Restoration of grey dunes:- a matter of scale?

Mark van Til & Dick Groenendijk

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

Main developments in grey dunes

Shrub encroachment 1

(since 1950)

3

• myxomatosis

• stabilisation

Main developments in grey dunes

Grass encroachment

(since 1980)

4

• nitrogen deposition

Main developments in grey dunes

Shrub encroachment 2

(since 1995)

2008

5

• invasive alien species

1989

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

In

dex:

Avera

ge

index b

ased

on m

onitori

ng

sta

tistics

in t

he

Neth

erl

ands

Source: CBS/PBL/Alterra; 2013

index of intact dune grasslands = 100

(reference ~1950)

Restoration projects

- along the Dutch mainland coast -

Noord-Hollands

Duinreservaat

Amsterdam Dunes

Meijendel

Kennemerduinen

7

Restoration projects

• large scale small scale

8

Middenveld - AD

Rozenwaterveld - AD

Restoration projects

Noord-Hollands Duinreservaat

- Egmond

- pilot blow outs

- small scale

Source: Natasja Nachbar 9

Restoration projects

Kennemerduinen

- NW natuurkern

- large scale

Source: Harm Botman & Elco Glimmerveen; PWN 10

Restoration projects

Amsterdam Dunes

- Tonneblink, Pollenberg

- small scale

11

Restoration projects

Meijendel

- sprang

- large scale

Dune slack

Parabolicdune

12

100m

Source: Dunea ; Google Earth

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

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

Effects of small scale restoration

management

Rozenwaterveld (AD) 2002

5 cm shallow sod cutting15

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

Effects of small scale restoration

management

Fauna:• strong positive effect

on grasshoppers

• increase of Red List

butterfly species

• quick return of

rabbits

17

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 120Meters

±

Small scale restoration managementDunes near Egmond (NHD) 2013

small scale blow out reactivation

Insects countings:

• many insects

• new > natural blow outs

• more specialists in

natural blow outs19

Small vs. large scale management

Insect countings

Egmond NW-natuurkern

20

Pattern

(dune grasslands)

Process

(grey dunes)

Scale or resolution

measures

(ha)

mowing

sod cutting

blow out reactivation

reactivationparabolicdunes

reactivationfrontal dunes

mosaicmanagement

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

Restoration projects

scale vs. time

Large scale measures:

# deep sod cutting

# parabolic dune recovery

# foredunes and middle dunes

long term recovery22

Restoration projects

scale vs. time

Small scale measures:

# mosaic management

# (shallow) sod cutting

# small blow out reactivation

# hinter dunes

short term recovery23

Small scale restoration management

in grey dunes?

• calcareous foredunes: self-supporting?24

Small scale restoration management

in grey dunes?

• decalcified and acidified hinter dunes, and

middle dunes

25

Large scale restoration management

in grey dunes?

• frontal dune and foredunes (strong wind dynamics)

26Source: Harm Botman

Large scale restoration management

in grey dunes?

• disturbed landscapes

27

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