Lake Superior's summer cooling of shorelines and adjacent inland forests: Implications for refugia of boreal forests and disjunct arctic–alpine plants
Abstract Climate refugia can serve as remnant habitat for cold‐adapted species and delay forest transitions. The world's largest freshwater lake by surface area, Lake Superior, serves as a model system for understanding cooling‐mediated refugia effects, as its cool summer water temperatures hav...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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Wiley
2023-12-01
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| Series: | Ecology and Evolution |
| Subjects: | |
| Online Access: | https://doi.org/10.1002/ece3.10833 |
| _version_ | 1797373100778586112 |
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| author | Ashley Hillman Scott E. Nielsen |
| author_facet | Ashley Hillman Scott E. Nielsen |
| author_sort | Ashley Hillman |
| collection | DOAJ |
| description | Abstract Climate refugia can serve as remnant habitat for cold‐adapted species and delay forest transitions. The world's largest freshwater lake by surface area, Lake Superior, serves as a model system for understanding cooling‐mediated refugia effects, as its cool summer water temperatures have maintained disjunct populations of arctic–alpine plants on its shoreline since deglaciation. It is known to affect local inland climates by providing a summer cooling effect; however, the inland temperature gradient and spatial patterns of cooling have not been well quantified. Here, we describe the extent, degree, and patterns of temperature buffering and examine drivers of buffering and disjunct plant occurrence for Lake Superior's north shore over a 3‐year period at distances of 10, 100 m, 1, 10, and 100 km inland. We analyzed temperature data by year, month, summer maximum (July), and growing degree days (GDD0) for each site. Average summertime cooling at shore sites (10 m) was ~5°C cooler than reference sites (100 km inland), with a maximum difference of −19.2°C. The magnitude of cooling varied geographically, with sites further west and southeast showing little to no cooling effect, while the exposed north‐central shore showed the highest degree of buffering (5.8°C cooler) and had a shorter growing season than reference sites. Finally, north‐central shorelines had fewer days above 16°C, a threshold above which disjunct plants are unlikely to grow. These sites also showed the highest proportion of disjunct arctic–alpine species, reflecting the highest buffering from inland sites. On north‐central shores, sites up to 10 km inland had less than 10 days per year warmer than 20°C, a threshold identified for boreal forest transition. An understanding of the extent of lake‐mediated cooling on adjacent forests can better inform the risk to disjunct species, inland forests, and vegetation transition models on Lake Superior's north shore. |
| first_indexed | 2024-03-08T18:45:30Z |
| format | Article |
| id | doaj.art-ebe277fd3414436c83a7cfb770afdde1 |
| institution | Directory Open Access Journal |
| issn | 2045-7758 |
| language | English |
| last_indexed | 2024-03-08T18:45:30Z |
| publishDate | 2023-12-01 |
| publisher | Wiley |
| record_format | Article |
| series | Ecology and Evolution |
| spelling | doaj.art-ebe277fd3414436c83a7cfb770afdde12023-12-29T00:26:15ZengWileyEcology and Evolution2045-77582023-12-011312n/an/a10.1002/ece3.10833Lake Superior's summer cooling of shorelines and adjacent inland forests: Implications for refugia of boreal forests and disjunct arctic–alpine plantsAshley Hillman0Scott E. Nielsen1Department of Renewable Resources University of Alberta Edmonton Alberta CanadaDepartment of Renewable Resources University of Alberta Edmonton Alberta CanadaAbstract Climate refugia can serve as remnant habitat for cold‐adapted species and delay forest transitions. The world's largest freshwater lake by surface area, Lake Superior, serves as a model system for understanding cooling‐mediated refugia effects, as its cool summer water temperatures have maintained disjunct populations of arctic–alpine plants on its shoreline since deglaciation. It is known to affect local inland climates by providing a summer cooling effect; however, the inland temperature gradient and spatial patterns of cooling have not been well quantified. Here, we describe the extent, degree, and patterns of temperature buffering and examine drivers of buffering and disjunct plant occurrence for Lake Superior's north shore over a 3‐year period at distances of 10, 100 m, 1, 10, and 100 km inland. We analyzed temperature data by year, month, summer maximum (July), and growing degree days (GDD0) for each site. Average summertime cooling at shore sites (10 m) was ~5°C cooler than reference sites (100 km inland), with a maximum difference of −19.2°C. The magnitude of cooling varied geographically, with sites further west and southeast showing little to no cooling effect, while the exposed north‐central shore showed the highest degree of buffering (5.8°C cooler) and had a shorter growing season than reference sites. Finally, north‐central shorelines had fewer days above 16°C, a threshold above which disjunct plants are unlikely to grow. These sites also showed the highest proportion of disjunct arctic–alpine species, reflecting the highest buffering from inland sites. On north‐central shores, sites up to 10 km inland had less than 10 days per year warmer than 20°C, a threshold identified for boreal forest transition. An understanding of the extent of lake‐mediated cooling on adjacent forests can better inform the risk to disjunct species, inland forests, and vegetation transition models on Lake Superior's north shore.https://doi.org/10.1002/ece3.10833climate refugiaLake effectLake Superiorvegetation transitions |
| spellingShingle | Ashley Hillman Scott E. Nielsen Lake Superior's summer cooling of shorelines and adjacent inland forests: Implications for refugia of boreal forests and disjunct arctic–alpine plants Ecology and Evolution climate refugia Lake effect Lake Superior vegetation transitions |
| title | Lake Superior's summer cooling of shorelines and adjacent inland forests: Implications for refugia of boreal forests and disjunct arctic–alpine plants |
| title_full | Lake Superior's summer cooling of shorelines and adjacent inland forests: Implications for refugia of boreal forests and disjunct arctic–alpine plants |
| title_fullStr | Lake Superior's summer cooling of shorelines and adjacent inland forests: Implications for refugia of boreal forests and disjunct arctic–alpine plants |
| title_full_unstemmed | Lake Superior's summer cooling of shorelines and adjacent inland forests: Implications for refugia of boreal forests and disjunct arctic–alpine plants |
| title_short | Lake Superior's summer cooling of shorelines and adjacent inland forests: Implications for refugia of boreal forests and disjunct arctic–alpine plants |
| title_sort | lake superior s summer cooling of shorelines and adjacent inland forests implications for refugia of boreal forests and disjunct arctic alpine plants |
| topic | climate refugia Lake effect Lake Superior vegetation transitions |
| url | https://doi.org/10.1002/ece3.10833 |
| work_keys_str_mv | AT ashleyhillman lakesuperiorssummercoolingofshorelinesandadjacentinlandforestsimplicationsforrefugiaofborealforestsanddisjunctarcticalpineplants AT scottenielsen lakesuperiorssummercoolingofshorelinesandadjacentinlandforestsimplicationsforrefugiaofborealforestsanddisjunctarcticalpineplants |