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