Comparison of the Carbon and Water Fluxes of Some Aggressive Invasive Species in Baltic Grassland and Shrub Habitats

Abstract

Biological systems are shaped by environmental pressures. These processes are implemented through the organisms exploiting their adaptation abilities and, thus, improving their spreading. Photosynthesis, transpiration, and water use efficiency are major physiological parameters that vary among organisms and respond to abiotic conditions. Invasive species exhibited special physiological performance in the invaded habitat. Photosynthesis and transpiration intensity of Fallopia japonica, Heracleum sosnowskyi, and Rumex confertus of northern and trans-Asian origin were performed in temperate extensive seminatural grassland or natural forest ecotones. The observed photosynthetically active radiation (PAR) ranged from 36.0 to 1083.7 μmol m⁻² s⁻¹ throughout the growing season depending on the meteorological conditions and habitat type. F. japonica and H. sosnowskyi settled in naturally formed shadowy shrub habitats characterized by the lowest mean PAR rates of 58.3 and 124.7 μmol m⁻² s⁻¹, respectively. R. confertus located in open seminatural grassland habitats where the mean PAR was 529.35 μmol m⁻² s⁻¹. Correlating with the available sunlight radiation (r = 0.9), the highest average photo assimilation rate was observed for R. confertus (p = 0.000). The lowest average intensity of photosynthesis rates was exhibited of F. japonica and H. sosnowskyi in shadowy shrub habitats. Transpiration and water use effectivity at the leaf level depended on many environmental factors. Positive quantitative responses of photosynthesis and transpiration to soil and meteorological conditions confirmed positive tolerance strategies of the invasive species succeeded by environmental adaptation to new habitats during their growing period sustained across a range of environments.