Models for Semideciduous Seasonal Forest Production of Leaves and Deciduousness: Recent Perspectives

The climate, mainly the water availability and temperature, drives the renewal of biomass in seasonal
forest ecosystem, and the greenness and leaf area of its canopy are responsive by climate variations.
The renewal of leaves indicated by deciduousness can be model to obtain the estimates of this
component as an additional compartment of the ecosystem carbon sink. In this study was investigated
the relationship between litterfall, climate variables, Leaf Area Index (LAI), and Normalized Difference
Vegetation Index (NDVI) in semideciduous forests, to test models to explain the leaf production and
deciduousness by time. The data were obtained in satellite images and in plots installed at forest
monitoring sites, visited monthly. The tests were conducted in eight semideciduous forest fragments.
Permanent plots were monitored monthly and LAI measurements and weighing of litterfall deposited
in nets. In this time, Landsat and IRS satellite images were obtained and processed for generation of
NDVI. The water balance was calculated for each day. The relationship among the variables “leaf dry
weight”, “LAI”, “NDVI” and climate variables were verified and regression models was build and
evaluated. With monitoring of the sites, the model was validated and reviewed with new variables and
data and three equations were compared. It is possible to estimate the fall and renew of leaves
biomass in semideciduous forests with reasonable precision. This study showed that only the leaf
component of the litterfall of a semideciduous forest in tropical climate can capture average 6.5
Mg.ha-1.yr-1 of CO2 and this amount can be estimated using climate, biophysics and vegetation index
variables.