Effects of climatic variability on the annual carbon sequestration by a boreal aspen forest

Abstract

To evaluate the carbon budget of a boreal deciduous forest, we measured CO2 fluxes using the eddy covariance technique above an old aspen (OA) forest in Prince Albert National Park, Saskatchewan, Canada, in 1994 and 1996 as part of the Boreal Ecosystem‐Atmosphere Study (BOREAS). We found that the OA forest is a strong carbon sink sequestering 200 ± 30 and 130 ± 30 g C m–2 y–1 in 1994 and 1996, respectively. These measurements were 16–45% lower than an inventory result that the mean carbon increment was about 240 g C m–2 y–1 between 1919 and 1994, mainly due to the advanced age of the stand at the time of eddy covariance measurements. Assuming these rates to be representative of Canadian boreal deciduous forests (area ≈ 3 × 105 km2), it is likely they can sequester 40–60 Tg C y–1, which is 2–3% of the missing global carbon sink. The difference in carbon sequestration by the OA forest between 1994 and 1996 was mainly caused by the difference in leaf emergence date. The monthly mean air temperature during March–May 1994, was 4.8 °C higher than in 1996, resulting in leaf emergence being 18–24 days earlier in 1994 than 1996. The warm spring and early leaf emergence in 1994 enabled the aspen forest to exploit the long days and high solar irradiance of mid‐to‐late spring. In contrast, the 1996 OA growing season included only 32 days before the summer solstice. The earlier leaf emergence in 1994 resulted 16% more absorbed photosynthetically active radiation and a 90 g C m–2 y–1 increase in photosynthesis than 1996. The concomitant increase in respiration in the warmer year (1994) was only 20 g C m–2 y–1. These results show that an important control on carbon sequestration by boreal deciduous forests is spring temperature, via the influence of air temperature on the timing of leaf emergence.

Climate change impacts and adaptation in forest management: a review

“…The earliest paper dated from 1949 (Gentilli 1949) analysing the effects of trees on climate, water and soil. Most studies prior to 1986 (and even some published later) focused on the effects of trees on local or wider regional climate (Lal and Cummings 1979;Otterman et al 1984;Bonan et al 1992), the implications of climate variability (Hansenbristow et al 1988;Ettl and Peterson 1995;Chen et al 1999), studies of tree and forest responses across climatic gradients (Grubb and Whitmore 1966;Bongers et al 1999;Davidar et al 2007) or responses to historical climate (Macdonald et al 1993;Huntley 1990;Graumlich 1993).…”

Gross primary production estimation from MODIS data with vegetation index and photosynthetically active radiation in maize

“…Temperature is an important environmental factor that affects respiration. An exponential relationship between NEE CO2 and T is often expected and this relationship can be used for daytime Re assessment, since the nocturnal NEE is generally considered equal to the ecosystem respiration [Baldocchi et al, 1997;Chen et al, 1999].…”

Growing Season Length as a Key Factor of Cumulative Net Ecosystem Exchange Over the Pine Forest Ecosystems in Europe

“…Research related to the influence of growing season length (GSL) on the annual (NEPy) fluxes variability were carried out both across Europe (Churkina et al, 2005) and locally -in such forest ecosystems as: boreal Scots Pine in Finland (Suni et al, 2003), boreal Trembling Aspen (Populus tremuloides) in Canada (Chen et al, 1999) we measured CO 2 fluxes using the eddy covariance technique above an old aspen (OA or broadleaf forest in the east of the USA (Dragoni et al, 2011). Despite the fact that the GSL for the above ecosystems was assigned by different methods, a positive linear correlation between these two quantities was observed -the GSL prolongation increased the NEP flux values.…”