Eighty-four Pinus elliottii trees aged 24 years were measured at breast height using Pilodyn, Resistograph, and increment borer. Resistograph amplitudes (A_E), width of each ring (R_E), and P value were recorded by Resistograph and Pilodyn methods, respectively. Wood basic density (ρ) was determined by increment coring. Correlation analyses of Pilodyn P values, A_E, R_E and ρ were performed.

Pilodyn P values were significantly negatively correlated with ρ (R =-0.30, P < 0.01). A_E was positively correlated with ρ (R = 0.50, P < 0.001). The strength of the correlation of A_E and Pilodyn P values increased from the 24^th ring to the 10^th ring and then decreased from 10^th to the pitch, suggesting accurate estimation of ρ by Pilodyn measurements; however, prediction of wood density in trees with large diameters was poor. A_E was positively correlated with ρ in general and produced a significant positive correlation (P<0.001) with ρ in rings produced from between 5 and 18 years of age. The correlation of A_E and R_E as measured using the Resistograph was positive between the 8^th and the 20^th rings, apart from the 12^th ring; however, other coefficients of correlation of A_E and R_E were negative. No corresponding results were obtained using the Pilodyn.

The Resistograph and Pilodyn devices can be used to indirectly and non-destructively assess basic density of Pinus elliottii, and although the Resistograph is more accurate for estimating basic density of Pinus elliottii wood, the Pilodyn has advantages regarding ease of use. Basic density of Pinus elliottii is high in mature wood (older than 8 years) and is relatively low in young wood.