Spatial characterization of factors inherent in the microendemism of the dwarf pequi tree (Caryocar brasiliense subsp. intermedium (Wittm.) PRANCE & M. F. Silva)

Abstract

The dwarf pequi tree, Caryocar brasiliense subsp. intermedium, is extremely restricted to ecological niches in the Cerrado biome. Thus, understanding the conditioning factors of the micro-endemism of this sub-species through its spatial distribution and the physical-chemical attributes of the soil was the objective of this research. The research was carried out in a fragment of rupestrian field. The area was divided into quadrants in which the number of pequi trees was quantified and the physicochemical characteristics of the soil were determined. The modeling of semivariograms was performed using semivariances, and ordinary kriging was used for spatial interpolation of variables with spatial dependence. The number of pequi trees, the altitude, the remaining phosphorus and the humidity showed a strong degree of spatial dependence, unlike the pH, the calcium and the magnesium, all of which had a pure nugget effect. The other variables showed a moderate degree of spatial dependence. The greater availability of bases (SB > 0.1 cmolc dm -3 ) and phosphorus (> 1.05 mg dm -3 ), the reduced percentage of moisture (< 5%) and low potential acidity (< 4.0 cmolc dm -3 ) were the factors positively related to the establishment and development of the dwarf pequi tree in the area.

Estrogenic activity and acute toxicity assessments of sediments from a chronically polluted estuarine area in southeastern Brazil

“…This area suffers from fluvial influences, aiding in sediment deposition due to calm waters. Isolated areas such as the Paquetá Island and its surroundings, where bottom currents occur, are excluded from this dynamic (Almeida, 1976;Amador, 1997;Machado et al, 2002).This scenario makes micropollution Guanabara Bay assessments challenging, and scarce data concerning sediment exposure effects are available.…”