INVESTIGATIONS ON THE CORRELATION PATTERN IN EVEN-AGED STANDS OF LARCH .2. DYNAMIC DESCRIPTION OF PHENOTYPIC CORRELATIONS BETWEEN NEIGHBORING OBSERVATIONS

The main topics of this study are a dynamic description of spatial nei ghbourhood correlation patterns of stands of larch and an analysis of temporal changes and time trends of such patterns during stand develop ment. For these investigations extensive data sets from a field trial with 27 ''entries'' (5 Larix europaea, 15 Larix leptolepis, 7 hybrids) have been used. Single tree measurements of this trial were available for 7 stages of stand development (ages: 11, 13, 18, 19, 42, 49 and 5 0 years). The measured traits are height and diameter at breast height . For the 2 ages 42 and 49 only diameter measurements were available. Additionally, the diameter values are transformed and analysed as indi vidual basal areas. The correlative structure of this trial for measur ements of neighbouring individuals [regular square spacing with wide s pacings (5 m x 5 m), no artificial thinning procedures] has been descr ibed by 12 different correlation coefficients. These coefficients are defined by considering quite different spatial configurations of compe titive neighbourhoods. In these procedures and analyses the diagonally located neighbours of a subject tree and its missing neighbours too a re explicitly considered. For the trait height one obtains for all age s a quite uniform correlation pattern: positive correlations with inte rmediate on numerical amount between the trait measurement of a subjec t tree and the corresponding value of its neighbourhood (for different spatial definitions of neighbourhood) and less stronger negative corr elations between the trait measurement of a subject tree and the numbe r of missing neighbours in its neighbourhood. The correlation patterns for the traits height and diameter are coincident for the ''early'' p eriod of stand development (11 to 19 years). This coincidence is true for the sign as well as for the approximate numerical amount of the di fferent correlation coefficients. For the ''late'' period of stand dev elopment (50 years), however, one obtains substantial differences betw een the correlation patterns for height and diameter. The correlations between the diameter measurement-of a subject tree and the correspond ing value for the sum of its neighbourhood are negative (for height th ey are positive) and the correlations between the diameter measurement of a subject tree and the number of missing neighbours in its neighbo urhood are positive (for height they are negative). In this wide spaci ng trial the correlation coefficient between height and diameter stron gly decreases from 0.88 at age 11 up to a surprisingly small value of 0.34 at age 50, i.e. the relationship between height and diameter disa ppears during stand development. The estimates of the correlation coef ficients as well as their detected interrelationships are of high reli ability since the correlation calculations of this study are based on very large numbers of observations (smallest sample size=1081, largest sample size=6279).