Equações para estimativa de volume de madeira para a região da bacia do Rio Ituxi, Lábrea, AM

Mimosa tenuiflora is a native pioneer tree from the Caatinga used commercially as firewood due to its high calorific value. It is deciduous, its trunk does not reach large diameters and it has good regrowth capacity. This study intended to determine the annual increment in diameter of M. tenuiflora and its correlation with rainfall, as basis for fuel wood management. Disks from the stem base of M. tenuiflora trees were collected in 2008 in Sertânia and Serra Talhada, Pernambuco State, from regrowth of trees coppiced in 2003 and in Limoeiro do Norte, Ceará State, from a plantation established in 2002. The trees have well-defined annual growth rings, highly correlated with annual precipitation and are well-suited for dendrochronological investigations. Forest managers must consider the influence of previous drier years in the wood production when predicting fuel wood harvesting. The high growth correlation with the previous year's rainfall in regions where the rains start after photoperiodic stimulation indicate the necessity of understanding the growth dynamics of the species under dry forest conditions through additional ecophysiology studies.

O estudo foi realizado em quatro remanescentes próximos a cidade de Corumbá, MS (19º05'-19º20' S e 57º40'-57º55' W), com o objetivo de verificar a variação da composição florística e estrutura da floresta decídua em diferentes relevos e tipos de solo. Quatro remanescentes foram amostrados pelo método de quadrantes. Três áreas foram amostradas com 20 pontos, e a quarta área foi amostrada com 50 pontos. Todas as árvores com circunferência à altura do peito > 9 cm foram amostradas. Na floresta estacional decidual aluvial foram amostradas 32 espécies, sendo as de maior valor de importância Attalea phalerata Mart. ex Spreng. (Arecaceae) e Aspidosperma australe Müll. Arg. (Apocynaceae). Nas duas áreas de floresta estacional decidual de terras baixas, foram amostradas 47 e 25 espécies, respectivamente, sendo Sebastiania discolor (Spreng.) Müll. Arg. (Euphorbiaceae) e Phyllostylon rhamnoides (J. Poiss.) Taub. (Ulmaceae) as mais importantes em ambas. No remanescente de floresta estacional decidual submontana foram amostradas 24 espécies, sobressaindo-se Acosmium cardenasii H.S. Irwin & Arroyo (Fabaceae) como a mais importante. A família mais rica nas áreas estudadas foi Fabaceae, com 16 espécies, seguida por Euphorbiaceae, com seis espécies, e por Apocynaceae, Rubiaceae e Sapindaceae, com três espécies cada. As duas áreas de florestas de terras baixas mostraram-se muito similares, tanto na composição florística, como na estrutura. A floresta aluvial apresentou composição florística e estrutura mais distintas das demais áreas. Estes remanescentes de florestas estacionais deciduais apresentaram estrutura e composição florística peculiares, com elementos do chaco e da caatinga, merecendo a intensificação de estudos botânicos e ecológicos. A survey was made on four deciduous forest remnants in the town of Corumbá, State of Mato Grosso do Sul (19º05'-19º20' S and 57º40'-57º55' W), aiming to verify the floristic and structure variation of deciduous forest remnants in different relief and types of soils. The four remnants were sampled through the point quarter method. Three areas were sampled through 20 points and the fourth area was sampled through 50 points. All trees with circumference at breast height > 9 cm were sampled. In the alluvial deciduous forest, 32 species were sampled, Attalea phalerata Mart. ex Spreng. (Arecaceae) and Aspidosperma australe Müll. Arg. (Apocynaceae) having the highest importance value indexes. In two areas of lowland deciduous forest 47 and 25 species were sampled, respectively; Sebastiania discolor (Spreng.) Müll. Arg. (Euphorbiaceae) and Phyllostylon rhamnoides (J. Poiss.) Taub. (Ulmaceae) being the most important in both. In the remnant of submontane deciduous forest 24 species were sampled, Acosmium cardenasii H.S. Irwin & Arroyo (Fabaceae) outstanding as the main species. The richest family was Fabaceae with 16 species, followed by Euphorbiaceae with six species, and Apocynaceae, Rubiaceae and Sapindaceae with five species each. Both areas of lowland forests showed to be very similar in floristic composition as well as in structure. The alluvial forest presented the most distinct structure and floristic when compared to the other areas. These remnants of deciduous forests have peculiar structure and floristic composition, containing species of the Chaco and Caatinga Provinces that require extensive botanical and ecological studies