Data from: Molecular and pollen-based vegetation analysis in lake sediments from central Scandinavia

Plant and animal biodiversity can be studied by obtaining DNA directly
from the environment. This new approach in combination with the use of
generic barcoding primers (metabarcoding) has been suggested as
complementary or alternative to traditional biodiversity monitoring in
ancient soil sediments. However, the extent to which metabarcoding truly
reflects plant composition remains unclear, as does its power to identify
species with no pollen or macrofossil evidence. Here, we compared
pollen-based and metabarcoding approaches to explore the Holocene plant
composition around two lakes in central Scandinavia. At one site, we also
compared barcoding results with those obtained in earlier studies with
species-specific primers. The pollen analyses revealed a larger number of
taxa (46), of which the majority (78%) was not identified by
metabarcoding. The metabarcoding identified 14 taxa (MTUs), but allowed
identification to a lower taxonomical level. The combined analyses
identified 52 taxa. The barcoding primers may favour amplification of
certain taxa, as they did not detect taxa previously identified with
species-specific primers. Taphonomy and selectiveness of the primers are
likely the major factors influencing these results. We conclude that
metabarcoding from lake sediments provides a complementary, but not an
alternative, tool to pollen analysis for investigating past flora. In the
absence of other fossil evidence, metabarcoding gives a local and
important signal from the vegetation, but the resulting assemblages show
limited capacity to detect all taxa, regardless of their abundance around
the lake. We suggest that metabarcoding is followed by pollen analysis and
the use of species-specific primers to provide the most comprehensive
signal from the environment.