areas, mowing is quite efficient at maintaining basiphilous pioneer stages. Grazing
is often applied in dry dunes to counter grass and shrub encroachment. Accumulation of organic matter is not counteracted by grazing, but perhaps retarded,
owing to a lower input of litter. The effect of grazing partly depends on the
productivity and nutrient limitations of the vegetation. Grazing does not affect P
availability, which is largely regulated by soil chemistry, but it may affect litter
input and N cycling. In dune areas with P limitation, such as calcareous soils, or
iron-rich soils with low organic matter content, productivity is already low and
grazing may counteract grass encroachment. In N-limited dunes, such as in the
Wadden islands, grazing may reduce net N mineralization and N availability to the
vegetation, thus reducing grass encroachment. However, in partly decalcified
middle dunes along the Holland coast with high availability of N and P, grazing
cannot prevent further grass encroachment (Kooijman and Hedenäs 2009).
15.2.2 Sod Cutting and Rewetting
Sod cutting is a widely applied management tool to reduce nutrient availability
in dune slacks, and is usually applied in combination with rewetting. Sod cutting
includes removal of the organic A horizon, leaving the mineral C horizon intact.
Also sod cutting has been practiced in dune areas in northwest Europe for a long
time. Rewetting and restoration of hydrological systems consist of eliminating
drainage ditches as much as possible, terminating groundwater abstraction
facilities, and decreasing evaporation intensities by cutting pine plantations
(Grootjans et al. 2002).
15.2.3 Initiating Aeolian Processes Again
As mentioned in the Sect.15.1, apart from changes in hydrology or high atmospheric deposition, a major problem in the Dutch dunes is the reduction of the
natural regeneration potential by the lack of aeolian dynamics.
Over the years, experiments on different scales have been conducted to reactivate dune dynamics, varying from local blowouts to parabolic dunes and even
foredune ridges (Arens and Geelen 2006). A survey of active blowouts in different
dune zones suggests that even apparently stable reference vegetation in the
neighborhood of the actual blowouts, may be affected (Table 15.1). In both calcareous and acid dunes, pH of the reference dune grasslands was higher than
values characteristic of the particular dune zone. However, the results of reactivation experiments have generally been less successful than expected. In many
cases, vegetation regrowth stabilized open sand rapidly after reactivation (Arens
and Geelen 2006).
242
A. P. Grootjans et al.
is often applied in dry dunes to counter grass and shrub encroachment. Accumulation of organic matter is not counteracted by grazing, but perhaps retarded,
owing to a lower input of litter. The effect of grazing partly depends on the
productivity and nutrient limitations of the vegetation. Grazing does not affect P
availability, which is largely regulated by soil chemistry, but it may affect litter
input and N cycling. In dune areas with P limitation, such as calcareous soils, or
iron-rich soils with low organic matter content, productivity is already low and
grazing may counteract grass encroachment. In N-limited dunes, such as in the
Wadden islands, grazing may reduce net N mineralization and N availability to the
vegetation, thus reducing grass encroachment. However, in partly decalcified
middle dunes along the Holland coast with high availability of N and P, grazing
cannot prevent further grass encroachment (Kooijman and Hedenäs 2009).
15.2.2 Sod Cutting and Rewetting
Sod cutting is a widely applied management tool to reduce nutrient availability
in dune slacks, and is usually applied in combination with rewetting. Sod cutting
includes removal of the organic A horizon, leaving the mineral C horizon intact.
Also sod cutting has been practiced in dune areas in northwest Europe for a long
time. Rewetting and restoration of hydrological systems consist of eliminating
drainage ditches as much as possible, terminating groundwater abstraction
facilities, and decreasing evaporation intensities by cutting pine plantations
(Grootjans et al. 2002).
15.2.3 Initiating Aeolian Processes Again
As mentioned in the Sect.15.1, apart from changes in hydrology or high atmospheric deposition, a major problem in the Dutch dunes is the reduction of the
natural regeneration potential by the lack of aeolian dynamics.
Over the years, experiments on different scales have been conducted to reactivate dune dynamics, varying from local blowouts to parabolic dunes and even
foredune ridges (Arens and Geelen 2006). A survey of active blowouts in different
dune zones suggests that even apparently stable reference vegetation in the
neighborhood of the actual blowouts, may be affected (Table 15.1). In both calcareous and acid dunes, pH of the reference dune grasslands was higher than
values characteristic of the particular dune zone. However, the results of reactivation experiments have generally been less successful than expected. In many
cases, vegetation regrowth stabilized open sand rapidly after reactivation (Arens
and Geelen 2006).
242
A. P. Grootjans et al.