The role of old-growth forest in the global Carbon Cycle

Transcription

1 The role of old-growth forest in the global Carbon Cycle E.-D. Schulze, S. Luyssaert, J. Grace MPI for Biogeochemistry, Jena University of Antwerp, Belgium University of Edinburgh, UK

2 Old-growth forest is a subset of primary forests According to TBFRA 2005 (FAO), Primary Forests are forests of native species, in which there are no clearly visible indications of human activity and ecological processes are not significantly disturbed Primary forest includes successional stages after disturbance.

3 Total area of primary forest (TBFRA 2005) total forest area (1000ha) primary forest % Africa Asia Europe+RUS N+C-America S-America Oceania Global total

4 10 Nations with largest primary forest (1000 ha): TBFRA 2005 Brazil RUS Canada USA (no report on Alaska) Peru Columbia Indonesia Mexico Bolivia Papua 25211

5 Presently there is no international agreement about the protection and persistence of primary forest The preamble of the Kyoto Protocol states: The mere presence of C-stocks is not accountable Based on the UNFCCC (1992, Art. 2) which states that only anthropogenic interferences with the climate shall be stabilized Thus, old growth forest is not accountable, unless it was put aside since 1990 The new REDD mechanism (Reduced Emissions from Deforestation and Degradation) may somewhat change the situation

6 Reporting and accounting of C-stocks: Nation Accountable in the Kyoto process Settlements un-managed Wetlands Croplands Forest Kyoto optional full C accounting if applied to be accounted in the other Annex I country JI UNFCCC reporting Grasslands ARD AR project to be added to the national balance Kyoto mandatory CDM non-annex I

7 However, if Australia accepts Art. 3.4 of the Kyoto protocol, an accounting of the value of old growth forest should be possible, if the conservation act was after 1990 In a carbon world, agriculture would have to pay forestry, and plantation forestry would have to pay conservation for its carbon sequestration Conservation must prove that it is a C-sink

8 E.-D. Schulze KohlenstoffBilanz in der Terrestrischen Biosphäre Janssens et al., 2003

9 Global Carbon Balance 1990 to 2000 (10 9 t C year -1 ) Emissions (fossil fuels, 1990) 6.3 ± 0.4 USA 1.6 Europe-EU Russia 0.8 Increase in the atmosphere 3.2 ± 0.1 (51%) Uptake by the oceans 1.7 ± 0.5 (28%) Net-uptake by the continents 1.4 ± 0.7 (22%) Emissions from land use 1.6 Uptake by continents 3.0 North America 0.8 Europe 0.4 Siberia 1.3 Tropics % of the European emissions are re-assimilated within Europe (more than the global average) % of the emissions of EU15 and Russia are re-assimilated in Europe and Siberia. - Re-assimilation in Siberia is through unmanaged coniferous forests.

10 The observation of primary forest acting as C- sink, contradicts the paradigm of Odum, that old ecosystems reach an equilibrium of production and respiration Politically the view of C neutrality has been used, to rejuvenate old growth forests by management, i.e. to commercially use the timber Primary forests have become an area of economic development

11 temperate boreal Luyssaert et al. subm.

12 temperate boreal Luyssaert et al. subm.

13 Odum hypothesis Net ecosystem productivity Gross productivity Total biomass Ecosystem respiration Gross productivity Present knowledge Total biomass Net ecosystem productivity Ecosystem respiration catastrophy Risk for damage Forest age Schulze et al. Subm.

14 Schulze et al. Oecologia 146:77-88 (2005)

15 Species composition of 240 year old stands Volume of stem biomass (m 3 ha -1 ) light taiga Age of main canopy (yrs) y = 1. 87x dark taiga VA1-P1 VA1-P3 TG4-P1 Picea Abies TG4-P2 BK1-P1 BK1-P2 VA1-P2 Picea Larix Larix Larix Larix Picea Abies Picea Picea Larix Pinus sib Larix Pinus sib Larix Betula Pinus sib Betula Pinus sib Pinus sib Betula Betula Betula Populus Pinus sib Pinus sylv Betula Pinus sib Picea Schulze et al. Subm.

16 forest establishment - after severe disturbance - after harvest managed un-managed >1000 yrs canopy loss severe disturbance (fire, wind) 100 yrs harvest thinning for regeneration selective logging thinning small gaps no regeneration self-thinning stand density too low to fill space maturity for commercial wood gaps of increasing size increasing calamities common dynamics of NPP, NEP, biomass, LAI old-growth - max. biomass of canopy trees - max. NEP, NPP increasing regeneration gap regeneration minor disturbances increasing desease loss of single trees Schulze et al. Subm.

17 Schulze et al. in prep.

18 E.-D. Schulze

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20 Konzept des maximalen Nutzens für das Klima Freibauer et al. High Revenue for C-sequestration Carbon content of the ecosystem small Protection Landuse-inensity Timber-use Bioenergy Food Productivity / accessibility Land-use priority high If revenues from Art 3.4 are accounted to the respective sources and sinks C-Price according to Substitutionefficiency

21 Conclusions Primary forests are C-sinks Sink-capacity increases with biomass, and biomass increases with age The decline of old growth forests is not due to age but due to increased risk of damage by fungal attack, wind and fire Primary forests maintain sink capacity due to their uneven age structure There are many similarities between managed and unmanaged forests. The main difference is the time of rotation and the product: Managed forest produces timber, un-managed forest produces dead-wood and soil carbon If we would economize sources and sinks, old growth forests would represent a high revenue.