Nitrogen nutrition of Echinocystis lobata depends on habitat

Abstract

Climate change is often associated with global warming. Vegetation is very sensitive to temperature changes. Echinocystis lobata is annual, thermophilic species, invasive in Lithuania. This plant grows along river banks, hydrochory is one of the reasons of successful its spread. Aquatic ecosystems are heavily affected by human activities, fertilisers in special. However, there is still a lack of information on this topic in the Baltic States. Plant nitrogen (N) concentrations could be helpfull tool assessing the impact of pollution on alien species spread. The aim of our study is to estimate the nitrogen concentration of the leaves of Echinocystis lobata populations depending on some parameters of the habitats: river size, condition, origin, land use types and geographical location. The 18 populations of E. lobata were collected in the Nemunas basin. Leaf N concentration expressed as a percentage of the dry mass (% d. m.) ranged from 3.72 % d. m. (Nemunas population) up to 4.91% d. m. (Atmata population). The most contrasting populations differed 1.32 times (p < 0.05). The mean leaf N concentration in the populations was 4.18% d. m. Compared to the most common adjacent riparian species of Lithuania - Lythrum salicaria, Stuckenia pectinata, Phalaris arundinacea, Bidens frondosa, Phragmites australis, Nuphar lutea, E. lobata populations had the highest leaf N concentration. Higher than average N concentrations were found in the populations growing in the center of Kaunas city, were former big enough N pollution from point sources was documented. Large rivers are more vulnerable to plant invasions, as can be seen in the case of E. lobata, which has spread intensively in Lithuania in recent decades. Larger Lithuanian rivers flow through the most populated cities, which are good donors of seeds of alien plant species grown as ornamental plants, thus facilitating multiple introductions.[...]Biologijos katedraGamtos mokslų fakultetasVilniaus Gedimino technikos universitetasVytauto Didžiojo universiteta