Transcript A GIS integration of topographic, geological and climatic

A GIS integration of
topographic, geological and
climatic data
for the analysis
of the Mt Etna forests
distribution (Sicily, Italy)
Virginia Puzzolo
Sten Folving
The aim of this work
was to provide a description of the
forests distribution in the study area
in relationship to some environmental
characteristics :
 Geological substrata
 Volcano slopes
 Elevations
 Aspects
 Slopes
 Precipitation and temperature
 Geological substrata and lava flows
location play an important role in the forests
distribution on an active Volcano
 Volcano slopes are another characteristic
which has to be considered when the analysis
is conducted on a Volcano which has a conic
shape
 Differences exposures (aspect), availability
of soil nutrients (slope) and humidity
(elevation) are also important features
 Precipitation and temperature are the first
parameters that have to be considered to
understand why a type of forest can survived
or no in a certain area
Study Area Location
The study area is
located in the eastern
part of Sicily on the
Mt Etna which is the
biggest active
Volcano in Europe
with an extension of
1570 km2 and an
elevation of about
3350 m a.s.l..
The forests of the study area are mainly
dominated by:
 Evergreen oak (Quercus ilex)
 Deciduous oaks (Quercus pubescens
sl., Quercus cerris)
 Pine (Pinus laricio)
 Beech (Fagus sylvatica)
 Birch (Betula aetnensis)
 Chestnut (Castanea sativa)
Evergreen oak forest
Pine forest
Beech forest Island (Dagala)
Forest-lava boundary
Data Layers
 Forest vegetation map
was extracted from the Mt.Etna vegetation map at scale
1:50.000 (Poli Marchese & Patti, 2000) that it was
previously digitised using a standard image processing
approach by supervised classification and postclassification smoothing (Lawrence et al., 1996);
 Geological map
at scale 1:50.000 (A.A.V.V., 1979) was digitised with the
traditional hand method using the software ArcInfo and later
it was converted from the vector to the raster format;
 Elevations, Slopes and Aspects maps
were derive from a 20 m resolution Digital Elevation Models
using the spatial analyst ArcView software;
 Temperature and Precipitation data
were obtained from the study area meteorological stations
beginning from 1960 to 1996.
Flowchart of the work
Vegetation
map
Forests
map
DTM
Digitizatio
n
Geological
map
Elevations
map
Aspects
map
Slopes
map
Forests
mask
Meteorological
data
Correlation tables
Volcano
slopes
masks
Forests spatial
distribution analysis
Mt Etna Forests Map
Evergreen Mediterranean
vegetation forests
Deciduous oak forests
Mixed oak and pine forests
Pine forests
Mixed pine and
broadleaves forests
Beech forests
Birch forests
Chestnut woods
N
5
0
5
10
15 Kilometers
Forests cover (%)
Evengreen Mediterranean vegetation forests
Deciduous oak forests
13%
40%
Mixed oak and pine forests
4%
Pine forests
Mixed pine and broadleaves forests
13%
Beech forests
3%
Birch forests
Chestnut woods
18%
3%
6%
The forests distribution was strongly
influenced by the volcanic activity of
the Mt.Etna in different ways:
it destroyed part of these forests
during the lava flows
it always interrupts the soil evolution
with the pyroclastic material
the volcanic substrata have different
petrographic characteristics
depending on their origins
and from its shape.
Geological Map of
the Mt Etna Forests
Reworked pyroclastic material
Lava flows and tephra of 20th century, up to 1974
Lava flows and tephra of 18th and 19th centuries
Lava flows and tephra of 12th to 17th centuries
Undated but mainly historical lava flows and tephra
Lavas with well preserved surface morphology
and associated tephra.
Lavas with degraded surface morphology and poorly
defined flow boundaries and associated tephra
Upper tuffs and lahars
Products of the Ellittico and of Leone eruptive centres
Volcanics rocks from the eruptive centres of Trifoglietto
Lavas, tephra and tuffaceous sediments from the
ancient alkalic centres
N
5
0
5
10
15 Kilometers
Deciduous oak forests
Mixed oak and pine forests
Pine forests
Mixed pine and broadleaves
forests
Beech forests
Birch forests
Chestnut woods
Reworked pyroclastic material
0,3
0,2
0,0
1,8
0,8
7,3
7,6
0,5
Lava flows and tephra of 20th century, up to 1974
0,3
1,6
5,8
1,3
3,9
3,3
5,3
1,5
Lava flows and tephra of 18th and 19th centuries
2,1
6,1
5,1
3,2
2,7
3,2
3,8
3,3
Lava flows and tephra of 12th and 17th centuries
21,0
20,5
15,5
7,7
7,0
28,8
0,6
4,1
Undated but mainly historical lava flows and tephra
24,9
12,1
6,3
12,5
22,8
11,1
36,7
15,1
24,1
17,7
3,7
12,8
25,0
9,8
0,0
16,5
10,8
20,0
29,1
22,8
24,6
5,9
11,9
23,7
Upper and lower tuffs and lahars
3,0
1,6
0,8
0,0
0,0
0,2
0,4
17,5
Products of the Ellittico and Leone eruptive centres
9,3
17,0
33,7
37,8
10,3
13,4
33,8
11,9
2,4
1,9
0,0
0,0
2,6
15,7
0,0
5,0
0,8
0,9
0,0
0,0
0,3
1,2
0,0
0,6
Forest types
Geological formations
Lavas with well preserved surface morphology and
associated tephra
Lavas with degraded surface morphology and
poorly defined flow boundaris; and associated
Volcanic rocks from the eruptive centres of
"Trifoglietto"
Lavas, tephra and tuffaceous sediments from the
Ancient Alkalic centres
Mongibello Unit
Evergreen Mediterranean
vegetation forests
Relationships between the Forest
type and the Geological formations
Almost all of the Etnean forests are
located on the Mongibello unit and
mostly on the undated laves and on
the products of Leone and Ellittico
eruptive centres
the beech forests were also developed
on the volcanic rocks of the
"Trifoglietto" eruptive centre
the chestnut woods were planted on
the upper tuffs and lahars
Forests distribution in relation to the
Volcano slopes
Deciduo us o ak fo rests
Evengreen Mediterranean
vegetation forests
N
N
W
0
W
E
SW
NE
0
NE
25
NE
E
SW
SE
S
W
0
E
SW
SE
S
E
W
SE
0
SW
SE
S
Birch fo rests
N
N
50
NE
NW
E W
0
SW
SE
S
NE
25
25
W
E
B eech fo rests
NW
25
0
0
50
50
NW
NE
S
N
50
NW
25
SW
M ixed pine and bro adleaves
fo rests
N
W
W
S
P ine fo rests
NW
E
SE
S
NE
25
SW
SE
50
NW
25
25
N
50
NW
NE
Chestnut wo o ds
N
50
50
NW
M ixed o ak and pine fo rests
0
E
SW
SE
S
Elevations Map
of the
Mt Etna forests
Elevation classes
0-500
500-1000
1000-1500
1500-2000
2000-2400
Forests distribution in relation to the
elevations
Evengreen M editerranean
m a.s.l. vegetatio n fo rests
M ixed o ak and pine fo rests
Deciduo us o ak fo rests
Chestnut wo o ds
2400
2400
2400
2100
2100
2100
1800
1800
1800
1600
1500
1500
1500
1200
1200
1200
1200
900
900
900
600
600
600
300
300
300
0
0
2400
2000
800
400
0
0,0
5,0
10,0
15,0
0,0
10,0
20,0
30,0
M ixed pine and bro adleaves
fo rests
Pine forests
2400
2400
2100
2000
1800
1600
1500
1200
1200
900
800
600
400
300
0
0,0
0
10,0
20,0
0
0,0
30,0
20,0
40,0
60,0
B eech fo rests
10,0
20,0
30,0
40,0
10,0
20,0
30,0
Beech forests
2400
2400
2100
2100
1800
1800
1500
1500
1200
1200
900
900
600
600
300
300
0
0,0
0,0
0
0,0
10,0
20,0
30,0
0,0
10,0
20,0
30,0
40,0
%
The forests extend from the base of the
Volcano to 1800-2300 m. a.s.l. and them
altitude range changes in function of the
forest type.
The basal belt is characterised by the
Evergreen Mediterranean vegetation
forests
The mountain belt is dominated by the
other types of species and, in particular,
by oak, pine, beech and birch in function
of the different Volcano slopes.
Aspects Map
of the
Mt Etna forests
Aspect classes
Flat
North
Northeast
East
Southeast
South
Southwest
West
Northwest
Forests distribution in relation to the
aspects
Evengreen M editerranean
vegetatio n fo rests
Deciduo us o ak fo rests
M ixed o ak and pine fo rests
Chestnut wo o ds
N
N
N
N
NW
W
30
30
NE
15
0
E
SW
SE
NW
W
W
0
E
SW
SE
S
P ine fo rests
M ixed pine and bro adleaves
fo rests
NE
15
0
E
SW
SE
S
NW
W
NW
W
30
0
SE
S
0
E
SE
W
NW
W
NE
15
0
E
SW
SE
S
B eech fo rests
B irch fo rests
N
N
30
30
E
SW
15
NW
S
NE
15
NE
SW
N
30
NW
15
S
N
30
30
NE
NE
15
0
E
SW
SE
S
NW
W
NE
15
0
E
SW
SE
S
The aspects are strongly connected
with the Volcano slope where the
forest is located.
 The evergreen and deciduous oak
forests are the less restrictive
 the other forests have, more or less,
the same exposure of the them slope
Slopes Map
of the
Mt Etna forests
Slope classes
0-9
10 - 19
20- 29
30- 39
40- 49
50 - 59
60- 69
Forests distribution in relation to the
slopes
All these forests prefer no very high
slopes
• They are normally located on slopes
between 0 and 20 %.
• An exception is the beech forest
located on the SE Volcano slope that
it reaches, in some points, slopes with
more of the 50 %.
The temperature
changes uniformly with the altitude around
the Volcano.
The rainfall
changes irregularly on the different
Volcano slopes and it reaches the highest
values on the eastern one because of its
exposure to the sea.
Conclusions
 Geological,
topographic
and
climatic
information is needed to extract useful
information for improving forest management
systems.
 All these variables can be weighted and
combined using GIS techniques that provide
an efficient tool for handling multi-source
data.
 The results obtained during this study have
showed how it is possible to combine all
these environmental characteristics to better
understand the forests distribution on an
active Volcano, like Mt Etna
Thank you very much
for your attention!