LITTER PRODUCTION IN SEASONAL SEMIDECIDUOUS FOREST ANDPterogyne nitens Tul. AND Eucalyptus urophylla S. T. Blake PLANTATIONS IN SOUTHWESTERN BAHIA STATE, BRAZIL

ABSTRACT

Leaf litter is a major component responsible for maintaining the productive capacity of forests; thus, knowledge on their production and composition can provide information to adjust management techniques. The objective of this study was to evaluate the monthly litter fall in a Seasonal Semideciduous Forest and two pure forest plantations (Pterogyne nitens and e deEucalyptus urophylla), located in city of Vitoria da Conquista, Bahia state, as well as to analyze the influence of climatic factors in this production. Leaf litter samples were collected during ten months, using 0.25 m² square collectors. The materials collected were screened (fractions: leaves, branches, bark and reproductive structures) and dried in a dry kiln at 60° C. The monthly average litter productions were 544.6, 522.6 and 179.5 kg ha^-1 in areas of Seasonal Semideciduous Forest,Eucalyptus urophylla and Pinus nitens, respectively. The leaves represented an increasing proportion of litter in three coverages (65% of the total). The average monthly production of leaves was higher in native forest, followed by Eucalyptus urophylla andPinus nitens. The contribution of branches was significantly lower in the Pinus nitens and did not vary between Seasonal Semideciduous Forest and Eucalyptus urophylla. The production of reproductive materials varied in the order: Eucalyptus urophylla > Seasonal Semideciduous Forest > Pinus nitens. The bark fraction did not vary between Seasonal Semideciduous Forest and Pinus nitens, being higher inEucalyptus urophylla. There was a significant negative correlation between total production and average air temperature in all studied coverage. Only on Pinus nitens were found significant associations with the litter production variables precipitation and wind speed.Eucalyptus urophylla forest and Seasonal Semideciduous Forest have similar aspects regarding leaf litter production, 67% higher than the production of Pinus nitens. The temporal variation of litter production of Pinus nitens shows up much more sensitive to the influence of climatic variables that Seasonal Semideciduous Forest andEucalyptus urophylla. The contribution of litter fractions followed the same order in all coverage studied: leaves > branches > reproductive structures > bark.

Keywords:
litter fall; deposition; madeira nova (new wood); eucalypts