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Dune grasslands and fauna


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Dynamic Dunes Congress 2015
Workshop: Dune grasslands and fauna - Dick Groenendijk

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Dune grasslands and fauna

  1. 1. Dynamic Dunes 2015 – 8 October 2015 Workshop Dune grasslands and fauna Dick Groenendijk • Overview on some PWN projects • Some results on fauna • Fauna related questions
  2. 2. Biodiversity hot spot: • Lime rich ( ) & lime poor ( ) dunes • C. 60-70% dune grasslands • Natura 2000 • >50% Dutch species
  3. 3. Northern Wheatear 1982 1988 1993 2000 2007
  4. 4. • Conservation measures to stop effects of problems like high nitrogen deposition, artificially settled dunes and fast succession. How to save all this biodiversity? How to keep the balance? • Doing already a lot and future plans (N2000, PAS, Life+, etcetera) are asking much more action. • Taking these measures can give rise to a feeling as if we are constantly on the verge of losing biodiversity due to our measures. Or are we regenerating processes in which our biodiversity can increase even more?
  5. 5. Conservation Measures Natural dynamic frontdunes Dynamics: creating small blowouts and large scale management in white dunes. Grazing: different densities, different scale.
  6. 6. Large scale rejuvenation: Buizerdvlak
  7. 7. Another large scale example: Noordwest natuurkern 2012
  8. 8. Noordwest natuurkern Large scale dynamics > regenerating dune processes Time aspect: c. >50 year development soils in dune grasslands Can fauna keep in pace? Discussion topic: “Too much emphasis on large scale rejuvenation processes may give magnificent landscape views, however, without the important biodiversity.” 2011 2013
  9. 9. Small scale: creating blowouts Idea is not new………………. Principle: Especially in the countryside
  10. 10. Small scale dynamics • Due to human activities, declining rabbit populations and increasing N-deposition, small scale dynamics disappeared; • Creating small scale blowouts are known measures in a programme counteracting the negative effects of nitrogen in the Netherlands (PAS); • First results show positive results.
  11. 11. Ook kleinschalig: aanleg stuifkuilen
  12. 12. Small scale blowouts: insect and arthropod counts 0 2 4 6 8 10 12 14 16 18 Hymenoptera Diptera Coleoptera Heteroptera Lepidoptera Orthoptera Arachnida Isopoda Averagenumberofindividualsper100m2perday Natural Reactivated
  13. 13. Small scale blowouts: specialised insects 0,00 1,00 2,00 3,00 4,00 5,00 6,00 7,00 8,00 9,00 Sphecodes albilabris Sphecidae Pompilidae Therevidae Cicindela hybrida Averagenumberofindividualsper100m2perday Natural Reactivated
  14. 14. Counts on insects and arthropods: small scale versus large scale reactivation Small scale blowouts at Westerberg 2013 Large scale dynamics at Houtglop 2014 Countings after one year Countings after two years
  15. 15. Counts on insects and arthropods: small scale versus large scale High impact of scale on insect densities On average factor 10 difference 0 10 20 30 40 50 60 70 total Averagenumberofindividualsper100m2perday large scale small scale
  16. 16. Ook kleinschalig: aanleg stuifkuilenDynamics • Small scale dynamics > important in dune grasslands • Large scale dynamics > important in recovering large scale processes • Insect fauna react swift and in small scale blowouts • Specialist species needs more time • In large scale rejuvenation projects much slower recovery of insect populations
  17. 17. Large parts in PWN-dunes are managed by grazing Grazing
  18. 18. Grazing Recent research: grazing increases the microclimatic conditions for (at least) grasshoppers. 2014 2013
  19. 19. 0,0 10,0 20,0 30,0 40,0 50,0 60,0 70,0 80,0 90,0 2013 2014 gemiddeld aantal Knopsprietjes Myrmeleotettix maculatus begraasd exclosure Grazing
  20. 20. • Heterogeneity is thus very important; every type of vegetation is home for different insects and, therefore, for different insectivorous predators. Conservation measures and fauna in dune grasslands • Gradient rich mosaic structure including dynamic parts, stable parts with short and tall vegetation and scrub preferably over large areas.
  21. 21. Fauna very important link • Urgent need to save smaller fauna !
  22. 22. Discussion on objectives Too much emphasis on large scale rejuvenation processes may give magnificent landscape views, however, without the important biodiversity. External factors are more important: nitrogen deposition, toxic substances (like dioxins), climate change. We can not change these external factors. Taking measures will not help to stop decreasing fauna trends. There are already many projects in our dunes and more is expected. Our fauna needs recovery time and rest!