Influence of Past Land Use on the Vegetation and Soils of Present Day Forest in the Vosges Mountains, France

1 Afforestation has been widespread in western Europe over the past 200 years. In France, nearly half of the current forested area has previously been used for agricultural purposes. 2 The impact of previous land use on vegetation (physiognomy, species richness and Ellenberg's indicator 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, cropland, garden) based on historical records. The potential bio-indicative value of δ15N as a marker of these previous land uses was also tested. 3 Previous croplands and gardens displayed a higher species richness than old forests (24, 27 and 16 species per plot, respectively), higher Ellenberg's indicator values for nitrogen, humidity and pH and higher vegetation cover. Vegetation of previous pastures was very similar to old forest. 4 Soils under previous agricultural lands displayed a higher phosphorus content, higher pH values and lower C/N ratios than old forests. δ15N was the lowest, at any depth, in old forests. 5 These differences could be interpreted as consequences of the fertility transfer which occurred from pastures to croplands or gardens, through the spread of animal manures on tilled areas. The persistence of such landscape differentiation, even a century later, should be taken into account in forest management.