Nature of Cansiglio: this Plateau, its Forest and Botanic Garden are a Jewel for the Alpine Flora.
The purpose of this page is to present the Nature of Cansiglio – and the Alpine Botanical Garden which lies in the middle – in the context of its geographical setting.
The Alpine Botanic Garden of Cansiglio owes its creation – in 1972 – to the work of Professor
Giangio Lorenzoni, teacher at Padova University, who conceived it, and
Professor Zanardo – then inspector of the Italian National Agency for the
Forests.
The garden was officially inaugurated in 1995 during the celebrations for
the 450th anniversary of the Padua Botanical Garden, and was dedicated –
right from the start – to the memory of Professor Lorenzoni.
It is an important reality in the area, not just for its beauty, but because
it allows to observe and get to know – in a condensed space – a high number of
plant species and habitats that are sometimes quite distanced from one another
in nature.
It also serves as an introduction to the different Alpine habitats
that can be encountered in the area, as the garden hosts most of the flora and
vegetation typical of the Col Nudo-Monte Cavallo massif (highest
elevation 2,471 m), comprising the foothill area.
The Alpine Botanic Garden of Cansiglio covers an area of ancient
human settlement, characterized by scarcity of surface water. It occupies a calcareous
site of around 3 hectares at about 1,000 m of altitude, and it is
articulated on different levels.
The modern representation in order beds and habitats allows visitors
to get to know and appreciate environments that are becoming endangered, rare – or, in some cases, have all but completely disappeared (above is a picture
showing the Rock Garden area).
In terms of individual plants, in the Alpine Botanic Garden of Cansiglio are
currently hosted many different species, some of which are seriously
endangered, while others are vulnerable.
As for the geologic aspect (more on this later), in the course of
these last few years it was possible to enlarge the garden so to include an
area of karstic origin (“carsismo a blocchi” in Italian), with dolines
and a natural sink-hole.
Much attention was given also to the creation of an Alpine pond –
locally known as ‘lama’ (see a picture below).
Other positive changes include the introduction of a more efficient system
of irrigation, the completion of a network of new paths and trails, an
expansion in the number of beds and habitats represented and the creation of
two peat-bogs – plus a space dedicated to officinal and poisonous
plants.
The transformation of beds into real habitats – all presented as
natural plant associations – provides a pleasant landscaped outlook to
the garden, and means a significant increase in the number of species hosted.
An analysis of the list of plants present within the garden over the course
of the years has allowed to assess the improvements that have taken place, and
to stress the scientific-didactic evolution of the garden itself.
On that respect, one should therefore notice that the number of species
has increased from 58 in 1978 to the current 750, while the prospect is
that of going above the figure of 1,000 – so to eventually get closer to the 1,500 plant
species that are naturally present in the area.
This is just a general overview of what the Alpine Botanic Garden of Cansiglio has
to offer. There is a specific page for more detailed information on the plants and habitats present in the garden, while the purpose of this page is to
concentrate more on the geographic and geologic/geomorphologic
setting in which the garden is located, and to investigate the nature of
Cansiglio at large (below, an image of the natural environment in which the
Botanic Garden is immersed).
The Geographic Setting
The territory here considered – the Cansiglio plateau – is
notoriously situated at the boundary between two important bio-geographical
regions: the Alpine and the Balcanic-Dinaric.
It thus represents a bio-geographical threshold, with Illyrian and
Dinaric influences expressed by a high rate of endemic species that make
this part of the Alps one of the most important conservation and
differentiation centres for the flora in the
whole Alpine chain.
The geological structure and the glacial phenomena contribute
to make this territory orographically complex, and therefore apt to host
potentially quite diverse habitats.
It is, in fact, a biodiversity hotspot, in which near-natural – and often
quite wild – environments coexist side by side with others in which the
traditional anthropic (human) activities have created ecological niches that
enrich the naturalistic heritage.
Geographically, this area includes the massifs of Col Nudo (2,472 m),
Monte Cavallo (2,251 m) and the Cansiglio proper – the latter with
two determining components when it gets to botanic investigation: on the one hand, the Cansiglio Forest, which represents an
extraordinary, unique reality in its own right; on the other hand, a section of the Cansiglio plateau belongs to Friuli,
which was the first region in Italy to publish a floristic atlas – that is, a
list of all the species of vascular flora divided by areas of distribution
within a given territory.
Another determining element to explain the high biodiversity in this area is
linked to its peripheral position at the margins of the Venetian plain, with
abundant precipitations: this is the main cause for the particularly lush
vegetation – bar the presence of a few pioneer plant species typical of the
dominant calcareous-Dolomitic substrate.
As for the flora of Cansiglio, there exist historical data on the management of the forest,
and single floristic reports, but one needs to reach the second half of the
last century – between the end of the 1960s and the 1980s – to register an
impulse in the research, with the first phyto-geographical considerations on
certain peculiarities of the vegetation of the area, and the first reliable
floral check-lists of the different nature reserves contained within Cansiglio.
In the following decade, more complete floristic checklists were made,
together with phyto-sociological synthesis on different habitats; as a
matter of fact, this territory was never treated as a homogenous entity, and
still today there are areas which were never fully explored (certain
neighbouring areas – such as Alpago – are still
not very well-known today, and lack in updated checklists for their flora).
In any event, the actual level of knowledge on the vascular flora of the
area allows to confirm biodiversity values that are superior to average, thus
witnessing to the elevated bio-geographic richness of the nature of Cansiglio.
From
the studies that were carried out, the most vulnerable habitats clearly
stand out, and the most elevated number of species at risk are among
those of Euro-Mediterranean
distribution (but with representatives also from temperate-cold climates).
Among the bands of vegetation of important bio-geographic interest within the nature of Cansiglio,
particularly noteworthy is the foothill area, rich in residual arid-steppic
habitats (most notably meadows).
On the Cansiglio plateau itself, and in the depressions that characterize
its pastures, the natural pools known as ‘lame’ are exceptionally
interesting habitats too – and not just for their flora, but for the extraordinary
overall contribution to local biodiversity.
In nearby Alpago, a biotope of relevant interest for its vegetation is the SE slope of Monte
Dolada (1,938 m): even though here the exceptional meadow habitats are
progressively evolving towards more shrubby formations, with loss of sites for
orchids, the ridge is nevertheless still relatively unspoilt, with important stations of Geranium
argenteum, Androsace villosa and the strikingly blue Eritrichium
nanum.
More so than other areas, the other side of Cansiglio – sloping down
towards the val Cellina – with the Pre-Alps around Claut also represents
a territory hosting elements of exceptional phyto-geographical value: here are
localized the extreme floral penetrations from the western Alps, such as Leontodon
tenuiflorus, Hymenolobus pauciflorus and Festuca alpestris.
From the east come instead species that find here their westernmost
expansion – and these include Festuca laxa, Thlaspi minimum, Gentiana
froehlichi and Primula wulfeniana.
As for the endemic plants from the Dolomites, we
find here the
south-easternmost stations for Campanula morettiana and Primula tyrolensis.
The local endemic component includes some precious entities such as Galium
margaritaceum, Spiraea decumbens subsp. tomentosa, Leontodon
berinii (pictured below) and – especially – Arenaria huteri; it is also worth mentioning an important disjointed station of Lembotropis
emeriflorus. Exceptional too is the recent find of Illyrian-Balcanic
species such as Daphne blagayana.
Finally, it is of extreme importance the discovery and description of a
carnivorous plant that thrives on damp, dripping rocks: Pinguicula poldinii.
The Natural Setting
From the foothill plains to the 2,471 m of Col Nudo, four out of the five vegetation
bands typical of mountain habitats (also known as “altimetric bands” )
are represented in the Alpine Botanic Garden of Cansiglio , with the sole exception of the
Mediterranean. Here follows a brief description of these vegetation bands.
In the so-called Middle-European band, which goes from the high
plains up to about 1,000 m of altitude, a mixed broadleaved woodland dominates,
composed mainly of oaks and hornbeam; at lower levels, woods have often been substituted by cultivated areas,
while at the highest altitudes man-made meadows and pastures still prevail. In
comparison to the potential situation, here only a reduced contingent of oaks
can be noticed – a circumstance determined both by natural climatic factors and
the frequent coppicing of the past that has highly favoured hornbeam.
The “orno-ostrieti” (an association composed of hop hornbeam
and Manna ash as dominant species) are the most frequent woods in the sub-montane vegetation band, on steep mountain slopes. The soil is
here often quite shallow, and based on layers of detritic origin.
The primitive “orno-ostrieti”
that grow on the lowest slopes of
Cansiglio present a floristic component similar to those of pinewoods
that
tolerate well humidity variations and running surface water. Only on
less steep slopes, where the topsoil is not being washed away by
precipitation, can one appreciate a noticeable contingent of more
exigent
species, in particular common hornbeam – especially so in those
locations exposed to
the north.
In damper habitats are fragments of mixed maple and ash
woodland, of good naturalistic value; sometimes a rarer combination maple-lime
can be found too – this particular association being protected at European
level.
Of relevant and absolutely high value for the local flora are also the residual fragments
of arid meadows: these habitats are usually composed by warmth-loving
species of Sub-Mediterranean or steppic origins, which often include a rich
presence of rare orchids – hence their being prioritized for protection at
European level.
Interesting too is the consortium of plants that can be found at the margins
between meadow and woodland, with a prevalence of Geranium sanguineum.
The areas more exposed to the influence of man – with small vineyards, orchards
and cultivated patches – are also quite important for the conservation of
biodiversity, even though they rarely host endangered species (these
agricultural environments are not represented in the garden).
The Sub-Atlantic climatic band – that corresponds roughly to the montane
zone – ranges from 800-900 m to 1,400-1,600 m and is characterized by a
prevalence of beech and mixed woodland of beech and Silver fir: here are found the lusher woodland formations, which go from the
warmth-loving associations of the external slopes to those of the mesic
(cooler) soils, to finish with the high-montane habitats rich in "tall herbs" (‘megaforbie’
in Italian).
In the depressions of the Cansiglio plateau, formations of Norway spruce
can also be observed; sometimes, on abandoned meadows, Norway spruce can behave
as a pioneer species too.
In the beech-wood (and in the mixed formations with Silver fir) are
some rare species for the whole of the Oriental Alps, and of a more Central
European distribution – such as Veronica montana, or the even rarer Cystopteris
sudetica, which has been included in the Red List of the Italian flora only
in recent years, and that can also be considered a precious bio-indicator.
The floral display is quite rich in eastern species too, as
demonstrated by the abundance of Cardamine trifolia, Euphorbia
carniolica, Lamium orvala and Dentaria enneaphyllos.
In stations that are fresher and more humid instead, the potential strength
of ash formations (Fraxinus excelsior) can be noticed – a tree
able to use and fix high quantities of nitrogen.
To be reported is also how under-use of agricultural land, elevated humidity
and the presence of a consistent colony of deer have favoured the diffusion of
an invasive coarse grass, Deschampsia caespitosa.
As said already, of substantial value are the natural pools (‘lame’)
and other biotopes that – as well as augmenting biodiversity – are
elective habitats for the reproduction of several animal species, especially amphibians.
Numerous are the entities of Red List present in these sites; as a rule of
thumb, all springs, wells and pools are to be considered essential habitats for
the functionality of the ecosystem, and here floral species such as the rare
carnivorous Drosera rotundifolia can also be found.
The oceanic climate, characterized by high rainfall, is evident in
the whole basin of Cansiglio when noticing the low level of the tree line,
reaching here only about 1,700 m of altitude.
The passage from the montane to the Alpine vegetation band is gradual,
and signaled by the habit of growth of stunted trees, which tend to become
smaller in size and form a basal ‘knee’.
The floristic composition also varies, becoming richer in cold-loving
entities that are typical of Sub-alpine shrubby habitats and of other
environments covered in snow for long periods; particularly relevant are the willow
formations, interspersed with Green alder, Rhododendron, Dwarf juniper and
ferns.
A unique role is played by Dwarf mountain pine – an emblematic species
for the whole Dolomites and Pre-Alpine area. In some cases, beech formations come into direct contact with Dwarf
mountain pine, while occasionally the latter even come down to the point of
colonizing the scree slopes, and occupying the lower valley floors. The shrubs of Dwarf mountain pine associated with Alpenrose (Rhododendron hirsutum) are to be considered a priority habitat at
European level.
All these presences mark the passage from the Alpine to the Boreal
climatic band, generally represented by conifer woodland, but in
Cansiglio these formations are not particularly rich, for orographic – as well
as climatic – reasons. In the Boreal band, Sub-alpine meadows can also be noticed – in the
past generally used as pastures and today especially rich in Ericaceae
species.
True Alpine meadows belong to the band above 2,000-2,200 m of
altitude, and are found in correspondence with environments that were strongly affected by the
glaciations: the sub-nival valleys of Monte Cavallo (2,251 m), for example, are a
particularly interesting hotspot for biodiversity, to be studied also for their
playing a role as ‘Nunatakker’ during the last glaciations
(that is, islands free from ice, where several plant species have remained and survived
since the ice-age), hence the presence, here, of relic entites – either sub-endemic or at the
margins of their natural area of distribution, with significant disjointed
stations (such species include Geranium argenteum, Arabis vochinensis,
Festuca laxa and Grafia golaka).
A fundamental contribution to biodiversity is given by the primitive
habitats (i.e. with superficial soil or even deprived of humus) and the a-zonal
habitats (that is, not tied to any particular altitudinal band).
Scree and detritus, also at lower level, host the most noble
of Alpine flora, with exceptional flowers and an important contingent of
endemic plants – one notable example of such species being Arenaria huteri.
The most common group of plants on the rock faces is the association combining
the endemic Spiraea decumbens with Alpine Cinquefoil (Potentilla
tomentosa); in similar conditions but in habitats that are more typical of
canyons, the association with ferns and Devils’ claw (Physoplexis
comosa) is quite widespread too.
Among the mossy habitats of the karstic rock faces of Cansiglio are plant
associations with Sedum hispanicum still to be investigated properly.
Various other notable plant communities – that are equally important – can
be studied on the loose detritus (scree) habitats of the Val Salatis, on the
south-eastern fringes of Alpago, the most
relevant of which is probably the association that takes its name from the Fescue grass Festuca laxa (Festucetum) – a species of clear Eastern (Illyrian)
provenance.
Numerous are the floral rarities that can be found in these environments,
with relic species that survived the quaternary glaciations and others of more
recent origin, which differentiated right at that point in time (such as Asplenium
fissum and Alyssum ovirense, for example).
Among the a-zonal habitats that deserve a particular mention are the river
beds, as it is in fact quite rare to observe stable environments in which
the hydro-geologic regime was not altered by man-made interventions (in
the image below, the area of the Botanic Garden dedicated to recreate
a dry river bed habitat).
Just outside the territory considered here, the existence of an extraordinary
habitat – of pre-eminent phyto-geographical value – is to be taken into
account too: the ‘magredi’.
These dry river beds are composed of herbaceous communities that have developed on the
meager alluvial soils of streams and torrents in the plains of western Friuli.
In these habitats are hosted plants of exceptional phyto-geographical value,
with a high ratio of endemic and disjointed species.
Of a-zonal character are also the pine formations with Black
Austrian pine (Pinus nigra) and Scots' pine (Pinus sylvestris),
which populate scree habitats and primitive soils exposed to strong conditions
of humidity, especially along the middle Piave valley.
These formations' floral variety is always very interesting: these are environments
that, given their orographic conditions, rarely have evolutionary possibilities –
if not with very long developmental times – and therefore tend to become stable
components of the landscape.
In the pinewoods of Black Austrian pine, elements of Eastern
gravitation dominate – such as Knautia ressmannii and Euphorbia
kerneri with Allium ochroleucum, Euphrasia cuspidata and Campanula
thyrsoides.
In the wood clearings one can observe several different other plant
communities, each of which can give out useful information on the prevailing
ecological factors – for instance, on the Cansiglio plateau there is a rare
association with Deadly Nightshade (Atropa belladonna), one with Epilobium
angustifolium, and another one with Raspberry (Rubus idaeus),
which has a tendency to colonize and close old meadow clearings, becoming
invasive at times.
Other aspects of degradation include – in wetter habitats – associations
dominated by Eupatorium cannabinum and/or Bittersweet (Solanum
dulcamara); typical are also the "tall herbs" associations, and other
communities with Senecio cordatus and Impatiens noli-tangere.
Even the sin-anthropic vegetation (linked to the presence of man) can
contribute to enrich the environment, as it can sometimes host certain floral
rarities; in this respect, one can be reminded of the case of Spergula arvensis
or of Peplis portula, which occupy the muddy banks of the pools (‘lame’).
All in all, the contribution of agricultural and pastoral activities to
biodiversity in this area cannot be underestimated; certainly, also, some habitats
have suffered more than others from intensive exploitation, and this has in
turn impoverished the soil, making woods and pastures poorer and less
productive. In more recent years there have been some ecologically
disputable interventions too – such as new conifer plantations and the damage
suffered by some wetland.
Despite the apparent homogeneity of its vegetation, though, for the variety
of situations it offers, the nature of Cansiglio can rightly be
considered a special laboratory apt to register the consequences of the most
recent climatic variations.
The most important areas for floristic interest need to be monitored; for
example, the tradition of cattle farming – and therefore the need of pastures
for grazing – is well consolidated in Cansiglio. Rarely do these habitats
conserve elements of extraordinary level for their flora, but it is important
that grazing is kept under control, avoiding both over- or under-use of the
land, as balance in the number of animals is important in order to preserve the meadows'
biodiversity.
Communities of invasive species are an even more frequent occurrence, and
the central issue here is that of proper woodland management.
Certainly, if such an important woodland and forest heritage such as the
Cansiglio has reached us today relatively intact, it means that this territory
has a specific vocation that deserves to be carried forward; also, it is
fundamental to allow visitors the possibility to observe and experiment the
natural evolution of certain areas of outstanding value – areas that need to be
kept out of the normal planning procedures, monitored, and treated
consequently.
For instance, some of the broadleaved species that were penalized in the
past, but that are native to this territory – such as beech – certainly
do deserve more attention; also, today it is desirable to develop a type of
forest that is closer to ‘natural’ types, while conserving and valuing
appropriately those stretches of old forest in which the biggest and oldest
specimens still thrive.
It is important, too, to ensure the permanence of meadow habitats, as
the population of deer in some areas impacts significantly on the floral
composition.
In general, and as a rule of thumb, in terms of governance it is vital
to give precedence to the conservation of those microhabitats and special
niches so to avoid – on the one hand – unconditional abandonment of the land
and, on the other, in order to contain those forms of semi-industrial exploitation that
simplify – but also trivialise – the habitats and, as a consequence, the
territory's biodiversity as a whole.
From a geologic point of view, the nature of Cansiglio as individuated here presents a
band to the north – and extended east to west – where rocks dating to the Secondary
period (Upper Jurassic/Cretaceous) surface: these are limestone of various formation, but mostly of marine origin
– as in fact most other rocks in the area. Moving to the south, one
encounters an older band of rocks, mainly constituted of Dolomia (‘Dolomite’),
and then again rocks from the Upper Jurassic/Cretaceous period.
An extended area of limestone (calcareous rock) from the Upper
Cretaceous follows: these are rocks typically deriving from ancient coral
reefs, and therefore rich in fossils; an exception is represented by the Alpago basin to the
west, where softer Tertiary rocks emerge – and these are mainly composed
of marl, molasses and clay.
To the south, one encounters again the huge escarpment that delimitates the Col
Nudo-Monte Cavallo group (maximum altitude 2,471 m), which is also linked
to a narrow band of soft Tertiary rocks that mark a boundary and the passage
from the massif to the plains of Veneto and Friuli.
We know from geology that this area (from Trias to the end of the Tertiary
era – a time lapse of nearly 200 million years) was occupied by the sea, so
that the rocks of these mountains are mainly of marine origin – a fact well
witnessed by the fossils that can still be found while walking in the area.
Towards the end of the Tertiary era, the orogenetic pushes from the South
became progressively more intense, fracturing and folding enormous blocks in
the most various ways, and sliding rock layers on top of each other, so that
the rocks that emerged from the sea were progressively attacked by the
atmospheric agents.
These pushes gave origin to big folds directed east-west, and to huge thrusts
that slid on top of each other along fault-lines; these phenomena affected more
intensely the northern section of Cansiglio but were less frequent in the
south, where the folds dominate.
Naturally, water and the melting ice from the Quaternary glaciations
looked for the easiest way to flow, thus eroding the bedrock, expanding the
discontinuities and forming deep valleys separated by ridges and vertiginous
rock walls; an exception is represented by the wide enclosed basins of tectonic
origin of Pian Cansiglio (to the west), Pian Cavallo (to the east) and Alpago.
In the Quaternary era there was an alternation of colder phases –
when the glaciers advanced – and warmer ones, during which the ice sheet
retreated, leaving along its way rock detritus and boulders that would later be termed
‘moraines’.
In the area considered here, particularly important was the Piave ice
sheet, whose basin roughly occupied the current riverbed.
The glacier of the eastern Dolomites was sliding down the actual Piave
valley; from there, a branch headed east into the Vajont valley,
while the main course of the glacier continued its journey south, eroding the
mountain slopes towards what is now known as Val Belluna, and giving the valley its typical glacial ‘U’ shape.
An additional minor section then branched off towards the Valle Lapisina
and Vittorio Veneto, skirting the Cansiglio and forming the so-called “moraine
amphitheatre of Vittorio Veneto” ('anfiteatro morenico di Vittorio Veneto').
The Alpago
basin was covered by this branch of the glacier, but because of its relatively
low altitude the Cansiglio plateau was not occupied by the ice sheet; snow
deposits were left only in the small depressions at its margins, such as at the
peat bogs at Palughetto and in other locations exposed to the north.
Worth mentioning are also the deposits of Loess: a fine yellow-brown
silt that was formed in a cold steppic climate, and was then brought and deposited by
the wind. Flint artifacts were found inside the Loess, dating back to the Epigravettiano
and Epi-Paleolithic periods; in fact, these finds represent first
evidence of the presence of man in Cansiglio and Pian Cavallo.
Karstic Phenomena
The ancient marine deposits, after having been transformed – over the course
of millions of years – into hard, calcareous Dolomite rock and softer Tertiary
marls were then pushed to the actual locations and fractured by orogenetic
forces pushing from the south; then, water from meteoric precipitation, which
has the capacity to melt limestone, penetrated along the fractures and
originated characteristic shapes.
Where calcareous rocks emerge and the shapes were flat – or concave – the
melting of limestone was quite significant, and a deepening of the original
fractures followed: the term “polje” is then used, in such cases, to define a
closed basin where the soil surface corresponds to the inclination of the
layers, which is further deepened by karstic phenomena – as it happens indeed on the
Cansiglio plateau.
In the interior of the basin one can distinguish other, smaller depressions
known as ‘uvala’; inside these are further small
cavities known as ‘doline’ (most of these are Slavonic terms).
These minor depressions are located especially where different rock layers
encroach, creating a natural point of absorption of rainfall water and
therefore enhancing a further melting of rocks; also, the ‘doline’ are
more numerous and of bigger proportions in the flat areas where limestone
formations emerge.
The phenomenon of thermal inversion – which is very prominent on the
Cansiglio plateau – favours karstic phenomena too: very often, fractures in the
rock are widened by corrosion, which forms big isolated boulders – especially
notable in the more elevated areas: this is the genesis of the so-called ‘block-like Karst’ (“carsismo a blocchi”).
On most calcareous surfaces one can also observe smaller corrosion
phenomena. All of the karstic shapes thus generated are of the so-called ‘covered’
type: block-like and small erosion phenomena that have all rounded edges, as
they are covered in mosses and lichens; on the contrary, further up in altitude
– where the vegetation is largely absent – one can notice that the shapes have
a much more spiky and cutting edge.
Naturally, water penetrates in the fractures, and once it has reached the
bottom of the ‘doline’ it continues its journey downwards creating wells
and cavities – karstic systems of huge depth and length that resemble ‘proper’
subterranean rivers. The majority of water going underground on the Cansiglio plateau then
resurfaces at the Livenza Springs, some 750 metres below at the foot of the mountains!
In Cansiglio were individuated and counted more than 200 subterranean
caves, and their development can be quite striking. The most important
sink-hole is the “Bus della Genziana” (the ‘Gentian Hole’),
which is nearly 600 m deep and develops for about 4 km, but there is also the “Bus
de la Lum”, which is perhaps the most impressive to see, despite being
'only' 185 metres deep.
Geomorphology Inside the Garden
Several geologic, tectonic and geomorphologic evidence underlies the
naturalistic value of the area. Right inside the Alpine Botanic Garden of Cansiglio is the passing
of an important fault-line, marking a boundary between reef limestone (“calcare
di scogliera”), which emerges to the south and in Cansiglio's lower
section, and the “Scaglia grigia” (a grayish marl limestone
that can be seen to the north).
The alteration of these two types of rock produces also two different types
of detritus, which are highly characteristic: reef limestone, very prone to
karstic modifications, generates a reddish clayey soil, while marl limestone –
less apt to be modified by karstic activity – has modeled the rocks in highly
characteristic forms.
It is also interesting to notice how, following measurements of the erosive
mechanisms acting on the rocks, an average annual lowering of about 100 to 300
millimeters has been detected on the Cansiglio plateau – depending on the type
of bedrock, precipitation and altitude.
From a geo-morphologic point of view, the little karstic well located
inside the garden can be termed a ‘snow well’, as snow can linger inside
it for the whole year, with a significant thermal inversion – thus creating a
characteristic microclimate (not surprisingly, it is called 'Bus del Giaz' –
the 'ice hole').
Another small sink-hole, which now tends to fill up, reminds us of
how karstic phenomena always keep their slow but unstoppable activity going,
with several points of absorption and subterranean cavities.
Detritus tends to disappear in the depths – especially in those areas were
the rocks are most fractured, and from these cavities cold air constantly comes
out throughout the year, keeping a steady temperature of about 6° to 9° C; in
fact, these holes were once used as natural fridges during the summer!
This ends the general presentation on the Nature of Cansiglio and on the environment in which the Alpine Botanic Garden of Cansiglio is located. Should you wish to read more,
may I remind you that on this website you can also find a detailed description
of the visit route within the Botanic Garden, with all of its different parts and
habitats described in depth.
http://www.italy-tours-in-nature.com/nature-of-cansiglio.html
http://www.italy-tours-in-nature.com/nature-of-cansiglio.html
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