Holocene evolution of lakes in the forest-tundra biome of northern Manitoba, Canada

QUATERNARY SCIENCE REVIEWS

卷:159

Article

Hobbs, William O.^1,9  Edlund, Mark B.¹  Umbanhowar, Charles E., Jr.²  Camill, Philip^3,4  Lynch, Jason A.⁵  Geiss, Christoph^6,7  Stefanova, Vania⁸ 

[1] Sci Museum Minnesota, St Croix Watershed Res Stn, 16910 152nd St North, Marine St Croix, MN 55047 USA

[2] St Olaf Coll, Dept Biol, Northfield, MN 55057 USA

[3] Bowdoin Coll, Environm Studies Program, Brunswick, ME 04011 USA

[4] Bowdoin Coll, Earth & Oceanog Sci Dept, Brunswick, ME 04011 USA

[5] US EPA, Off Air & Radiat, 1200 Penn Ave NW, Washington, DC 20460 USA

[6] Trinity Coll, Dept Phys, Hartford, CT 06106 USA

[7] Trinity Coll, Environm Sci Program, Hartford, CT 06106 USA

[8] Univ Minnesota, Dept Earth Sci, 310 Pillsbury Dr SE, Minneapolis, MN 55455 USA

[9] Washington State Dept Ecol, POB 14700, Olympia, WA 98504 USA

关键词: Subarctic;    Paleolimnology;    Diatoms;    Lake ontogeny;    Holocene Thermal Maximum;    Northern Manitoba;    Little Ice Age;    Anthropocene;   

DOI  :  10.1016/j.quascirev.2017.01.014

来源: Elsevier

【 摘 要 】

The late-Quaternary paleoenvironmental history of the western Hudson Bay region of Subarctic Canada is poorly constrained. Here, we present a regional overview of the post-glacial history of eight lakes which span the forest-tundra biome in northern Manitoba. We show that during the penultimate drainage phase of Lake Agassiz the lake water had an estimated pH of -6.0, with abundant quillwort (Isoetes spp.) along the lakeshore and littoral zone and some floating green algae (Botryococcus spp. and Pediastrum sp.). Based on multiple sediment proxies, modern lake ontogeny in the region commenced at -7500 cal yrs BP. Pioneering diatom communities were shaped by the turbid, higher alkalinity lake waters which were influenced by base cation weathering of the surrounding till following Lake Agassiz drainage. By -7000 cal yrs BP, soil development and Picea spp. establish and the lakes began a slow trajectory of acidification over the remaining Holocene epoch. The natural acidification of the lakes in this region is slow, on the order of several millennia for one pH unit. Each of the study lakes exhibit relatively stable aquatic communities during the Holocene Thermal Maximum, suggesting this period is a poor analogue for modern climatic changes. During the Neoglacial, the beginning of the post-Little Ice Age period represents the most significant climatic event to impact the lakes of N. Manitoba. In the context of regional lake histories, the rate of diatom floristic change in the last 200-300 years is unprecedented, with the exception of post-glacial lake ontogeny in some of the lakes. For nearly the entire history of the lakes in this region, there is a strong linkage between landscape development and the aquatic ecosystems; however this relationship appears to become decoupled or less strong in the post-LIA period. Significant 20th century changes in the aquatic ecosystem cannot be explained wholly by changes in the terrestrial ecosystem, suggesting that future changes to the lakes of N. Manitoba will be strongly influenced by direct climatic effects to the lakes. (C) 2017 Elsevier Ltd. All rights reserved.

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