Acta geographica Slovenica, 58-2, 2018, 87–100
THE ENHANCEMENT OF CULTURAL
LANDSCAPES IN MOUNTAIN
ENVIRONMENTS: AN ARTIFICIAL
CHANNEL HISTORY (TORRENT-NEUF,
CANTON VALAIS, SWITZERLAND) AND
THE ROLE OF TREES AS NATURAL
ARCHIVES OF WATER FLOW CHANGES
Irene Bollati, Emmanuel Reynard, Davide Cagnin, Manuela Pelfini
The Torrent Neuf artificial channel in the section excavated in the argilloschists.
Specimens of Picea abies (L.) H. Karst., on which dendrochronological analysis
was performed, are distributed along the channel.
IR
E
N
E
 B
O
L
L
A
T
I
58-2_07p_4137-Irene Bollati_acta49-1.qxd  12.9.2017  9:01  Page 87
Irene Bollati, Emmanuel Reynard, Davide Cagnin, Manuela Pelfini, The enhancement of cultural landscapes in mountain …
DOI: https://doi.org/10.3986/AGS.4137
UDC: 911.53:582.091(494)
COBISS: 1.01
The enhancement of cultural landscapes in mountain environments: An artificial
channel history (Torrent-Neuf, Canton Valais, Switzerland) and the role of trees
as natural archives of water flow changes
ABSTRACT: Cultural landscapes represent one of the best examples of the interaction between human
and natural environment and cultural trails are an effective way for their valorization. The Torrent-Neuf
(Canton Valais, Switzerland) is a cultural trail realized in 2009 along one of the artificial channels used in
the region since Medieval times to move water resources from tributary valleys to irrigated lands. Slope
instability processes and high maintenance costs provoked the abandonment of the artificial channel in
1934. In 2005 water flow was restored in it. Dendrochronological analyses, carried out on trees growing
along the artificial channel banks, allowed collecting information about natural and man-induced hydro-
logical changes, contributing to increase the global value of the whole area.
KEY WORDS: cultural landscape, tree rings, geomorphological processes, Bisses (artificial channels), cul-
tural trails, Swiss Alps
Povečanje vrednosti kulturnih pokrajin na gorskih območjih: zgodovina
namakalnega kanala Torrent-Neuf v švicarskem kantonu Valais in vloga
dreves kot naravnih arhivov sprememb v vodnem pretoku
POVZETEK: Kulturne pokrajine so eden najboljših primerov interakcije med človeškim in naravnim okoljem,
kulturne poti pa so učinkovit način njihovega vrednotenja. Kulturno pot Torrent-Neuf v švicarskem kantonu
Valais so odprli leta 2009. Poteka ob enem izmed namakalnih kanalov, ki so jih na tem območju vse od
srednega veka uporabljali za to, da so vodo iz rečnih dolin speljali na namakalna zemljišča. Zaradi pobočnih
procesov in visokih vzdrževalnih stroškov so kanal leta 1934 opustili, leta 2005 pa vanj znova napeljali vodo.
Z dendrokronološkimi analizami dreves, ki rastejo na njegovih bregovih, so bili zbrani podatki o naravnih
in antropogenih hidroloških spremembah, kar je prispevalo k povečanju splošne vrednosti celotnega območja.
KLJUČNE BESEDE: kulturna pokrajina, drevesne letnice, geomorfološki procesi, umetni kanali, kulturne
poti, švicarske Alpe
Irene Bollati, Davide Cagnin, Manuela Pelfini
Earth Science Department, Università degli Studi di Milano
irene.bollati@unimi.it, cagnin.davide@gmail.com, manuela.pelfini@unimi.it
Emmanuel Reynard
Institute of Geography and Sustainability, University of Lausanne
emmanuel.reynard@unil.ch
The paper was submitted for publication on February 2nd, 2016.
Uredništvo je prejelo prispevek 2. februarja 2016.
88
58-2_07p_4137-Irene Bollati_acta49-1.qxd  12.9.2017  9:01  Page 88
1 Introduction
Within the European Landscape Convention, landscape is defined as »an area, as perceived by people, whose
character is the result of the action and interaction of natural and/or human factors« (Niţă et al. 2015). Landscape
may assume different values in relation to human perception (Panizza and Piacente 2003). The relation-
ship between human communities and the natural environment is close and may change during time mainly
as a consequence of climate change influencing geomorphological processes (e.g., Evans and Clague 1994),
of land use (e.g., Serra, Pons and Saurí 2008) and of economic and cultural factors (e.g., Fan et al. 2014).
Vice versa, human activities influence and affect landscape evolution itself (e.g. Goudie 2013).
The combination of natural modeling of a territory and human action gives origin to cultural landscapes
that are more precisely defined by UNESCO (2012) as »cultural properties [that] represent the combined works
of nature and of man.« Examples of human artifacts contributing to the delineation of cultural landscapes
are present in very different morphoclimatic and morphogenetic environments. »The dying town« of Civita
di Bagnoregio (Central Italian Apennines) (Figure 1) is one of the most exemplar cases for the troubled human-
nature relationship due to the strict interaction between active badlands shaped on clays (i.e., geological
heritage) and the town (i.e., cultural heritage). The village, built on a residual mesa using blocks from the
more resistant volcanoclastic deposits, is »dying« as a consequence of the lowering of the shale topographic
level and the contemporary retreat of volcanoclastic cliffs due to rockfalls (Gregori 2011).
Human-induced changes may be more or less persistent depending on the local environmental char-
acteristics, as explained by Latocha (2015) about a National Park of Ireland, where old anthropogenic landforms
persist despite strong depopulation after the middle nineteenth century. Such signs of the long-lasting
human–environmental interaction may become meaningful educational opportunities (Latocha 2015). This
is also the case of the remnants of the 1st World War conserved inside glaciers and in some high mountain
sites, as in the Alps (Ortles-Cevedale Group; Diolaiuti and Smiraglia 2010). High mountain environments
represent in particular key areas to observe the ongoing rapid changes in natural biotic (e.g. tree line shifting;
Leonelli, Pelfini and Morra Di Cella 2009; or colonization of deglaciated areas by vegetation; Garbarino
et al. 2010) and abiotic systems (e.g., glacier fluctuations; Diolaiuti and Smiraglia 2010) also in relation
with human activities (e.g., impact of tourism on erosion rates along mountain trails; Pelfini and Santilli 2006).
More in detail, at higher altitudes glacier advances and retreats conditioned hydrological availability
Acta geographica Slovenica, 58-2, 2018
89
Figure 1: Civita di Bagnoregio (Central Italian Apennine), the »dying town«, is a cultural landscape, where the nature-man interaction is particularly
meaningful. The town is a candidate for the insertion in the UNESCO World Heritage List. The access to the town is granted by an artificial viaduct due
to erosional lowering of the topographic surface that connects Civita to the main Bagnoregio town.
IR
E
N
E
 B
O
L
L
A
T
I
58-2_07p_4137-Irene Bollati_acta49-1.qxd  12.9.2017  9:01  Page 89
Irene Bollati, Emmanuel Reynard, Davide Cagnin, Manuela Pelfini, The enhancement of cultural landscapes in mountain …
90
(Barnett, Adam and Lettenmaier 2005), travelling possibilities in the past and economic activities as sum-
mer skiing in more recent times (e.g., Diolaiuti et al. 2006). As a cascade effects, at lower altitudes, cultivated
areas changed in their location according with stream activities and modifications (e.g., Piao et al. 2010).
In recent times cultural and thematic paths have been proposed to promote natural and cultural land-
scapes accompanied by guides and/or panels, helpful for acquiring knowledge about the changing landscapes
under changing climate conditions (Garavaglia and Pelfini 2011) or human activities. Changes in land-
scape features, such as the aesthetic attributes (Smrekar, Polajnar Horvat and Erhartič 2016), influence the
landscape perception by local populations, visitors and tourists (Garavaglia et al. 2012; Schirpke et al. 2013)
as well as socio-economic changes can impact on the immaterial cultural heritage (Hidalgo, Borsdorf and
San Martín 2014). In the particular case of mountain landscapes, many human activities were abandoned
during the past decades, with serious consequence on the loose of cultural traditions (Benayas et al. 2007)
and territory maintenance, as it is the case of slope terraces (Tarolli, Preti and Romano 2014). An exam-
ple of ancient abandoned activities interacting with natural components (i.e., water, geomorphological
processes and vegetation) is represented by the network of artificial channels that have been used since
Medieval times to irrigate agricultural land in the Rhone River watershed (Canton Valais, Switzerland)
(Lehmann 1913; Mariétan 1948; Bratt 1995; Papilloud 1999; Reynard 2008). They are called Bisses in the
French speaking part of the canton and Suonen or Wasserleite in the German speaking area. The unstable
conditions provoked by active geomorphic processes on the mountain slopes (Michelet 1998), along which
some of the suspended channels were built, were responsible for the very high maintenance costs, induc-
ing their abandonment. It is the case of the Torrent-Neuf (translation: »new channel«; TN) (see Figure 2a),
a channel located in the Savièse municipality was built between 1430 and 1448 AD. The TN was partly
abandoned and replaced by an underground tunnel between 1934 and 1935 (Mariétan 1934; Schweizer
and Reynard 2011). An interesting project of restoration, started in 2001, was addressed to the creation
of a cultural trail to enhance the channel building techniques and the relations with the natural environ-
ment (Figure 2), especially with the geomorphological processes active along the trail itself.
The restoration was aimed at recovering an important cultural component of the landscape (Hauge
1988) to favor inhabitants and tourists’ behavior towards environmental conservation (Zhang et al. 2015).
In the cultural landscape evaluation, multidisciplinary approaches to investigate interaction between
biological and abiological components of the environment are growing in importance (Büntgen et al. 2006;
McEwan and Mc Carthy 2008; Leonelli, Pelfini and Morra Di Cella 2009; Bollati et al. 2016). Among them,
dendrochronological analyses are considered precious source for environmental and climatic informa-
tion (Fritts 1976) as well as human impact (Röpke et al. 2011; Leonelli et al. 2012) and evolution rates
(Bollati et al. 2012; Stara, Tsiakiris and Wong 2015) as trees record them in the annual rings characteristics.
Figure 2: Building techniques used for the TN, from less resistant lithotypes on the left to more resistant lithotypes on the right: a) normal cross section
of the channel; excavation in the more erodible lithotypes (photo by Bollati Irene); b) channel cut into the rock (photo by Cagnin Davide); c) hanging
channel; especially used for more resistant lithotypes (photo by Reynard Emmanuel). Sketches by Schmid (1935): in white, soft rocks (see section a);
in grey, hard rock, in section b and c.
58-2_07p_4137-Irene Bollati_acta49-1.qxd  12.9.2017  9:01  Page 90
Dendrochronological analyses have been recently performed to investigate the evolution rate of cultural
landscapes (Bollati et al. 2012; Stara et al. 2015). 
The aim of this work is: i) to analyze the role of trees bordering the TN banks as a natural archive of
natural and man-induced hydrological changes; ii) to assess the educational value of tree rings as a source
of information about drainage changes, possibly adding value to the cultural landscape; iii) to improve the
global value of the trail in relation with its historical, geomorphological, natural and emotional components.
2 Study area
The TN runs along the left side of the Morge River, a right tributary of the Rhone River (Fig. 3b). In this part
of the Rhone River watershed, climate is continental, characterized by low mean annual rainfall (600 mm/y
as recorded at Sion meteorological station (SMS) 500 m a.s.l., 4 km away from the study area; data:
Meteoswiss … 2016), high mean annual temperature, relatively to the geographical position of the site with-
in the Alps (9.6°C in Sion) and a strong daily and annual thermal excursion (Reynard 1995). Annual rainfall
altitudinal gradient is estimated to be 35 mm/100 m below 1500 m a.s.l. Therefore, the mean annual rain-
fall in the studied area (1150 m, Figure 3a) is about 830 mm/y. Mean annual temperature is about 7.1°C.
The Morge River valley is eroded by fluvial and glacial processes in sedimentary rocks of the Helvetic
domain (Masson, Herb and Steck 1980), owing to the Sublage nappe. In the middle part of the valley con-
cerned by this research, limestone alternates with schist levels. Due to the nappe configuration and the
general dipping of rock strata towards South-East, the transverse profile of the Morge River valley is very
asymmetric: the left side of the valley – the sector occupied by the investigated artificial channel – is very
steep, whereas the right side presents more gentle slopes. On the left side, the most frequent slope process-
es are rock falls, debris flows and debris and snow avalanches that frequently damaged the TN (Michelet 1998).
Along the TN, the alternation of lithologies, characterized by different resistance to erosion, geotechni-
cal stability and permeability properties, induced the use of different techniques suitable for the different
rock typologies (Mariétan 1961; Reynard et al. 2012) (Figure 4). Where calcareous lithotypes are more abun-
dant, the suspended channel techniques (Figure 2c) were preferred to the excavation (Figures 2a; 2b) that
is more suitable for the argilloschists outcrops and it is the most used in the entire Canton of Valais. 
Due to the slope processes affecting especially the upper part of the TN, the open-air tunnel was replaced
by an underground tunnel in 1934–1935 (Mariétan 1934; Schweizer and Reynard 2011). Water flow was
reactivated in some sections of the TN only in 2001. In 2008, within the framework of a cantonal trend
of revaluation of artificial channels, the Association pour la Sauvegarde du Torrent-Neuf (Internet 1) and
the municipality of Savièse started the refurbishment of the TN path aimed to tourist use. In 2009 the TN
was first re-opened to public after being equipped with informative panels about the history and build-
ing techniques (Reynard et al. 2012). Moreover, according to the analysis of geomorphic processes insisting
on the trail (Michelet 1998), infrastructures that combine safety conditions and adrenaline experience for
the users were designed along the trail (i.e., Tibetan bridges) (Figures 4a, 4b). The banks of the TN are
characterized, especially in the excavated final reach where argilloschists outcrop, by abundant vegetation
among which Norway spruce (Picea abies L. Karst. – PaK) is dominant.
3 Methods
Dendrochronological investigations were conducted on trees growing on the TN banks in the portion where
argilloschists mainly outcrop, and in the surrounding area. As reported in literature, tree rings allow detec-
tion of natural water scarcity with a response that differs according to the species (Abrams, Ruffner and
Morgan 1998) and climate context (Mediterranean climate; Battipaglia et al. 2009). The response of PaK
to climate variations depends also on the altitude of the specimens (Modrzynski and Eriksson 2002). In
various study cases PaK demonstrated to be sensitive to drought stress (Burczyk and Giertych 1991) as
for the Northern forest ecosystems (Aakala and Kuuluvainen 2011), also in sites with similar mean cli-
mate conditions as those of the study area (Gryc et al. 2012). Severe droughts may even lead to suffering
as far as mortality of trees (e.g., Ogle, Whitham and Cobb 2000), especially when associated with rocky
or stony substrate (Mäkinen, Nöjd and Mielikäinen 2001) or other severe disturbances (i.e., fire, human
activity, insects; Liang et al. 2003).
Acta geographica Slovenica, 58-2, 2018
91
58-2_07p_4137-Irene Bollati_acta49-1.qxd  12.9.2017  9:01  Page 91
Irene Bollati, Emmanuel Reynard, Davide Cagnin, Manuela Pelfini, The enhancement of cultural landscapes in mountain …
92
Conthey
Sion
Savièse
Grimisuat
Arpelistock
Sublage
Sérac
Wildhorn
Prabé
Prabé Tunnel
Pra
bé 
pip
e
Tsa
nd
ra 
cha
nn
el
Len
tine
 cha
nne
l
Torrent–N
euf
Torre
nt-Ne
uf
Mt Gond
Fava
Sanetschhorn
 
M
o rge River
 Crests and main peaks
Rivers
Main localities
Fig. 5
Bridge
Fig. 4a
Main channels (still in use)
Prabé tunnel and
underground pipes in use
since 1935
Part of the Torrent–Neuf
channel not in use
between 1935–2001
N
0 1 2 km
Tsan#euron
Glacier
Brotset
Glacier
Rh
on
e R
ive
r
Morge River
watershed
Sion
Zermatt
Monte Rosa
Martigny
Brig
Visp
0 10
km
Areas with numerous
bisses and Suonen 
Areas with annual
rainfall < 800 mm
Areas with annual
rainfall > 2800 mm 
SWITZERLAND
Valais
a
b
Si
on
ne
 R
iv
er
M
orge River
N
ét
ag
e R
iv
er
Rho
ne R
iver
Figure 3: Geographic location and climatic setting of the study area: a) Map of Valais with position of the Morge River watershed;
b) Map of the Morge River watershed with the main hydrographic and irrigation features and location of Figure 5.
58-2_07p_4137-Irene Bollati_acta49-1.qxd  12.9.2017  9:01  Page 92
Rigling et al. (2003) investigated, in a similar physiographic area as that of the TN, by means of den-
drochronological analyses the response of Pinus sylvestris L. to artificial hydrological changes. They found
out that irrigation mitigates the negative effect of climate on the trees and the correlation between radial
growth and the summer temperature changes is positive. They registered in addition a radial growth break-
down due to the cessation of irrigation and a period of 6 years necessary for a complete recovering. 
In the present work, the analyses were focused on PaK and the attention was mainly addressed towards
the time interval of water flow interruption (1934/1935–2001/2005). The sampling of PaK was performed
during summer 2010, focusing on three main clusters of trees along the TN banks (Figure 5):
• 16 trees in the portion of the TN that was completely closed to water flow during the time interval
1934/1935–2001/2005 (D);
• 14 trees in the down valley portion of the TN that was always in use (I);
• 15 trees in the stand uphill to the TN, where the TN influence is considered to be totally absent. This
group is considered as the reference site (R).
Two cores for each tree were taken using an increment borer, at the standard height of 1.30 m. Tree-
rings width was measured (accurate to 0.01 mm) using the LINTAB and TSAP systems (Rinn 1996), and
image analysis was made with WinDENDRO software (Regent Instruments Inc. 2001). The cross-dating
of the dendrochronological series was processed visually, considering the coefficients GLK (Gleichläufigkeit;
Acta geographica Slovenica, 58-2, 2018
93
IR
E
N
E
 B
O
L
L
A
T
I
Figure 4: Different views of the TN cultural trail: a) one of the Tibetan bridges as visible from the road running on the opposite side of the Morge valley,
in 2010; b) the same bridge taken from the trail in 2010; c) the forest and the TN in 2011, in the area where dendrochronological sampling (series D)
was performed in 2010.
58-2_07p_4137-Irene Bollati_acta49-1.qxd  12.9.2017  9:01  Page 93
Irene Bollati, Emmanuel Reynard, Davide Cagnin, Manuela Pelfini, The enhancement of cultural landscapes in mountain …
Eckstein and Bauch 1969) and the Cross Date Index – CDI (Schmidt 1987), and then statistically using
the COFECHA program (Correlation Coefficient, C; Holmes, Adams and Fritts 1986). Mean chronologies
were built from single growth curves and then the growth trend responsible of masking growth anomalies
were removed using Arstan software (Cook 1985) through the application of an individual spline.
The anomaly index, based on the yearly percentage growth variation (positive and negative) with respect
to the mean of the four previous years, with threshold values at 40%, 55% and 70%, was considered for
investigating abrupt growth changes (e.g., Bollati et al. 2012). This index is usually an indicator of the suf-
fering of trees and, in the specific case, the correlation with the natural or artificial water privation was searched
for. The comparison of abrupt growth changes in R, I and D series and with climatic data acquired at the SMS
were used for discriminating the origin of the anomalies and for discussing the possible effects of the water
diversion.
4 Results
The average indexed chronologies of the R, D, I clusters of trees of PaK for the time interval 1901–2009
are reported in Figure 6a. Anomaly indexes are reported in Figure 6b.
The quantitative parameters show good correlation values: GLK > 69, CDI > 70 and C = 0.399–0.645.
94
T
or
re
n
t–
N
eu
f
Aba
ndo
ned
 sec
tor
Se
cto
rU
nd
er
gr
ou
n
M
or
ge
 R
iv
er
Figure 5: Sampling clusters of PaK along the TN: D, portion of the TN that was closed to water flow during the time interval 1934/1935–2001/2005;
I, down valley portion of the TN that has been always in use; R, stand uphill to the TN, not in direct contact with the TN, considered as reference site.
Figure 6: Comparison between results from dendrochronological analysis and climate records from SMS; data: Meteoswiss) for the time interval 1901–2009.
a) Standardized tree ring chronologies in sites R, I, D, and Average; the stars indicate drought events that find correspondence in the growth rate;
b) Anomaly index (%) for R, I, D, and Average chronologies for the time interval 1904–2009; c) Annual and Spring + Summer (March to August)
rainfall depths. Representation of dry years when annual (black circle) and Spring + Summer (grey circle) or both (black dot) rainfall depths are below
the average on the considered time interval (1901–2009); d) Mean Summer temperature.p
m
58-2_07p_4137-Irene Bollati_acta49-1.qxd  12.9.2017  9:01  Page 94
Acta geographica Slovenica, 58-2, 2018
95
0
0,
2
0,
4
0,
6
0,
81
1,
2
1,
4
1,
6
1,
8
R
I
D
A
ve
ra
ge
1516171
8
19202
1
222
30
10
0
20
0
30
0
40
0
50
0
60
0
70
0
80
0
90
0
A
n
n
u
al
 r
ai
n
fa
ll
 (
m
m
)
Sp
ri
n
g+
 S
u
m
m
er
 r
ai
n
fa
ll
 (
m
m
)
A
n
n
u
al
 m
ea
n
 r
ai
n
fa
ll
 (
m
m
)
Sp
ri
n
g 
+
 S
u
m
m
er
 m
ea
n
 r
ai
n
fa
ll
 (
m
m
)
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
Standardized detrended
Chronologies–Index
Rainfall (mm) Summer temperature (°C)–
12
0
–
10
0
–
80
–
60
–
40
–
200204060
R
I
D
A
ve
ra
ge
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
Anomaly Index (%)
58-2_07p_4137-Irene Bollati_acta49-1.qxd  12.9.2017  9:01  Page 95
Irene Bollati, Emmanuel Reynard, Davide Cagnin, Manuela Pelfini, The enhancement of cultural landscapes in mountain …
Visually, no opposite growth trends were highlighted among the series, not even in the time intervals
close to 1934/1935 and 2001/2005, when a different behavior could be expected at least between I and D
series.
The comparison with climatologic data (Figure 6c, 6d) helped us in detecting which anomalies may
be due to natural droughts, generally those present in all the chronologies, and which ones are instead relat-
ed to artificial water suppression.
For what concerns the climatic record, an evident increase in summer temperatures was recorded in
specific years (e.g., 1904, 1911, 1921, 1925, 1941–1943, 1949, 1962, 1964, 1976, 2003; Figure 6d). Analyzing
the seasonal rainfall data in the time interval 1901–2009, dry years, in which the annual or spring-sum-
mer (March to August) rainfall depths are below the average for the period, could be detected. The drought
events are distinguished with different symbols in Figure 6c.
Years characterized by rainfall scarcity are highlighted by the anomaly indexes (Figure 6b). The main
negative growth anomalies correspond to the years 1920–1921, 1933–1934, 1972, 1975–1976, 1984, 1996,
1998, 2003. In some cases the negative anomaly continued also in the next years (i.e., 1933–1934, 2003).
Moreover, the most negative values of the anomaly index were recorded when low rainfall depths were
registered for consecutive years (e.g., 1920–1921, 1933–1934, 1972–1976, 1996–1998).
Tree rings series, before the TN deviation, show how drought events (i.e., 1920–1921) induced a more
severe negative anomaly in the R series, the only one that could not benefit of the TN water supply.
In the tree ring chronologies, the 1934 year, when trees were water flow deprived, is in the framework
of a general negative trend (Figure 6b) that had yet started in 1933 and would culminate in 1935 in all the
D, I and R series (40–55% tree cores with negative anomaly). The starting of the negative anomaly, before
the TN deviation, may suggest that the closure was not the cause of the abrupt growth reduction. Nevertheless,
the D series recorded growth values below I and R series starting from the year 1934 until 1944. The D series
shows a more difficult recovering after the low annual rainfall period started two years before. It suffered
the water privation more deeply than R series because probably less accustomed to water scarcity. In fact the
previous drought events were mitigated, for the trees of the D series, by the artificial water supply. In the
same time interval, I series, on the contrary, look like to respond less severely to drought than the D and
R series since the water was still provided abundantly along this reach of the TN. Hence, for this first event
of water supply change, the only difference among the series that emerges from tree rings seems to consist
in the magnitude of the negative growth change (Figure 6a, 6b) and the relative velocity in recovering pos-
itive growth values.
For what concerns the re-opening of the TN, in the time interval 2001–2005, an evident positive anom-
aly was recorded in all the three chronologies in 2001 (Figures 6a, 6b). The series directly involved in the
activity of the TN (I and more D) present a greater positive peak in 2001 respect to R series and this behav-
ior may be probably linked with the renewed water availability through the TN. A severe drought event
in 2003, a year characterized by high temperature and low rainfall depths, once again provoked a tree suf-
fering until 2007, as evidenced in all the series. This natural drought event was less suffered by the I series
probably for the more constant water supply through time respect to D series and for the supplementary
water contribution by TN respect to the R series.
5 Discussion and conclusion
The different phases of human interventions on the TN reflect the response to both human needs and nat-
ural conditions along the left side of the Morge River valley: 1) the building of the first TN track along the
Mount Prabé flanks, due to the necessity of a supplementary water contribute due to the regional climat-
ic conditions; 2) the artificial diversion of the TN inside the mountain due to the water driven and gravity
processes interesting the mountain side, and the relative costs of maintenance; 3) the restoration of the
original path as a cultural trail adopting special devices in order to guarantee the coexistence of tourism
with geomorphic processes in safety conditions.
Along the cultural trail, following the ancient track of the TN, it is possible to make observations on
the relationships between human and natural environment in terms of both impact and risk (Cendrero
and Panizza 2009).
96
58-2_07p_4137-Irene Bollati_acta49-1.qxd  12.9.2017  9:01  Page 96
Dendrochronological investigations on PaK allowed us to make some interesting observations on the
relationships between climate, vegetation and human activities (i.e., impact). The TN does not represent
an environment so limited by climate to induce suffering or marked growth decrease in trees after water
diversion. The analyzed PaK confirm anyway a sensitivity to rainfall regime by well recording the drought
years. According to Rigling et al. (2003) man-induced hydrological change may mitigate or exasperate the
negative effect of natural hydrological change on trees. Even if the water diversion along the TN did not heav-
ily affected trees growth neither when the TN was closed nor when water started to flow again, the TN
chronologies show: 1) how depletion in water availability may influence and slow down the recovery of a »normal
growth« after drought years; 2) drought years less affect tree growth when the TN is active. Hence, trees grow-
ing on the TN banks recording the drainage changes and climate events, represent new opportunities to
disseminate knowledge deciphered from natural archives (Garavaglia and Pelfini 2011; Bollati et al. 2011).
For what concerns the second aspect (i.e., risk), in the central portion of the trail, where Tibetan bridges
allow the visitors to cross debris flow prone areas (Figures 4a, 4b), the effects of geomorphological process-
es inducing the channel abandonment are clearly observable in safety conditions. Here the emotional
component of the landscape favors the knowledge of hazardous processes and increases the value of the
cultural trail and landscape, offering possible applications in terms of hazard and risk education (Pelfini
et al. 2009; Coratza and De Waele 2012).
Both the natural components considered in this research (i.e., trees as archives of hydrological, climatic
and human related data and geomorphological features testifying hazards) increase the scientific and edu-
cational values of this cultural landscape, especially in relation with its historical and emotional components.
These results can be proposed as a new way of »reading« the environmental history widening the poten-
tial public that is interested not only in the recovery of cultural traditions but also in the interactions between
natural and cultural components of a dynamic landscape.
ACKNOWLEDGEMENT: We thank the Institute of Geography and Sustainability of the University of
Lausanne for funding part of this research and Jean-Michel Fallot (University of Lausanne) for providing
climatic data.
7 References 
Aakala, T., Kuuluvainen, T. 2011: Summer droughts depress radial growth of Picea abies in pristine taiga
of the Arkhangelsk province, northwestern Russia. Dendrochronologia 29-2. DOI: https://doi.org/
10.1016/j.dendro.2010.07.001
Abrams, M. D., Ruffner, C. M., Morgan, T. A. 1998: Tree-ring response to drought across species and con-
trasting sites in the ridge and valley of central Pennsylvania. Forest Science 44-4.
Barnett, T. P., Adam, J. C., Lettenmaier, D. P. 2005: Potential impacts of a warming climate on water avail-
ability in snow-dominated regions. Nature 438. DOI: https:/doi.org/10.1038/nature04141
Battipaglia, G., Saurer, M., Cherubini, P., Siegwolf, R. T. W., Cotrufo, M. F. 2009: Tree rings indicate dif-
ferent drought resistance of a native (Abies alba Mill.) and a nonnative (Picea abies (L.) Karst.) species
co-occurring at a dry site in Southern Italy. Forest Ecology and Management 257-3. DOI: https://doi.org/
10.1016/j.foreco.2008.10.015
Benayas, J. R., Martins, A., Nicolau, J. M., Schulz, J. J. 2007: Abandonment of agricultural land: an overview
of drivers and consequences. CAB Reviews: Perspectives in Agriculture, Veterinary Science, Nutrition
and Natural Resources 2-57. DOI: https://doi.org/10.1079/PAVSNNR20072057
Bollati, I., Pelfini, M., Pellegrini, L., Bazzi, A., Duci, G. 2011: Active geomorphosite and educational appli-
cation: a didactical itinerary along Trebbia river (Northern Apennines Italy). Les géosciences au service
de la société. Géovision 37.
Bollati, I., Della Seta, M., Pelfini, M., Del Monte, M., Fredi, P., Palmieri, E. L. 2012: Dendrochronological
and geomorphological investigations to assess water erosion and mass wasting processes in the Apennines
of Southern Tuscany (Italy). Catena 90. DOI: https://doi.org/10.1016/j.catena.2011.11.005
Bollati, I., Reynard, E., Lupia Palmieri, E., Pelfini, M. 2016: Runoff impact on active geomorphosites in
unconsolidated substrate. A comparison between landforms in glacial and marine clay sediments: two
case studies from the Swiss Alps and the Italian Apennines. Geoheritage 8-1. DOI: https://doi.org/10.1007/
s12371-015-0161-0
Acta geographica Slovenica, 58-2, 2018
97
58-2_07p_4137-Irene Bollati_acta49-1.qxd  12.9.2017  9:01  Page 97
Irene Bollati, Emmanuel Reynard, Davide Cagnin, Manuela Pelfini, The enhancement of cultural landscapes in mountain …
Bratt, G. 1995: Bisses of Valais: the Man-made watercourses in Switzerland. Gerrards Cross.
Büntgen, U., Bellwald, I., Kalbermatten, H., Schmidhalter, M., Frank, D. C., Freund, H., Esper, J. 2006: 700 years
of settlement and building history in the Lötschental, Switzerland. Erdkunde 60-2. DOI: https://doi.org/
10.3112/erdkunde.2006.02.02
Burczyk, J., Giertych, M. 1991: Response of Norway Spruce (Picea-Abies [L] Karst) annual increments to
drought for various provenances and locations. Silvae Genetica 40, 3–4.
Cendrero, A., Panizza, M. 1999: Geomorphology and environmental impact assessment: an introduction.
Supplementi di Geografia Fisica e Dinamica Quaternaria 3-3.
Cook, E. R. 1985: A time series approach to tree-ring standardization. Ph.D. Thesis, University of Arizona.
Tucson.
Coratza, P., De Waele, J. 2012: Geomorphosites and natural hazards: teaching the importance of geomor-
phology in society. Geoheritage 4-3. DOI: https://doi.org/10.1007/s12371-012-0058-0
Diolaiuti, G., Smiraglia, C., Pelfini, M., Belò, M., Pavan, M., Vassena, G. 2006: The recent evolution of an
Alpine glacier used for summer skiing (Vedretta Piana, Stelvio Pass, Italy). Cold Regions Science and
Technology 44-3. DOI: https://doi.org/10.1016/j.coldregions.2005.11.006
Diolaiuti, G., Smiraglia, C. 2010: Changing glaciers in a changing climate: how vanishing geomorphosites
have been driving deep changes in mountain landscapes and environments. Géomorphologie 16-2.
DOI: https://doi.org/10.4000/geomorphologie.7882
Eckstein, D., Bauch, J. 1969: Beitrag zur Rationalisierung eines dendrochronologischen Verfahrens und
zur Analyse seiner Aussagesicherheit. Forstwissenschaftliches Centralblatt 88-1. DOI: https://doi.org/
10.1007/BF02741777
Evans, S. G., Clague, J. J. 1994: Recent climatic change and catastrophic geomorphic processes in moun-
tain environments. Geomorphology 10-1. DOI: https://doi.org/10.1016/0169-555X(94)90011-6
Fan, P., Xie, Y., Qi, J., Chen, J., Huang, H. 2014: Vulnerability of a coupled natural and human system in
a changing environment: dynamics of Lanzhou’s urban landscape. Landscape Ecology 29-10. DOI:
https://doi.org/10.1007/s10980-014-0061-8
Fritts, H. C. 1976: Tree Rings and Climate. London
Garavaglia, V., Diolaiuti, G., Smiraglia, C., Pasquale, V., Pelfini, M. 2012: Evaluating tourist perception of
environmental changes as a contribution to managing natural resources in glacierized areas: a case study
of the Forni glacier (Stelvio National Park, Italian Alps). Environmental Management 50-6. DOI:
https://doi.org/10.1007/s00267-012-9948-9
Garavaglia, V., Pelfini, M. 2011: Glacial geomorphosites and related landforms: A proposal for a dendro-
geomorphological approach and educational trails. Geoheritage 3-1. DOI: https://doi.org/10.1007/
s12371-010-0027-4
Garbarino, M., Lingua, E., Nagel, T. A., Godone, D., Motta, R. 2010: Patterns of larch establishment fol-
lowing deglaciation of Ventina glacier, Central Italian Alps. Forest Ecology and Management 259-3.
DOI: https://doi.org/10.1016/j.foreco.2009.11.016
Goudie, A. 2013: The human impact on the natural environment: Past, present, and future. Hoboken.
Gregori, L. 2011: Bagnoregio la ‘città che muore’: paleografia e storia di un ‘geomorfosito’. La cartografia 27.
Gryc, V., Hacura, J., Vavrík, H., Urban, J., Gebauer, R. 2012: Monitoring of xylem formation in Picea abies
under drought stress influence. Dendrobiology 67.
Hauge, L. 1988: Galdane, Laerdal, Western Norway–management and restoration of the cultural landscape.
The Cultural landscape: past, present and future. Cambridge.
Hidalgo, R., Borsdorf, A., San Martín, G. 2014: Socio-spatial change in the world heritage site Valparaíso.
Erde 145-4. DOI: https://doi.org/10.12854/erde-145-20
Holmes, R. L., Adams, R. K., Fritts, H. C. 1986: Tree-ring chronologies of North America: California, Eastern
Oregon and Northern Great Basin with procedures used in the chronology development work includ-
ing user manual for computer program COFECHA and ARSTAN. Chronology Series 6, University of
Arizona, Laboratory of tree-ring research. Tucson.
Internet 1: http://www.torrent-neuf.ch (20. 6. 2016).
Latocha, A. 2015: Past human activities recorded in the landscape: A case study from the Glenveagh National
Park, Ireland. Landscape Research 40-3. DOI: https://doi.org/10.1080/01426397.2013.829807
Lehmann, L. 1913: L’irrigation dans le Valais. Paris.
98
58-2_07p_4137-Irene Bollati_acta49-1.qxd  12.9.2017  9:01  Page 98
Leonelli, G., Pelfini, M., Morra Di Cella, U. 2009: Detecting climatic treelines in the Italian Alps: The influ-
ence of geomorphological factors and human impacts. Physical Geography 30-4. 
Leonelli, G., Battipaglia, G., Siegwolf, R. T. W., Saurer, M., Morra Di Cella, U., Cherubini, P., Pelfini, M. 2012:
Climatic isotope signals in tree rings masked by air pollution: A case study conducted along the Mont
Blanc Tunnel access road (Western Alps, Italy). Atmospheric Environment 61. DOI: https://doi.org/
10.1016/j.atmosenv.2012.07.023
Liang, E., Xuemei, S., Zhaochen, K., Jinxing, L. 2003: The extreme drought in the 1920s and its effect on
tree growth deduced from tree ring analysis: a case study in North China. Annual of Forest Science 60.
DOI: https://doi.org/10.1051/forest:2003007
Mäkinen, H., Nöjd, P., Mielikäinen, K. 2001: Climatic signal in annual growth variation in damaged and
healthy stands of Norway spruce (Picea abies (L.) Karst.) in Southern Finland. Trees 15-3. DOI:
https://doi.org/10.1007/s004680100089
Mariétan, I. 1934: Le bisse de Savièse. Bulletin Murithienne 51.
Mariétan, I. 1948: Les bisses. La lutte pour l’eau en Valais. Neuchâtel.
Mariétan, I. 1961: Notes de sciences naturelles sur Savièse et le Sanetsch. Bulletin Murithienne 78.
Masson, H., Herb, R., Steck, A. 1980: Helvetic Alps of Western Switzerland. Geology of Switzerland, part
B. Basel.
McEwan, R. W., Mc Carthy, B. C. 2008: Anthropogenic disturbance and the formation of oak savanna in cen-
tral Kentucky, USA. Journal of Biogeography 35-5. DOI: https://doi.org/10.1111/j.1365-2699.2007.01857.x
Meteoswiss – CLIMAP-net, 2016. Internet 1: http://www.meteoswiss.admin.ch/home/services-and-pub-
lications/beratung-und-service/datenportal-fuer-experten.html (20. 6. 2016).
Michelet, J. 1998: Etudes des risques naturels prévisibles dans le face N-W du Prabé. Projet de réfection
du Bisse du Torrent-Neuf, Institut de Géographie, Université de Lausanne. Lausanne.
Modrzynski, J., Eriksson, G. 2002: Response of Picea abies populations from elevational transects in the
Polish Sudety and Carpathian mountains to simulated drought stress. Forest Ecology and Management
165, 1–3. DOI: https://doi.org/10.1016/S0378-1127(01)00651-X
Niţă, A., Buttler, A., Rozylowicz, L., Pătru-Stupariu, I. 2015: Perception and use of landscape concepts in
the procedure of Environmental Impact Assessment: Case study–Switzerland and Romania. Land Use
Policy 44. DOI: https://doi.org/10.1016/j.landusepol.2014.12.006
Ogle, K., Whitham, T. G., Cobb, N. S. 2000: Tree-ring variation in pinyon predicts likelihood of death fol-
lowing severe drought. Ecology 81-11. DOI: https://doi.org/10.1890/0012-9658(2000)081[3237:TRVIPP]
2.0.CO;2
Panizza, M., Piacente, S. 2003: Geomorfologia culturale. Bologna.
Papilloud, J. H. 1999: L’épopée des bisses. Les Bisses du Valais. Sierre.
Pelfini, M., Santilli, M. 2006: Dendrogeomorphological analyses on exposed roots along two mountain
hiking trails in the Central Italian Alps. Geografiska Annaler Series A 88-3. DOI: https://doi.org/
10.1111/j.1468-0459.2006.00297.x
Pelfini, M., Brandolini, P., Carton, A., Piccazzo, M. 2009: Geotourist trails: a geomorphological risk-impact
analysis. Geomorphosites. München.
Piao, S., Ciais, P., Huang, Y., Shen, Z., Peng, S., Li, J., Fang, J. 2010: The impacts of climate change on water
resources and agriculture in China. Nature 467. DOI: https://doi.org/10.1038/nature09364
Reynard, E. 1995: L’irrigation par les bisses en Valais. Approche géographique. Annales Valaisannes 70.
Reynard, E. 2008: Les bisses du Valais, un exemple de gestion durable de l’eau? Lémaniques 69.
Reynard, E., Varone, P., Reynard, D., Vernez, P. 2012: Le Torrent-Neuf de Savièse, un patrimoine remis en
valeur. Savièse.
Rigling, A., Bräkera, O. U., Forster, A. T., Schweingruber, F. H. 2003: Effects of irrigation on diameter growth
and vertical resin duct production in Pinus Sylvestris L. on dry sites in the Central Alps, Switzerland.
Forest Ecology and Management 175, 1–3. DOI: https://doi.org/10.1016/S0378-1127(02)00136-6
Rinn, F. 1996: TSAP. Time Series Analysis and Presentation, Version 3.0. Reference Manual. Heidelberg.
Röpke, A., Stobbe, A., Oeggl, K., Kalis, A. J., Tinner, W. 2011: Late-Holocene land-use history and envi-
ronmental changes at the high altitudes of St Antönien (Switzerland, Northern Alps): combined evidence
from pollen, soil and tree-ring analyses. The Holocene 21-3. DOI: https://doi.org/10.1177/0959683610385727
Schirpke, U., Hölzler, S., Leitinger, G., Bacher, M., Tappeiner, U., Tasser, E. 2013: Can We Model the scenic
beauty of an alpine landscape? Sustainability 5-3. DOI: https://doi.org/10.3390/su5031080
Acta geographica Slovenica, 58-2, 2018
99
58-2_07p_4137-Irene Bollati_acta49-1.qxd  12.9.2017  9:01  Page 99
Irene Bollati, Emmanuel Reynard, Davide Cagnin, Manuela Pelfini, The enhancement of cultural landscapes in mountain …
Schmid, R. 1935: Ancien bisse de Savièse: Tunnel du Muzerin. Martigny.
Schmidt, B. 1987: Ein dendrochronologischer Befund zum Bau der Stadtmauer der Colonia Ulpia
Traiana. Bonner Jahrbuch 187.
Schweizer, R., Reynard, E. 2011: La gestion d’un réseau complexe d’irrigation en 2010: L’exemple du coteau
de Savièse. Les Bisses, Economie, Société, Patrimoine. Sion.
Serra, P., Pons, X., Saurí, D. 2008: Land-cover and land-use change in a Mediterranean landscape: a spa-
tial analysis of driving forces integrating biophysical and human factors. Applied Geography 28-3. DOI:
https://doi.org/10.1016/j.apgeog.2008.02.001
Smrekar, A., Polajnar Horvat, K., Erhartič, B. 2016: The beauty of landforms. Acta geographica Slovenica
56-2. DOI: https://doi.org/10.3986/AGS.3039
Stara, K., Tsiakiris, R., Wong, J. L. 2015: Valuing trees in a changing cultural landscape: A case study from
Northwestern Greece. Human Ecology 43-1. DOI: https://doi.org/10.1007/s10745-014-9706-0
Tarolli, P., Preti, F., Romano, N. 2014: Terraced landscapes: from an old best practice to a potential haz-
ard for soil degradation due to land abandonment. Anthropocene 6. DOI: https://doi.org/10.1016/
j.ancene.2014.03.002
UNESCO, 2012. Operational Guidelines for the Implementation of the World Heritage Convention. Paris.
Zhang, Y. L., Zhang, J., Zhang, H. L., Cheng, S. W., Guo, Y. R., Ma, J. H., Sun, J. R. 2015: The impact of the
cognition of landscape experience on tourist environmental conservation behaviours. Journal of Mountain
Science 12-2. DOI: https://doi.org/10.1007/s11629-014-3150-x
100
58-2_07p_4137-Irene Bollati_acta49-1.qxd  12.9.2017  9:01  Page 100