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Bufferstrips for biomass production Ben Christen, University of Aarhus, Denmark.

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Presentation on theme: "Bufferstrips for biomass production Ben Christen, University of Aarhus, Denmark."— Presentation transcript:

1 Bufferstrips for biomass production Ben Christen, University of Aarhus, Denmark

2 Contents Background Buffer function and designs Establishment Performance Policy development

3 Background Water Framework directive requires ’good eclogical status’ by 2015/2027 Danish ’Plans for the aquatic environment III’ aim to further reduce nitrate pollution by 30% Bioenergy policy ’Grøn Vækst’ (green growth) opens lake shores and stream banks 5000 miles of watercourses Production potential >100,000 tonnes/a

4 Buffer design and function All Buffer Types N-removal: 30-99% P-removal: 20-99% Pesticide removal: 10- 100% mainly dependent on width Most suitable layout for biomass production identified: 3-zone structure with grass, short rotation forestry + undisturbed zone

5 Grass strip Function Slows and spreads runoff Filters sediment Resists erosion by rill flow Takes up nutrients during growing season Denitrification Production potential Biomass for bioenergy (6-16 t/DM/a) Hay and silage Pasture for extensive grazing Biogas feedstock

6 Short rotation forestry zone Function Infiltration of water passing through grass strip Captures fine sediment Removes pesticides Immobilises nutrients Denitrification Production potential Woodchips (5-14 t/DM/a) Firewood (5-8 m 3 /a) Pulpwood Timber for higher value uses

7 Undisturbed zone Function Reduces bank erosion Protects buffer structure in flood events Buffers maintenance and harvest operations in other two zones Enhancement of stream ecology (shade, debris) Production potential Occasionally timber of larger dimensions but low quality

8 Buffer design variants Fast Bioenergy Miscanthus, reed canary grass, willow, alder, poplar Higher value timber Grass mixture, bird cherry, oak, field maple, hornbeam, lime

9 Buffer design variants continued Gentle slope Reed grass or grass mixture, alder, birch, field maple, poplar 10% slope Grass mixture, birch, field maple, pear, black locust, alder

10 Buffer design variants - drainage Drains broken by ditch before reaching buffer strip Reed grass, alder, poplar, downey birch, elm

11 Establishing a productive buffer

12 Landscape impact projection

13 Planning DitchGrass stripGrey and red alder

14 Construction – May 2011

15 Establishment

16 Performance forecast Tree speciesLatin name Age of max. mean annual increment a Max. mean annual increment m 3 ha -1 Mean DM wood density kg/m 3 Max. mean annual t DM ha -1 Field MapleAcer campestre L.15-2577505,3 SycamoreAcer pseudoplatanus L.30115906,5 Black AlderAlnus glutinosa L.15-2015.54907,6 Grey alderAlnus incana L.12-1618.54909,1 Green AlderAlnus viridis L.Unknown b 55702,9 Silver BirchBetula pendula L.15-30116306,9 Downey BirchBetula pubescens L.15-3086805,4 HornbeamCarpinus betulus L.20-3057703,9 Common AshFraxinus Excelsior L.40-5076704,7 Poplar hybrids Populus deltoides L. based and other hybrids Unknown c 3941016 AspenPopulus tremula L.unknown164507,2 Aspen hybridsPopulus tremula L. basedunknown2345010,3 Bird CherryPrunus avium L.3095805,2 Common pearPyrus communis L.10-1576804,8 Pendunculate Oak Sessile Oak Quercus robur L. Quercus petraea L. 4076704,7 Red oakQuercus rubra L.2586705,4 Black LocustRobinia pseudoacacia L.15117308,0 Willow hybrids Salix viminalis L. based and other hybrids Unknown d 2752014,0 Lime Tilia cordata L. Tilia platyphyllos L. 30115205,7 White ElmUlmus laevis L.20-2576404,5

17 Economics Buffer land use typesOverall In rotationGrass/clover a PastureSRCSRF b Undisturbed c Energy balanceGross Margin Production system (% of area):(MJ/ha/yr)(approx. £/ha/yr) Winter wheat d 100%150500 A) High energy yield30%35% 104240 B) High energy yield + drainage ditch35% 30%76245 C) Multipurpose, intermediate slope30%55%15%66150 D) Multipurpose, pronounced slope50%25% 48200 E) Extensive, steep slope20%70%10%74130 F) Extensive, slope independent70%20%10%53265 G) Woodland, slope independent90%10%8376 Key figures: Dry matter yield (t DM/ha/yr)1085960 Energy yield (MJ/ha/yr) e 17090551501000 Energy input (MJ/ha/yr)201451080 Energy Balance (MJ/ha/yr)1507650140920 Gross margin (DKK/ha/yr)45004000300015007500

18 Policy development: Fuzzy Cognitive Mapping (FCM) Procedure to involve different stakeholders in a research or management process Method to extract, depict and analyze different kinds of knowledge Way to put academic, regulatory and practical knowledge on equal footing in an expert network

19 FCM-how-to Example question: Why do tourists come to Scotland and how does that affect rural development? Concepts -pristine wilderness -wildlife -salmon fishing -grouse moor management -golf courses -forestry -rural employment -transport infrastructure -… Pristine wilderness Wildlife Salmon fishing Golf courses Grouse moor management Forestry Rural employment Transport infrastructure

20 An expert network from the CREW Workshop, 03.11.11

21 Policy impacts derived

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