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Boakye EA, Houle D, Bergeron Y, Girardin MP, Drobyshev I. Insect defoliation modulates influence of climate on the growth of tree species in the boreal mixed forests of eastern Canada. Ecol Evol 2022; 12:e8656. [PMID: 35342593 PMCID: PMC8932224 DOI: 10.1002/ece3.8656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 01/25/2022] [Accepted: 02/06/2022] [Indexed: 11/06/2022] Open
Abstract
Increasing air temperatures and changing precipitation patterns due to climate change can affect tree growth in boreal forests. Periodic insect outbreaks affect the growth trajectory of trees, making it difficult to quantify the climate signal in growth dynamics at scales longer than a year. We studied climate-driven growth trends and the influence of spruce budworm (Choristoneura fumiferana Clem.) outbreaks on these trends by analyzing the basal area increment (BAI) of 2058 trees of Abies balsamea (L.) Mill., Picea glauca (Moench) Voss, Thuja occidentalis L., Populus tremuloides Michx., and Betula papyrifera Marsh, which co-occurs in the boreal mixedwood forests of western Quebec. We used a generalized additive mixed model (GAMM) to analyze species-specific trends in BAI dynamics from 1967 to 1991. The model relied on tree size, cambial age, degree of spruce budworm defoliation, and seasonal climatic variables. Overall, we observed a decreasing growth rate of the spruce budworm host species, A. balsamea and P. glauca between 1967 and 1991, and an increasing growth rate for the non-host, P. tremuloides, B. papyrifera, and T. occidentalis. Our results suggest that insect outbreaks may offset growth increases resulting from a warmer climate. The observation warrants the inclusion of the spruce budworm defoliation into models predicting future forest productivity.
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Affiliation(s)
- Emmanuel Amoah Boakye
- Chaire industrielle CRSNG‐UQAT‐UQAM en aménagement forestier durableInstitut de Recherche Sur Les ForêtsUniversité du Québec en Abitibi‐Témiscamingue (UQAT)Rouyn‐NorandaQuébecCanada
| | - Daniel Houle
- Ministère des Forêts, de la Faune et des ParcsDirection de la recherché forestièreQuébecQuébecCanada
- Ouranos Climate Change ConsortiumMontréalQuébecCanada
| | - Yves Bergeron
- Chaire industrielle CRSNG‐UQAT‐UQAM en aménagement forestier durableInstitut de Recherche Sur Les ForêtsUniversité du Québec en Abitibi‐Témiscamingue (UQAT)Rouyn‐NorandaQuébecCanada
- Forest Research CentreUniversité du Québec à MontréalMontréalQuébecCanada
| | - Martin P. Girardin
- Natural Resources CanadaCanadian Forest ServiceLaurentian Forestry CentreQuébecQuébecCanada
| | - Igor Drobyshev
- Chaire industrielle CRSNG‐UQAT‐UQAM en aménagement forestier durableInstitut de Recherche Sur Les ForêtsUniversité du Québec en Abitibi‐Témiscamingue (UQAT)Rouyn‐NorandaQuébecCanada
- Southern Swedish Forest Research CentreSwedish University of Agricultural SciencesAlnarpSweden
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Sánchez-Pinillos M, D'Orangeville L, Boulanger Y, Comeau P, Wang J, Taylor AR, Kneeshaw D. Sequential droughts: A silent trigger of boreal forest mortality. GLOBAL CHANGE BIOLOGY 2022; 28:542-556. [PMID: 34606657 DOI: 10.1111/gcb.15913] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Accepted: 08/30/2021] [Indexed: 06/13/2023]
Abstract
Despite great concern for drought-driven forest mortality, the effects of frequent low-intensity droughts have been largely overlooked in the boreal forest because of their negligible impacts over the short term. In this study, we used data from 6876 permanent plots distributed across most of the Canadian boreal zone to assess the effects of repeated low-intensity droughts on forest mortality. Specifically, we compared the relative impact of sequential years under low-intensity dry conditions with the effects of variables related to the intensity of dry conditions, stand characteristics, and local climate. Then, we searched for thresholds in forest mortality as a function of the number of years between two forest surveys affected by dry conditions of any intensity. Our results showed that, in general, frequent low-intensity dry conditions had stronger effects on forest mortality than the intensity of the driest conditions in the plot. Frequent low-intensity dry conditions acted as an inciting factor of forest mortality exacerbated by stand characteristics and environmental conditions. Overall, the mortality of forests dominated by shade-tolerant conifers was significantly and positively related to frequent low-intensity dry conditions, supporting, in some cases, the existence of thresholds delimiting contrasting responses to drought. In mixtures with broadleaf species, however, sequential dry conditions had a negligible impact. The effects of frequent dry conditions on shade-intolerant forests mainly depended on local climate, inciting or mitigating the mortality of forests located in wet places and dominated by broadleaf species or jack pine, respectively. Our results highlight the importance of assessing not only climate-driven extreme events but also repeated disturbances of low intensity. In the long term, the smooth response of forests to dry conditions might abruptly change leading to disproportional mortality triggered by accumulated stress conditions. Forest and wildlife managers should consider the cumulative effects of climate change on mortality to avoid shortfalls in timber and habitat.
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Affiliation(s)
- Martina Sánchez-Pinillos
- Centre for Forest Research, Université du Québec à Montréal, Montreal, Quebec, Canada
- Faculty of Forestry and Environmental Management, University of New Brunswick, Fredericton, New Brunswick, Canada
| | - Loïc D'Orangeville
- Faculty of Forestry and Environmental Management, University of New Brunswick, Fredericton, New Brunswick, Canada
| | - Yan Boulanger
- Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, Quebec City, Quebec, Canada
| | - Phil Comeau
- Department of Renewable Resources, University of Alberta, Edmonton, Alberta, Canada
| | - Jiejie Wang
- Faculty of Forestry and Environmental Management, University of New Brunswick, Fredericton, New Brunswick, Canada
| | - Anthony R Taylor
- Faculty of Forestry and Environmental Management, University of New Brunswick, Fredericton, New Brunswick, Canada
- Natural Resources Canada, Canadian Forest Service, Atlantic Forestry Centre, Fredericton, New Brunswick, Canada
| | - Daniel Kneeshaw
- Centre for Forest Research, Université du Québec à Montréal, Montreal, Quebec, Canada
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Chavardès RD, Gennaretti F, Grondin P, Cavard X, Morin H, Bergeron Y. Role of Mixed-Species Stands in Attenuating the Vulnerability of Boreal Forests to Climate Change and Insect Epidemics. FRONTIERS IN PLANT SCIENCE 2021; 12:658880. [PMID: 33995456 PMCID: PMC8117013 DOI: 10.3389/fpls.2021.658880] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 04/07/2021] [Indexed: 06/12/2023]
Abstract
We investigated whether stand species mixture can attenuate the vulnerability of eastern Canada's boreal forests to climate change and insect epidemics. For this, we focused on two dominant boreal species, black spruce [Picea mariana (Mill.) BSP] and trembling aspen (Populus tremuloides Michx.), in stands dominated by black spruce or trembling aspen ("pure stands"), and mixed stands (M) composed of both species within a 36 km2 study area in the Nord-du-Québec region. For each species in each stand composition type, we tested climate-growth relations and assessed the impacts on growth by recorded insect epidemics of a black spruce defoliator, the spruce budworm (SBW) [Choristoneura fumiferana (Clem.)], and a trembling aspen defoliator, the forest tent caterpillar (FTC; Malacosoma disstria Hübn.). We implemented linear models in a Bayesian framework to explain baseline and long-term trends in tree growth for each species according to stand composition type and to differentiate the influences of climate and insect epidemics on tree growth. Overall, we found climate vulnerability was lower for black spruce in mixed stands than in pure stands, while trembling aspen was less sensitive to climate than spruce, and aspen did not present differences in responses based on stand mixture. We did not find any reduction of vulnerability for mixed stands to insect epidemics in the host species, but the non-host species in mixed stands could respond positively to epidemics affecting the host species, thus contributing to stabilize ecosystem-scale growth over time. Our findings partially support boreal forest management strategies including stand species mixture to foster forests that are resilient to climate change and insect epidemics.
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Affiliation(s)
- Raphaël D. Chavardès
- Institut de Recherche sur les Forêts, Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, QC, Canada
- Groupe de Recherche en Écologie de la MRC-Abitibi, Université du Québec en Abitibi-Témiscamingue, Amos, QC, Canada
| | - Fabio Gennaretti
- Institut de Recherche sur les Forêts, Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, QC, Canada
- Groupe de Recherche en Écologie de la MRC-Abitibi, Université du Québec en Abitibi-Témiscamingue, Amos, QC, Canada
| | - Pierre Grondin
- Direction de la Recherche Forestière, Ministère des Forêts, de la Faune et des Parcs, Québec, QC, Canada
| | - Xavier Cavard
- Institut de Recherche sur les Forêts, Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, QC, Canada
| | - Hubert Morin
- Département des Sciences Fondamentales, Université du Québec à Chicoutimi, Saguenay, QC, Canada
| | - Yves Bergeron
- Institut de Recherche sur les Forêts, Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, QC, Canada
- Université du Québec à Montréal, Montréal, QC, Canada
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