7 research outputs found
Vegetation characteristics and eco-hydrological processes in a pristine mire in the Ob River valley (Western Siberia)
Relations between vegetation characteristics
and eco-hydrological processes were
assessed in a pristine mire in the valley of the
Ob River (Western Siberia). Along a transect
from the terrace scarp to the river, field data were
collected on vegetation composition, peat stratigraphy,
peat chemistry, hydrology and hydrochemistry.
Based on floristic composition, eight
vegetation communities were distinguished.
Hydraulic head measurements were used to
obtain an indication of groundwater flow directions.
The water balance of the mire was calculated
with a two-dimensional steady-state
numerical groundwater model. Water types were
defined based on cluster analysis of hydrochemical
data. The results revealed that the dominant
hydrological factor in the Ob mire is the discharge
of groundwater, which supplies about threefold
more water than net precipitation. Although the
discharge flux decreases with increasing distance
from the terrace scarp, high water levels and a
ââgroundwater-likeââ mire water composition were
observed in the major part of the study site.
Precipitation and river water play only a minor
role. Despite dilution of discharging groundwater
with rainwater, spatial differences in pH and
solute concentrations of the surficial mire water
are small and not reflected in the vegetation
composition. Although small amounts of silt and
clay were found in the peat in the proximity of the
river, indicating the occurrence of river floods in
former times, no river-flood zone could be recognized
based on hydrochemical characteristics or
vegetation composition. A comparison of the Ob
mire with well-studied and near-natural mires in
the Biebrza River valley (Poland) revealed
substantial differences in both vegetation characteristics
and the intensity and spatial pattern of eco-hydrological processes. Differences in the origin and ratios of water fluxes as well as a
dissimilar land use history would seem to be key
factors explaining the differences observed