 |
| Titel |
Structures and processes of biological soil crusts during initial ecosystem genesis of an artificial watershed in Lusatia, NE Germany |
| VerfasserIn |
Roland Spröte, Thomas Fischer, Maik Veste, Aaron Yair, Wolfgang Wiehe, Philipp Lange, Oliver Bens, Thomas Raab, Reinhard F. Hüttl |
| Konferenz |
EGU General Assembly 2010
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250035121
|
|
|
|
|
|
| Zusammenfassung |
| The influence of biological soil crusts (BSC) in natural ecosystems on structures
and processes is well investigated. In southern Brandenburg (NE Germany) it was
possible to study the development of BSCs during initial ecosystem genesis on the
artificial water catchment “Hühnerwasser”. The experimental site is located in the
recultivation area of the lignite open-cast mining district of southern Brandenburg
(Germany).
The geomorphological differentiation at the site was related to crust development, where
substrate-dependent water availability defined the crust types. The mosaic-like pattern of the
BSCs was associated with the distribution of fine-grained material. We defined three types if
BSC: (a) initial cyanobacterial crusts (BSC-I), (b) cyanobacterial and green algae crusts on
the soil surface (BSC-CG) and (c) crusts with mosses (BSC-M) between dense vegetation.
The chlorophyll A content as an index for the biomass of the cryptogams increased
significantly with crust type from 0.97 mg m-2 (BSC-I), 6.34 mg m-2 (BSC-CG) to 13.32
mg m-2(BSC-M).
The sandy substrates with high contents of silt and clay were poorly sorted and spatially
re-distributed by fluvial and aeolian processes. The contents of silt and clay were
15.9%-23.8% in the cyanobacterial crusts (BSC-I, BSC-CG) and 30.5% in the moss-crust
(BSC-M). The pH values were about 7 (neutral) in all BSCs. The heighest Corg contents
were found in BSC-CG (0.51%), but were not significantly lower in BSC-I (0.47%)
and BSC-M (0.44%), where Corg concentrations of the original substrate ranged
from 0.16 to 0.22% at construction of the catchment. The BSC types were very
heterogeneously distributed and developed. Different crust types occurred in small-scale
patches.
Cyanobacteria which exude mucilaginous material and the rhizoids and protonemata of
mosses contributed to aggregating sand grains and enhanced the topsoil stability.
Furthermore, filamentous cyanobacteria and algae partially filled in the matrix pores and
enmeshed sand grains, and in a wet condition extracellular polymeric substances (EPS)
clogged the available pore space.
Once settled, the crusts influenced the water regime of the soils. They were not
pronounced hydrophobic, yet surface polarity differed between the crust types. Water
infiltration was influenced by two factors: (i) the crust type, where infiltration rates were
highest on almost bare substrate (BSC-I) and least when cyanobacteria and green algae
formed a dense cover on the surface (BSC-CG), and (ii) the texture. Compared to BSC-CG,
infiltration rates were elevated in BSC-M, pointing to decline of surface sealing when mosses
penetrated the dense microphytic crust. However, the relationships among crust types, water
repellency, particle size composition and infiltration are complex and need further
investigation on different scales.
This project is part of the Transregional Collaborative Research Centre 38 “Structures and
processes of the initial ecosystem development phase in an artificial water catchment” and
funded by the Deutsche Forschungsgemeinschaft. |
|
|
|
|
|
|