SAMPLING PROCESSES FOR Carapa guianensis AUBL. IN THE AMAZON

Diego Dos Santos Vieira,Bruno Lafetá Oliveira,João Ricardo Vasconcellos Gama,Talita Godinho Bezerra,Anna Karyne Costa Rego,Marcio Leles Romarco De Oliveira

doi:10.1590/01047760201824032514

Abstract

ABSTRACT The objective of this study was to analyze the adaptive cluster sampling (ACS), simple random sampling (SRS) and systematic sampling (SS) processes to obtain the number of ha-1 trees of Carapa guianensis Aubl. in the Amazon. The data were obtained through 100% inventory and sampling simulations, considering a DBH ≥ 25 cm, a sampling intensity of 4%, a maximum error of 10% and plots of 0.09, 0.16 and 0.25 ha. The last two sizes were only used to analyze their effect on the ACS estimators. The processes were evaluated for accuracy, precision (E%) and confidence interval (CI), while the mean ha-1 of the processes were compared with that of the 100% inventory by the Z test. The ACS process showed no significant difference between its average ha-1 trees and the 100% inventory, and it was also the most accurate and the only one whose CI was true. However, it presented a final sample intensity 3.6 times greater than the simple and systematic random samplings, in addition to E% above 10%, which makes it unacceptable, legally, and economically unfeasible. The other processes had densities significantly higher than the 100% inventory, with sample intensities lower than ACS and E% lower than 10%, making them legally viable. The use of larger plots in the ACS implies larger clusters and a greater tendency to underestimate the number of trees, resulting in larger sample errors and less accuracy.

Highlights

The Carapa guianensis Aubl. is one of the most promising non-timber forest species due to its versatility and variety of uses
In the 100% inventory, 2.45 trees.ha-1 were recorded, while the simple random sampling (SRS), systematic (SS) and adaptive clustering (ACS) presented mean values of 2.73, 2.79 and 2.54 trees.ha-1, respectively (Table 1). These values were lower than those described by Klimas et al (2007), Tonini et al (2009) and Guarino et al (2014), who found, on average, 15.4 trees.ha-1, but was within the range specified by Ferraz et al (2002) for terra firme forests (0.3 to 9.0 trees.ha-1) in the Amazon
It was observed that the SRS and systematic sampling (SS) processes presented sample errors (E%) lower than 10%, at 95% probability, but were statistically less accurate than the adaptive cluster sampling (ACS) (0.09 ha) and with significant tendencies to overestimate the mean trees.ha-1, when compared to the 100% inventory (Table 2)

Summary

Introduction

The Carapa guianensis Aubl. (andiroba) is one of the most promising non-timber forest species due to its versatility and variety of uses. (andiroba) is one of the most promising non-timber forest species due to its versatility and variety of uses It is a native species of the Amazon, with medium to large trees that can reach 2 m in diameter and 30 m in height, with a bitter bark that detaches in large plates (Ferraz et al, 2002). Traditional populations usually use leaf and bark tea for the same therapeutic purposes as oil (Silva; Almeida, 2014). With all these functions, andiroba became part of the National List of Medicinal Plants of the Brazilian National Health System, defined as the list of plant species with the potential to advance in the stages of the production chain and generate products of interest for the Ministry of Health of Brazil, reinforcing its importance in the country

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Conclusion