Survival and acclimatation of<b><i>Populus nigra</i></b>to drier conditions after damming of an alpine river, southeast France

Abstract

Poplars occur in riparian areas where the water table depth generally varies with the elevation of the adjacent river. Changes in stream flow caused by diversion projects can affect the riparian community; this may lower the water table below the rooting zone of some tree species and cause then to suffer from a water shortage. Obligate riparian trees require access to a permanent water supply and are usually intolerant to low water potentials, being poorly adapted to water stress. In this paper, the survival of black poplars (Populus nigra) downstream of a dam constructed in the 1960s on the Drac river at the foot of the French Alps is reported. The growth, water consumption, and water status of some of these trees are compared with those of other poplars located downstream and growing under wetter conditions. Although water consumption and development were quite different for both, their method of water regulation seemed to be quite similar.