Freitag, 30. August 2013

Field Trip to Duisburg-Homberg (August 25th, 2013)

Last Week, I participated in a Field Trip to Homberg in Duisburg, Western Germany. This Field Trip was organized by the Botanischer Verein Bochum e. V., which I belong. The trip went to the floodplains of the Rhine in this area. We looked for some interesting species, which are common at the shore of the Lower Rhine.

1) Areal

Homberg is a former village, which is located at the western shore of the River Rhine in North-Rhine Westphalia, Western Germany. In 1975 it became part of the larger City of Duisburg on the eastern shore of the Rhine. However, with the large river as a kind of barrier, Homberg (and other urban districts like Hochheide and Baerl) remain mostly independent from the rest of Duisburg. For many people, Homberg is more part of the Lower Rhine plains than of the Ruhr Area like the Rest of Duisburg.

Duisburg-Homberg: floodplains (pasture)

The actual area of the Field Trip were a small part of the floodplains in this region. Located directly at the Shore of the Rhine, the areal is exposed to frequently flooding. Plants, which grow here, have to deal with this circumstance and its side-effects like permanent wetness, mechanical stress due to flow or wind and a high entry of nutrients by the water.

Small group of trees with Silver Willows

Large Trees are missing completely. The Silver willow (Salix alba) and sometimes the black alder (Alnus glutinosa) are the largest and most common trees in this region.

In summary, the areal can be divided in three parts

  1. The Pasture: This is a large meadow between the dyke and the river. It's used as a pasture and also as a kind of basin for the water, when it occurs on the shore. In this area, you can find many different species, which are typical for wet meadows and extensively used pastures like Lamium album or Heracleum sphondylium.
  1. Gravel pit: The bottom of Rhine contains much gravel, which is used by industry as building material. The gravel is dug out by excavators. This creates large pits and a kind of ruderal wastelands with a denser soil. When flooded, the soil became muddy. Such places are settled by pioneers like Datura stromonium, Pulicaria vulgaris or Polygonum ficifolius.
gravel pit
  1. Sandbar & Gravel banks: Last but not least, the Field Trip leads to the shore of the Rhine. Here, we found two different types of soil: sand and gravel. In contrast to the gravel pit, the soil isn't dense and not so muddy (but some muddy places with silt are also possible). Anyway, this soils are also rather the home of pioneers like Stachys palustris, Bolbochoenus maritimus, Potentilla anserina or Cynodon dactylon.


    gravel shore
Curiously, you can also find some exotic species in this area, which are definetly not native to Germany. Their seeds were stranded by the river and sometimes, they begin to grow. Such species are different sorts of tomatoes (Solanum lycopersicum), melons (Cucumis agg.) or even rice (Oryza sativa). A large River like the Rhine is just a kind of dump and the seeds of such plants can enter the river by waste water or food waste.

another view on the gravel pit

Unfortunately, the areal was flooded for a long time and as a result, many plants aren't flowering. However, we still found many different species in the floodplains, as you can see on the following pictures.

2) Species

The following list contains the most important, interesting or typical plants, which were found in the area. Green are plants from the pasture, brown are plants from the gravel pit and yellow are plants from the sanbank and the gravel bank.

3) Pictures

3.1 Pasture

 Brassica nigra

 Eryngium campestre

Lamium album

Lysimachia vulgaris

 Lepidium latifolium

Sapponaria officinalis

Cichorium intybus
3.2 Gravel Pit

 Amaranthus albus 

 Amaranthus powelii

Chenopodium ficilifolius

 Chenopodium glaucum

Datura stramonium

 Euphorbia esula

 Medicago falcata

Pulicaria vulgaris

3.3 Sandbank & Gravel Bank

 Bolboschoenus maritiumus

Corispermum leptopterum

Cynodon dactylon

 Juncus compressus

 Potentilla anserina

 Salix alba

Butomus umbellatus

 Solanum lycopersicum

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