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Riparian flora of the Oker river

The Oker river flows through several different landscapes by a relative short length of about 125 km. From the source to the mouth it covers a change of altitude of 850 m. The riparian flora along the Oker is changing too. On basis of floristic similarity the river has been divided into eight different reaches. Species whose occurrence is mainly limited to one specific reach of the river are called "index-species". Often they are indicators for natural environment, geology, hydraulic engineering or agricultural exploitation.
 
 
Harz Mountains Hilly Harz foreland
I.
 Oker above Altenau
V.
 Oker between the edge of the Harz and Vienenburg 
II.
 Oker within Altenau
VI.
 Oker between Vienenburg and Schladen 
III.
 Oker dam
VII.
 Oker between Schladen and Braunschweig 
IV.
 Oker between dam and the edge of the Harz
Lowland
VIII.
 Oker between Braunschweig and the mouth
 

"Index-" species of the Oker reaches
Species / Reaches:
I
II
III
IV
V
VI
VII
VIII
Vaccinium myrtillus
V
.
.
II
.
.
.
.
Dryopteris dilatata
IV
.
.
II
.
.
.
.
Calamagrostis villosa
IV
.
.
I
.
.
.
.
Trientalis europaea
IV
.
.
I
.
.
.
.
Geranium sylvaticum
.
V
.
.
.
.
.
.
Polygonum bistorta
.
IV
.
.
.
.
.
.
Vicia sepium
.
IV
.
II
.
.
.
.
Poa chaixii
.
IV
.
I
.
.
.
.
Phyteuma spicatum
I
V
.
II
.
.
.
.
Alchemilla vulgaris agg.
I
V
.
I
.
.
.
.
Chelidonium majus
.
IV
.
.
.
.
I
I
Anthoxanthum odoratum
II
V
.
.
.
I
.
I
Ranunculus ficaria
I
IV
.
.
.
II
I
I
Veronica chamaedrys
.
V
.
I
I
.
II
I
Lapsana communis
.
V
II
.
.
II
I
I
Gnaphalium uliginosum
.
.
V
.
.
.
.
.
Spergularia rubra
.
.
IV
.
.
.
.
.
Juncus filiformis
.
.
IV
.
.
.
.
.
Carex ovalis
.
.
V
I
.
.
.
.
Rumex acetosella
.
.
V
.
.
.
.
I
Alopecurus aequalis
.
.
V
.
.
.
.
I
Galium uliginosum
.
.
IV
.
.
.
.
I
Rorippa palustris
.
.
V
.
I
.
.
I
Rumex crispus
.
.
V
.
.
.
I
I
Polygonum persicaria
.
.
V
I
.
.
I
I
Senecio viscosus
.
II
IV
.
II
I
.
I
Polygonum lapathifolium
.
.
V
.
.
.
II
II
Cardamine amara
.
.
.
V
II
II
.
.
Luzula luzuloides
.
II
.
IV
.
.
.
.
Carex remota
I
II
II
IV
.
.
.
.
Geranium robertianum
I
II
.
V
.
II
I
I
Silene vulgaris
.
II
.
I
IV
II
.
.
Armeria halleri
.
.
.
.
IV
I
.
.
Festuca ovina agg.
.
II
.
.
V
III
.
I
Impatiens glandulifera
.
.
.
I
I
IV
.
.
Mentha aquatica
.
.
.
.
II
IV
II
I
Viola tricolor
.
II
.
.
I
IV
II
I
Veronica hederifolia
.
.
.
.
.
V
II
I
Solidago gigantea
.
.
.
I
.
IV
II
I
Papaver rhoeas
.
.
.
.
II
I
IV
.
Angelica archangelica
.
.
.
.
.
.
.
V
Festuca arundinacea
.
.
.
.
.
.
I
IV
Rorippa amphibia
.
.
.
.
.
.
II
IV
Atriplex prostrata agg.
.
.
.
.
.
.
III
V
 
 
Longitudinal profile of the Oker river and its reaches
(changed and supplemented after WEBER-OLDECOP 1969)
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