The climate envelope of Alaska’s northern treelines: implications for controlling factors and future treeline advance. Primary data and analyses 2019 - 2021
Understanding the key mechanisms that control northern treelines is important to accurately predict biome shifts and terrestrial feedbacks to climate. At a global scale, it has long been observed that elevational and latitudinal treelines occur at similar mean growing season air temperature (GSAT) i...
Main Authors: | , , , , , |
---|---|
Format: | Dataset |
Language: | unknown |
Published: |
Arctic Data Center
2021
|
Subjects: | |
Online Access: | https://search.dataone.org/view/urn:uuid:bff83e11-c3be-47ff-8f57-3267fb05ee3a |
id |
dataone:urn:uuid:bff83e11-c3be-47ff-8f57-3267fb05ee3a |
---|---|
record_format |
openpolar |
spelling |
dataone:urn:uuid:bff83e11-c3be-47ff-8f57-3267fb05ee3a 2024-03-03T19:46:32+00:00 The climate envelope of Alaska’s northern treelines: implications for controlling factors and future treeline advance. Primary data and analyses 2019 - 2021 Colin Maher Roman Dial Neal Pastick Rebecca Hewitt M. Torre Jorgenson Patrick Sullivan All land area of U.S. state of Alaska north of 66° N latitude. ENVELOPE(-168.0,-140.0,72.0,66.0) BEGINDATE: 2019-10-01T00:00:00Z ENDDATE: 2021-07-01T00:00:00Z 2021-01-01T00:00:00Z https://search.dataone.org/view/urn:uuid:bff83e11-c3be-47ff-8f57-3267fb05ee3a unknown Arctic Data Center tundra-taiga ecotone Growth limitation hypothesis boreal forest permafrost Picea Picea glauca Picea glauca Dataset 2021 dataone:urn:node:ARCTIC 2024-03-03T19:17:24Z Understanding the key mechanisms that control northern treelines is important to accurately predict biome shifts and terrestrial feedbacks to climate. At a global scale, it has long been observed that elevational and latitudinal treelines occur at similar mean growing season air temperature (GSAT) isotherms, inspiring the growth limitation hypothesis (GLH) that cold GSAT limits aboveground growth of treeline trees, with mean treeline GSAT ~6-7 degrees celsius (°C). Treelines with mean GSAT warmer than 6-7 °C may indicate other limiting factors. Many treelines globally are not advancing despite warming, and other climate variables are rarely considered at broad scales. Our goals were to test whether current boreal treelines in northern Alaska correspond with the GLH isotherm, determine which environmental factors are most predictive of treeline presence, and to identify areas beyond the current treeline where advance is most likely. We digitized ~12,400 kilometers (km) of treelines (greater than 26K points) and computed seasonal climate variables across northern Alaska. We then built a generalized additive model predicting treeline presence to identify key factors determining treeline. Two metrics of mean GSAT at Alaska’s northern treelines were consistently warmer than the 6-7 °C isotherm (means of 8.5 °C and 9.3 °C), indicating that direct physiological limitation from low GSAT is unlikely to explain the position of treelines in northern Alaska. Our final model included cumulative growing degree-days, near-surface (≤ 1 meters (m)) permafrost probability, and growing season total precipitation, which together may represent the importance of soil temperature. Our results indicate that mean GSAT may not be the primary driver of treeline in northern Alaska or that its effect is mediated by other more proximate, and possibly non-climatic, controls. Our model predicts treeline potential in several areas beyond current treelines, pointing to possible routes of treeline advance if unconstrained by non-climatic factors. Dataset permafrost taiga Tundra Alaska Arctic Data Center (via DataONE) ENVELOPE(-168.0,-140.0,72.0,66.0) |
institution |
Open Polar |
collection |
Arctic Data Center (via DataONE) |
op_collection_id |
dataone:urn:node:ARCTIC |
language |
unknown |
topic |
tundra-taiga ecotone Growth limitation hypothesis boreal forest permafrost Picea Picea glauca Picea glauca |
spellingShingle |
tundra-taiga ecotone Growth limitation hypothesis boreal forest permafrost Picea Picea glauca Picea glauca Colin Maher Roman Dial Neal Pastick Rebecca Hewitt M. Torre Jorgenson Patrick Sullivan The climate envelope of Alaska’s northern treelines: implications for controlling factors and future treeline advance. Primary data and analyses 2019 - 2021 |
topic_facet |
tundra-taiga ecotone Growth limitation hypothesis boreal forest permafrost Picea Picea glauca Picea glauca |
description |
Understanding the key mechanisms that control northern treelines is important to accurately predict biome shifts and terrestrial feedbacks to climate. At a global scale, it has long been observed that elevational and latitudinal treelines occur at similar mean growing season air temperature (GSAT) isotherms, inspiring the growth limitation hypothesis (GLH) that cold GSAT limits aboveground growth of treeline trees, with mean treeline GSAT ~6-7 degrees celsius (°C). Treelines with mean GSAT warmer than 6-7 °C may indicate other limiting factors. Many treelines globally are not advancing despite warming, and other climate variables are rarely considered at broad scales. Our goals were to test whether current boreal treelines in northern Alaska correspond with the GLH isotherm, determine which environmental factors are most predictive of treeline presence, and to identify areas beyond the current treeline where advance is most likely. We digitized ~12,400 kilometers (km) of treelines (greater than 26K points) and computed seasonal climate variables across northern Alaska. We then built a generalized additive model predicting treeline presence to identify key factors determining treeline. Two metrics of mean GSAT at Alaska’s northern treelines were consistently warmer than the 6-7 °C isotherm (means of 8.5 °C and 9.3 °C), indicating that direct physiological limitation from low GSAT is unlikely to explain the position of treelines in northern Alaska. Our final model included cumulative growing degree-days, near-surface (≤ 1 meters (m)) permafrost probability, and growing season total precipitation, which together may represent the importance of soil temperature. Our results indicate that mean GSAT may not be the primary driver of treeline in northern Alaska or that its effect is mediated by other more proximate, and possibly non-climatic, controls. Our model predicts treeline potential in several areas beyond current treelines, pointing to possible routes of treeline advance if unconstrained by non-climatic factors. |
format |
Dataset |
author |
Colin Maher Roman Dial Neal Pastick Rebecca Hewitt M. Torre Jorgenson Patrick Sullivan |
author_facet |
Colin Maher Roman Dial Neal Pastick Rebecca Hewitt M. Torre Jorgenson Patrick Sullivan |
author_sort |
Colin Maher |
title |
The climate envelope of Alaska’s northern treelines: implications for controlling factors and future treeline advance. Primary data and analyses 2019 - 2021 |
title_short |
The climate envelope of Alaska’s northern treelines: implications for controlling factors and future treeline advance. Primary data and analyses 2019 - 2021 |
title_full |
The climate envelope of Alaska’s northern treelines: implications for controlling factors and future treeline advance. Primary data and analyses 2019 - 2021 |
title_fullStr |
The climate envelope of Alaska’s northern treelines: implications for controlling factors and future treeline advance. Primary data and analyses 2019 - 2021 |
title_full_unstemmed |
The climate envelope of Alaska’s northern treelines: implications for controlling factors and future treeline advance. Primary data and analyses 2019 - 2021 |
title_sort |
climate envelope of alaska’s northern treelines: implications for controlling factors and future treeline advance. primary data and analyses 2019 - 2021 |
publisher |
Arctic Data Center |
publishDate |
2021 |
url |
https://search.dataone.org/view/urn:uuid:bff83e11-c3be-47ff-8f57-3267fb05ee3a |
op_coverage |
All land area of U.S. state of Alaska north of 66° N latitude. ENVELOPE(-168.0,-140.0,72.0,66.0) BEGINDATE: 2019-10-01T00:00:00Z ENDDATE: 2021-07-01T00:00:00Z |
long_lat |
ENVELOPE(-168.0,-140.0,72.0,66.0) |
genre |
permafrost taiga Tundra Alaska |
genre_facet |
permafrost taiga Tundra Alaska |
_version_ |
1792544830658707456 |