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Drivers of biodiversity change in British alpine habitats [Andrea Britton]

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Drivers of biodiversity change in British alpine habitats. Presented by Andrea Britton at the "Perth II: Global Change and the World's Mountains" conference in Perth, Scotland in September 2010.

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Drivers of biodiversity change in British alpine habitats [Andrea Britton]

  1. 1. Drivers of biodiversitychange in British alpinehabitats Andrea Britton, Alison Hester, Colin Beale, Richard Hewison & Willie Towers
  2. 2. UK alpine habitats Wide variety of habitats Strong oceanic influence Important role of lower plants High biodiversity value Ecosystem services  C storage  Water cycle
  3. 3. Anthropogenic impactsLocal scale drivers: Recreation impacts  Hiking  Skiing Grazing Management
  4. 4. Anthropogenic impacts Sulphur depositionPollutant deposition: Sulphur  Deposition declining  Persistent effects Nitrogen  Deposition remains high Source: www.apis.ac.uk Source: ROTAP 2010
  5. 5. Anthropogenic impactsClimate change: 1961-2004 Temperature  Average 1°C rise since 1961 Precipitation  60% increase in winter rainfall Snowfall  30% reduction in days with snow cover
  6. 6. Alpine vegetation is exposed to multiple drivers of change… How has biodiversity responded over the last 40 years?
  7. 7. Birse and Robertson Survey 700+ plots recorded 1960-1980 205 plots resurveyed 2004-6 Range of typical alpine communities Recorded species composition & sward structure
  8. 8. Overall change: plot scale  Mean species richness  Plot-level diversity increased from 16 to 19 (Shannon) has declined 25 2.0 *** *** Mean Shannon Index HMean species richness 20 1.5 15 1.0 10 0.5 5 0 0.0 old new Old New
  9. 9. Overall change: landscape scale New sill is significantly lower (P<0.001) Spatial turnover of composition reduced – more homogeneous Old data New data
  10. 10. Habitat specific changes Richness change differs between 4 Mean change in species richness higher plants and Highers Bryos bryophytes 3 Higher plants increase most in 2 snowbed and springs, no change 1 in fell field 0 Bryophytes increase most in fell field, he ath eath eath l field wbed rings land land land s h na ium rium h l Fe Sno Sp rass ras grass decline in tall Juncus llu in Ca acc comi t G sG s du cu V a un Nar grassland R J
  11. 11. Species trendsWinners: Losers: Middle altitude, widespread  High altitude, northern species species
  12. 12. How do observed changes compare with experimental studies?
  13. 13. Example: Alpine Calluna heath Changes in survey plots:  Increased higher plant and bryophyte richness  Increased Calluna cover  Reduced lichen cover  Increased sward height
  14. 14. Culardoch long-term experimental site Nitrogen addition  Grazing Warming (open top chambers)  Burning
  15. 15. Driver responses – Higher plants Survey finding: increased 40 35 Mean shoot extension (mm) Calluna cover 30 Experimental response: 25 20  Positive response to 0 kg N 10 kg N both N addition and 15 20 kg N 50 kg N warming 10 1998 2000 2002 2004 2006 2008 2010  Increased shoot Year growth 45 OTCs installed -OTC  Increased flowering 40 +OTC Mean shoot extension (mm) 35 No change in species 30 composition (after 10 25 20 years) 15 10 1998 2000 2002 2004 2006 2008 2010 Year
  16. 16. Driver responses - lichens Survey finding: decreased lichen cover 10 Experimental response: 8 Lichen species richness rapid decline in cover and 6 richness with N addition 4 Sensitive to low loads & 2 concentrations 0 0 kg 10 kg 20 kg 50 kg Lichen abundance also N addition (kg N ha-1 y-1) related to sward height – indirect effect of climate and/or grazing
  17. 17. Conclusions UK alpine habitats are changing Species of sub-alpine habitats are expanding while alpine specialists decline Nature of change is habitat specific Experimental studies show that multiple drivers can contribute to observed changes Future studies: avoid considering single drivers in isolation
  18. 18. Acknowledgements Scottish Government & DEFRA for fundingJulia Fisher, Dave Riach and Heather Armitage for help with field work Thank YOU for listening

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