Cargando…

Paludification reduces black spruce growth rate but does not alter tree water use efficiency in Canadian boreal forested peatlands

BACKGROUND: Black spruce (Picea mariana (Mill.) BSP)-forested peatlands are widespread ecosystems in boreal North America in which peat accumulation, known as the paludification process, has been shown to induce forest growth decline. The continuously evolving environmental conditions (e.g., water t...

Descripción completa

Detalles Bibliográficos
Autores principales: Beaulne, Joannie, Boucher, Étienne, Garneau, Michelle, Magnan, Gabriel
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Springer Singapore 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8550502/
https://www.ncbi.nlm.nih.gov/pubmed/34721933
http://dx.doi.org/10.1186/s40663-021-00307-x
_version_ 1784590972929179648
author Beaulne, Joannie
Boucher, Étienne
Garneau, Michelle
Magnan, Gabriel
author_facet Beaulne, Joannie
Boucher, Étienne
Garneau, Michelle
Magnan, Gabriel
author_sort Beaulne, Joannie
collection PubMed
description BACKGROUND: Black spruce (Picea mariana (Mill.) BSP)-forested peatlands are widespread ecosystems in boreal North America in which peat accumulation, known as the paludification process, has been shown to induce forest growth decline. The continuously evolving environmental conditions (e.g., water table rise, increasing peat thickness) in paludified forests may require tree growth mechanism adjustments over time. In this study, we investigate tree ecophysiological mechanisms along a paludification gradient in a boreal forested peatland of eastern Canada by combining peat-based and tree-ring analyses. Carbon and oxygen stable isotopes in tree rings are used to document changes in carbon assimilation rates, stomatal conductance, and water use efficiency. In addition, paleohydrological analyses are performed to evaluate the dynamical ecophysiological adjustments of black spruce trees to site-specific water table variations. RESULTS: Increasing peat accumulation considerably impacts forest growth, but no significant differences in tree water use efficiency (iWUE) are found between the study sites. Tree-ring isotopic analysis indicates no iWUE decrease over the last 100 years, but rather an important increase at each site up to the 1980s, before iWUE stabilized. Surprisingly, inferred basal area increments do not reflect such trends. Therefore, iWUE variations do not reflect tree ecophysiological adjustments required by changes in growing conditions. Local water table variations induce no changes in ecophysiological mechanisms, but a synchronous shift in iWUE is observed at all sites in the mid-1980s. CONCLUSIONS: Our study shows that paludification induces black spruce growth decline without altering tree water use efficiency in boreal forested peatlands. These findings highlight that failing to account for paludification-related carbon use and allocation could result in the overestimation of aboveground biomass production in paludified sites. Further research on carbon allocation strategies is of utmost importance to understand the carbon sink capacity of these widespread ecosystems in the context of climate change, and to make appropriate forest management decisions in the boreal biome. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s40663-021-00307-x.
format Online
Article
Text
id pubmed-8550502
institution National Center for Biotechnology Information
language English
publishDate 2021
publisher Springer Singapore
record_format MEDLINE/PubMed
spelling pubmed-85505022021-10-29 Paludification reduces black spruce growth rate but does not alter tree water use efficiency in Canadian boreal forested peatlands Beaulne, Joannie Boucher, Étienne Garneau, Michelle Magnan, Gabriel For Ecosyst Research BACKGROUND: Black spruce (Picea mariana (Mill.) BSP)-forested peatlands are widespread ecosystems in boreal North America in which peat accumulation, known as the paludification process, has been shown to induce forest growth decline. The continuously evolving environmental conditions (e.g., water table rise, increasing peat thickness) in paludified forests may require tree growth mechanism adjustments over time. In this study, we investigate tree ecophysiological mechanisms along a paludification gradient in a boreal forested peatland of eastern Canada by combining peat-based and tree-ring analyses. Carbon and oxygen stable isotopes in tree rings are used to document changes in carbon assimilation rates, stomatal conductance, and water use efficiency. In addition, paleohydrological analyses are performed to evaluate the dynamical ecophysiological adjustments of black spruce trees to site-specific water table variations. RESULTS: Increasing peat accumulation considerably impacts forest growth, but no significant differences in tree water use efficiency (iWUE) are found between the study sites. Tree-ring isotopic analysis indicates no iWUE decrease over the last 100 years, but rather an important increase at each site up to the 1980s, before iWUE stabilized. Surprisingly, inferred basal area increments do not reflect such trends. Therefore, iWUE variations do not reflect tree ecophysiological adjustments required by changes in growing conditions. Local water table variations induce no changes in ecophysiological mechanisms, but a synchronous shift in iWUE is observed at all sites in the mid-1980s. CONCLUSIONS: Our study shows that paludification induces black spruce growth decline without altering tree water use efficiency in boreal forested peatlands. These findings highlight that failing to account for paludification-related carbon use and allocation could result in the overestimation of aboveground biomass production in paludified sites. Further research on carbon allocation strategies is of utmost importance to understand the carbon sink capacity of these widespread ecosystems in the context of climate change, and to make appropriate forest management decisions in the boreal biome. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s40663-021-00307-x. Springer Singapore 2021-05-12 2021 /pmc/articles/PMC8550502/ /pubmed/34721933 http://dx.doi.org/10.1186/s40663-021-00307-x Text en © The Author(s) 2021 https://creativecommons.org/licenses/by/4.0/Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) .
spellingShingle Research
Beaulne, Joannie
Boucher, Étienne
Garneau, Michelle
Magnan, Gabriel
Paludification reduces black spruce growth rate but does not alter tree water use efficiency in Canadian boreal forested peatlands
title Paludification reduces black spruce growth rate but does not alter tree water use efficiency in Canadian boreal forested peatlands
title_full Paludification reduces black spruce growth rate but does not alter tree water use efficiency in Canadian boreal forested peatlands
title_fullStr Paludification reduces black spruce growth rate but does not alter tree water use efficiency in Canadian boreal forested peatlands
title_full_unstemmed Paludification reduces black spruce growth rate but does not alter tree water use efficiency in Canadian boreal forested peatlands
title_short Paludification reduces black spruce growth rate but does not alter tree water use efficiency in Canadian boreal forested peatlands
title_sort paludification reduces black spruce growth rate but does not alter tree water use efficiency in canadian boreal forested peatlands
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8550502/
https://www.ncbi.nlm.nih.gov/pubmed/34721933
http://dx.doi.org/10.1186/s40663-021-00307-x
work_keys_str_mv AT beaulnejoannie paludificationreducesblacksprucegrowthratebutdoesnotaltertreewateruseefficiencyincanadianborealforestedpeatlands
AT boucheretienne paludificationreducesblacksprucegrowthratebutdoesnotaltertreewateruseefficiencyincanadianborealforestedpeatlands
AT garneaumichelle paludificationreducesblacksprucegrowthratebutdoesnotaltertreewateruseefficiencyincanadianborealforestedpeatlands
AT magnangabriel paludificationreducesblacksprucegrowthratebutdoesnotaltertreewateruseefficiencyincanadianborealforestedpeatlands