c.Howland, Maine

J. Ranson
Goddard Space Flight Center

K. Paw U
University of California, Davis

 The Howland Backup Supersite has been the focus of intensive
studies over the past several years including activities
of the Spruce Fir Cooperative, National Acidic Deposition
Project and Mountain Cloud Chemistry program.  NASA Headquarters-sponsored
Forest Ecosystem Dynamics‹Multisensor Aircraft Campaign (FED-MAC)
experiments were conducted at the Howland site during August-September
1989, March 1990, June and July 1990.  Along with airborne
SAR data, forest canopy and soil characteristic ground truth
measurements were also acquired.  Additional aircraft measurements,
including ER-2 AVIRIS, C-130 ASAS and UH-1 (optical radiometers),
have been acquired since 1989.  Data from aircraft and field
measurements have been cataloged in a computerized data base
which is available through the Forest Ecosystem Dynamics
Project at GSFC Biospheric Sciences Branch.
 On or near the site, there are a variety of different-aged
clearings, small plantations, and larger expanses of natural
forest cover.  The natural forest is a transitional boreal
with major forest types of mixed hardwoods (aspen, birch)
spruce-hemlock, and hemlock-mixed hardwoods.  Because of
the glacial history of the area, soil drainage classes vary
from well drained to very poorly drained over a limited distance
producing a complex mosaic of forest communities.  In addition,
significant areas of bogs and wetlands occur throughout the
area.  This variety of forest ecosystem types within a localized
area was a primary factor for selection of this site.  Another
important consideration was the excellent logistics in place
to support field and aircraft activities.
 Existing forest stand measurements include species composition,
DBH, height, height to live crown, angle of bole, leaf area
index estimates, soil characteristics including moisture,
and profiles of the surface.  These measurements were typically
made within 20 m diameter plots within the site.  An intensive
study of a spruce stand included measurements of species,
DBH, and the location of every tree within a 200x200 m area.
 In addition to the plot measurements, several spruce and
hemlock trees were cut down and destructively sampled to
determine branch size and angle distributions for radar scattering
models.  Additional measurements of canopy and stand attributes
are being acquired as needed.