Evapotranspiration across plant types and geomorphological units in polygonal Arctic tundra
Coastal tundra ecosystems are relatively flat, and yet display large spatial variability in ecosystem traits. The microtopographical differences in polygonal geomorphology produce heterogeneity in permafrost depth, soil temperature, soil moisture, soil geochemistry, and plant distribution. Few measu...
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ftcdlib:oai:escholarship.org:ark:/13030/qt4d1322c5 2024-01-07T09:41:26+01:00 Evapotranspiration across plant types and geomorphological units in polygonal Arctic tundra Raz-Yaseef, Naama Young-Robertson, Jessica Rahn, Thom Sloan, Victoria Newman, Brent Wilson, Cathy Wullschleger, Stan D Torn, Margaret S 2017-10-01 application/pdf https://escholarship.org/uc/item/4d1322c5 unknown eScholarship, University of California qt4d1322c5 https://escholarship.org/uc/item/4d1322c5 public Biological Sciences Ecology Engineering Environmental Sciences Geomatic Engineering Arctic tundra Evapotranspiration Greenhouse gases Moss Polygon structure Environmental Engineering article 2017 ftcdlib 2023-12-11T19:07:47Z Coastal tundra ecosystems are relatively flat, and yet display large spatial variability in ecosystem traits. The microtopographical differences in polygonal geomorphology produce heterogeneity in permafrost depth, soil temperature, soil moisture, soil geochemistry, and plant distribution. Few measurements have been made, however, of how water fluxes vary across polygonal tundra plant types, limiting our ability to understand and model these ecosystems. Our objective was to investigate how plant distribution and geomorphological location affect actual evapotranspiration (ET). These effects are especially critical in light of the rapid change polygonal tundra systems are experiencing with Arctic warming. At a field site near Barrow, Alaska, USA, we investigated the relationships between ET and plant cover in 2014 and 2015. ET was measured at a range of spatial and temporal scales using: (1) An eddy covariance flux tower for continuous landscape-scale monitoring; (2) An automated clear surface chamber over dry vegetation in a fixed location for continuous plot-scale monitoring; and (3) Manual measurements with a clear portable chamber in approximately 60 locations across the landscape. We found that variation in environmental conditions and plant community composition, driven by microtopographical features, has significant influence on ET. Among plant types, ET from moss-covered and inundated areas was more than twice that from other plant types. ET from troughs and low polygonal centers was significantly higher than from high polygonal centers. ET varied seasonally, with peak fluxes of 0.14 mm h−1 in July. Despite 24 hours of daylight in summer, diurnal fluctuations in incoming solar radiation and plant processes produced a diurnal cycle in ET. Combining the patterns we observed with projections for the impact of permafrost degradation on polygonal structure suggests that microtopographic changes associated with permafrost thaw have the potential to alter tundra ecosystem ET. Article in Journal/Newspaper Arctic Barrow permafrost Tundra Alaska University of California: eScholarship Arctic |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
unknown |
topic |
Biological Sciences Ecology Engineering Environmental Sciences Geomatic Engineering Arctic tundra Evapotranspiration Greenhouse gases Moss Polygon structure Environmental Engineering |
spellingShingle |
Biological Sciences Ecology Engineering Environmental Sciences Geomatic Engineering Arctic tundra Evapotranspiration Greenhouse gases Moss Polygon structure Environmental Engineering Raz-Yaseef, Naama Young-Robertson, Jessica Rahn, Thom Sloan, Victoria Newman, Brent Wilson, Cathy Wullschleger, Stan D Torn, Margaret S Evapotranspiration across plant types and geomorphological units in polygonal Arctic tundra |
topic_facet |
Biological Sciences Ecology Engineering Environmental Sciences Geomatic Engineering Arctic tundra Evapotranspiration Greenhouse gases Moss Polygon structure Environmental Engineering |
description |
Coastal tundra ecosystems are relatively flat, and yet display large spatial variability in ecosystem traits. The microtopographical differences in polygonal geomorphology produce heterogeneity in permafrost depth, soil temperature, soil moisture, soil geochemistry, and plant distribution. Few measurements have been made, however, of how water fluxes vary across polygonal tundra plant types, limiting our ability to understand and model these ecosystems. Our objective was to investigate how plant distribution and geomorphological location affect actual evapotranspiration (ET). These effects are especially critical in light of the rapid change polygonal tundra systems are experiencing with Arctic warming. At a field site near Barrow, Alaska, USA, we investigated the relationships between ET and plant cover in 2014 and 2015. ET was measured at a range of spatial and temporal scales using: (1) An eddy covariance flux tower for continuous landscape-scale monitoring; (2) An automated clear surface chamber over dry vegetation in a fixed location for continuous plot-scale monitoring; and (3) Manual measurements with a clear portable chamber in approximately 60 locations across the landscape. We found that variation in environmental conditions and plant community composition, driven by microtopographical features, has significant influence on ET. Among plant types, ET from moss-covered and inundated areas was more than twice that from other plant types. ET from troughs and low polygonal centers was significantly higher than from high polygonal centers. ET varied seasonally, with peak fluxes of 0.14 mm h−1 in July. Despite 24 hours of daylight in summer, diurnal fluctuations in incoming solar radiation and plant processes produced a diurnal cycle in ET. Combining the patterns we observed with projections for the impact of permafrost degradation on polygonal structure suggests that microtopographic changes associated with permafrost thaw have the potential to alter tundra ecosystem ET. |
format |
Article in Journal/Newspaper |
author |
Raz-Yaseef, Naama Young-Robertson, Jessica Rahn, Thom Sloan, Victoria Newman, Brent Wilson, Cathy Wullschleger, Stan D Torn, Margaret S |
author_facet |
Raz-Yaseef, Naama Young-Robertson, Jessica Rahn, Thom Sloan, Victoria Newman, Brent Wilson, Cathy Wullschleger, Stan D Torn, Margaret S |
author_sort |
Raz-Yaseef, Naama |
title |
Evapotranspiration across plant types and geomorphological units in polygonal Arctic tundra |
title_short |
Evapotranspiration across plant types and geomorphological units in polygonal Arctic tundra |
title_full |
Evapotranspiration across plant types and geomorphological units in polygonal Arctic tundra |
title_fullStr |
Evapotranspiration across plant types and geomorphological units in polygonal Arctic tundra |
title_full_unstemmed |
Evapotranspiration across plant types and geomorphological units in polygonal Arctic tundra |
title_sort |
evapotranspiration across plant types and geomorphological units in polygonal arctic tundra |
publisher |
eScholarship, University of California |
publishDate |
2017 |
url |
https://escholarship.org/uc/item/4d1322c5 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic Barrow permafrost Tundra Alaska |
genre_facet |
Arctic Barrow permafrost Tundra Alaska |
op_relation |
qt4d1322c5 https://escholarship.org/uc/item/4d1322c5 |
op_rights |
public |
_version_ |
1787422238259019776 |