Relationships between wood volume increments by stem analysis and water balance in the semi-arid interior of northeastern Brazil
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annual wood volume increments
In the semi-arid region of northeastern Brazil, drought deciduous thorny shrub forest which is locally called caatinga is widely spread. Using four trunks of Clitoria cearensis Hub., which is one of the caatinga tree species, stem analysis was applied to estimate annual wood volume increments. Regarding evaluation of water stress in this region, water storage in the soil was calculated by the Thornthwaite and Mather's method, and the annual amount was estimated by the variable timing year method. As a result, it was found that the wood volume growth was dependent on seasonal cycles between the rainy and dry seasons. In such a region, temperature is not a decisive factor for plant growth, wood volume growth is dependent on how long soil moisture was successively retained. The species used in this study is one of the pioneer species in the plant succession process of the caatinga forest. Trees in this group quickly react to annual changes of effective amounts of water, and the increments are also large, but have small tolerance of aridity. Therefore, it is thought that the fluctuation of wood volume increment of Clitoria cearensis Hub. is directly influenced by the semi-arid climate of northeastern Brazil. If the same analysis is applied to other species in different succession stages, it becomes possible to evaluate total increments of caatinga stand in a unit area.
広島大学総合科学部紀要. IV, 理系編