Effect of initial espacement on crown and stem development in Honduras Caribbean pine

Abstract

This study examines effects of initial espacement on crown and stem development in Pinus caribaea Mor. var. hondurensis Barr, and Golf, in North Queensland. Measurements of many tree and branch characteristics were taken in plantation stands aged 11-12 years which were established at five square espacements (2.132, 2.442, 2.742, 3.052 and 3*662 m) in a 5 * 4 randomised block design. The design was replicated at Bowenia (Lat. 23° 52T S, Long. 150° 37’ S) and Kennedy CLat. 18° 12’ S, Long. 145° 57’ S). In some cases, effects of initial spacing on select stems (high pruned (5-2 m) final crop trees - 250 s ha-1) were similar at the two locations e.g. stem dbhob and volume of the lower bole (9-5 m section) both increased significantly (p < 0.01) with increase in spacing whereas absolute form quotient and bark thickness at breast height were not affected. In other cases, effects were different. Total height growth increased significantly Cp < 0.01) with increase in spacing at Bowenia but was not affected at Kennedy, and taper of the lower bole increased significantly (p < 0.01) at Kennedy but was unaffected at Bowenia. Of the other characteristics measured on select stems at Bowenia (but not at Kennedy due to the effects of a fire), crown depth, green crown percent, branch size and potential knot size increased with spacing (p < 0.01), whereas height to the lower green crown, age of branches and their arrangement around the bole were not affected. Average branch size was greater on the northernside of a tree than on the southern side at all spacings.