Response to Different Thinning Intensity in Calabrian Pine (Pinus Brutia Ten.) Plantations in Turkey

Abstract

Calabrian pine (Pinus brutia Ten.) is one of the main species, under commercial plantation in western of Turkey.These plantations are cover an area of 0.707 million ha. This paper presents the growth response of 25 yr old Calabrian pine plantation to thinnings of different intensities in Burdur in western of Turkey. The thinning intensity was measured by using the residual basal area (%) as parameter. In spring of 1990, 1995 and 2000, three treatments were tested;
unthinned, moderately thinned and heavily thinned with respectively 0%, 15-20% and 35-40% of basal area removed.The statistical design of the experiment was a randomized incomplete block with two blocks and three treatments. In 2005, the sample trees data were collected from each of three different thinning intensities: unthinned (n=372),moderately thinned (n=243) and heavily thinned (n=214). Variables such as diameter at breast height (dbh), tree height
and tree volume were measured. Growth rate ratios of dbh in moderately thinned and heavily thinned stands were 1.07 and 1.30, respectively. Tree height and tree volume growth rates were 0.97 and 1.06 for moderately thinned and 1.23 and 1.64 heavy thinned plots, respectively. The largest values for the mean tree were observed with the heaviest thinning treatment. This analysis indicated that heavily thinned drastically affects the dbh, tree height and tree volume growth rate.Growth rate interpretations were supported by statistical multivariate analysis of variance using Wilk’s ( ) and Hotelling’s T2 tests. The Wilk’s test was carried out on mean vector of 3 variables in three study populations. The nullhypothesis (Fc =31.679> Ft=3.743) was rejected at the 0.001 level of significance. Growth rate interpretations were supported by analysis of variance using Duncan’s test of range multiple. Thus, the results indicated that heavily thinned
was significantly influenced the rapid growth rates of planted Calabrian pine stands.