| Summary: | The paper presents the impact of periodic
soil drought on physiological parameters important
for bioproductivity of mountain beech populations.
The investigated forest population was located near
Fruška gora mountain peak, where water runs off quickly,
and consequently lack of soil humidity develops very
often. Decreasing trends of photosynthesis, transpiration,
water use efficiency and stomatal conductance (gs) during
the growing season were evident, in correlation with a
shortage of precipitation. Diurnally, photosynthesis of
beech leaves showed rhythmical changes. It was the most
intensive in the morning, then decreased between noon
and 1 pm, and increased again during early afternoon.
High leaf temperature and water deficit in the deeper
soil layers caused a decreasing trend in photosynthesis
and daily rhythmic changes of the transpiration rate and
water use efficiency. Although surface soil water capacity
did not show a significant decreasing trend from July to
September, a lack of precipitation was observed, which
probably caused a lack of moisture in deeper soil layers,
resulting in a decline in photosynthesis and transpiration.
Physiological status, linked to primary photosynthetic
productivity of forests, could be a significant indicator of
environmental conditions and trends in climate changes.
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