Nicotiana glauca als invasive Pflanze auf Fuerteventura
The quick spreading of Nicotiana glauca was the reason for investigating its biology and ecology. Nicotiana glauca is a quickly growing glabrous and semi-evergreen shrub or small tree with overhanging branches and egg-shaped leaves. The most important reasons for the success in spreading are according to own investigations: (1) Nicotiana glauca germinates at temperatures between 7°C and [at least] 30°C, whereas the greatest success is reached at 20°C/15°C day-night change. The germination occurs also in 1 mMol KNO3. (2) Juvenile plants grow very quickly, because their large leaves are responsible for adequate efficiency of assimilation. Already during the first year the plants are flowering and reach hights of more than 3 m. (3) Nicotiana glauca is relatively tolerant to mechanical damages. The species is also able to grow on soils with low salinity. High salinity or longer lasting flooding is however not tolerated. (4) Big shrubs are able to produce about 10.000 to 1.000.000 very small seeds. Only hydrochory (ombrohydrochory) is an effective mode of long-distance dispersal; the invasions during the last decades are caused first of all by soil transports due to road constructions. With respect to the biomass Nicotiana glauca is the most important neophyte of the island. On Fuerteventura this species grows on the borders of roads, in settlements, on gravel beds of episodical waters and in other often disturbed habitats up to 640 m. Most of the Stands of Nicotiana glauca belong to the class Pegano-Salsoletea, the species is however able to penetrate into other plant communities. What are the ecological effects of invading Nicotiana glauca to the indigenious flora and Vegetation? Nicotiana glauca builds up mostly very scattered Stands, so competition for light is of no importance. The high transpiration of Nicotiana glauca could generate problems for flat-rooting plants in water supply.