INFLUENCE OF PAST LAND-USE ON THE VEGETATION AND SOILS OF PRESENT-DAYFOREST IN THE VOSGES MOUNTAINS, FRANCE

1 Afforestation has been widespread in western Europe over the past 20 0 years. In France, nearly half of the current forested area has previ ously been used for agricultural purposes. 2 The impact of previous la nd use on vegetation (physiognomy, species richness and Ellenberg's in dicator value) and soil (carbon, nitrogen, phosphorus contents and pH) in the Vosges mountains (north-eastern France) was studied. Previous land uses were classified into four categories (old forest, pasture, c ropland, garden) based on historical records. The potential bio-indica tive value of delta(15)M as a marker of these previous land uses was a lso tested. 3 Previous croplands and gardens displayed a higher specie s richness than old forests (24, 27 and 16 species per plot, respectiv ely), higher Ellenberg's indicator values for nitrogen, humidity and p H and higher vegetation cover. Vegetation of previous pastures was ver y similar to old forest. 4 Soils under previous agricultural lands dis played a higher phosphorus content, higher pH values and lower C/N rat ios than old forests. delta(15)N was the lowest, at any depth, in old forests. 5 These differences could be interpreted as consequences of t he fertility transfer which occurred from pastures to croplands or gar dens, through the spread of animal manures on tilled areas. The persis tence of such landscape differentiation, even a century later, should be taken into account in forest management.