ABSTRACT
ABSTRACT Currently, there is a lack of studies on the correct utilization of continuous distributions for dry tropical forests. Therefore, this work aims to investigate the diameter structure of a brazilian tropical dry forest and to select suitable continuous distributions by means of statistic tools for the stand and the main species. Two subsets were randomly selected from 40 plots. Diameter at base height was obtained. The following functions were tested: log-normal; gamma; Weibull 2P and Burr. The best fits were selected by Akaike's information validation criterion. Overall, the diameter distribution of the dry tropical forest was better described by negative exponential curves and positive skewness. The forest studied showed diameter distributions with decreasing probability for larger trees. This behavior was observed for both the main species and the stand. The generalization of the function fitted for the main species show that the development of individual models is needed. The Burr function showed good flexibility to describe the diameter structure of the stand and the behavior of Mimosa ophthalmocentra and Bauhinia cheilantha species. For Poincianella bracteosa, Aspidosperma pyrifolium and Myracrodum urundeuva better fitting was obtained with the log-normal function.
Subject(s)
Trees/growth & development , Tropical Climate , Forests , Plant Dispersal/physiology , Reference Values , Trees/classification , Brazil , Statistics, Nonparametric , Anacardiaceae/growth & development , Aspidosperma/growth & development , Caesalpinia/growth & development , Bauhinia/growth & development , Mimosa/growth & development , Biodiversity , Geographic MappingABSTRACT
Os fatores ambientais, tais como: temperatura do ar, umidade relativa do ar e radiação solar, influenciam no comportamento fisiológico dos vegetais refletindo no seu crescimento e desenvolvimento. O objetivo do trabalho foi avaliar o comportamento fisiológico em mudas de pata-de-vaca ao longo do dia e constatar qual o melhor horário para a realização de determinações de trocas gasosas. Para tanto, foram realizadas avaliações de temperatura da folha, radiação fotossinteticamente ativa, resistência estomática e transpiração, utilizando-se um porômetro, das 8:00 às 17:00 horas, em intervalos de uma hora entre as medidas. A espécie apresenta oscilações no seu mecanismo fisiológico em função do horário de avaliação e das condições climáticas, sendo o intervalo mais indicado para a realização de determinações das trocas gasosas das 10:00 às 13:00 horas.
Environmental elements, such as air temperature, relative humidity and solar radiation, affect the physiological behavior of plants, which is reflected in their growth and development. The objective of this study was to evaluate the physiological changes of Brazilian Orchid Tree seedlings over a typical day and find the best time to carry out determinations of gas exchanges. For this end, we evaluated temperature of the leaf, photosynthetically active radiation, stomatal resistance and perspiration, using a porometer, from 8:00 a.m. to 05:00 p.m., in intervals of one hour between measurements. The species presents oscillations in its physiologic mechanism in function of the time of evaluation and climatic conditions, being the most suitable interval to determine gas exchanges from 10:00 a.m. to 01:00 p.m.