Dendroecologia de Tabebuia aurea (Manso) Benth. & Hook e Tabebuia heptaphylla (Vell.) Toledo (Bignoniaceae) no Pantanal de Mato Grosso, Brasil

• Autor(a) principal: Leite, Patricia Tiemi de Paula
• Data de Publicação: 2012
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFMT
• Texto Completo: http://ri.ufmt.br/handle/1/1804
• topic: Dendroclimatologia; Modelo de crescimento; Anéis de crescimento; El niño; CNPQ::CIENCIAS BIOLOGICAS::ECOLOGIA; Dendroclimatology; Growth model; Tree rings; El niño

The Pantanal is one of the largest wetlands in the world which has been suffering an increase in deforestation for the establishment of cultivated pastures and agriculture lands, putting in danger its ecosystems. Tabebuia aurea (Manso) Benth. & Hook. and Tabebuia heptaphylla (Vell.) Toledo (Bignoniaceae) are two deciduous tree species growing in the huge Pantanal wetland, often forming monospecific stands. Although these species are abundant in the Pantanal, there still a lack of information regarding their adequate management. The same occurs for the influence of precipitation and the El Niño and La Niña events on these species. Therefore, the objective of this study was to construct growth curves for both species, define the minimum logging diameter (MLD) and the cutting cycle (CC) for each one, using the dendrochronology as a science for this. Furthermore, there was also evaluated if there is a relation between the precipitation and the tree rings width and if the El Niño and La Niña affect both species growth. To do this there were collected stem disks and cores of 27 trees from T. aurea and 23 from T. heptaphylla. All samples were collected at the Northen Pantanal of Mato Grosso State, about 100 km away from Cuiabá, Brazil. From all trees we measured diameter at breast height (DBH) and tree height. After this, the transversal sections of the samples were left to dry on air temperature and then they were polished to analyze the wood anatomical features of the tree rings. Afterwards, ring-width was measured to construct individual diameter growth curves. This data was correlated to the precipitation historical series for the study area, which comprehends a period of 1912 to 2010. In a same way, data for El Niño and La Niña on the period of 1950 till 2006 was used. The dendrochronology applied to both species lead to an adequate construction of their growth curves. T. aurea achieves the MLD of 50 cm of DBH with 156 years, while T. heptaphylla reaches the MLD of 40 cm in 122 years. The feeling cycle differed only slightly between T. aurea (31.2 years) and T. heptaphylla (30.5 years). The correlation between precipitation and chronology of both species was significant only for T. aurea. On the other hand, El Niño showed significant influence over the growth of both species. For T. aurea all regions of El Niño (1+2, 3, 4 and 3.4) resulted in an increase in growth, while the inverse occurred for T. heptaphylla. Only the specie T. heptaphylla showed significant growth difference in years of La Niña, when it increased its growth.