Sledování fenologie modřínu opadavého (Larix decidua Mill.) v oblasti Drahanská vrchovina

Abstract

The phenological study on the onset and duration of individual phenological phases of European larch (Larix decidua Mill.) has been performed using sample trees growing in the research station of the Faculty of Forestry and Wood Technology, MUAF Brno for altogether 15 years. This study involves also recording of meteorological data. In this region, the European larch is an introduced woody species and its share in the stand composition is approximately 8%. In European larch, the phenological stages have a markedly periodic character but they are also largely dependent on a complex of exogenous conditions, especially of climatic effects; this was corroborated also in studies on the phenology of other forest tree species growing in this region. Results of this phenological study demonstrated that the spring phenophases were influenced above all by air temperatures while the autumn ones were dependent, besides temperatures and precipitation, also on the duration of assimilation apparatus activities. The onset of breaking of needles occurred between Days 89 and the 110 of the calendar year. A full development of the assimilation area was reached between Days 125 and 150. The onset of individual phenophases was determined by threshold air temperatures, which were markedly different in individual forest trees. This requirement could be expressed at best by the sum of effective temperatures (i.e. air temperatures above 5 °C). In the analysed fifteen-year study period, the sum of effective temperatures for European larch ranged from 1 301.0 to 2 337.0 °C within the period delimited by dates of the flushing and 100-percent fall (abscission) of needles.Results of a long-term phenologic monitoring of forest woody species may be used when evaluating the condition of forest stands from the viewpoint of expected global climatic changes.