Modern non-pollen palynomorphs sedimentation along an elevational gradient in the south-central Pyrenees (southwestern Europe) as a tool for Holocene paleoecological reconstruction

Abstract

Non-pollen palynomorphs (NPPs) are microfossils other than pollen and spores from plants found within samples prepared for pollen analyses. Their utility as paleoecological indicators is rapidly growing because of their potential to complement palynological reconstructions of past communities and environments. The study of modern NPP sedimentation patterns using surface samples from different substrates, vegetation types, and environmental conditions is needed to characterize the main environmental and anthropogenic factors involved in establishing ecological gradients. Here, we analyze modern NPP distribution along an elevational transect from the south-central Pyrenees. We use these data to test the potential influence of elevation, vegetation type, sampling sites, and human disturbance on modern NPP distribution and to obtain a NPP modern-analog model, which will enhance further paleoecological interpretations. Our study used the same surface samples obtained in a previous modern-analog palynological study, along an elevational transect from 870 to 2600 m a.s.l. We identified 55 NPPs, including 13 unidentified morphotypes that were described and depicted. Individual NPP analysis and multivariate statistical methods showed that altitude plays a significant role in the NPP distribution along the transect, but other factors such as soil moisture, landscape openness, and grazing intensity also influenced the composition of NPP assemblages. Our results also recognized some characteristic NPP assemblages linked to elevational vegetation belts and individual NPP morphotypes related with specific microhabitats, both with potential paleoecological indicator capacity. This work is a first step to improve the knowledge of the NPP’s indicator value in the study area.