Distribution of homobaric and heterobaric leafed species in the Brazilian Cerrado and seasonal semideciduous forests

Abstract

The spatial and temporal distributions of vegetation can be influenced by edaphic and environmental factors as well as disturbances. The present study was undertaken to characterize the distribution and spatial dependence of species diversity in a fragment of semideciduous seasonal forest after a disturbance event by fire and to identify changes during natural regeneration. The fire, occurred in 1999, and surveys were undertaken in 2000, 2005 and 2014 in 26 geo-referenced plots (400 m²) distributed along two transects. The Fire Damage Index (FDI) in each plot was based on a scale from 0 to 5, and all of the arboreal individuals with diameters at breast height (DBH) ≥ 5 cm were identified in each plot. Species diversity was calculated using the Shannon index (H'), and species richness (S) was estimated using species accumulation curves; variations between the surveys compared based on the means and standard errors. The S, H' and FDI data were submitted to non-spatial exploratory and geostatistical analyses. After adjusting the semivariograms, the levels of spatial dependence were classified, and interpolation of the variables values were performed using ordinary kriging to characterize their spatial distributions in the form of maps. Spatial analysis was used to identify and characterize differences between the post-fire surveys in terms of the configurations of the arboreal community. The fire event influenced the spatial and temporal structures of the variables S and H'. These variables showed spatial dependence and aggregated distributions, with reduction in the distance under spatial influences and a uniformity of individuals distribution in the forest fragment at the different surveys. This research characterized the distribution and spatial dependence of the variables S and H' in a forest fragment after a fire event and the alterations in the arboreal community structure during natural regeneration. Rev. Biol. Trop. 65 (2): 525-534. Epub 2017 June 01.

Leaf architecture and anatomy of Asteraceae species in a xerophytic scrub in Mexico City, Mexico

“…Almost all species (98%) have a vascular bundle sheath, but only in 73% of these there are sheath extensions, whereas sclerified cells associated with bundle sheaths are rare in the species studied, as in other members of the family (Aytas-Akcin and Akcin, 2017). Bundle sheaths have also been recorded for other taxa of Asteraceae (Bombo et al, 2012;Chwil et al, 2015;Mendes et al, 2016;De Sousa et al, 2018;Lusa et al, 2018) and they appear to be one of the most common traits in the family.…”

Aspectos Dimensionais De Sementes De Dimorphandra Mollis Para Estudo Da Variabilidade Entre Populações De Plantas

“…As sementes do Css podem ter sido expostas a interferências ambientais maiores, pois são sujeitas à fatores casuísticos como estiagem, fogo, variação da umidade relativa, temperatura, ventilação, entre outros (Gomes et al, 2016). Estes fatores são capazes de afetar o estado fisiológico das plantas matrizes (Mendes et al, 2016), com potenciais reflexos tanto nos caracteres vegetativos, naturalmente mais plásticos, como por exemplo, número de folhas, número de folíolos por folhas, tamanho da copa, entre outros, quanto nos reprodutivos, incluindo aqui os caracteres morfológicos das sementes.…”