Ecological restoration of speciesrich grasslands and heaths on
former agricultural lands
Roland Bobbink
Outline of presentation
BIOGEOCHEMICAL WATER-MANAGEMENT & APPLIED RESEARCH ON ECOSYSTEMS
• Introduction
- restoration on former agricultural lands
- bottlenecks
• Restoration of species-rich grasslands
- calcareous grasslands (H6210) &
species-rich Nardus grasslands (H6230)
• Restoration of heathlands
- dry & wet heathlands (4030 & 4010)
• Conclusions
Bottlenecks for the restoration on
former agricultural lands
Abiotics:
• Too high levels of nutrients (N, P!!)
• Changed hydrology
• sometimes: too high soil buffering
Biotics:
• Hardly any seed bank of typical plant species
• Strongly degraded soil life (dominance of
bacteria, different micro-mesofauna)
• Restricted dispersion capacity of many
species (both animals & plants)
• Fragmented landscape, high isolation grade
=> Combination of measures.
Without restoration: long-term
dominance of Juncus effuses or
grasses (Holcus)
Possible solutions of
bottlenecks
• Adequate removal of top soil (removal
of P);
• Addition of biota:
- Fresh hay addition (seed addition);
- Addition of sods (vegetation plus soil);
- Soil addition.
=> examples from the Netherlands (grasslands &
heaths)
Restoration of calcareous grasslands on former
agricultural lands
(South Limbourg)
Verlengde Bemelerberg
O = topsoil removal
C = control
M = + hay addition
First: measurements of P availability (P-Olsen)
Microlmol P/kg dry soil
Autumn 2007: top soil removal (20-40 cm)
Soil chemistry before and after restoration (2010-12)
Before restoration
Control
Topsoil removal Topsoil rem. & hay
Verlengde Bemelerberg: after 5 jaar (2012)
Number of
vascular species
(2 x 2 m);
Red = Red list
species
Van Noordwijk
et al. 2013
Control
Topsoil removal
Topsoil rem. & hay
2013
Photo: W. Verbeke
Addition fresh hay & seed addition
(Noordenveld)
After 2 years
Control : blue (= only topsoil
removal)
Topsoil removal + hay: red
Topsoil rem. + hay + seeds:
green
Project Noordenveld (200 ha)
166 ha top soil removal
Hydrological measures
Experimental setup
 Gradient in soil pH
 Gradient in addition of
biota
Foto Hans
Dekker
Sod addition (Noordenveld/Dwingelderveld)
Fresh hay addition
Addition of sod material
(Noordenveld/Dwingelderveld): field trial
Before/ after P-availability
(Noordenveld/Dwingelderveld)
And now the vegetation:
Summer 2014
Fungal-bacterial ratio (PLFA analysis) of soil
community (dry heathexp.)
Control
Hay addition
Sod addition
PLFA finger printing: 2009 (5 to 15
cm) compared to 2013
6,0
Original
2009-DG
2009-WG Deep
Horizon
5,0
4,0
3,0
PC2 (18%)
2,0
PM
1,0
C
S
C
0,0
-7,0
-6,0
-5,0
-4,0
Reference
sites
2013-Ref/W
-3,0
-2,0
-1,0
0,0
1,0
PM
PM
-1,0
S
S
PM
-2,0
2013-Ref/D
S
-3,0
PC1 (27%)
• Open shape 2009, filled shape 2013
• Squares wet, Diamonds dry, Circles reference
• 2013 treatments:
• pH: red=acidic, black=control, green=limed
• PM=plant material, S=sods, C=control
C
PM
2,0
3,0
Treatment sites
S
S
C
C
C
PM
4,0
PLFA: 2009 (5 to 15 cm) compared to
2013
6,0
Original
2009-DG
2009-WG Deep
Horizon
5,0
4,0
3,0
PC2 (18%)
2,0
PM
1,0
C
S
C
0,0
-6,0
-5,0
-4,0
Reference
sites
2013-Ref/W
-3,0
-2,0
-1,0
0,0
1,0
PM
S
Sods
S
S
PM
-2,0
2013-Ref/D
S
-3,0
PC1 (27%)
• Open shape 2009, filled shape 2013
• Squares wet, Diamonds dry, Circles reference
• 2013 treatments:
• pH: red=acidic, black=control, green=limed
• PM=plant material, S=sods, C=control
PM
PM
-1,0
S
C
Control
C
-7,0
C
C
PM
2,0
3,0
PM
4,0
PLFA: 2009 (5 to 15 cm) compared to
2013
6,0
Original
2009-DG
2009-WG Deep
Horizon
5,0
4,0
3,0
PC2 (18%)
2,0
PM
1,0
C
S
C
0,0
-6,0
-5,0
-4,0
Reference
sites
2013-Ref/W
-3,0
-2,0
-1,0
0,0
1,0
PM
S
Sods
S
S
PM
-2,0
2013-Ref/D
S
-3,0
PC1 (27%)
• Open shape 2009, filled shape 2013
• Squares wet, Diamonds dry, Circles reference
• 2013 treatments:
• pH: red=acidic, black=control, green=limed
• PM=plant material, S=sods, C=control
PM
PM
-1,0
S
C
Control
C
-7,0
C
C
PM
2,0
3,0
PM
4,0
Cover Calluna vulgaris (Noordenveld dry heath
exp)
Control
Hay addition
Sod addition
Soil addition & heathland development
(Noordenveld/Dwingelderveld): after 2 years
(Carex pilufera, Rumex acetosella)
Soil addition & heathland development
(Noordenveld/Dwingelderveld): after 3 years
Number of heathland species, third year
(Noordenveld; dry condition)
Control
Hay addition
Sod add
Red List species only in plots with sod addition
Conclusions
• Top-soil removal restored approriate nutrient-poor
soil conditions on former agricultural land;
• Abiotic measurements are in most cases necessary to
obtain adequate measures;
• Transfer of fresh hay from good donor sites is very
efficient to restore typical species richness in
grasslands (after top soil removal);
• Addition of seeds of rare species (not in hay) is
needed to get a more complete situation;
• Addition of crushed sods seems succesfull in the
restoration of the vegetation and the soil community
of heaths (dry & wet) (till now no long-term data)
• The succession of the communities is dependent of
the abiotic conditions after restoration;
• Post-restoration management is needed in seminatural ecossytems.
Thanks to:
• many co-workers :
Maaike Weijters, Evi Verbaarschot,
Roos Loeb, Mark van Mullekom, Rudy
van Diggelen, Arrie van der Bij, Toos
van Noordwijk, Nina Smits, Mark
Pawlett, Jim Harris & Jan Frouz …..
•Many people of the nature
conservation agencies!!!
• The Dutch OBN programme
• NWO Biodiversity programme