ECOTYPIC VARIATION OF XYLEM EMBOLISM, PHENOLOGICAL TRAITS, GROWTH-PARAMETERS AND ALLOZYME CHARACTERISTICS IN FAGUS-SYLVATICA

1. Variation in late-winter xylem embolism, phenological traits, growth parameters, xylem anatomy and allozyme characteristics were examined in four populations of European beech (Fagus sylvatica) from different geographical origins in Italy. 2. Ultrasonic acoustic emissions from plant stems were measured during winter. Late-winter xylem embolism was quantified before budburst. The timing of budburst was recorded and plant growth parameters were monitored during the spring. The dimension and density of xylem conduits were measured. The genetic variability was investigated using isoenzymes as genetical markers. 3. Significant differences between populations in the rate of acoustic emissions, late-winter embolism, phenological traits and spring growth parameters were observed. Xylem embolism was higher in populations that displayed a higher rate of acoustic emissions during winter. The most embolized population displayed later budburst and slower growth in the spring. No significant differences in xylem anatomy were found. 4. Six out of 10 isoenzymatic loci showed significantly different allele frequencies between populations, but no clear association was found between the genetic variation and the variation of the other traits investigated.