Dynamic Dunes Congress 2015 Keynote: Mark van Til & Dick Groenendijk - Restoration of grey dunes a matter of scale

1. Restoration of grey dunes:
- a matter of scale?
Mark van Til & Dick Groenendijk

2. Contents
• Main developments in grey dunes
• Restoration projects along the Dutch mainland coast
• Chronosequence research grey dunes
• Effects of restoration management on vegetation and
fauna
• Natural recovery of grey dunes
• Conclusions
2

3. Main developments in grey dunes
Shrub encroachment 1
(since 1950)
3
• myxomatosis
• stabilisation

4. Main developments in grey dunes
Grass encroachment
(since 1980)
4
• nitrogen deposition

5. Main developments in grey dunes
Shrub encroachment 2
(since 1995)
2008
5
• invasive alien species
1989

6. Main developments in grey dunes
Loss of biodiversity: target species in dune grasslands
 still decreasing
6
0
10
20
30
40
50
60
70
80
90
100
1950 1960 1970 1980 1990 2000 2010
Index:Averageindexbasedonmonitoring
statisticsintheNetherlands
Source: CBS/PBL/Alterra; 2013
index of intact dune grasslands = 100
(reference ~1950)

7. Restoration projects
- along the Dutch mainland coast -
Noord-Hollands
Duinreservaat
Amsterdam Dunes
Meijendel
Kennemerduinen
7

8. Restoration projects
• large scale  small scale
8
Middenveld - AD
Rozenwaterveld - AD

9. Restoration projects
Noord-Hollands Duinreservaat
- Egmond
- pilot blow outs
- small scale
Source: Natasja Nachbar 9

10. Restoration projects
Kennemerduinen
- NW natuurkern
- large scale
Source: Harm Botman & Elco Glimmerveen; PWN 10

11. Restoration projects
Amsterdam Dunes
- Tonneblink, Pollenberg
- small scale
11

12. Restoration projects
Meijendel
- sprang
- large scale
Dune slack
Parabolic
dune
12
100m
Source: Dunea ; Google Earth

13. 0 1-6 11-226-11 22-33 33-44 54-74 >74
0
10
20
30
Chronosequence grey dunes
• Luchterduinen (Amsterdam Dunes)
• soil and vegetation development
13Source: Aggenbach et al. 2013

14. Chronosequence grey dunes
Lessons learned:
• soil development > 40-60 year
• species rich grey dune vegetation > 40-60 years
• lime rich grey dunes: N species stays high
(buffering capacity)
• lime poor soils: N species declines (acidification)
14

15. Effects of small scale restoration
management
Rozenwaterveld (AD) 2002
5 cm shallow sod cutting
15

16. 2002 = before sod cutting
Effects of small scale restoration
management
Vegetation:
• quick return of
grey dune species
• open varied structure
(2010: bare sand 20%)
16

17. Effects of small scale restoration
management
Fauna:
• strong positive effect
on grasshoppers
• increase of Red List
butterfly species
• quick return of
rabbits
17

18. Effects of small scale restoration
management
Rozenwaterveld
2009:
• upscaling to mosaic
management
• 11 ha of different
measures
diep plaggen
maaien
sod cutting 10 cm ondiep plaggen
stuifkuil herstel
sod cutting 5 cm
mowing blow out recovery
18
0 30 60 90 120
Meters
±

19. Small scale restoration management
Dunes near Egmond (NHD) 2013
small scale blow out reactivation
Insects countings:
• many insects
• new > natural blow outs
• more specialists in
natural blow outs 19

20. Small vs. large scale management
Insect countings
Egmond NW-natuurkern
20

21. Pattern
(dune grasslands)
Process
(grey dunes)
Scale or
resolution
measures
(ha)
mowing
sod cutting
blow out
reactivation
reactivation
parabolic
dunes
reactivation
frontal dunes
mosaic
management
0,1 1 10
Egmond
NHD
foredunes landscape
restoration
Rozenwater-
veld AD
hinter dunes
VLS-canal
AD
foredunes
NW
natuurkern
K’duinen
foredunes
Sprang
Meijendel
middle dunes
Middel/Oost-
duinen
hinter dunes
Heemskerk
NHD
frontal dunes
Southwest
AD
foredunes
restoration
project
reference
21
Voorne
foredunes
Tonneblink/
Pollenberg AD
hinter dunes

22. Restoration projects
scale vs. time
Large scale measures:
# deep sod cutting
# parabolic dune recovery
# foredunes and middle dunes
 long term recovery
22

23. Restoration projects
scale vs. time
Small scale measures:
# mosaic management
# (shallow) sod cutting
# small blow out reactivation
# hinter dunes
 short term recovery
23

24. Small scale restoration management
in grey dunes?
• calcareous foredunes: self-supporting?
24

25. Small scale restoration management
in grey dunes?
• decalcified and acidified hinter dunes, and
middle dunes
25

26. Large scale restoration management
in grey dunes?
• frontal dune and foredunes (strong wind dynamics)
26Source: Harm Botman

27. Large scale restoration management
in grey dunes?
• disturbed landscapes
27

28. Conclusions
Restoration of grey dunes: a matter of scale!
• large scale management
 disturbed landscapes
 frontal and foredunes
 slow, long term recovery of grey dunes
• small scale mosaic management
 especially effective in hinter dunes
 quick, short term recovery of grey dunes
 grazing as follow up
28