WILD C-4 PLANTS IN GERMANY AND SWEDEN - A COMPILATION IN VIEW BY CLIMATE-CHANGE

48 species of wild C-4 plants are listed for Germany and Sweden. The d ifference in occurence of all species found (Germany: 47; Sweden: 23) and for the indigenous species (Germany: 9; Sweden: 3) is attributed t o the temperature gradient. The most of the C-4 plants in either count ry occur as a result of anthropogenic influencies, in particular agric ulture and industry. Only few species have been able to establish them selves in existing natural plant communities. One of the few examples is the Polygono-Chenopodietum plant society in the valleys of southern and central Germany. Analysis of the ecological characteristics revea led that C-4 plants are mostly annual herbs and adapted to high nutrie nt concentrations in soils. They are frequently found in saline areas, prefer well lit as well as maritime and climatically favoured locatio ns. Most of the species are highly competitive. The changes in their s patial distributions presently observed, are closely connected to chan ges in land use efficiency. The shifting to the North of cultivated ar eas as a consequence of global climate change combined with the increa sed probability of extreme weather events may lead to a further spread of those C-4 species which are adapted. This effect is opposing the e ffect of increased CO2-concentrations which will favour C-3 plants.