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Free keywords:
Amazonia; Aerial photography; Flooding gradient; Landsat TM; Remote sensing; Succession; Várzea
Abstract:
In Central Amazonian white-water floodplains (várzea),
different forest types become established in relation to the
flood-level gradient. The formations are characterized by
typical patterns of species composition, and their
architecture can be quantified using large-scale aerial
photography. Crown sizes, tree heights, the projected crown
area coverage and the gap frequencies influence the light
reflectance in the upper canopy, and provide information
which facilitates a classification of different forest types by
satellite imagery.
Results of ground analysis indicate that at the average
flood-level of 3 m, species diversity and architecture of the
forests changes, thus justify the classification into the
categories of low várzea (várzea baixa) and high várzea
(várzea alta). The structure of low várzea depends on the
successional stage, and species diversity increases with
increasing age of the formations. Within the early
successional stages of low várzea, a homogeneous, nonstratified
canopy is developped, with uniform tree heights
and crown extensions, resulting in a smooth canopy surface.
Gap frequency is low. Therefore, these forests show a
simple behaviour pattern in pixel distribution and are easy
to detect, when scanned by TM images. In subsequent
successional stages, tree heights and crown areas increase,
and an initial stratification is developed. Gap frequency
tends to increase with increasing age of the formations. In
high várzea, only one successional stage was found and
species diversity is higher than in all low-várzea formations.
Tree heights reach 45 m and stratification is well defined.
The more complex architecture of the high várzea results in
the most diffuse behaviour patterns of pixel distribution,
when scanned by TM image data
