Energy wood thinning as a part of stand management

Transcription

1 Energy wood thinning as a part of stand management SNS Growth and Yield Researchers' Meeting Kokkola, Finland 8 11 June, 2009 Dr. Anssi Ahtikoski Metsäntutkimuslaitos Skogsforskningsinstitutet Finnish Forest Research Institute

2 Energy wood thinning according to a case study in Finland The data consisted of 22 Scots pine (Pinus sylvestris L.) and 21 Norway spruce (Picea abies [L.] Karst.) dominated unmanaged juvenile stands (i.e no precommercial thinnings done) Site fertility class was based on the forest site types of Cajander (1949): for pine dryish or fresh and for spruce fresh or grovelike site types Total density in each stand was over stems ha -1 Tree and crown heights were predicted for the tally trees by KPL-software (Heinonen 1994) Stands originate from several different studies (e.g. Valkonen & Ruuska 2003, Kaila et al. 2006)

3 An example of stand characteristics Solid lines=maxs Dotted lines = mins

4 Stand projections Growth and yield of the stands were estimated according to alternative management schedules Alternative management schedules were produced by MOTTI stand simulator

5 Alternative management schedules (Traditional, pure) industrial wood production in which precommercial thinning (at dominant height 5 m, both tree species) is conducted so that either 2000 (pine) or 1800 (spruce) stems are left growing, first commercial thinning is conducted at dominant height m (pine) and at 13 m (spruce), and stem number after the first commercial thinning is either 1000 (pine) or 900 (spruce), other thinning according to silvicultural recommendations (2006) and rotation is determined by diameter criterion = IWP_1 Combined production schedules: CP_2= precommercial thinning intensity 3000 stems/ha, energy wood thinning at dominant height 8 m CP_3= precommercial thinning intensity 3000 stems/ha, energy wood thinning at dominant height 10 m CP_4= precommercial thinning intensity 3000 stems/ha, energy wood thinning at dominant height 12 m CP_5= precommercial thinning intensity 4000 stems/ha, energy wood thinning at dominant height 8 m CP_6= precommercial thinning intensity 4000 stems/ha, energy wood thinning at dominant height 10 m CP_7=precommercial thinning intensity 4000 stems/ha, energy wood thinning at dominant height 12 m Precommercial thinning in each alternative conducted at dominant height 5m (both tree species) NOTE: The effect of whole-tree harvesting (i.e. nutrient loss) was taken into account by reducing growth in stand projections. Technically the growth reduction was estimated on the basis of the dry mass and nitrogen concentration of the harvested tree compartments. Then the nitrogen loss was converted to the procentual growth loss according to empirical experiments (see, e.g. Jacobson et al. 2000)

6 Schematic illustration on alternative management schedules Pure industrial wood production, IWP_1 Basal area Precommercial thinning First thinning Other thinnings & final cut according to silvicultural recommendations t, time Combined production regimes, CP_2 -> CP_7 Precommercial thinning: Less density A bit wider range with respect to time Other thinnings & final cut according to silvicultural recommendations First thinning: Combined production of pulpwood and energywood significantly wider range with respect to time cutting removal in some case larger than in pure industrial wood production (alternative CP_6 and CP_7)

7 An example of cutting removals ( CP_7=precommercial thinning intensity 4000 stems/ha, energy wood thinning at dominant height 12 m )

8 Growth and yield results, Scots pine Mean annual increment, MAI IWP_1: industrial wood production CP_2 - CP_7: combined energy and industrial wood production alternatives Question Why the MAI is even bigger in some combined production alternatives than in pure industrial wood production?! Answer The growing stock of combined wood production alternatives is higher compared to industrial wood production during the time between precommercial thinning and first commercial thinning This additional volume (due to higher growing stock) is enough to secure higher MAI during the rotation, despite the fact that the time span for it is only from 5 m dominant height to app. 10 to 12 m dominant height

9 Growth and yield results, Norway spruce Mean annual increment, MAI Conclusion No clear evidence whether the combined wood production favours growth and yield or not (the issue merits further studying, though)

10 ...What about money, i.e. financial performance? First, we take private forest owner s point of view (i.e cutting incomes valued at stumpage) Two approaches: 1) present generation and net present valuing, and 2) bare land value analysis (Faustman s rotation model and infinite series) 1) 2) In brief, up-dated stumpage prices, dimensions (timber assrtments) and costs were applied in the calculations

11 Results on financial performance According to 1), net present valuing ( e.g. CP_3_3 refers to alternative CP_3 with the assumption that energy wood price is 3 /m 3 )

12 Results on financial performance According to 2), bare land value analysis Conclusion Regardless of the calculation method (either net present valuing or bare land value analysis) there is no significant difference in financial performance between pure industrial wood production and combined wood production alternatives

13 Feasibility approach Energy wood procurement seen as an financial entity To determine possible profits pertaining to different actors such as private forest owner, contractor and power plant from forest to power plant Idea to reveal whether the combined wood production alternatives are feasible in the actual market conditions prevailing in Finland Applied costs: 5 /m 3 for roadside chipping 5 /m 3 for long distance trasportation A fixed costs of 50 for the translocation (from one stand to another) of a harvester, forwarder and chipper Organization costs of 4 /m 3 Energy wood price at power plant 12 /MWh Stand specific energy wood harvesting costs calculated according to functions of Laitila et al. (2004) Government subsidies either included or exluded from the assessments Conversion factors: 1 solid cubic meter (s-m 3 ) equals 2.43 loose cubic meters (l-m 3 ), and 1 s-m 3 equals 2 MWh, on average

14 Feasibility approach calculation method k = management alternative CP_2,.. CP_

15 Feasibility approach, average cutting and forest haulage costs associated with alternative management schedules Red square= lowest value Blue circle= highest value

16 Feasibility approach - results

17 Conclusions Combined production did not decrease the possibilities to produce industrial wood There were no significant differences either on MAIs or rotation periods between industrial wood production alternative and combined wood production alternatives Financial performance (either by net present valuing or by bare land value analysis) was more or less identical between alternatives thus, from the financial point of view it does not matter which alternative a private forest owner chooses during one rotation For a private forest owner a minimum of 3 /solid-m 3 for price of energy wood is required for financially viable energy wood thinning in pine stands and 8 /solid-m 3 in spruce stands these prices can be met in prevailing actual markets However, state (government) subsidies are essential for economic viability of energy wood thinnings in Finland Finally, further (empirical) studies are required to establish well-defined evidence on the effect of nutrient loss to stand development, particularly with Norway spruce

18 References Heikkilä, J., Siren, M., Ahtikoski, A., Hynynen, J., Sauvula, T. & Lehtonen, M Energy wood thinning as a part of the stand management of Scot pine and Norway spruce. Silva Fennica 43(1): Ahtikoski, A., Heikkilä, J., Alenius, V. & Siren, M Economic viability of utilizing biomass energy from young stands the case of Finland. Biomass and bioenergy 32 (2008):