Resumo em Inglês:

Abstract Croton cajucara Benth. and C. sacaquinha Croizat are known as “sacaca” and “sacaquinha”, respectively in the Amazon region. Both species are used in Amazon folk medicine for their pharmacological potential, associated mainly with rich phytochemical properties of leaves and essential oil. Aiming to identify and determine the number of secretory structures related to essential oil yield, leaves were harvested in the medicinal plant garden of Embrapa Amazonia Oriental, Belem, Pará, Brazil, and were submitted to microscopy techniques and essential oil extraction. The species presented differences in trichome types and frequency, as well as essential oil yield. Furthermore, a positive relationship between frequency of secretory trichomes and essential oil yield was observed. The results obtained highlight the potential of Croton species to provide oils and could represent a viable alternative for sustainable exploration and a source of income for Amazonian communities.

Resumo em Inglês:

Abstract The study proposes a sampling method, termed the probability proportional to the average geometric area of occupation, method in which a set of trees along a row is selected as the sampling unit with a probability proportional to the geometrical average area per tree - PPGA. An experiment was conducted in Pinus taeda stands under three management regimes to compare estimates of density, basal area, and wood volume per hectare obtained from the proposed method and those from a conventional forest inventory. Additionally, the results were evaluated through sampling simulations using census data from Eucalyptus sp. stands. Sample estimators were developed based on PPGA within the sampling unit. Since the mean geometrical average area per tree varies among randomly distributed sampling units, the method is classified as probability proportional to size sampling and referred to as probability proportional to the average geometric area of occupation. The probability proportional to the average geometric area of occupation method proved effective across various ages and management conditions in both pine and eucalyptus stands.

Resumo em Inglês:

Abstract An assessment on tree stand structure and mangrove plant diversity was conducted in Pulau Semut, Pulau Busung, and Pulau Tok Haji of Setiu Lagoon, Terengganu. Three 100 m×20 m plots were randomly set up at study sites. The trees were enumerated, identified and measured for their stem diameter in each plot. 18 species representing 11 families, including 13 exclusive and 5 non-exclusive mangrove species were recorded. Rhizophora apiculata from Rhizophoraceae dominated with the highest Important Value (IVI) of 89.49 (1491 individuals). This forest comprise mainly young trees with 80% of trees consist ≤10 cm DBH. Pulau Semut exhibited the highest species diversity and richness, compare to Pulau Busung and Pulau Tok Haji. Seven species had IVI values more than 10, indicating mixed mangrove forest characteristic. This study provides an important data for future sustainability management, protection and conservation of mangrove forest in east coast of Peninsular Malaysia.

Resumo em Inglês:

Abstract Pinus occidentalis and Pinus caribaea are important conifers in La Sierra, Dominican Republic, used to recover degraded ecosystems. A study on their wood density obtained from stem discs at three relative heights (RH) as a composite sample showed that wood density increased with age class for both species and decreased with RH in the stem. A mixed repeated measures analysis of variance, followed by a regression approach to the effects model, indicates a statistically significant interaction between species, age class (AC), RH, [ , P ≤0.000, partial =0.814]. Simple bidirectional interactions between factors and all simple main effects are statistically significant. Basic density (BD) increased with age class for both species and decreased with RH in the stem. Pinus occidentalis had a 14.6% higher average wood density and is endemic. Therefore, efforts must be made to provide better silvicultural practices so that its population continues to be a viable asset.