Large carbon uptake by an unmanaged 250-year-old deciduous forest in Central Germany

Unmanaged forests at a late stage of successional development are considered to be insignificant as carbon sinks, since in theory, assimilation is thought to be balanced by respiration. However, little experimental evidence for this hypothesis exists so far for forests at the ecosystem level. Therefore, we performed continuous eddy covariance measurements of carbon dioxide over an unmanaged beech forest in the Hainich National Park in Central Germany as part of the EU project CARBOEUROFLUX. This forest shows typical characteristics of an ‘advanced’ forest with large dead wood pools, a diverse stand structure and a wide tree age class distribution, up to 250 years. This forest was a large carbon sink over 2 years, with 494 g C m −2 per year in 2000 and 49 0gCm −2 per year in 2001. Daytime summer fluxes were strongly controlled by photosynthetic photon flux density ( R 2 = 0.7–0.9), with minor effects of the ratio of diffuse to total downward radiation or the vapor pressure deficit. Nighttime CO 2 fluxes were mainly controlled by soil temperature ( R 2 = 0.8) and soil moisture. In addition, high nighttime CO2 fluxes (4–6 mol m −2 s −1 ) were found directly before and during bud break in spring as well as just after leaf fall of both years (2000 and 2001), reflecting stand physiology corresponding to phenological changes, independent of soil temperature. Additional wind profile measurements at five heights within the canopy revealed a decoupling of above and below canopy air flow under conditions of low friction velocity ( u ∗ < 0. 4ms −1 ), probably indicating down slope drainage. In conclusion, unmanaged forests at a comparatively late stage of successional development can still act as significant carbon sinks with large implications for forest management practice and negotiations about biological sinks within the Kyoto Protocol. © 2003 Elsevier Science B.V. All rights reserved.

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

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

[3]  S. Gower,et al.  Aboveground net primary production decline with stand age: potential causes. , 1996, Trends in ecology & evolution.

[4]  Richard H. Waring,et al.  Evidence of Reduced Photosynthetic Rates in Old Trees , 1994, Forest Science.

[5]  R. Stull.  An Introduction to Boundary Layer Meteorology , 1988 .

[6]  R. Keane,et al.  Are old forests underestimated as global carbon sinks? , 2001 .

[7]  T. Minayeva,et al.  Carbon dioxide exchange of a Russian boreal forest after disturbance by wind throw , 2002 .

[8]  M. Aubinet,et al.  Long term carbon dioxide exchange above a mixed forest in the Belgian Ardennes , 2001 .

[9]  Riccardo Valentini,et al.  The long way from Kyoto to Marrakesh: Implications of the Kyoto Protocol negotiations for global ecology , 2002 .

[10]  Dennis D. Baldocchi,et al.  Measuring and modelling seasonal variation of carbon dioxide and water vapour exchange of a Pinus ponderosa forest subject to soil water deficit , 2000 .

[11]  Ray Leuning,et al.  The relative merits of open‐ and closed‐path analysers for measurement of eddy fluxes , 1996 .

[12]  Giorgio Matteucci,et al.  Seasonal net carbon dioxide exchange of a beech forest with the atmosphere , 1996 .

[13]  B. Amiro,et al.  Paired‐tower measurements of carbon and energy fluxes following disturbance in the boreal forest , 2001 .

[14]  A. Goldstein,et al.  Carbon dioxide and water vapor exchange by young and old ponderosa pine ecosystems during a dry summer. , 2001, Tree physiology.

[15]  N. Jensen,et al.  Similar net ecosystem exchange of beech stands located in France and Denmark , 2002 .

[16]  R. McMillen,et al.  An eddy correlation technique with extended applicability to non-simple terrain , 1988 .

[17]  Eric Ceschia,et al.  The carbon balance of a young Beech forest , 2000 .

[18]  E. Schulze.  Der CO2-Gaswechsel der Buche (Fagus silvatica L.) in Abhängigkeit von den Klimafaktoren im Freiland , 1970 .

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

[20]  E. K. Webb,et al.  Correction of flux measurements for density effects due to heat and water vapour transfer , 1980 .

[21]  Dennis D. Baldocchi,et al.  Measuring and modelling carbon dioxide and water vapour exchange over a temperate broad‐leaved forest during the 1995 summer drought , 1997 .

[22]  E. Falge,et al.  Deciduous Forests: Carbon and Water Fluxes, Balances and Ecophysiological Determinants , 2003 .

[23]  J. Wilczak,et al.  Sonic Anemometer Tilt Correction Algorithms , 2001 .

[24]  J. Lloyd,et al.  On the temperature dependence of soil respiration , 1994 .

[25]  P. Jarvis.  Atmospheric carbon dioxide and forests , 1989 .

[26]  N. Jensen,et al.  Two years of continuous CO2 eddy-flux measurements over a Danish beech forest , 2001 .

[27]  Corinna Rebmann,et al.  Soil Respiration in Beech and Spruce Forests in Europe: Trends, Controlling Factors, Annual Budgets and Implications for the Ecosystem Carbon Balance , 2000 .

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

[29]  Walter Senn,et al.  A cospectral correction model for measurement of turbulent NO2 flux , 1995 .

[30]  Frans T. M. Nieuwstadt,et al.  Temperature measurement with a sonic anemometer and its application to heat and moisture fluxes , 1983 .

[31]  D. Paslier,et al.  Net Exchange of CO2 in a Mid-Latitude Forest , 1993, Science.

[32]  T. A. Black,et al.  Responses of net ecosystem exchanges of carbon dioxide to changes in cloudiness: Results from two North American deciduous forests , 1999 .

[33]  E. Schulze,et al.  Carbon balance of a southern taiga spruce stand in European Russia , 2002 .

[34]  Yadvinder Malhi,et al.  A Re-Evaluation of Long-Term Flux Measurement Techniques Part I: Averaging and Coordinate Rotation , 2003 .

[35]  Markus Reichstein,et al.  Ecosystem respiration in two Mediterranean evergreen Holm Oak forests: drought effects and decomposition dynamics , 2002 .

[36]  Ü. Rannik,et al.  Estimates of the annual net carbon and water exchange of forests: the EUROFLUX methodology , 2000 .

[37]  D. Mollicone,et al.  Carbon and water exchanges of two contrasting central Siberia landscape types: regenerating forest and bog , 2000 .

[38]  James S. Clark,et al.  Terrestrial biotic responses to environmental change and feedbacks to climate , 1996 .

[39]  David Y. Hollinger,et al.  Carbon dioxide exchange between an undisturbed old-growth temperate forest and the atmosphere , 1994 .

[40]  Nina Buchmann,et al.  Net CO2 and H2O fluxes of terrestrial ecosystems , 1999 .

[41]  Michael G. Ryan,et al.  Age-Related Decline in Forest Productivity: Pattern and Process , 1997 .

[42]  T. Foken,et al.  Tools for quality assessment of surface-based flux measurements , 1996 .

[43]  W. Oechel,et al.  FLUXNET: A New Tool to Study the Temporal and Spatial Variability of Ecosystem-Scale Carbon Dioxide, Water Vapor, and Energy Flux Densities , 2001 .

[44]  Monique Y. Leclerc,et al.  Footprint prediction of scalar fluxes from analytical solutions of the diffusion equation , 1990 .