International Archives of the Phot
Measure of LAI (Leaf Area Index)
The LAI (Leaf Area Index) is commonly used to define the
photosynthetic surface of a tree crown. At the same time it
measures the cover degree and it can be associated with full
forestry development or its primary productivity.
For each test area we measured this index with the LICOR-
LAI2000 Plant Canopy Analyser. To get more data, we split a
sample area (test area 26) in four subplots (NE: North East;
NW: North West; SE: South East; SW: South West). It wasn't
possible to do the same to the other parcel (test area 36) for two
reasons: slope conditions and forestry management (high
forest).
LAI
Area test 26 NE 4,2
Area test 26 NW 4,23
Area test 26 SE 4,3
Area test 26 SW 3,97
Area test 36 4,37
Table 2. The LAI values measured in the test areas.
4.2. Cutting of all the timbers in the two training areas
In order to have a real measure of biomass present in the two
small test areas, soon after the acquisition of the satellite image
we cut all timbers. Trees have been cut at 0,3m of height on the
trunk. All branches have been cut and divided from logs (fig.4).
All trunks have been cut every 2 m (so 2,3m, 4,3m and so on),
in order to transport easily all the wood outside the forest.
Figure 4. Branches divided from logs (source: CETA).
4.3. Weighing of the cut logs and of the leaves
All trunks and the secondary branches also have been weighted.
At regard of leaves weighing, the procedure adopted has been
quite complicated. For cach area test, after the cutting
opgration, we have first removed all trunks and branches, and
after we collected all the leaves on the large piece of cloth. We
have stocked all leaves to make a parallelepiped form (fig.5)
and we weight a volume evaluate indicative. From sample
weight we derived the weight of foliage.
ogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B4. Istanbul 2004
—
Wood Biomass q. Foliage
(Trunk + Branches) Kg
Area test 26 NE 29 93
Area test 26 NW 35 102
Arca test 26 SE 19 90
Area test 26 SW 31 60
Area test 36 178 144
Table 3. The wood biomass and foliage weighted.
Figure 5. The parallelepiped form of leaves (source: CETA).
4.4. Estimation of the wood biomass, using some different
dendrometric tablets
From height and diameter of trees, we estimated the wood
biomass using three different dendrometric tablets: Regional
tablets (from Friuli-Venezia Giulia; FVG, and Emilia-
Romagna) and Alpine table (from LS.A.F.A. Institute — "Istituto
Sperimentale per I’ Assestamento Forestale e per l' Apicoltura").
Wood Biomass FVG Emilia I.S.A.F.A.
Romagna
Area test 26 NE 19 26 31
Area test 26 NW 23 28 34
Arca test 26 SE 28 17 20
Area test 26 SW 12 16 28
Area test 36 107 1 131 166
Table 4. The wood biomass estimated by dendrometric tablets.
The second stage has been developed in the following two
steps:
4.5. Acquisition of the Quickbird scene
After having located our test areas, we acquired a high-
resolution satellite image. We needed this kind of information
because we could cut only these small test areas. If you want lo
compare real wood biomass and vegetation index, you need à
high-resolution image. In fact, with a Landsat? ETM+ imag
(pixel resolution 30m), for example, you need at least 900 m
sampling area. For this reason we used a Quickbird image
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