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| Titel |
Hydraulic and nutritional feedback controls surface patchiness of biological soil crusts at a post-mining site. |
| VerfasserIn |
Thomas Fischer, Stella Gypser, Maria Subbotina, Maik Veste |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250105102
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| Publikation (Nr.) |
 EGU/EGU2015-4551.pdf |
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| Zusammenfassung |
| In a recultivation area located in Brandenburg, Germany, five types of biocrusts (initial BSC1,
developed BSC2 and BSC3, mosses, lichens) and non-crusted mineral substrate were
sampled on tertiary sand deposited in 1985-1986 to investigate hydrologic properties of
crust patches. It was the aim of the study to demonstrate that (I) two types of BSC
with alternative nutritional and hydraulic feedback modes co-exist in one area and
that (II) these feedback modes are synergic. The sites to sample were selected by
expertise, trying to represent mixed sites dominated by mosses, by lichens, and by
visually in the field observable surface properties (colour and crust thickness) for the
non-crusted substrate and BSC1 to 3. The non-crusted samples contained minor
incrustations of the lichen Placynthiella oligotropha, young leaflets of the moss Ceratodon
purpureus, as well as very sparsely present individuals of the green algae Ulothrix spec.,
Zygogonium spec. and Haematococcus spec. The sample BSC1 was not entirely covered
with microphytes, crust patches were smooth, and P. oligotropha was observed to
develop on residues of C. purpureus and on unspecified organic detritus. BSC2
covered the surface entirely and was dominated by P. oligotropha and by Zygogonium
spec. The sample BSC3 consisted of pad-like patches predominantly growing on
organic residues. The moss sample was dominated by C. purpureus and Zygogonium
spec. growing between the moss stemlets directly on the mineral surface, the lichen
sample was dominated by Cladonia subulata with sparsely scattered individuals of C.
purpureus. Hierarchical cluster analysis revealed that BSC2 was floristically and
chemically most similar to the moss crust, whereas BSC3 was floristically and
chemically most similar to the lichen crust. Crust biomass was lowest in the non-crusted
substrate, increased to the initial BSC1 and peaked in the developed BSC2, BSC3, the
lichens and the mosses. Water infiltration was highest on the substrate, and decreased
to BSC2, BSC1 and BSC3. Non-metric multidimensional scaling revealed that
the lichens and BSC3 were associated with water soluble nutrients (NO3, NH4,
K, Mg, Ca) and with pyrite weathering products (pH, SO4), thus representing a
high nutrient low hydraulic feedback mode. The mosses and BSC2 represented a
low nutrient high hydraulic feedback mode. These feedback mechanisms were
considered as synergic, consisting of run-off generating (low hydraulic) and run-on
receiving (high hydraulic) BSC patches. Three scenarios for BSC succession were
proposed. (1) Initial BSCs sealed the surface until they reached a successional stage
(represented by BSC1) from which the development into either of the feedback modes was
triggered, (2) initial heterogeneities of the mineral substrate controlled the development
of the feedback mode, and (3) complex interactions between lichens and mosses
occurred at later stages of system development. It was concluded that, irrespective of
successional pathways, two synergic feedback mechanisms contributed to the generation
of self-organized surface patchiness. Such small-scale microsite differentiation
with different BSCs has important implications for the vegetation in post-mining
sites.
Reference
Fischer, T., Gypser, S., Subbotina, M., Veste, M. (2014) Synergic hydraulic and
nutritional feedback mechanisms control surface patchiness of biological soil crusts on
tertiary sands at a post-mining site. Journal of Hydrology and Hydromechanics
62(4):293–302 |
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