Massive mortality of aspen following severe drought along the southern edge of the Canadian boreal forest

By M. Michaelian, E. Hogg, R. Hall, E. Arsenault. Global Change Biology, 2011

425 citations recorded by the source corpus.

Drought‐induced, regional‐scale dieback of forests has emerged as a global concern that is expected to escalate under model projections of climate change. Since 2000, drought of unusual severity, extent, and duration has affected large areas of western North America, leading to regional‐scale dieback of forests in the southwestern US. We report on drought impacts on forests in a region farther north, encompassing the transition between boreal forest and prairie in western Canada. A central question is the significance of drought as an agent of large‐scale tree mortality and its potential future impact on carbon cycling in this cold region. We used a combination of plot‐based, meteorological, and remote sensing measures to map and quantify aboveground, dead biomass of trembling aspen (Populus tremuloides Michx.) across an 11.5 Mha survey area where drought was exceptionally severe during 2001–2002. Within this area, a satellite‐based land cover map showed that aspen‐dominated broadleaf forests occupied 2.3 Mha. Aerial surveys revealed extensive patches of severe mortality (>55%) resembling the impacts of fire. Dead aboveground biomass was estimated at 45 Mt, representing 20% of the total aboveground biomass, based on a spatial interpolation of plot‐based measurements. Spatial variation in percentage dead biomass showed a moderately strong correlation with drought severity. In the prairie‐like, southern half of the study area where the drought was most severe, 35% of aspen biomass was dead, compared with an estimated 7% dead biomass in the absence of drought. Drought led to an estimated 29 Mt increase in dead biomass across the survey area, corresponding to 14 Mt of potential future carbon emissions following decomposition. Many recent, comparable episodes of drought‐induced forest dieback have been reported from around the world, which points to an emerging need for multiscale monitoring approaches to quantify drought effects on woody biomass and carbon cycling across large areas.

Subfields: Atmospheric Science, Global and Planetary Change

View Paper: https://www.semanticscholar.org/paper/8cd408dedb2d686380d4ff262cf0c43517dc3d28

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Citations in the corpus

Frost hardiness vs. growth performance in trembling aspen: an experimental test of assisted migration (2013, background): “Michaelian et al. (2011) conducted a detailed survey covering an area of 11 5 million hectares in western Canada to assess the impact of drought-induced aspen dieback.”
A global view of aspen: Conservation science for widespread keystone systems (2020, background): “2013) which can result in widespread aspen dieback and regeneration failures (Michaelian et al. 2011; Anderegg et al. 2013).”
The roles of hydraulic and carbon stress in a widespread climate-induced forest die-off (2011, background): “Kurz WA, Stinson G, Rampley GJ, Dymond CC, Neilson ET (2008) Risk of natural disturbances makes future contribution of Canada’s forests to the global carbon cycle highly uncertain.”
Recent declines of Populus tremuloides in North America linked to climate (2013, background): “A climate moisture index (CMI), which represents precipitation minus potential evapotranspiration, was estimated using the simplified Penman–Montieth method of Hogg (1997).”
Effects of climate extremes on the terrestrial carbon cycle: concepts, processes and potential future impacts (2015, background): “Global Change Biology published by John Wiley & Sons Ltd., 21, 2861–2880 and tree mortality will increase the susceptibility to triggers such as lightning and human ignition, causing fires as an indirect concurrent or lagged effect (c.f. Figs 1d and 4; Michaelian et al., 2011).”
Remote sensing of forest pest damage: a review and lessons learned from a Canadian perspective* (2016, background): “…increasing temperatures have led to insect outbreaks resulting in defoliation, dieback, and mortality, with changes to stand dynamics throughout much of the southern boreal forest (Michaelian et al. 2011), including in the boreal mixedwoods (Moulinier et al. 2013) and elsewhere (Allen et al. 2010).”
A synthesis of tree functional traits related to drought-induced mortality in forests across climatic zones (2017, background): “…of drought on growth, carbon storage, hydraulic conductance and wood properties (Kavanagh et al. 1999; Anderegg et al. 2012; Adams et al. 2013) and the consequences of drought on stand dynamics and regeneration (Chapin et al. 2004; Soja et al. 2007; Moser et al. 2010; Michaelian et al. 2011).”