Productivity of forests in the Eurosiberian boreal region and their potential to act as a carbon sinkAa synthesis

• Published in: Global change biology 1999-01, Vol.5 (6), p.703-722
• Main Authors: Schulze, E-D, Lloyd, J, Kelliher, F M, Wirth, C, Rebmann, C, Luehker, B, Mund, M, Knohl, A, Milyukova, I M, Schulze, W, Ziegler, W, Varlagin, AB, Sogachev, A F, Valentini, R, Dore, S, Grigoriev, S, Kolle, O, Panfyorov, MI, Tchebakova, N, Vygodskaya, N N
• Format: Article
• Language: English
• ISSN: 1354-1013

Based on review and original data, this synthesis investigates carbon pools and fluxes of Siberian and European forests (600 and 300 million ha, respectively). We examine the productivity of ecosystems, expressed as positive rate when the amount of carbon in the ecosystem increases, while (following micrometeorological convention) downward fluxes from the atmosphere to the vegetation (NEE=Net Ecosystem Exchange) are expressed as negative numbers. Productivity parameters are Net Primary Productivity (NPP=whole plant growth), Net Ecosystem Productivity (NEP=CO sub(2) assimilation minus ecosystem respiration), and Net Biome Productivity (NBP=NEP minus carbon losses through disturbances bypassing respiration, e.g. by fire and logging). Based on chronosequence studies and national forestry statistics we estimate a low average NPP for boreal forests in Siberia: 123 gC m super(-) super(2) y super(-) super(1) . This contrasts with a similar calculation for Europe which suggests a much higher average NPP of 460 gC m super(-) super(2) y super(-) super(1) for the forests there. Despite a smaller area, European forests have a higher total NPP than Siberia (1.2-1.6 vs. 0.6-0.9 x 10 super(1) super(5) gC region super(-) super(1) y super(-) super(1) ). This arises as a consequence of differences in growing season length, climate and nutrition. For a chronosequence of Pinus sylvestris stands studied in central Siberia during summer, NEE was most negative in a 67-y old stand regenerating after fire (-192 mmol m super(-) super(2) d super(-) super(1) ) which is close to NEE in a cultivated forest of Germany (-210 mmol m super(-) super(2) d super(-) super(1) ). Considerable net ecosystem CO sub(2) -uptake was also measured in Siberia in 200- and 215-y old stands (NEE:174 and -63 mmol m super(-) super(2) d super(-) super(1) ) while NEP of 7- and 13-y old logging areas were close to the ecosystem compensation point. Two Siberian bogs and a bog in European Russia were also significant carbon sinks (-102 to -104 mmol m super(-) super(2) d super(-) super(1) ). Integrated over a growing season (June to September) we measured a total growing season NEE of -14 mol m super(-) super(2) summer super(-) super(1) (-168 gC m super(-) super(2) summer super(-) super(1) ) in a 200-y Siberian pine stand and -5 mol m super(-) super(2) summer super(-) super(1) (-60 gC m super(-) super(2) summer super(-) super(1) ) in Siberian and European Russian bogs. By contrast, over the same period, a spruce