LONG TERM CONSEQUENCES OF INTENSIVE BIOMASS HARVESTING IN BOREAL FOREST ENVIRONMENT

Transcription

1 LONG TERM CONSEQUENCES OF INTENSIVE BIOMASS HARVESTING IN BOREAL FOREST ENVIRONMENT Eero Kubin Finnish Forest Research Institute, Muhos Layout Tuula Aspegren Metsäntutkimuslaitos Skogsforskningsinstitutet Finnish Forest Research Institute HydroPredict 2010 Conference September 2010 Prague, Czech Republic

2 2 KEY WORDS INTENSIVE BIOMASS HARVESTING NITROGEN CYCLE GROUNDWATER QUALITY BOREAL FORESTS Layout Tuula Aspegren

3 3 Content 1. Background 2. Case Kivesvaara 3. Results 4. New challenges 5. Conclusions

4 4 1. Background Forests in Finland Round wood consumption since 1955 Use of wood for energy and goal of use by 2020

5 5 The world s forests Finland belongs mainly to the Boreal Forest Zone

6 6 Roundwood consumption in Finland by category of use, In , roundwood consumption for energy generation included also marginal quantities of industrial roundwood used in other consumption categories by e.g. small-sized dwellings, traffic and civil engineering. Sources: Finnish Forest Industries Federation; OSF: Finnish Forest Research Institute

7 7 The total use of forest chips and the goal of use by 2020 Source: Metla, Forest Statistics Information Service 2010 use goal

8 8 Structure of old spruce stand in northern Finland (66 o 22' N, 29 o 15' S) Based on the doctoral thesis by Eero Kubin 1984 Biomass kg/ha % % of total TREE LAYER NEEDLES LIVING BRANCHES ,5 14,2 BRANCH SYSTEM CONES DEAD BRANCHES ,2 3,4 EPIPHYTES TRUNK TOTAL BIOMASS WOOD ,7 47,0 BUSHES BARK TOTAL BIOMASS ,9 0,1 ROOT SYSTEM TOTAL BIOMASS ,0 100,0% 76 GROUND-LAYER VEGETATION DWARF SHRUBS HERBS AND GRASSES MOSSES ROOT SYSTEMS LITTER AND RAW HUMUS TOTAL BIOMASS TOTAL BIOMASS TOTAL BIOMASS DWARF SHRUBS HERBS AND GRASSES ,3 0,5 13,0 66,9 3,3 100,0% 12 LITTER RAW HUMUS TOTAL AMOUNT TOTAL AMOUNT ,0 73, ,0% All organic layers Source: Havas, P. & Kubin, E Structure, growth and organic matter content in the vegetation cover of an old spruce forest in Northern Finland. Ann. Bot. Fennici 20(2):

9 9 Harvesting forest biomass is strongly increasing There are, however, open questions about the environmental effects, e.g. carbon flow, nutrients leaching to the groundwater and how to save site fertility

10 10 Perspective: Forest biomass harvesting in boreal forests needs more environmental research

11 11 2. Case Kivesvaara Kivesvaara research site is located in the middle of boreal forest zone in Finland Long-term ecological research since 1974 Extended 2007 to include the stump harvesting

12 12 Case Kivesvaara: Groundwater research in Hautala and Pahalouhi experimental sites Site preparation, soil and air temperature, nutrient leaching to surface water. Founded Site preparation. Nutrient leaching into the groundwater. Founded Cleaning the sapling stand. Founded 1984 Mounding, different tree species, nutrient leaching to surface water. Founded 1986 Direct seeding with different soil treatment methods 2002 Prescribed burning 2002 Lysimeters o 28'N, 27 o 33 E Stump removal

13 13 3. Results

14 14 The results are based on over samples, from each over 10 elements were analyzed since 1985

15 15 Leaching of nitrate nitrogen into groundwater: Hautala Waste wood left NO - N µg/l 3 Clearcutting, Cleacutting, waste wood not collected left Uncut Uncut control Cleacutting 1986 Waste wood left Clearcutting June 20, Year Waste wood harvested NO - N µg/l 3 Clearcutting, Cleacutting, waste wood collected harvested Uncut control Clearcutting June 20, Cleacutting 1986 Waste wood harvested Year

16 16 Leaching of nitrate nitrogen into groundwater: Pahalouhi Waste wood left Cleacutting, waste wood left Uncut control Cleacutting 1986 Waste wood left Waste wood harvested Cleacutting, waste wood harvested Uncut control Cleacutting 1986 Waste wood harvested

17 17 Natural regeneration was also included 2002 No felling Seed tree cutting, pine Groundwater well Spruce shelterwood

18 18 Leaching after natural regeneration is less compared with clearcutting NO 3 -N µg/l

19 19 4. New challenges and research

20 20 New research on stump harvesting in Metla (Finnish Forest Research Institute) Financed also by the Ministry of Agriculture and Forestry

21 21 Project title: Ecological and silvicultural impacts of stump removal and harvesting of logging residues

22 Researh group Reseach Project leader Eero Kubin, groundwater Professor, Dr Anne Tolvanen, plant succession Professor, Dr Hannu Ilvesniemi, carbon flow Senior scientist, Dr Eila Tillman-Sutela, seed and restocking Researcher, Dr Oili Tarvainen, mycorrhiza Senior scientist Dr Juha Piispanen, chemical analyses Assistant researher, MSc (For.) student, Tanja Murto, carbon flow, restocking Other staff Metsätalousinsinööri Jorma Pasanen Suunnittelija Ari Kokko Tutkimusavustaja Reijo Seppänen Muhoksen toimipaikan laboratoriohenkilökuntaa

23 23 Project layout Uncut forest Clearcutting Clearcutting + scalp mounding + spruce planting Clearcutting + scalp mounding + collected 70 % of logging residure + spruce planting Block III Clearcutting + scalp mounding + collected 70 % of logging residure + stump removal, left 25 stump/ha + spruce planting Clearcutting + scalp mounding + collected 100 % of logging residure + stump removal, 100 % + spruce planting Block I

24 24 Project objective New iformation for forestry practice and policy makers

25 25 Actions in Längelmäki stump harvesting study areas Uncut forest Clear cutting Harvesting of logging residue Stump removal

26 26 Preliminary results: nitrate in groundwater after stump harvesting Northern boreal zone NO 3 -N µg/l Southern boreal zone NO 3 -N µg/l

27 27 5. Conclusions

28 28 NO 3 -N cycle in the boreal forest. What are the effects of climate change and whole tree harvest with lifting stumps? Natural state Conventional cutting Whole tree harvesting N-cycle N-cycle N-cycle Deposition: Interception + + Leaching: Depends on site + + (?) Decomposition: Slow + + (?)

29 29 Conclusions Nitrogen leaching is increasing after cutting and harvesting. Maximum, however, in Kivesvaara study site is about 1 mg/l. EU limit value 50 mg/l. Re-vegetation and stocking have important role to minimize nitrogen leaching New technology has been developed for harvesting the stumps, but the environmental effects are still unknown Nitrogen cycle in changing environment and intensive biomass harvesting needs more research, especially long term monitoring

30 Groundwater monitoring in Hautala, Finland NO 3 - N µg/l Short monitoring 3 years Uncut control Waste not collected Clearcutting: June 20,

31 Groundwater monitoring in Hautala, Finland NO 3 - N µg/l 5 years monitoring Uncut control Waste not collected Clearcutting: June 20,

32 Groundwater monitoring in Hautala, Finland NO 3 - N µg/l Long-term monitoring Uncut control Waste not collected Clearcutting: June 20,

33 Photo Eero Kubin Photo Eero Kubin