Virginia Puzzolo Sten Folving

Virginia PuzzoloSten Folving

A GIS integration of topographic, geological

and climatic data for the analysis

of the Mt Etna forests distribution (Sicily, Italy)

The aim of this work

Geological substrata Volcano slopes Elevations Aspects Slopes Precipitation and temperature

was to provide a description of the forests distribution in the study area in relationship to some environmental characteristics :

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..

Evergreen oak (Quercus ilex) Deciduous oaks (Quercus pubescens

sl., Quercus cerris) Pine (Pinus laricio) Beech (Fagus sylvatica) Birch (Betula aetnensis) Chestnut (Castanea sativa)

The forests of the study area are mainly dominated by:

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 post-classification 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 workVegetation

mapDTM

Forests mask

Elevations map

Slopes map

Aspects map

Forests map

Meteorological data

Forests spatial distribution analysis

Digitization

Correlation tablesVolcano slopes masks

Geological map

5 0 5 10 15 Kilometers

N

Evergreen Mediterranean vegetation forestsDeciduous oak forestsMixed oak and pine forestsPine forestsMixed pine and broadleaves forestsBeech forestsBirch forestsChestnut woods

Mt Etna Forests Map

Forests cover (%)

40%13%

4%

13%

3%6%

3%18%

Evengreen Mediterranean vegetation forests

Deciduous oak forests

Mixed oak and pine forests

Pine forests

Mixed pine and broadleaves forests

Beech forests

Birch forests

Chestnut woods

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 materialthe volcanic substrata have different

petrographic characteristics depending on their origins

and from its shape.

5 0 5 10 15 Kilometers

N

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 tephraUpper tuffs and lahars

Lavas, tephra and tuffaceous sediments from the ancient alkalic centres

Products of the Ellittico and of Leone eruptive centres

Volcanics rocks from the eruptive centres of Trifoglietto

Geological Map of the Mt Etna Forests

Relationships between the Forest type and the Geological formations

Forest types

Geological formations

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

Lavas with well preserved surface morphology and associated tephra

24,1 17,7 3,7 12,8 25,0 9,8 0,0 16,5

Lavas with degraded surface morphology and poorly defined flow boundaris; and associated

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

Volcanic rocks from the eruptive centres of "Trifoglietto"

2,4 1,9 0,0 0,0 2,6 15,7 0,0 5,0

Lavas, tephra and tuffaceous sediments from the Ancient Alkalic centres

0,8 0,9 0,0 0,0 0,3 1,2 0,0 0,6

Eve

rgre

en M

edite

rrane

an

vege

tatio

n fo

rest

s

Dec

iduo

us o

ak fo

rest

s

Mix

ed o

ak a

nd p

ine

fore

sts

Pin

e fo

rest

s

Mix

ed p

ine

and

broa

dlea

ves

fore

sts

Bee

ch fo

rest

s

Birc

h fo

rest

s

Che

stnu

t woo

ds

Mongibello U

nit

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


0

25

50N

NE

E

SE

S

SW

W

NW


0

25

50N

NE

E

SE

S

SW

W

NW


0

25

50N

NE

E

SE

S

SW

W

NW

Chestnut woods

0

25

50N

NE

E

SE

S

SW

W

NW


0

25

50N

NE

E

SE

S

SW

W

NW

Beech forests

0

25

50N

NE

E

SE

S

SW

W

NW

Birch forests

0

25

50N

NE

E

SE

S

SW

W

NW

Pine forests

0

25

50N

NE

E

SE

S

SW

W

NW

Elevation classes0-500500-10001000-15001500-20002000-2400

Elevations Map of the Mt Etna forests

Forests distribution in relation to the elevations


0,0 5,0 10,0 15,00

400

800

1200

1600

2000

2400


0,0 10,0 20,0 30,00

300

600

900

1200

1500

1800

2100

2400


0,0 20,0 40,0 60,00

300

600

900

1200

1500

1800

2100

2400

Chestnut woods

0,0 10,0 20,0 30,00

300

600

900

1200

1500

1800

2100

2400

Pine forests

0,0 10,0 20,0 30,00

300

600

900

1200

1500

1800

2100

2400


0,0 10,0 20,0 30,0 40,00

400

800

1200

1600

2000

2400

Beech forests

0,0 10,0 20,0 30,00

300

600

900

1200

1500

1800

2100

2400

Beech forests

0,0 10,0 20,0 30,0 40,00

300

600

900

1200

1500

1800

2100

2400

m a.s.l.

%

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.

SoutheastSouth Southwest West Northwest

Aspect classesFlat NorthNortheastEast

Aspects Map of the Mt Etna forests

Forests distribution in relation to the aspectsEvengreen Mediterranean

vegetation forests

0

15

30N

NE

E

SE

S

SW

W

NW


0

15

30N

NE

E

SE

S

SW

W

NW


0

15

30N

NE

E

SE

S

SW

W

NW

Chestnut woods

0

15

30N

NE

E

SE

S

SW

W

NW

Pine forests

0

15

30N

NE

E

SE

S

SW

W

NW


0

15

30N

NE

E

SE

S

SW

W

NW

Beech forests

0

15

30N

NE

E

SE

S

SW

W

NW

Birch forests

0

15

30N

NE

E

SE

S

SW

W

NW

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

Slope classes0 - 910 - 1920- 2930- 3940- 4950 - 5960- 69

Slopes Mapof theMt Etna forests

Forests distribution in relation to the slopes


0

20

40

60

80


0

20

40

60

80


0

20

40

60

80

Chestnut woods

0

20

40

60

80

Pine forests

0

20

40

60

80


0

20

40

60

80

Beech forests

0

20

40

60

80

Birch forests

0

20

40

60

80

%

%

• 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 %.

All these forests prefer no very high slopes

The temperaturechanges uniformly with the altitude around the Volcano.

1918

17

1715

17

16

15

8

0 5 10 15 20

65

194275

285

348

405

560

589

590

680

698

750

750

780

1725

°C

0

10

20N

NE

E

SE

S

SW

W

NW

The rainfallchanges irregularly on the different Volcano slopes and it reaches the highest values on the eastern one because of its exposure to the sea.

49

67

47

38

82

82

96

42

108

48

101

57

62

56

62

0 20 40 60 80 100 120

65

194

275

285

348

405

560

589

590

680

698

750

750

780

1725

mm

-25

25

75

125N

NE

E

SE

S

SW

W

NW

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 muchfor your attention!

Documents

Virginia Puzzolo Sten Folving