A project was set up in 1996 to monitor management regimes (shrub removal, grazing and mowing) implemented in different nature reserves along the west Belgian coast. The project integrates botanical, zoological, hydrological and pedological research at several levels (Bonte et al., 1997). The soil study aims to produce a comprehensive and effective system of soil description, and in this paper we propose the methodology used for recording soil characteristics at the most detailed research level. The initial period of the monitoring project runs for 3 years

Ampe, C.

Langohr, R.

Open Marine Archive

COMPREHENSIVE AND EFFECTIVE RECORDING OF 
EDAPHIC CHARACTERISTICS OF DUNE ECOSYSTEMS AS 
APPLIED IN THE MONITORING PROJECT OF THE 
FLEMISH COASTAL DUNES
C. AMPE and R. LANGOHR
Soil Science Unit, University
In troduction
A project was set up in 1996 to m onitor m anagem ent regimes (shrub removal, grazing 
and mowing) im plem ented in different nature reserves along the west Belgian coast. 
The project integrates botanical, zoological, hydrological and pedological research at 
several levels (Bonte et al., 1997). The soil study aims to produce a comprehensive 
and effective system of soil description, and in this paper we propose the m ethodology 
used for recording soil characteristics at the m ost detailed research level. The initial 
period of the m onitoring project runs for 3 years.
M ethodology
Soils are described on the basis of both  field and laboratory characteristics.
Field description
Two levels of detail are used.
1. Soils in 80 perm anent quadrats (3 x 4m) situated in (approximately) 30 x 50m 
plots representing 16 m anagem ent regimes (including the controls) and spread 
over six sites, situated in  the W esthoek Nature Reserve and the Flemish Nature 
Reserve of Houtsaegerduinen, were investigated in great detail. Mini-soil 
profiles, 50 x 40cm and approxim ately 50cm deep, were dug for w hich vertical 
and horizontal sections were studied.
2. At a num ber of o ther sites in the W esthoek Nature Reserve, Dune M archand, 
Ter Yde, Oostvoorduinen and Schuddebeurze soil profiles were investigated in 
less detail by observations of profiles produced by using a hand  auger.
First a m ore general description of the soil profile was recorded. This description partly 
followed the Food and Agriculture Organisation (FAO) guidelines (1990), bu t this
Recording Edaphic Characteristics in the Flemish Dunes 419
standard technique for soil profile description provides insufficient data for an u n d er­
standing of the ecosystem dynamics. Based on literature, m ainly from The Netherlands, 
and personal experience we added a num ber of param eters to be described.
Dune soils are often shallow for root penetration and the humus form will play a 
very im portant role in increasing the available nutrients and m oisture for plant growth. 
The term inology according to Green et al. (1993) was employed for the description 
of the hum us form. The param eters considered were horizon designation and depth, 
m oisture status, colour, fabric including structure, texture and character, roots, soil 
flora and fauna.
The thickness of the biological active layer ('bi' horizon), the sum of the horizons w here 
the m ajority of the roots are concentrated, is often limited in sandy dune soils. Form er 
research along a topo-chronosequence in the W esthoek Nature Reserve has show n 
that in hollows the thickness of the biological active layer was often limited to about 
20cm. This biological active layer was underlain by a m ore compact ('d') horizon w ith  
almost no m ore roots. Bulk density m easurem ents resulted in the following values: 
1.35 (n = 49), 1.50 (n = 121) and 1.56 (n = 436) g per cm3 for the Abi, Bbi and Cd 
horizons respectively. On the micro-ridges the biological active layer became thicker, 
often due to bioturbation caused, for example, by rabbits, and rooting was m ore 
developed in the resultant air spaces (Ampe and Langohr, 1993). The thickness of the 
biological layer was m easured from the vertical section or determ ined w ith a p en e­
tration rod of surface area 1cm2.
The limited thickness of the biologically active layer has im portant consequences 
for w ater and nu trien t supply. Firstly, the w ater available to plants in dune soils 
am ounts to only a few per cent of the total am ount of w ater present and is only higher 
in those surface horizons w ith som ew hat greater organic m atter (OM) content. 
Secondly, if the groundw ater table is at a greater depth than  the sum  of the th ick­
nesses of the biological active layer and the capillary rise, plants encounter great 
problems in w ater uptake. Due to a limited thickness of the biological active layer, the 
system is very sensitive to disturbances.
In this study particular attention was paid to rooting characteristics. Size (diameter), 
abundance, orientation and species are determ ined on the vertical as well as on the 
horizontal section. In some profiles live roots were observed growing in old hum ified 
root galleries. It can be deduced that on the one hand  we have plants which grow 
w ith the accreting dune such as Ammophila arenaria and Salix repens, and on the other 
hand  there are plant species which m ake use of the presence of these old hum ified 
root galleries in later successional stages. If these old root galleries are missing, further 
colonization of the dune will be very slow.
Specific rooting characteristics of different plant species have also been investigated 
as these m ay explain w hy some plant species are m ore competitive th an  others in 
their struggle for w ater and nu trien t supply.
Extent of décalcification is determ ined w ith HCl (2N). Décalcification can vary w ithin 
the profile due to:
420 MONITORING: METHODS AND APPLICATIONS
• the presence of buried decalcified hum ic horizons;
• the active process of deposition w hereby the soil is regularly showered w ith
fresh calcareous sand;
• lateral supply w ith calcareous seepage water;
• turbation activity by animals (rabbits, moles, mice) or people (forest m anage­
m ent, thinning).
The pattern  of décalcification can also be very irregular over short distances in space, 
resulting in a mosaic of caldcóle and calcifuge vegetation.
The soil is tested for water repellency under field conditions and also on air-dry samples 
in the laboratory. Soils w hich are w ater repellent show a certain resistance to w ater 
penetration, a com m on characteristic of dune soils (Dekker and Jungerius, 1990). The 
model of hom ogeneous w etting fronts cannot be applied in such soils. Preferential 
flows develop in tongues or fingers along roots, in microdepressions or less repellent 
areas, or follow buried horizons. Along these preferential flow routes w ater can reach 
the groundw ater table m uch faster than  w ould norm ally be expected. In the field, 
patches of moist soil surrounded by completely dry patches can be observed. W ater 
repellency is therefore another factor causing dune soils to be drier than  expected.
Oxidation-reduction features were described. Abundance, size, contrast, boundary, 
colour, the activity status and the related distribution of the m ottling were recorded. 
Active m ottling can be represented by the presence of a rusty rim  especially along 
Carex roots. On the horizontal section, sharp concentric rust-coloured m ottling 
surrounding a live root can be seen; on the vertical section this kind of m ottling forms 
rusty vertical streaks along the root. U-shaped mottles can very clearly be seen on 
horizontal sections, their m orphology consisting of a dark, sometimes black nucleus 
-  a dead root channel -  surrounded by the U-shaped rusty colouring. Indeed, due to 
lateral w ater flow the original concentric m ottle becomes U-shaped w ith the closed 
end showing the direction from w here the w ater flow comes. Apart from these very 
striking types of mottling, a rust-coloured soil m atrix can be observed in some horizons.
Other special features can be observed on the vertical and horizontal sections. Plough 
layers or th in  bands that are probably buried algal bands are examples of such features.
Sampling strategy
Siting of the mini-profile and sampling took place on one of the four sides of the 
perm anent quadrat w ith a preference for the southern. In the mini-profile bulk samples 
were taken for each horizon. For some representative horizons undisturbed samples 
(5 replicates of cores of 100cm3) were taken on the horizontal section for bulk density 
determ ination.
For the surface mineral horizon betw een 0-5 and 0 -1 0cm, a composite sample was 
taken consisting of 5 subsamples. Because of persisting dry conditions of the soil or 
the presence of thick roots (Salix repens) or rhizomes (Iris pseudacorus), neither the 
gouge auger nor the grass plot sampler (a small auger designed for grass-covered
Recording Edaphic Characteristics in the Flemish Dunes 421
terrain, pressed into the soil by stepping on the container which subsequently collects 
the sample) proved to be practical. Therefore rings w ith  a height of 5 and 10cm were 
used to sample the soil.
The humus profile was sampled at some selected sites. For this a stainless steel cylinder 
w ith a diam eter of 25cm and a height of 20cm was ham m ered into the soil. The L, F, 
H and A horizons were taken off separately and placed in bags. For each perm anent 
quadrat this sampling was repeated three times.
Laboratory analysis
The following analyses are provisionally being considered as appropriate.
M ain horizons: colour, w ater repellency, bulk density, pH H2 O, pH KCl, CaCCb, 
organic carbon.
Samples betw een 0-5 and 0 -1 0cm depth based on m ixed sampling: w ater repel­
lency, pH H2 O, pH KCl, CaCCb, organic carbon, N, Cation Exchange Capacity.
Samples of the hum us profile: air dry weight, pH H2O, pH KCl, organic carbon 
and N.
Acknowledgments
This research is co-financed by the LIFE nature project ICCI.
References
A m pe, C. and Langohr, R. (1993), 'Distribution and dynamics of shrub roots in recent coastal 
dune valley ecosystems of Belgium', Geodermar 56, 37-55.
Bonte, D., A m pe, C., Hoffm ann, M., Langohr, R., Provoost, S. and Herrier, J.L. (1997), 
'Monitoring research in the Flemish dunes: from a descriptive to an integrated approach', in 
C.H. Ovesen (ed.), Coastal Dunes-Management, Protection and Research, report from a European 
seminar, Skagen, Denmark, August 1997. National Forest and Nature Agency, Geological 
Survey of Denmark and Greenland.
Dekker, L.W. and Jungerius, P.D. (1990), 'Water repellency in the dunes with special 
reference to The Netherlands', Catena Supplement, 18, 173-83.
Food and Agriculture Organisation (1990), Guidelines for Profile Description, 3rd edn, Food 
and Agriculture Organisation, Rome.
Green, R.N., Trowbridge, R.L. and Klinka, K. (1993), Towards a Taxonomic Classification of 
Humus Forms, Forest Science, Monograph 29, Society of American Foresters, Bethesda, MD.


Comprehensive and effective recording of edaphic characteristics of dune ecosystems as applied in the monitoring project of the Flemish coastal dunes

Comprehensive and effective recording of edaphic characteristics of dune ecosystems as applied in the monitoring project of the Flemish coastal dunes

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