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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
Biodiversity hot spot:
• Lime rich ( ) & lime poor ( ) dunes
• C. 60-70% dune grasslands
• Natura 2000
• >50% Dutch species
Northern Wheatear
1982 1988 1993 2000 2007
• 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?
Conservation Measures
Natural dynamic frontdunes
Dynamics: creating small blowouts and large scale management in white dunes.Grazing: different densities, different scale.
Large scale rejuvenation: Buizerdvlak
Another large scale example:
Noordwest natuurkern
2012
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
Small scale: creating blowouts
Idea is not new……………….
Principle:
Especially in the countryside
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.
Ook kleinschalig: aanleg stuifkuilen
Small scale blowouts: insect and arthropod counts
0
2
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Hymenoptera Diptera Coleoptera Heteroptera Lepidoptera Orthoptera Arachnida Isopoda
Ave
rage
nu
mb
er
of
ind
ivid
ual
s p
er
10
0 m
2p
er
day
Natural
Reactivated
Small scale blowouts: specialised insects
0,00
1,00
2,00
3,00
4,00
5,00
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7,00
8,00
9,00
Sphecodes albilabris Sphecidae Pompilidae Therevidae Cicindela hybrida
Ave
rage
nu
mb
er
of
ind
ivid
ual
s p
er
10
0 m
2p
er
day
Natural
Reactivated
Counts on insects and arthropods:
small scale versus large scale reactivation
Small scale blowouts
at Westerberg 2013Large scale dynamics
at Houtglop 2014
Countings after one year Countings after two years
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
Ave
rage
nu
mb
er
of
ind
ivid
ual
s p
er
10
0 m
2p
er
day
large scale
small scale
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
Large parts in PWN-dunes are managed by grazing
Grazing
Grazing
Recent research: grazing increases the microclimatic conditions for (at least) grasshoppers.
2014 2013
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
• 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, stableparts with short and tall vegetation and scrub preferably over large areas.
Fauna very important link
• Urgent need to save smaller fauna !
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!
