Анотация: Pinus heldreichii forests in pristine condition can still be found in Pirin National Park in Bulgaria. Although they are of high conservational value still numerous questions for their structure, the physiological and genetic peculiarities of the species exist. Here we present results for several tree ring chronologies constructed along altitudinal gradient and different exposures. We also studied the variation of anatomical leaf parameters like number of resin ducts and stomata. We found that the oldest trees in the valley reach 800 years and are situated on isolated by rock bands sites close to the local treeline. Forests on the slopes at the bottom of the valley are 200-300 years old with single older trees. Many of them are probably shaped by fires in the past. We found similar variability in tree ring chronologies from different exposures. Only one chronology constructed from a mixed coniferous forest was found to differ at certain periods from the other chronologies. The most probable reason for this is exogenous disturbance like a fire. We did not find enough evidence that the anatomical traits of the needles are altitude dependent, although number of resin ducts and the number of stomata on the outer surface were found to increase with altitude

Забележки: Conference ` Forestry: Bridge to the future `, may 13-15, 2010, Sofia