vn a strong
] synthetic
er of 1999.
roximately
ound.
ydel of the
ut data for
'ments and
omass, the
1999). The
polarized.
rof a: P3
le over the
7
,
Moisture
ys. The P3
ntersection
flew at an
ch resulted
: Company
rowing on
o 30 years
he stands
to contain
chosen for
] extent of
] in Figure
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004
Figure 2. Landsat image of Waverly site
The numbers also correspond to the ages of the trees - larger
numbers indicating older trees. The dark area in the image
between sites 5 and 6 is Airfield Pond. The very light regions
are clear cuts while the regions that are a little darker than the
clear cuts are regions of newly planted trees. Site 1 consists of
trees that are 2 years old at the time of the experiment. A
picture showing the small trees in site 1 and the 18 year old
trees in site 5 is shown in Figure 3. The boundaries of the sites
can be seen in the Landsat image. The difference between site !
and 5 is clear, however it is difficult to see the difference
between trees in sites 2 through 6 because the canopies are
dense and mask the ground.
Figure 3. Two-year-old trees of site 1 with 18-year-old trees of
site 5 in the background.
3. ESTARDATA
The ESTAR data will be examined from two different
perspectives: spatial and temporal. In the spatial case, the
biomass of different stands will be compared to their brightness
temperatures. In the second case, two stands will be examined
as a function of time to see how their brightness temperatures
vary with changes in soil moisture.
In Figure 4 an image generated from the ESTAR flight of
November 15 is shown. The sites have been numbered as above
using the same convention as shown in the Landsat image.
Also, the local road system has been superimposed on the
image. The colors correspond to brightness temperatures whose
scale is shown on the right hand side of the figure. Airfield
Pond is clearly visible on the image although not in the same
detail as in the Landsat image. The difference between the 2
years trees of site 1 and the 18-year-old trees of site 5 is clearly
visible.
mn
261
251
latitude
36.88 p i ] 1 Í 1 LL = Li
-77.10 -77.08 -77.06 77.04 .-77.,02
longitude
Figure 4. ESTAR brightness temperature maps for flights on
November. 15, 1999
International Paper Company has supplied us with the biomass
of trunks for site 1 through 5. Twenty percent was added to
account for branches and needles to obtain the total biomass of
each site. The biomass in tons/hectare is plotted in Figure 5
versus the brightness temperature in degrees Kelvin from the
November 15, 1999 flight. The sixth site, which is privately
owned, consists of huge trees, which are most likely over
seventy years old. Their biomass has been determined from
basal area estimates and represents the highest point on the
curve. A regression curve obtained by using a least squares fit
is also shown in Figure 5. Considering that the radiometer has a
resolution on the order of 1°K, one is able to predict the
biomass from the brightness temperature with a good degree of
accuracy.
An important issue from the perspective of monitoring biomass
is the effect of changes in soil moisture on the brightness
temperature. The flights took place over a period of five
months, during which a variety of different moisture conditions
have been encountered. providing data to address this question.
Radiometric Biomass Sensing
280
270
260
250
240
230
BRIGHT NESS(Kelvin)
220
0 50 100 150 200 250
BIOMASS(Tn/ha)
Figure 5. Brightness temperature vs. biomass
To study these effects of soil moisture, closer attention has been
concentrated on site 1 and site 5. which will be called the
Airfield Pond Regeneration (APR) site and the Airfield Pond
Mature (APM) site, respectively. Soil moisture values have
been recorded at these two sites for each of the four over-flights
and measurements have been made of tree architecture. The
