Abstract:
The purpose of this study is to analyse gas- exchange parameters and chlorophylls synthesis in order to establish the
photosynthetic capacity of some ligneous plants with invasive behaviour in comparison with native trees in areas of
Danube Delta. The investigation was carried nearly of Razelm Lake (Beștepe hill), a xerophilous coastal meadow with
clumps of trees (fallow vine plantation) and in three other plots (Plaur I, Plaur II and Pătlăgeanca) situated along Chilia
branch. Photosynthesis rate registered lower values in Amorpha fruticosa (3.53 µmol m-2
-s
-1
) in comparison with Populus
alba, young plantation (33 µmol m-2
-s
-1
), lower value in Ailanthus altissima (13.5 µmol m-2
-s
-1
) in comparison with
Fraxinus ornus (14.54 µmol m-2
-s
-1
), comparable values in Acer negundo with Amorpha fruticosa (close to 3.5 µmol m2
-s
-1
). Generally, the investigated invasive plant registered a lower respiration rate than non-invasive/native species.
Transpiration was direct proportional with photosynthesis rate and with stomatal conductance. Photo-assimilatory
pigments represented by chlorophyll a, chlorophyll b and carotenoids as total registered in Ailanthus altissima being by
approximative 1.4 times higher in comparison with Crataegus monogyna and Fraxinus ornus (Beștepe station), by 1.5
times higher in Amorpha fruticosa than Acer negundo in ruderal area (Plaur I) and having close values at Amorpha
fruticosa and Populus alba in riparian plantation (Plaur II). Analysis of photosynthetic capacity revealed the competition
strategy between invasive plant and native or even among invasive, especially co-dominant species such as Amorpha
fruticosa vs. Populus alba, Amorpha fruticosa vs. Acer negundo, Ailanthus altissima vs. Fraxinus ornus and Eleagnus
angustifolia against Salix alba in studied areas.
