MAPPING OF FOREST CLEARANCE
IN ‘EUA, TONGA
VEGETATION MAPPING
INTRODUCTION
Brief HistoryCurrent Practice Database SetupGIS SetupImage Interpretation
BACKGROUND HISTORY
Training with LandCare on GIS Arc ViewLandCare mapped the clearings with High
Precision GPSMapped Forest according to Compartments
WHAT WERE THE PROBLEMS?
No GPS equipments to digitally map the clearings and Forest Compartments after the LandCare left.
No back up copies available
WHAT WAS USED?
Tape MeasureSuunto CompassClinometerField Book
WHAT RECORDED IN THE FIELD BOOK
Stations / PointsDistanceForward BearingsBackward Bearings
HOW THIS WAS CONVERTED DIGITALLY?
Data from the field were entered into Spreadsheet, get the X and Y Coordinates of the starting point from the GIS ARCVIEW Map to calculate X and Y accumulation.POINT DISTANCE F/BEARING B/BEARING X_Co Y_Co X_Accum Y_Accum
001 57 77 257 -174.308 -21.376 0.00 0.000
002 60 167 347 -174.309 -21.378 2.33 2.55
003 55 257 77 -174.31 -21.38 3.04 3.43
004 45 347 167 -174.312 21.382 4.42 4.22
Highlight only X & Y Coordinates column and save as dbf file
POINTDISTANCE
(m) F/BEARING B/BEARING X_Co Y_Co X_Accum Y_Accumu
001 57 77 257 -174.308 -21.376 0.00 0.00
002 60 167 347 -174.309 -21.378 2.33 2.55
003 55 257 77 -174.31 -21.38 3.04 3.43
004 45 347 167 -174.312 -21.382 4.42 4.22
DATA PROCESSING
GIS ARCVIEW
Open ARCVIEW File, Go to View and click on New Theme, Points
The Points appear on the map, joint the points and convert to Shapefile
GIS/GPS TRAINING
MapInfoHand held Garmin
How the Hand held Garmin was used?
Clearings inside the ‘Eua Forest Plantation were marked with GPS
Steps of Data Processing
Data transfer from GPS to Computer
Data is cleaned up, saved and then go to MapInfo professional and import file
X_Co Y_Co ns:ele PointName
-174.917 -21.3737 303.3 001
-174.917 -21.3738 303.7 002
-174.917 -21.3739 300.8 003
-174.917 -21.3739 301.3 004
-174.917 -21.3738 303.9 005
Create Point by getting X and Y Coordinates, joint and edit
SATTLELLITE INTERPRETATION
‘Eua 2005 Image
DIGITIZED CLEARINGS
Forest Clearings outside the ‘Eua Forest Plantation were also digitized but only on Woodland, Broadleaved and Conifer Forest Plantation
Difference between the interpretation and field check
less clearing on the imageMore clearings on the ground
Reasons for differences between interpretation and
field check Image that was used is ‘Eua 2005 ImageBetween 2005 and 2010 new clearings took
place
Clearance 2010
• ‘Eua:87 sqkm• Clearance: 114.54 Ha (1990- 2010• ‘Eua Forest Plantation: 714 Ha
THANK YOU!
MALO ‘AUPITO
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