ABSTRACTS / RESUMES - Comitato Glaciologico Italiano

ERIK L.H. CAMMERAAT
A hierarchical approach to the geomorphological
development of hillslope and catchment geomorphology:
two contrasting examples from a semi-arid
and a humid temperate region
Department of Physical Geography and Soil Science,
University of Amsterdam, Nieuwe Prinsengracht 130,
NL 1018 VZ Amsterdam, The Netherlands
In the last 5 years a new approach is being developed to
explain hillslope and catchment evolution from a systems
dynamic point of view, incorporating a hierarchical approach.
This approach to geomorphological evolution is
focusing on the spatio-temporal domains of relevant processes
as well as the linkage between processes and process
related patterns. Furthermore, it will be clear that erosion
and water fluxes are strongly related to biological controls
such as vegetation cover and pattern, and soil biological
activity. Between these three components water, soil and
vegetation/soil fauna feedback mechanisms exist, which
control eco-geomorphic processes. The approach followed
here is originally adapted from ecological system dynamics
approaches and is applied to understand the geomorphological
evolution for different types of geo-ecosystems.
In this presentation a demonstration is given using this approach
for two areas, with very different climatological
characteristics, and which results in a very different set of
processes and geo-ecosystem properties, driving geomorphological
evolution. One site is located in semi-arid
south-eastern Spain (in the Guadalent'n basin), and the second
demonstrates the application for a basin in temperate
humid Luxembourg. The processes and patterns in the semi-arid
area are driven by water limitation, and competition
for water whereas in the humid temperate areas
process-pattern relationships are directed by a surplus in
water.
This hierarchical approach is underlined by data which have
been collected and which are relevant for the different
spatio-temporal domains studied. They include monitoring
of temporal and spatial variation of fine scale properties
such as soil structure and soil biological activity. At all sea­
1es of interest monitoring of runoff and sediment yield and
through- and pipeflow were determined using both experimental
techniques and spatially nested designs of field
measurements.
For both areas the importance and linkage of fine scale
processes (soil aggregation, soil structural changes, soil
faunal activity), operating on a scale of the square meter, to
a broader scale is demonstrated, and their specific implication
for hillslope scale processes and patterns is indicated.
On this broader scale, both in space en time, other processes
are active (flow concentration and hillslope runoff, erosion
features, vegetation patterns) and are partially directed
by finer scale processes. The influence of the interme-
diate scale level on the basin scale is demonstrated and can
explain the geomorphological evolution of the catchment.
Also the influence of frequency magnitude relationships
for precipitation will be discussed as these, and other perturbations
have an important effect on the evolution of the
landscape.
It was found for the semi-arid sites that the patchiness of
the vegetation or vegetation structure, which reflects many
important fine and intermediate scale processes and properties,
determines the hydrological conditions under which
flow concentration and consequently erosion takes placeo
These processes are strongly influenced by biological
feedbacks in the system. For the humid temperate area, it
was concluded that runoff generating areas were strongly
related to the (micro- )topography, which was maintained
by clear feed-back mechanisms controlled by the effect of
soil biological activity on soil structure and preferential
flow paths of water. It can be concluded that, under seminatural
conditions, and under conditions recovering from
perturbations in the gee-ecosystem, the hierarchical approach
as presented here, can be used to explain hillslope
and basin geomorphological evolution.
NICOLETTA CANNONE 1, MAURO GUGLIELMIN 2 ,
& AUGUSTO PIROLA 1
Alpine vegetation in the periglacial environment
and the effect of a different Holocenic glacial evolution
(M. Foscagno area, Upper Valtellina, Italy)
1Istituto di Botanica, Universita di Pavia,
via S. Epifanio 14, 27100 Pavia, Italy
2 Servizio Geologico, Regione Lombardia, via F. Filzi 22, Milano, Italy
The aim of this work is the analysis of alpine and snowpatch
vegetation in an area interested by periglacial phenomena
and, partially, by old glacial episodes to verify if there
is an influence of these phenomena on the composition
and the characteristics of vegetation and in which way this
influences are expressed. The study area is Monte Foscagno,
Upper Valtellina, Italy. In particular, were studied
two opposite slopes of Monte Foscagno: the glacial cirque
La Foppa and, on the other side, the valley named La Vallaccia.
In the glacial cirque La Foppa is possible to observe
tardiglacial moraines, many rock glacier, of which has been
described the rock glacier named La Foppa I, poligonal
soils, striped soils and boulder stream. La Vallaccia is characterized
by periglacial forms of which the most important
is a rock glacier with complex degree of activity that
results one of the widest rock glacier of Lombardy. The
upper part of La Vallaccia has been interested by recent
glacial episodes: in fact, here there are many late Holocenic
moraines, probably of the Little Ice Age.
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