Population study of Gonopterodendron sarmientoi (Palo Santo), Departments of Presidente Hayes and Boquerón, Paraguay

Abstract

The investigation was referred to a pioneer population study at country level Gonopterodendron sarmientoi (Palo Santo) realized at the Estancia Santa Herminia S.R.L. Fortin General Diaz, Department of Presidente Hayes and Boquerón, Region Occidental, Paraguay, 23° 37’17,98’’ S and 60° 42’31,09’’ W. Methodologically was started from a conglomerated installation of three sample plots units, (500 x 20m) divided into 25 sub-plots with a total of 75 sub-plots. The objective has been the study of Gonopterodendron sarmientoi population in a xerófito forest of Dry Chaco ecoregion, in site conditions of the study area. The hypothesis is that the population of Gonopterodendron sarmientoi presents a continuous distribution in its vertical structure and diametric. The study consisted of measurement and observation of all individuals of the specie ? 5 cm in diameter at breast height (DAP). For characterization of the forest study they were measured all individuals of other species with DAP ? 10 cm in 1 ha, considering as quantitative variables: the number of individuals, the total height and the DAP; and qualitative variables: the health status and phenology. They registered 376 individuals/ha, with 19 species, 19 genera and 13 botanical families. In its vertical structure, the forest presented a maximum height of 22.60 m, with three distinct layers; the lower (?11.32 m), considered the most important 351 individuals/ha, the average (11.32 m - 17 m) with 23 individuals/ha and the higher (17 - 22.60 m) with 2 individuals/ha. The Gonopterodendron sarmientoi population study had presented an absolute abundance of 59 individuals/3 ha, equivalent to an average of 19.66 individuals/ha, and had demonstrated high variability in the trees number/ha, even when it refers with 95% of confidence; the average population amount is in a range between 5.87 and 33.45 individuals/ha. The dominance of the species under study presents an average of 1.2347 m2/ha; regarding to the distribution of individuals by diameter class; the biggest quantity is concentrated in the classes of 05 to 9.9 cm and 10 to 19.9 cm 5 individuals/ha, and the fewest in the class from 20 to 29.9 cm with 2,66 individuals/ha. In the vertical structure it has been registered as a greater height 25,59 m; in the lower layer is registered the presence of 44 individuals/ 3 ha, in the middle stratum 11 individuals/3 ha and the upper layer 4 individuals/3 ha; the total volume of Gonopterodendron sarmientoi population, is 13,41m3 ha. It is hoped that these data will contribute to the conservation and sustainable use efforts of the species at the country and regional levels.