Vegetation Index Field Data Measurement

3.5 Vegetation Index

Remote sensing technology using satellite image has a view of large areas of the surface to estimate the vegetation index value. Normalized Difference Vegetation Index was chosen for the vegetation analysis because the different resolution and time acquisition of three available images will contain different aspect that need to be normalized. NDVI of QuickBird Satellite imagery data obtained by the product of the ratio of near infrared and red channels, is formulated as follow RED NIR RED NIR NDVI + − =

3.6 Field Data Measurement

The selected trees must come from the population of interest, represent the major species in the forest and represent all size classes. The method of field sampling applied for collecting field data is quadrate sampling, with 30m x 30m plot size. The scheme for distributing sample over the area of interest, use stratified systematic random sampling. Stratification done for the forest cover becomes A, B, C, D type. A systematic way was chosen to spread the plant in row evenly, and then the trees were measured for each row randomly. Stratification will achieve greater precision provided that the strata have been chosen so that members of the same stratum are as similar as possible in respect of the characteristic of interest. The diameter breast height was calculated from the girth of the trees and converted to the trees diameter. Trees total height was measured by using vertex that has the function of measuring heights, distance, angle inclination and air temperature. The x and y trees canopy was also measured by using vertex. 36 Figure 3.4 The sampling scheme for field measurement data. Leaf Area Index LAI was measured by using manual calculation that combine the digital leaf measurement for each leaf area then multiply by the total leaf calculated in the each observation trees the divided by x and y canopy area. The digital camera is utilized for take a picture of leaf to be converted to digital form. Leaf area measurement utilized the Autocad Map Software. The procedure is described in Figure 3.5. The sequential method to measure LAI manually are: 1 taking a picture of an average trees leaf that represent the leaf of each tree species within observation plot; 2 measure the real length of the trees leaf, real length measurement used for calibration between leaf picture and width length of real leaf; 3 digitize the area of leaf in a software and derive the real leaf area for each leaf area within plot observation; 4 total leaf in each tree species within observation plot was counted manually by using the total leaf for each branch approach; 5 multiply the total leaf with leaf area; 6 the total leaf divided by the canopy area where the trees are projected. 37 Figure 3.5 General flow of LAI field measurement.

3.7 Calculating Biomass using Allometric Equation tonha