Marcel Török-Oance, Rodica Török-Oance,

Alexandru Onaca, Florina Ardelean, Mircea Voiculescu

This work was supported by CNCSIS – UEFISCSU, project number PNII – IDEI 1075/2009

and by CNMP, project number PNII – GEOMORF 32-140/2008.

• The most massive and highest part of the

Romanian Carpathians

• 10 % of the mountain areas lies above 2000 m

• The maximum elevation is 2544 m

(Moldoveanu Peak, Făgăraş Mountains)

The Southern Carpathians

•The presence of the

vegetation levels:

- the alpine level

(> 2200 m)

- the subalpine level

(from treeline to 2200 m)

- the coniferous forest

level (from 1300-1400 m

to around 1800 m)

- the deciduous forest

level (< 1300-1400 m).

•The Carpathians are a

very old living space

with intense human

activity. The most

important activity which

affect the timberline area

is the grazing.

The Southern Carpathians have a temperate mountain climate.

- the mean annual air temperatures vary between 7°C and –2°C above

2100 m (-2.6°C at Omu Peak, 2505m).

-the mean annual precipitations values are between 700 mm and 1200 mm

The variation of the

mean annual air

temperature and of the

mean annual

precipitation at the

Omu meteorogical

station (2505 m),

1964-2006 interval

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The aim

• to detect the changes of the timberline/treeline using

remote sensing data, old vegetation maps and field data

during the last 50 years

The data

Old maps: 1:20,000 topogrpaphical maps (1930 - 1953 edition)

1:25,000 topographic maps (1980 edition)

Forestry cadastre maps (1:10,000)

Airphotos: black and white airphotos (1956 and 1972)

color airphotos (2005, 2008)

Satelite images: Landsat TM/ETM+ images (1988, 2002 and 2006),

SPOT images (2008)

Field data (including GPS data)

Methods

At regional scale:

- the supervised classification of the Landsat images in order to obtain Land

cover maps from different periods.

- the change detection method (Landsat TM/ETM+ scenes)

- the estimation of changes using Land Change Modeler tool (Idrisi Andes

software)

At local scale:

- both visual and GIS analysis based on old and recent cartographic

documents, airphotos and recent high resolution satellite images (SPOT).

-Field data were used:

- to differentiate the training sites (more than 300 points for each satellite

scene)

- for the accuracy assessment of the supervised classification

- to identify the vegetation types, the geomorphological present-day

processes and the human impact on the timberline/treeline

Sun azimuth = 137.1989028 degrees

Sun elevation angle = 61.8029487 degrees

The map of analytical hillshading

Digital Elevation Model (DEM)

The classification of the satellite images

Landsat TM and ETM+ images:

For the Retezat – Godeanu Massif: August 1998- August 2006

For the Făgăraş Massif: August 1996- August 2004

1. The mitigation of the topographic effect - the shadows generated by steep

slopes exaggerate the difference in reflectance information coming from the same

landcover type. Shading is the main problem in using satellite imagery for

classification purposes in high mountain areas.

Mitigation of the topographic effect based on DEM

Landsat image - Band 4 (NIR)

Landsat image - Band 4 (NIR)

after the correction

The classification of the satellite images

1. The creation of the spectral signatures for each landcover type

- the differentiation of the spectral test areas (training sites)

- the creation of the spectral signatures

2. The classification of the

satellite images with the

maximum likelihood

method

The validation of the classification demonstrated that the accuracy is

between 87 and 93%. The most errors were detected in the extreme

shadow areas.

Because our study is focused only on the

timberline/treeline area, we eliminated all the areas

below 1400m and we grouped the landcover types in

four classes: pastures, shrubs, forests and waters.

THE CHANGE DETECTION METHOD

Change detection image = Earlier image – Later image

In all the change detection images we could observe that there are areas with

significant changes (the values of the pixels were beyond + 2SD or -2SD)

THE LAND CHANGE MODELER TOOL (Idrisi software)

- is based on cross-tabulation analysis that compares two

landcover images of the same area from different periods of time

The gains and losses of the landcover types

in Retezat – Godeanu Massif (1988-2004)

Net change of the landcover types

in Ţarcu and Godeanu Mountains

In the massifs where the pasturage was

very intense the natural boundaries of the

forest domain have changed.

The treeline ecoton has been destroyed by

burning of the subalpine shrubs and by

clearing

The intensity of the pasturage activity could be

expressed by the density of the sheepfolds in the

alpine area (numbers of sheepfolds/km2).

1965

2008

(Emm. de Martonne, 1921

2006

SPOT, 2.5 m resolution

The Godeanu and the Cernei Mountains

2008

2008

Gains and losses in forests in Tulişa Mountains

Gains and losses in shrubs in Tulişa Mountains

Muntele Mic Massif

Areas with no evident changes

The Retezat Mountains -the

first national park in Romania

(1935).

There are no changes of the

timberline.

The treeline ecoton is present

and well preserved.

There is no advance of the

forest because the timberline

is mainly geomorphologicaly

determined.

The gains and losses of the

landcover types in Făgăraş

Mountains (1986-2000)

The Northern

Slope

The Southern

Slope

Avalanche paths that penetrate the forest on the northern slope of the Făgăraş Mountains

The map of the geomorphological risk in

Balea Valley

1953

SPOT, 2008

The comparison between the timberline in 1953 and in 2008 on the

northern slope of the Făgăraş Mountains

The gains and losses of the landcover

types on the southern slope of the

Făgăraş Mountains (1988-2004)

SPOT, 2008

Comparison between the theoretical (climatic)

timberline and the real timberline

The Northern Slope

The Southern Slope

The Arjana Massif - the lowest area (1512 m) in Southern

Carpathians where subalpine level was identified

1952

1952

Airphoto, 2005

Airphoto, 2005

1952

SPOT, 2008

1.72 ha

• The human impact in the subalpine and alpine levels, especially the

grazing, has a great contribution in shaping the present day timberline

configuration.

• In almost all areas with intense pasturage activities the treeline ecoton

has been destroyed and the timberline is 300-400 m lower than the

theoretical (climatic) limit of the forest.

• In the areas with abandoned alpine pastures the dominant process is the

advance of the shrubs and spruce seedlings. In some cases we noticed

also the recover of the timberline. At low altitudes this process is more

intense i. e. Arjana Massif.

• In the protected areas (Retezat National Park) there are no significant

changes of the timberline. The treeline ecoton is also well preserved.

• In the areas where the timberline is a geomorpholgical one, there are

also no important changes (the northern slope of the Fagaraș Mountains

and the Retezat Mountains).

• Although there is an obvious trend of the temperature to increase we

could not established if the process of the forest recover is a consequence

of the climatic change

CONCLUSIONS

In the further studies:

- to improve the method for the reducing the topographic effect

- to use satellite images with very high resolution

- to establish representative test areas for the monitorization of the

vegetation changes

- to collect climatic data from the timberline area using data loggers

THANK YOU !