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| Titel |
Soil aggregation, erodibility, and erosion rates in mountain soils (NW Alps, Italy) |
| VerfasserIn |
S. Stanchi, G. Falsone, E. Bonifacio |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1869-9510
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| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 6, no. 2 ; Nr. 6, no. 2 (2015-04-20), S.403-414 |
| Datensatznummer |
250115439
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| Publikation (Nr.) |
 copernicus.org/se-6-403-2015.pdf |
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| Zusammenfassung |
Erosion is a relevant soil degradation factor in mountain agrosilvopastoral
ecosystems that can be enhanced by the abandonment of agricultural land and
pastures left to natural evolution. The on-site and off-site
consequences of soil erosion at the catchment and landscape scale are
particularly relevant and may affect settlements at the interface with
mountain ecosystems. RUSLE (Revised Universal Soil Loss Equation) estimates
of soil erosion consider, among others, the soil erodibility factor (K),
which depends on properties involved in structure and aggregation. A
relationship between soil erodibility and aggregation should therefore be
expected. However, erosion may limit the development of soil
structure; hence aggregates should not only be related to erodibility but
also partially mirror soil erosion rates. The aim of the research was to
evaluate the agreement between aggregate stability and erosion-related
variables and to discuss the possible reasons for discrepancies in the two
kinds of land use considered (forest and pasture).
Topsoil horizons were sampled in a mountain catchment under two vegetation
covers (pasture vs. forest) and analyzed for total organic carbon, total
extractable carbon, pH, and texture. Soil erodibility was computed, RUSLE erosion
rate was estimated, and aggregate stability was determined by wet sieving.
Aggregation and RUSLE-related parameters for the two vegetation covers were
investigated through statistical tests such as ANOVA, correlation, and
regression.
Soil erodibility was in agreement with the aggregate stability parameters;
i.e., the most erodible soils in terms of K values also displayed weaker
aggregation. Despite this general observation, when estimating K from
aggregate losses the ANOVA conducted on the regression residuals showed
land-use-dependent trends (negative average residuals for forest soils,
positive for pastures). Therefore, soil aggregation seemed to mirror the
actual topsoil conditions better than soil erodibility. Several hypotheses
for this behavior were discussed. A relevant effect of the physical
protection of the organic matter by the aggregates that cannot be considered
in $K$ computation was finally hypothesized in the case of pastures, while in
forests soil erodibility seemed to keep trace of past erosion and depletion
of finer particles. A good relationship between RUSLE soil erosion rates and
aggregate stability occurred in pastures, while no relationship was visible
in forests. Therefore, soil aggregation seemed to capture aspects of actual
vulnerability that are not visible through the erodibility estimate.
Considering the relevance and extension of agrosilvopastoral ecosystems
partly left to natural colonization, further studies on litter and humus
protective action might improve the understanding of the relationship among
erosion, erodibility, and structure. |
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