RESUMO
Phytosociological analysis in native forests is performed considering the horizontal and vertical structure of the studied population, whose most expressive parameters are the density, dominance, frequency, value of coverage and value of importance of species. Many phytosociological studies include a value of importance of species calculated by adding density, dominance and frequency, in their relative forms, however, this estimator is a mathematical impropriety because the result is a sum of indexes and does not express the true meaning of species' value. This is because the estimator is still influenced predominantly by the density of occurrence of species and cannot capture the relevant hierarchical participation of emerging species that occur with low density in the biocoenosis. In this work, we propose a new index to characterize the value of importance of species based on the hierarchy and spatial absolute probability of the species in the biocoenosis, illustrated with data from a forest fragment of semideciduous tropical forest located in Cassia, MG, Brazil. The new index appropriately expressed the importance of species in the evaluated fragment.
Assuntos
Biodiversidade , Monitorização de Parâmetros Ecológicos/métodos , Florestas , Brasil , Modelos Biológicos , Densidade Demográfica , Especificidade da Espécie , Clima TropicalRESUMO
Generally, the forest companies use the total one year planting area as a minimum stratum of the total population and, consequently, the forest inventory processing has been conducted by applying the stratified random sampling to it. This study was carried out in the National Forest of Tres Barras, Brazil, and it aimed to classify and map the sites of Pinus elliottii stands. A systematic sampling was structured into clusters and applied independently by compartments. The clusters, in maltese cross, were composed of four sampling subunits, using Prodan sampling method with a fixed number of six trees. By analysis of the methodology it was possible to confirm the hypothesis: a) the selective thinning cause expressive increase of volumetric variability within compartments; b) the variation of sites within the compartments causes volumetric expansion of variance and this grows proportionally to the quality of the sites; c) the stratification in sites results in minimum variance within them; d) the stratification in sites resulted in until to 91% reduction of variances within them.
Assuntos
Florestas , Pinus/crescimento & desenvolvimento , Brasil , Análise EspacialRESUMO
Este trabalho teve por objetivo avaliar a bioatividade de óleos essenciais de sassafrás (Ocotea odorifera) e eucalipto (Eucalyptus viminalis) no controle de larvas e adultos de cascudinho (Alphitobius diaperinus), comparando-se seu potencial inseticida. Os óleos essenciais foram obtidos por meio de extração por arraste a vapor de água em escala piloto. Foi empregada a técnica de papel de filtro contaminado para a avaliação do número de insetos mortos. No bioensaio definitivo, foram selecionadas 11 concentrações e um controle (solvente) para determinação da taxa de mortalidade e CL50 dos dois óleos testados. As larvas foram mais suscetíveis que os adultos ao óleo essencial de sassafrás e menos suscetíveis que os adultos, quando expostas ao óleo de eucalipto. Tanto larvas quanto adultos de A. diaperinus foram mais suscetíveis ao óleo essencial de sassafrás (CL50 adulto 0,26mL l-1 e larva 0,12mL l-1) que ao de eucalipto (CL50 adulto 1,37mL l-1 e larva 1,72mL l-1), por via de intoxicação por contato (Ocotea odorifera: Larva y=3,3916+1,4699logx; Adulto; y=0,9486+2,8576logx; e Eucaliptus viminalis: Larva y=1,3643+1,6254logx; Adulto y=1,4487+1,6623logx). Conclui-se que os óleos essenciais de sassafrás e eucalipto podem ser empregados para o controle do cascudinho como uma nova estratégia no manejo integrado dessa praga.
This research aimed to evaluate the sassafras (Ocotea odorifera) and eucalyptus (Eucalyptus viminalis) essential oils on the control of larvae and adults of lesser mealworm (Alphitobius diaperinus), comparing their insecticide potential. The essential oils were produced through water vapor extraction in a semi industrial scale. Contaminated paper filter technique was applied to evaluate the insect mortality. In the current experiment twelve concentrations were included for evaluation and among them one control (solvent) in order to settle the mortality rate and LC50 of the two tested essential oils. The larvae were more susceptible then the adults to sassafras essential oil exposure and less susceptible than the adults, when exposed to eucalypt essential oil. Larvae as well as adults of A. diaperinus were more susceptible to the sassafras (LC50 adults 0.26mL l-1 and larvae 0.12mL l-1) than the eucalyptus essential oil (LC50 adults 1.37mL l-1 and larvae 1.72mL l-1), by contact intoxication (Ocotea odorifera: Larvae y=3,3916+1,4699logx; Adult y=0,9486+2,8576logx; e Eucaliptus viminalis: Larvae y=1,3643+1,6254logx; Adult y=1,4487+1,6623logx). It is concluded that the essential oils of sassafras and eucalyptus can be used to control lesser mealworm and used as a new integrated strategy for management of this pest.