Despite growing concern about biodiversity loss due to the ongoing biodiversity and climate crises, scientists have relatively little understanding of the pace and complexity of biodiversity change over preceding millennia.
To address this challenge, ecologists from the University of Edinburgh, University of St Andrews and National Tsing Hua University, Taiwan have applied a recently developed technique to explore how plant biodiversity responded to changes in climate, land use and woodland extent over the past 8,000 years at two sites in Scotland: one in an ancient woodland, and one where woodland has given way to blanket peat bog.
For the first time, researchers analysed records of ancient pollen grains, which lie preserved in layers of peat and are important archives of past changes in plant communities.
This technique allowed the group to investigate changes in the number of plant species, but also the number of functional groups and evolutionary history captured in plant communities throughout thousands of years of environmental change.
This multidimensional approach to measuring biodiversity reveals patterns of biodiversity change which would not otherwise be detectable, and allows these different aspects of biodiversity to be directly compared.
The two sites showed different responses to long-term changes in climate and land use. The development of a large area of thick, acidic peat over centuries at the blanket bog site led to steady but long-term biodiversity change and a lasting shift away from woodland cover.
At the ancient woodland site, biodiversity changed rapidly as a complex mosaic of different habitat types allowed different species, evolutionary lineages and functional groups to persist and recolonise through multiple disturbances.
However, there has been a steep decline in all types of biodiversity over the past 1200 years, as human management of the woodland led to pine predominating over a previously varied mix of tree species.
The research was published by the British Ecological Society.
Dr Amelia Penny, Lecturer in Ecological Science, School of GeoSciences, University of Edinburgh, who led the study, said, "This study illustrates the complex character and dynamics of long-term biodiversity change at two contrasting sites in Scotland. The methods used in this study could be applied more widely to palaeoecological records, to help us understand the history of biodiversity change in our landscapes, and its possible futures under environmental change."
