EUCALYPTUS STAND SAMPLE PLOTS COMPARED: FIXED AREA AND FIXED NUMBER OF TREES

Almeida, Danilo Roberti Alves de; Leite, Helio Garcia; Gorgens, Eric Bastos

doi:10.1590/0100-67622016000300016

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Articles • Rev. Árvore 40 (3) • May-Jun 2016 • https://doi.org/10.1590/0100-67622016000300016 copy

EUCALYPTUS STAND SAMPLE PLOTS COMPARED: FIXED AREA AND FIXED NUMBER OF TREES

AMOSTRAGEM COM PARCELAS DE ÁREA FIXA E DE ÁREA DEFINIDA PELO NÚMERO DE COVAS EM UM POVOAMENTO DE EUCALIPTO

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

This study compares sampling methods based on plots of fixed area and based on a fixed number of trees. The study was conducted in a Eucalyptus forest surveyed using three plot types: rectangular with fixed area, circular with fixed area and fixed number of trees. The estimation accuracies were evaluated for the average diameter per plot and for the number of stems, the basal area and the volume per plot. The null hypothesis of equality between the sampling methods was assessed by t-test. No significant differences were found between the three sampling methods.

Keywords:
Plots; Forest inventory; Methodology

Table 1 Stand volume (40 hectares) and the sampling error (95% CI) for each sampling setup. “Circular” means sampling strategy had fixed area and circular shape. “Trees” means sampling strategy had fixed number of trees. “Rectangular” means sampling strategy had fixed area and fixed rectangular shape.

	Circular	Rectangular	Trees
Total volume	9,442	9,746	9,585
Relative samplingerror (%)	±7.1	±7.6	±6.8

Table 2 P-values for the nine t-test comparisons between three sample setups.

	Circular x Trees	Circular x Rectangular	TreesxRectangular
Number of Stems	0.86 ^ns ns no significant difference diferença não signficativa	0.54 ^ns ns no significant difference diferença não signficativa	0.64 ^ns ns no significant difference diferença não signficativa
Basal Area (m²)	0.65 ^ns ns no significant difference diferença não signficativa	0.40 ^ns ns no significant difference diferença não signficativa	0.63 ^ns ns no significant difference diferença não signficativa
Average Diameter (cm)	0.77 ^ns ns no significant difference diferença não signficativa	0.84 ^ns ns no significant difference diferença não signficativa	0.93 ^ns ns no significant difference diferença não signficativa
Volume (m³)	0.75 ^ns ns no significant difference diferença não signficativa	0.53 ^ns ns no significant difference diferença não signficativa	0.74 ^ns ns no significant difference diferença não signficativa

Sociedade de Investigações Florestais Universidade Federal de Viçosa, CEP: 36570-900 - Viçosa - Minas Gerais - Brazil, Tel: (55 31) 3612-3959 - Viçosa - MG - Brazil
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[1] *Corresponding author.