Geoestatística isolada e integrada à análise fatorial exploratória para a caracterização espacial dos fatores inerentes à ocorrência do pequizeiro – anão (Caryocar brasiliense subsp. intermedium (Wittm.) Prance & M. F. Silva Caryocaraceae)

Abstract

The pequi tree is a species of great environmental, social and economic relevance. The species Caryocar brasiliense Cambess is subdivided into two subspecies, one of arboreal size (C.brasiliense. subsp. brasiliense) and the other shrub (C. brasiliense subsp. intermedium), popularly known as dwarf pequi tree. The dwarf pequi tree has interesting characteristics for the genetic improvement of the common pequi tree, such as precocity, small size and fruiting period in a non-coinciding season. What is intriguing about the dwarf pequi tree is its extremely restricted spatial distribution, as it is isolated in some ecological niches. Therefore, understanding the factors intrinsic to its natural occurrence by contrasting the spatial distribution of pequi tree individuals in relation to the physical-chemical attributes of the soil was an objective of this thesis. Another objective was to subsidize future programs for the conservation of this subspecies and for the genetic improvement and management of the commercial C. brasiliense Cambess species. The research was carried out in a natural area of 25.2 ha, whose predominant soil is a dystrophic litholic Neosol with cover formed by a fragment of rocky field, located in the municipality of Ibiá-MG. Chapter I uses geostatistics (ordinary kriging) as a tool to study the distribution structure of the spatial dependence of the subspecies in relation to soil attributes (physicochemical attributes). In this chapter, it was found that the greater availability of bases (SB > 0.1 cmolc dm-3) and phosphorus (> 1.05 mg dm-3), reduced percentages of moisture (< 5%) and low potential acidity (< 4.0 cmolc dm-3) were the factors positively related to the establishment and development of dwarf pequi trees in the area. Among these, soil moisture is the factor in the highly conditioning area. In chapter II, geostatistics was integrated (ordinary kriging) with the multivariate technique of exploratory factor analysis, in order to know the correlations between the variables, map them and characterize the factors related to the occurrence of the dwarf pequi tree. Exploratory factor analysis allowed the reduction of the number of variables (19 variables for 5 factors) without loss of information quality, since the 5 factors cumulatively explained 83.9% of the variance of the variables. The spatial distribution of the factors allowed us to verify that even in the conditions of high acidity and high aluminum saturation characteristic of the study area, slightly lower levels of these ions allowed the formation of microhabitats favorable to the greater development of the dwarf pequi tree. (subtle changes in soil fertility). It was also clear the sensitivity of the dwarf pequi tree to soil moisture and its resistance to water stress, since it is on a shallow and sandy soil. The dwarf pequi tree is adapted to harmful environmental conditions to most cultivated crops and is sensitive to environmental changes. Thus, knowing the characteristics associated with its natural occurrence was important to support efforts for the preservation and conservation of the subspecies, preventing its extinction and helping programs for the improvement and management of the species C. brasiliense Cambess.