Influence of Low Frequency Variability on Climate and Carbon Fluxes in a Temperate Pine Forest in Eastern Canada

Thorne, Robin; Arain, M. Altaf

doi:10.3390/f6082762

Cited by 7 publications

(2 citation statements)

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“…The largest difference occurred during November and December, where temperatures were 2.6°C and 7.2°C greater than normal, respectively (Table ; MacDonald Lake AWS), with the monthly average temperature not falling below 0°C until January, one month later than normal. Fall 2015 experienced a strong El Niño (Multivariate ENSO Index >2.4 late summer/early fall) and strong positive North Atlantic Oscillation (NAO Index November (1.74) and December (peak, 2.24; NOAA, ), both of which tend to result in warmer than usual temperatures in the Great Lakes Region (e.g., Thorne & Arain, ), where the effects of teleconnections can be amplified when more than one influencing climatic driver is involved (Bai, Wang, Sellinger, Clites, & Assel, ). Temperatures remained slightly above normal from January through March before falling below the monthly average in April 2016 by 3°C.…”

Section: Resultsmentioning

confidence: 99%

Ice processes on medium‐sized north‐temperate lakes

Ariano

Brown

2019

Hydrological Processes

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Lake ice supports a range of socio-economic and cultural activities including transportation and winter recreational actives. The influence of weather patterns on ice-cover dynamics of temperate lakes requires further understanding for determining how changes in ice composition will impact ice safety and the range of ecosystem services provided by seasonal ice cover. An investigation of lake ice formation and decay for three lakes in Central Ontario, Canada, took place over the course of two winters, 2015-2016 and 2016-2017, through the use of outdoor digital cameras, a ShallowWater Ice Profiler (upward-looking sonar), and weekly field measurements. Temperature fluctuations across 0°C promoted substantial early season white ice growth, with lesser amounts of black ice forming later in the season. Ice thickening processes observed were mainly through meltwater, or midwinter rain, refreezing on the ice surface. Snow redistribution was limited, with frequent melt events limiting the duration of fresh snow on the ice, leading to a fairly uniform distribution of white ice across the lakes in 2015-2016 (standard deviations week to week ranging from 3 to 5 cm), but with slightly more variability in 2016-2017 when more snow accumulated over the season (5 to 11 cm). White ice dominated the end-of-season ice composition for both seasons representing more than 70% of the total ice thickness, which is a stark contrast to Arctic lake ice that is composed mainly of black ice. This research has provided the first detailed lake ice processes and conditions from medium-sized north-temperate lakes and provided important information on temperate region lake ice characteristics that will enhance the understanding of the response of temperate lake ice to climate and provide insight on potential changes to more northern ice regimes under continued climate warming. KEYWORDS ice thickness, lake ice, Shallow Water Ice Profiler, snow cover, temperate region 1 | INTRODUCTION Global lake abundance is highest for latitudes 45-75°N (Verpoorter, Kutser, Seekell, & Tranvik, 2014), resulting in lakes comprising a large portion of the Northern Hemisphere. In some regions, lakes are estimated to represent up to 40% of the total surface area (Duguay et al., 2003). Research investigating the response of ice phenology to climate change is important for understanding the role lakes play in surface-atmosphere interactions (Duguay et al., 2003) and the annual recurrence of freeze-thaw cycles allows ice phenology to be a useful proxy indicator for climate change (Futter, 2003; Magnuson et al., 2000); both lake ice cover and thickness are considered "Essential Climate Variables" by the Global Climate Observing System (GCOS, 2016). Investigation into the spatial and temporal patterns of ice phenology has occurred at a magnitude of spatial scales spanning single lakes to the hemisphere scale. Some recent examples include Cheng ;33:2434-2448. wileyonlinelibrary.com/journal/hyp et al. (2014), who investigate ice thickness and duration for Lake Orajärvi in nor...

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Section: Resultsmentioning

confidence: 99%

Ice processes on medium‐sized north‐temperate lakes

Ariano

Brown

2019

Hydrological Processes

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“…Lower frequency oscillations such as the PDO and PNA have also been linked to F NEE variability (e.g. Wharton et al 2009a, Thorne and Arain 2015; however, the robustness of these findings is limited by the lack of multiple events at even the longest running flux tower sites. Sites with biometric measurements, however, can have much longer measurement records (e.g., >50 years) spanning multiple major PNA or PDO cycles.…”

Section: Introductionmentioning

confidence: 99%

Climate indices strongly influence old-growth forest carbon exchange

Wharton

Falk

2016

Environ. Res. Lett.

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We present a decade and a half (1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013) of carbon dioxide fluxes from an old-growth stand in the American Pacific Northwest to identify ecosystem-level responses to Pacific teleconnection patterns, including the El Niño/Southern Oscillation (ENSO). This study provides the longest, continuous record of old-growth eddy flux data to date from one of the longest running Fluxnet stations in the world. From 1998 to 2013, average annual net ecosystem exchange ( F NEE ) at Wind River AmeriFlux was −32±84 g C m −2 yr −1 indicating that the late seral forest is on average a small net sink of atmospheric carbon. However, interannual variability is high (>300 g C m −2 yr −1 ) and shows that the stand switches from net carbon sink to source in response to climate drivers associated with ENSO. The old-growth forest is a much stronger sink during La Niña years (mean F NEE =−90 g C m −2 yr −1 ) than during El Niño when the stand turns carbon neutral or into a small net carbon source (mean F NEE =+17 g C m −2 yr −1 ). Forest inventory data dating back to the 1930s show a similar correlation with the lower frequency Pacific North American (PNA) and Pacific Decadal Oscillation (PDO) whereby higher aboveground net primary productivity ( F ANPP ) is associated with cool phases of both the PNA and PDO. These measurements add evidence that carbon exchange in old-growth stands may be more sensitive to climate variability across shorter time scales than once thought.

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