Reconstructing past vegetation based on fossil and modern pollen data in Sougna mountain (Western Rif mountains - Northern Morocco)

Abstract

The process of quantifying and reconstructing past vegetation changes is a crucial step towards comprehending the dynamics of human-environment interactions throughout time. In this study, we present a reconstruction of the vegetation cover of the Sougna mountain (Western Rif Mountain) over the last 6000 yr based on multivariate statistical analysis (cluster analysis and non-metric multidimensional scaling, NMDS) of 31 modern pollen samples, and detailed fossil pollen record. The integrated approach, used in this study was able to identify and differentiate six distinct modern vegetation communities. Moreover, the analysis linked fossil pollen records with these modern vegetation communities as their analogues. The information on the contemporary vegetation cover of the modern pollen sites was used to determine the past vegetation changes of the fossil pollen site in the Sougna mountain. The vegetation changes estimated from this analysis reveal a higher degree of landscape openness than what was initially indicated by the fossil pollen percentages. The results of this study demonstrate a marked decline in forest ecosystems during the last millennium, indicating a significant transformation in vegetation over time. Additionally, the analysis indicates that some species have diminished their distribution range and relocated to more suitable environments. The methodology employed in this study, which combines fossil pollen data with modern pollen data and vegetation in a single NMDS analysis, permits reconstruction of the past vegetation by identifying statistically their modern analogues.