Lake effect on summer cooling of shorelines and adjacent inland forests on Lake Superior’s north shore
Cite this dataset
Hillman, Ashley; Nielsen, Scott (2023). Lake effect on summer cooling of shorelines and adjacent inland forests on Lake Superior’s north shore [Dataset]. Dryad. https://doi.org/10.5061/dryad.q83bk3jpc
Abstract
Climate refugia, or areas that are projected to remain relatively stable under climate change, can serve as remnant habitat or steeping stones for species dispersal. The largest freshwater lake in the world by surface area, Lake Superior, serves as a model system for understanding cooling-mediated local refugia, as its cool summer water temperatures and wave action have maintained shoreline habitats suitable for disjunct opulations for arctic-alpine plants since deglaciation. It is known to affect local climates by providing a summer cooling effect near its shorelines, however, the inland gradient of change and spatial patterns of cooling has not been quantified. Here, we describe the extent of the inland cooling gradient, the degree of temperature buffering, and patterns of cooling for Lake Superior's north shore over a 3-year period. Specifically, we established 7 transects along Lake Superior's north shore, with temperature data loggers placed at 10 m, 100 m, 1 km, 10 km, and 100 km inland. We analyzed temperature data by year, month, summer maximum, and growing degree days (GDD0) for each site. Summertime cooling at shore sites (10m) was ~5 °C cooler than inland control sites (100 km), while sites 10 km from the shore were still 1.6 °C cooler than control sites. Magnitude of cooling varied geographically, with sites further west and southeast showing little to no cooling effect. Site on the exposed north and northeast shore where disjunct arctic-alpine plants are most common showed the highest degree of temperature buffering. We also found that shoreline sites on the north and northeast shore had shorter growing seasons compared to inland control sites. Finally, the number of days per year warmer than 16 °C, a maximum temperature threshold associated with arctic-alpine plant occurrences, averaged 65 days per year at 10 m sites and 82 days per year at control sites. The north shore of Lake Superior serves as a transition zone between temperate deciduous forests and boreal forests and is predicted to transition to deciduous forests under climate change. An understanding of the extent of lake-mediated cooling on adjacent forests can better inform risk to arctic-alpine disjunct species, inland forests, and overall vegetation transition models on Lake Superior's north shore.
README
GENERAL INFORMATION
Dataset title: Lake effect on summer cooling of shorelines and adjacent inland forests on Lake Superior’s north shore
Author Information
A. Corresponding Author Contact Information
Name: Ashley Hillman
Institution: University of Alberta
Email: hillman@ualberta.caB. Principal Investigator Contact Information
Name: Scott Nielsen
Institution: University of Alberta
Email: scottn@ualberta.caDate of data collection (single date, range, approximate date): July 2018- July 2021
Geographic location of data collection: Lake Superior, Ontario, Canada
Information about funding sources that supported the collection of the data: Natural Sciences and Engineering Research Council of Canada (NSERC)
DATA & FILE OVERVIEW
This dataset contains time series temperature data for 7 transects arranged west to east on Lake Superior's north shore.
Due to file size, raw data is separated by Location. Mean daily temperature is provideded for all data in the file Hillman_mean daily temperature.csv
Additional files used in analysis are included, such as Growing Degree Days (calculated outside of R), and disjunct arctic-alpine plant occurrence information for each shoreline site.
- File List:
A) Hillman_Marathon raw data.csv
B) Hillman_Montreal River Harbour raw data.csv
C) Hillman_Rossport raw data.csv
D) HIllman_Schreiber raw data.csv
E) Hillman_Terrace Bay raw data.csv
F) Hillman_Thunder Bay raw data.csv
G) Hillman_Wawa raw data.csv
H) Hillman_disjunct_prop.csv
I) Hillman_GDD_all.csv
J) Hillman_ met station differences.csv
K) Hillman_site differences.csv
#########################################################################
DATA-SPECIFIC INFORMATION FOR: All raw data files
- Variable List:
* Year - Year of data collection
* Month - Month of data collection
* Day - Day of data collection
* Time - Time of day of data collection
* Location - Name of transect, assigned based on the nearest town to the transect
* Site - Name of logger location within a transect
* Distance_m - Distance of Site from Lake Superior's shoreline, provided in metres
* Exposure - refers to exposure of shoreline of associated transect. Exposed shores do not have offshore islands buffering them from high winds and waves, while unexposed sites are protected by offshore islands.
* Temp - temperature reading for associated date and time. Data is provided in °C
Missing data codes: NA
Specialized formats or other abbreviations used: None
#########################################################################
DATA-SPECIFIC INFORMATION FOR: Hillman_Mean daily temperatures.csv
- Variable List:
* Location - Name of transect, assigned based on the nearest town to the transect
* Site - Name of logger location within a transect
* Year - Year of data collection
* Date - Date of data collection, provided in month/day/year
* Distance_m - Distance of Site from Lake Superior's shoreline, provided in metres
* Exposure - refers to exposure of shoreline of associated transect. Exposed shores do not have offshore islands buffering them from high winds and waves, while unexposed sites are protected by offshore islands.
* mean.temp - Mean daily temperature, provided in °C
Missing data codes: NA
Specialized formats or other abbreviations used: None
#########################################################################
DATA-SPECIFIC INFORMATION FOR: Hillman_site differences.csv
- Variable List:
* Location - Name of transect, assigned based on the nearest town to the transect
* Site - Name of logger location within a transect
* Year - Year of data collection
* Date - Date of data collection, provided in month/day/year
* Distance_m - Distance of Site from Lake Superior's shoreline, provided in metres
* Exposure - refers to exposure of shoreline of associated transect. Exposed shores do not have offshore islands buffering them from high winds and waves, while unexposed sites are protected by offshore islands.
* mean.temp - Mean daily temperature, provided in °C
* temp_100 - Mean daily temperature of each transect's associated 100 km reference logger, provided in °C
* temp_diff - Difference in temperature between mean.temp and temp_100
* elevation - Elevation of each logger site above the lake surface, provided in metres
* elev_100km - Elevation of each transect's associated 100 km reference logger, provided in metres
* elev_diff - difference in elevation between elevation and elev_100km
* shore_width - width of shoreline adjacent to the 10 m logger of each transect, determined as the distance in metres from the water's edge to continuous treeline.
* depth_neg - Average depth of water within 10 km of shore, for each transect. Values are negative to reflect depth. Provided in metres
* offshore_temp - Average surface water temperature within 10 km of shore, for each transect. Provided in °C
* latitude - Latitude of each site
Missing data codes: NA
Specialized formats or other abbreviations used: None
#########################################################################
DATA-SPECIFIC INFORMATION FOR: Hillman_met station differences.csv
- Variable List:
* Location - Name of transect, assigned based on the nearest town to the transect
* Site - Name of logger location within a transect
* Year - Year of data collection
* Date - Date of data collection, provided in month/day/year
* Distance_m - Distance of Site from Lake Superior's shoreline, provided in metres
* Exposure - refers to exposure of shoreline of associated transect. Exposed shores do not have offshore islands buffering them from high winds and waves, while unexposed sites are protected by offshore islands.
* mean.temp - Mean daily temperature, provided in °C
* temp_100 - Mean daily temperature of each transect's associated 100 km reference logger, provided in °C
* temp_diff - Difference in temperature between mean.temp and temp_100
* temp_met - Mean daily temperature of nearest meterological station, provided in °C
* met_diff - Difference in temperature of between mean.temp and temp_met
Missing data codes: NA
Specialized formats or other abbreviations used: None
#########################################################################
DATA-SPECIFIC INFORMATION FOR: Hillman_disjunct_prop.csv
- Variable List:
* Location - Name of transect, assigned based on the nearest town to the transect
* Site - Name of logger location within a transect
* Year - Year of data collection
* Date - Date of data collection, provided in month/day/year
* Distance_m - Distance of Site from Lake Superior's shoreline, provided in metres
* Exposure - refers to exposure of shoreline of associated transect. Exposed shores do not have offshore islands buffering them from high winds and waves, while unexposed sites are protected by offshore islands.
* mean.temp - Mean daily temperature, provided in °C
* temp_100 - Mean daily temperature of each transect's associated 100 km reference logger, provided in °C
* temp_diff - Difference in temperature between mean.temp and temp_100
* elevation - Elevation of each logger site above the lake surface, provided in metres
* elev_100km - Elevation of each transect's associated 100 km reference logger, provided in metres
* elev_diff - difference in elevation between elevation and elev_100km
* shore_width - width of shoreline adjacent to the 10 m logger of each transect, determined as the distance in metres from the water's edge to continuous treeline.
* depth_neg - Average depth of water within 10 km of shore, for each transect. Values are negative to reflect depth. Provided in metres
* offshore_temp - Average surface water temperature within 10 km of shore, for each transect. Provided in °C
* latitude - Latitude of each site
* prop_disj - proportion of total species at each shoreline site that are considered to be disjunct arctic-alpine species
* gdd - Growing Degree Days above base temperature threshold of 0°C, calculated for the growing season of April 1 - Sept 30, 2019
* thresh_days - Average number of days per year
Missing data codes: NA
Specialized formats or other abbreviations used: None
#########################################################################
DATA-SPECIFIC INFORMATION FOR: Hillman_GDD_all.csv
- Variable List:
* Location - Name of transect, assigned based on the nearest town to the transect
* Site - Name of logger location within a transect
* Distance_m - Distance of Site from Lake Superior's shoreline, provided in metres
* gdd0 - Growing Degree Days above base temperature threshold of 0°C, calculated for the growing season of April 1 - Sept 30, 2019
Missing data codes: NA
Specialized formats or other abbreviations used: None
Funding
Natural Sciences and Engineering Research Council