Humusprofielontwikkeling bij primaire successie in kustduinen

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1 Humusprofielontwikkeling bij primaire successie in kustduinen
05/04/2017 Humusprofielontwikkeling bij primaire successie in kustduinen Rein de Waal, Bas van Delft

2 Humusprofielontwikkeling: Primaire successie in kustduinen
05/04/2017 Oorspronkelijk kalkrijk zand leemgehalte < 5 % snelle ontkalking Now I will present to you some examples of humus profile development series in Dutch ecosystems. The first example is about primary succession in coastal dunes KLIK These dunes are characterised by initially calcareous sand, with a very low loam content. Decalcification in these sands is a relativaly fast proces

3 Humusprofielontwikkeling kustduin (initiële fase)
05/04/2017 pH(KCl) 0-5cm 4,5 - 6,5 3,5 - 4,5 3,5-4,0 3.0-3,5 2,5 - 3,0 10 cm L F H 0 cm Ah/AC AE 10 cm AB or B 20 cm Oorspronkelijk kalkrijk zand snelle decompositie humusvorm: kalkzandmull vegetatie: Liguster verbond humusvorm verandert door ontkalking C decalcification (free CaCO3) 30 cm What you see here is an early stage of succesion in dune forests. After the sand is fixed by gras and herbs, a shrub phase has developed with shrubs like Sambucus nigra and Hippophae rhamnoides. KLIK In this early stage, the sand is still calcareous, which promotes fast decompostion of organic matter. The humus form is a calcareous sandmull As you will see later, this humus form will change due to decalcification 40 cm

4 Humusprofielontwikkeling kustduin
05/04/2017 20 cm 10 cm 0 cm 40 cm 30 cm AE Ah/AC AB of B H F L ontkalking (vrij CaCO3) 4,5 - 6,5 3,5 - 4,5 3,5-4,0 3.0-3,5 2,5 - 3,0 pH(KCl) 0-5cm C humusvorm verandert door ontkalking: uitspoeling van kalk zand heeft geen zuurbuffer snelle verzuring bovengrond langzame decompositie accumulatie van organische stof In this diagram a chronosequence of humus forms is presented. As we saw before, the initial profile is almost entirely calcareous. KLIK Because of eluviation of calciumcarbonate, the soil becomes more and more decalcified and pH values in the topsoil decrease significantly. These changes are refelcted by the humus profile, which is characterised by accumulation of organic matter and initial podsolisation. Chronosequentie

5 Humusprofielontwikkeling kustduin (eindfase)
05/04/2017 20 cm 10 cm 0 cm 40 cm 30 cm AE Ah/AC AB or B H F L decalcification (free CaCO3) 4,5 - 6,5 3,5 - 4,5 3,5-4,0 3.0-3,5 2,5 - 3,0 pH(KCl) 0-5cm C In the final stage, a significant amount of humus has accumulated on top of the soil The humus form is a Forest-xeromormoder Nutrient availability and acidity are low, and the forest is a Quercion roboris KLIK humusvorm veranderd door ontkalking: humusvorm: Bosxeromormoder vegetatie: Zomereik-verbond

6 Humusprofielontwikkeling kustduin
05/04/2017 20 cm 10 cm 0 cm 40 cm 30 cm AE Ah/AC AB or B H F L Ontkalking (vrij CaCO3) 4,5 - 6,5 3,5 - 4,5 3,5-4,0 3.0-3,5 2,5 - 3,0 pH(KCl) 0-5cm C 1 bodemeenheid 5 humusvormen! In this chronosequence we can recognise 5 different humus forms, that represent different stages of succession. On a soil map we only would have seen 1 soil unit! KLIK Kalkzandmull Zure zandmull Ecto- zandmull Duin- zandmullmoder Bos- mormoder

7 Humusprofiel kustduin, initiële fase
05/04/2017 Hydromull Vaagmull Krijtmull Akkermull Zandmull Wormmull Hydromullmoder Xeromullmoder Hydromoder Eerdmoder Xeromoder Xeromormoder Veenmosmor Mesimor Mull Mullmoder Moder Mormoder Mor T S Kalkzandmull Terrestrische mull Kalkrijk zand leem < 20% I have come almost at the end of my presentation. Now I will illustrate how the profiles in the examples are classified. KLIK The initial stage in the dunes is called a Calcareous sand mull. This is a terrestrial mull in calcareous sand with a low loam content

8 Humusprofiel kustduin, eindfase
05/04/2017 Hydromull Vaagmull Krijtmull Akkermull zandmull Wormmull Hydromullmoder Xeromullmoder Hydromoder Eerdmoder Xeromoder Xeromormoder Veenmosmor Mesimor Mull Mullmoder Moder Mormoder Mor T S Bos-xeromormoder Terrestrische mormoder Hh < 2 cm F+H > 5 cm The final stage of the succession in cosatal dunes is a Forest-xeromormoder This is a terrestrial mormoder, and the subgroups are devided on relative thickness of F and H-horizons KLIK

9 05/04/2017 © Wageningen UR