Seasonal variations of gas exchange parameters in mono-dominated by Fagus sylvatica and Picea abies stands

Svetoslav Anev and Sonya Damyanova
University of Forestry, 10 Kliment Ohridski Blvd., 1797 Sofia, Bulgaria

Abstract

Anev, S. & Damyanova, S. (2024). Seasonal variations of gas exchange parameters in mono-dominated by Fagus sylvatica and Picea abies stands. Bulg. J. Agric. Sci., 30 (Supplement 1), 138–143

In carrying out the long-term ecological monitoring activities in the forest site “Petrohan”, the seasonal variations of photosynthetic light-response curves were studied in mono-dominated by European beech (Fagus sylvatica L.) natural forest and Norway spruce (Picea abies Karst.) plantation in West Stara Planina Mountain. The results showed that light curves vary much more during vegetation season in Norway spruce than in European beech. While the beech had gas-exchange parameters confirming its shade tolerance, the spruce was more intolerant to shade. Maximal photosynthesis was highest in spruce in June and permanently decreased in August and October. In contrast to spruce, beech did not have a clear vegetative peak in gas exchange. Still, it achieved a stable carbon balance and a higher carbon-use efficiency, especially before the middle of the growing season. The light-use efficiency of beech and spruce remained relatively constant at whole studied season, confirming this parameter’s species-specific character.

Keywords: light-response curve; seasonal variation; LTER forest site

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