Pollen and non-pollen palynomorph indicators of vegetation and highland grazing activities obtained from modern surface and dung datasets in the eastern Pyrenees
Résumé
This paper presents the study of modern pollen and non-pollen palynomorph assemblages carried out along an altitudinal gradient from 1242 to 2541 m a.s.l. in the south-eastern Pyrenees. This research aimed to analyse highland pollen and NPP in relation to vegetation and grazing, and to evaluate the local and regional significance of modern pollen deposition. A pilot study on modern Pyrenean dung samples was also done to evaluate the role of pollen and NPP assemblages in herbivorous excrements as indicators of local highland grazing activities. Redundancy analysis showed that grazing and altitude are the most significant variables to explain pollen and NPP variability in this high-mountain area. It also made it possible to characterise pollen and NPP indicators of types of highland vegetation and grazing pressure. This constitutes a useful tool for the interpretation of fossil records in terms of local vegetation and land-use, despite the over-representation of most pollen types in this mountain context. Results obtained from the study of dung datasets corroborate the significant role of coprophilous fungi as local indicators of herbivores in Mediterranean high-mountain areas and suggest the potential value of endo- and exoparasite remains in the identification of the local presence of domestic animals. Finally, the abundance of traditional anthropogenic pollen indicators in the modern dung samples studied has made it possible to question their regional indicator value in relation to grazing activities and to suggest the potential value of taxa with no ruderal and nitrophilous preferences as indicators of the local presence of animals in highland areas.