In:
Climate of the Past, Copernicus GmbH, Vol. 18, No. 2 ( 2022-02-28), p. 363-380
Kurzfassung:
Abstract. Biological diversity is inextricably linked to community stability and
ecosystem functioning, but our understanding of these relationships in
freshwater ecosystems is largely based on short-term observational,
experimental, and modelling approaches. Using a multidecadal diatom record
for the past ca. 16 000 years from Lake Baikal, we investigate how diversity
and palaeoproductivity have responded to climate change during periods of
both rapid climate fluctuation and relative climate stability. We show
dynamic changes in diatom communities during the past 16 000 years, with
decadal shifts in species dominance punctuating millennial-scale seasonal
trends. We describe for the first time in Lake Baikal a gradual shift from
spring to autumnal diatom communities that started during the Younger Dryas
and peaked during the Late Holocene, which likely represents orbitally driven
ecosystem responses to long-term changes in seasonality. Using a
multivariate classification tree, we show that trends in planktonic and
tychoplanktonic diatoms broadly reflect both long-term climatic changes
associated with the demise of Northern Hemisphere ice sheets and abrupt
climatic changes associated with, for example, the Younger Dryas stadial.
Indeed, diatom communities are most different before and after the boundary
between the Early and Middle Holocene periods of ca. 8.2 cal kyr BP, associated
with the presence and demise of Northern Hemisphere ice sheets respectively.
Diatom richness and diversity, estimated using Hill's species numbers, are
also shown to be very responsive to periods characterized by abrupt climate
change, and using knowledge of diatom autecologies in Lake Baikal, diversity
trends are interpreted in terms of resource availability. Using diatom
biovolume accumulation rates (BVARs; µm3 cm−2 yr−1), we
show that spring diatom crops dominate palaeoproductivity for nearly all of
our record, apart from a short period during the Late Holocene, when
autumnal productivity dominated between 1.8–1.4 cal kyr BP.
Palaeoproductivity was especially unstable during the Younger Dryas,
reaching peak rates of 18.3 × 103 µm3 cm−2 yr−1 at
ca. 12.3 cal kyr BP. Generalized additive models (GAMs), which explore
productivity–diversity relationships (PDRs) during pre-defined climate
periods, reveal complex relationships. The strongest statistical evidence for
GAMs were found during the Younger Dryas, the Early Holocene, and the Late
Holocene, i.e. periods of rapid climate change. We account for these
differences in terms of climate-mediated resource availability, and the
ability of endemic diatom species in Lake Baikal to adapt to extreme forms
of living in this unique ecosystem. Our analyses offer insight into how
productivity–diversity relationships may develop in the future under a
warming climate.
Materialart:
Online-Ressource
ISSN:
1814-9332
DOI:
10.5194/cp-18-363-2022
Sprache:
Englisch
Verlag:
Copernicus GmbH
Publikationsdatum:
2022
ZDB Id:
2217985-9
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