THE PECULIARITIES OF CLIMATIC FLUCTUATIONS -RELATED EVAPOTRANSPIRATION FROM OLIGOTROPHIC FOREST MIRES OVERGROWN WITH PINE

摘要

In the Dubrava reservation evapotranspiration from oligotrophic forest mires overgrown with pine was investigated for 30 years (1969-1999) by the method of water balance. It has been determined that average actual evapotranspiration (Ep from oligotrophic mires in wet vegetation periods (the quantity of precipitation (P_(Ⅴ-Ⅸ) > 410 mm) approximately makes up 383.7 mm and is 120 mm lower than potential evaporation (E_0) calculated by the Dirse (2000) method. In dry vegetation periods (P_(Ⅴ-Ⅸ) > 300 mm) evapotranspiration from oligotrophic bogs is relatively insignificant (nearly 1.2 times less than in wet vegetation periods) and comprises 53% from potential evaporation (E_0). The quantity of water used for evapotranspiration from ledum pine (Pinetu ledosum) forest depends upon stand productivity (R~2 = 0.25; F = 4.7; p = 0.046) only in wet vegetation periods and in these of average humidity (P_(Ⅴ-Ⅸ) > 300 mm). However, evapotranspiration (E_f) from high forest mires, which was determined over the whole period (1969-1999), 66% depends upon the quantity of precipitation over the whole vegetation period and 30% upon potential evaporation.