TRAITS RELATED TO STEM VOLUME YIELD CAPACITY IN SAMPLE TREES OF PINUS-SYLVESTRIS L AND PINUS-CONTORTA DOUGL

Species, provenances and even individual trees are known to differ in stem volume yield capacity, even when grown on the same site. Increase d knowledge of the fundamental mechanisms for different productivity i s essential for the success of breeding research and for the maximizat ion of yield. Genetically homogeneous tree materials were selected on the basis of expected differences in stem volume yield capacity and tr ees were sampled and destructively analysed. The hypothesis to be test ed was that yield capacity is correlated to certain traits of trees. H igh correlations with stem volume yield capacity were shown for harves t index, needle-use efficiency and mineral-nutrient-use efficiency. On ly weak correlations were shown for needle longevity and nitrogen conc entration in needles. Also, indications were found that phenotypic pla sticity was correlated positively to stem volume growth capacity. An a ttempt to correlate the ability to retranslocate nitrogen from dying n eedles with yield capacity failed.