Comparing the carbon budgets of boreal and temperate deciduous forest stands

Boreal and temperate deciduous forests at northern mid-latitudes play an important role in the global carbon cycle. We analyze 3 years (1996-1998) of eddy-covariance carbon dioxide flux measurements from two contrasting deciduous forest ecosystems in the boreal and temperate regions of central Canada. The two forest stands have similar ages, heights, and leaf area indices but differ in species composition and climate. Mean annual net ecosystem produc- tivity (NEP) was similar for the two ecosystems, varying between 0.7 and 2.7 t C·ha -1 (boreal) and 0.6 and 2.4 t C·ha -1 (temperate). In the boreal ecosystem, interannual differences in NEP were primarily controlled by early spring tempera - ture. The warm spring of 1998 caused early leaf out and increased photosynthesis but had little effect on respiration. In the temperate ecosystem, the same warm spring not only caused early leaf out but also increased respiration and drought stress. The contrasting impact of the warm spring on annual NEP at the two sites illustrates the complexity of interpreting climatic impacts on the forest carbon balance. It also illustrates two competing influences of climate change on NEP: spring warming, which promotes photosynthesis and increases NEP, and increased soil temperature and drought, which promote respiration and reduce photosynthesis, thus reducing NEP. We discuss the need for a con- sistent data post-processing methodology in ecosystem intercomparisons. We also compare our results with a recent synthesis of data from European forests. Resume : Les forets decidues temperees et boreales situees dans la partie nord des latitudes moyennes jouent un role important dans le cycle global du carbone. Nous avons analyse trois annees (1996-1998) de mesures de flux de dioxyde de carbone effectuees avec la methode des correlations turbulentes dans deux ecosystemes forestiers decidus contrastes des regions temperees et boreales du centre du Canada. Les deux peuplements forestiers ont un âge, une hauteur et un indice de surface foliaire similaires mais different par leur composition en especes et par le climat. La

[1]  Dennis D. Baldocchi,et al.  Seasonal variation in carbon dioxide exchange over a Mediterranean annual grassland in California , 2004 .

[2]  Alan G. Barr,et al.  Year‐round observations of the energy and water vapour fluxes above a boreal black spruce forest , 2003 .

[3]  T. A. Black,et al.  Ecophysiological controls on the carbon balances of three southern boreal forests , 2003 .

[4]  Steve Frolking,et al.  Interannual variability in the peatland‐atmosphere carbon dioxide exchange at an ombrotrophic bog , 2003 .

[5]  T. A. Black,et al.  Effects of seasonal and interannual climate variability on net ecosystem productivity of boreal deciduous and conifer forests , 2002 .

[6]  Ü. Rannik,et al.  Gap filling strategies for defensible annual sums of net ecosystem exchange , 2001 .

[7]  Ü. Rannik,et al.  Productivity overshadows temperature in determining soil and ecosystem respiration across European forests , 2001 .

[8]  W. Rouse,et al.  Interannual variability of net ecosystem CO2 exchange at a subarctic fen , 2000 .

[9]  Jonathan M Adams,et al.  Carbon balance gradient in European forests: Interpreting EUROFLUX , 2000 .

[10]  W. Massman.  A simple method for estimating frequency response corrections for eddy covariance systems , 2000 .

[11]  Hans Peter Schmid,et al.  Measurements of CO2 and energy fluxes over a mixed hardwood forest in the mid-western United States , 2000 .

[12]  O. Atkin,et al.  Response of root respiration to changes in temperature and its relevance to global warming , 2000 .

[13]  Sune Linder,et al.  Botany: Constraints to growth of boreal forests , 2000, Nature.

[14]  J. Norman,et al.  Correcting eddy-covariance flux underestimates over a grassland , 2000 .

[15]  Wenjun Chen,et al.  Increased carbon sequestration by a boreal deciduous forest in years with a warm spring , 2000 .

[16]  Ü. Rannik,et al.  Respiration as the main determinant of carbon balance in European forests , 2000, Nature.

[17]  Michael G. Ryan,et al.  Evidence that decomposition rates of organic carbon in mineral soil do not vary with temperature , 2000, Nature.

[18]  John Grace,et al.  Respiration in the balance , 2000, Nature.

[19]  P. Reich,et al.  Acclimation of respiration to temperature and CO2 in seedlings of boreal tree species in relation to plant size and relative growth rate , 1999 .

[20]  X. Lee,et al.  Long‐term observation of the atmospheric exchange of CO2 with a temperate deciduous forest in southern Ontario, Canada , 1999 .

[21]  T. A. Black,et al.  Effects of climatic variability on the annual carbon sequestration by a boreal aspen forest , 1999 .

[22]  Gloor,et al.  A Large Terrestrial Carbon Sink in North America Implied by Atmospheric and Oceanic Carbon Dioxide Data and Models , 2022 .

[23]  Harden,et al.  Sensitivity of boreal forest carbon balance to soil thaw , 1998, Science.

[24]  C. Tucker,et al.  Increased plant growth in the northern high latitudes from 1981 to 1991 , 1997, Nature.

[25]  C. D. Keeling,et al.  Increased activity of northern vegetation inferred from atmospheric CO2 measurements , 1996, Nature.

[26]  J. William Munger,et al.  Measurements of carbon sequestration by long‐term eddy covariance: methods and a critical evaluation of accuracy , 1996 .

[27]  J. William Munger,et al.  Exchange of Carbon Dioxide by a Deciduous Forest: Response to Interannual Climate Variability , 1996, Science.

[28]  K. Jon Ranson,et al.  The Boreal Ecosystem-Atmosphere Study (BOREAS) : an overview and early results from the 1994 field year , 1995 .

[29]  H. Neumann,et al.  A comparison of bowen ratio and eddy correlation sensible and latent heat flux measurements above deciduous forest , 1994 .

[30]  Walter C. Oechel,et al.  Recent change of Arctic tundra ecosystems from a net carbon dioxide sink to a source , 1993, Nature.

[31]  R. Guy,et al.  Cytochrome and alternative pathway respiration in white spruce (Picea glauca) roots. Effects of growth and measurement temperature , 1991 .

[32]  C. Priestley,et al.  On the Assessment of Surface Heat Flux and Evaporation Using Large-Scale Parameters , 1972 .