Biodiversity Trends
Within the Holocene
John Birks, Vivian Felde, and
Alistair Seddon
University of Bergen
‘Anthropocene’ has suddenly become a buzzword in
ecology and biogeography in the last few years, despite
no clear definition for its lower boundary
Recent publications on temporal trends of different units
or interest in biodiversity across in the ‘Anthropocene’
Alien species
Conservation
Coral growth
Temporal ecology
Forestry
Defaunation
Plant biodiversity
Island biogeography
Archaeogenomics &
ancient DNA
Observational techniques for biodiversity
Biological control
Biodiversity changes
Speciation
‘Anthropocene’ now well established in vocabulary and
research agenda of ecologists, conservationists, and
biogeographers even though there is no agreed definition.
Band-wagon effect!
McGill et al. (2015) identify four spatial scales and
four measures of biodiversity and two trends
Type of diversity
Alpha (α) diversity
α-diversity trend
Spatial beta (β)
diversity
The number of taxa present in an assemblage
Changes in α-diversity through time
Changes in assemblage composition across space
(e.g. comparing dissimilarity between the
composition of several assemblages for one time
period)
Spatial β-diversity Changes in spatial β-diversity through time (e.g.
trend
decreases through time leading to biotic
homogenisation (Sax and Gaines, 2003))
Temporal βChanges in assemblage composition through
diversity or
time, usually quantified as the dissimilarity
turnover
between each time step.
Biomass
A robust measure of abundance that is often
correlated with various ecosystem functions
Spatial scale
Global
The entire planet within which extinction and
speciation are the dominant processes
MetaA scale that includes spatial heterogeneity and within
community which dispersal is the dominant ecological process
Local
A scale that is dominated by interactions between taxa
and by environmental constraints
Also define a fourth spatial scale of organisation
“biogeographical – a scale within which speciation and
global extinctions are the dominant processes (Rosenweig
1995)”
Do not see how this differs from global spatial scale or
how to make it operational.
Prefer the simple Sax and Gaines (2003) three spatial
scales – global, regional, and local.
McGill et al. (2015)
Four spatial scales, four aspects of biodiversity, 15 trends
 hypothetical trend  evidence-based trend ? little or no evidence
Suggest at meta-community (regional) scale increase in αdiversity and decrease in N or biomass, and at local scale
hypothetical increase in temporal -diversity and biomass
In McGill et al. (2015) and the other 13 papers on
biodiversity and ecology in the ‘Anthropocene’ no
mention of
1. The onset of the ‘Anthropocene’ - ?50, 100, 200, 500,
2000, or even the last 5000–7000 years (‘early
Anthropocene’)
2. Biodiversity in the preceding Holocene
Obvious questions that follow McGill et al. (2015) are
• What were the biodiversity trends in the Holocene?
• Are the ‘Anthropocene’ trends a continuation of
trends in the Holocene and are they contingent on
these trends or are they unique relative to Holocene
trends?
Holocene Biodiversity Trends
1. Global scale – few data except for mammals, birds,
and marine mega-fauna. Mainly human-induced
extinctions
2. Meta-community (‘regional’) scale – pollen
assemblages from lakes and bogs provide inferences
about floristic and landscape richness and diversity
3. Local scale – less data available from local-scale
pollen assemblages. Little change in biodiversity
trends
Modern pollen richness (Hill N0) and diversity (Hill N1, N2)
are, in part, a function of contemporary floristic richness
and diversity (-diversity) (Felde et al. 2015)
and of landscape mosaic structure
(Matthias et al. 2015)
Alpha-diversity – rarefaction (analytical or repeated
resampling) to estimate N0, N1, and N2
Compositional turnover (temporal -diversity) – rateof-change or turnover metric (Birks 2007)
Spatial -diversity – diversity partitioning or spatiotemporal analysis of pollen assemblages (Blarquez et
al. 2014)
Biomass – pollen-accumulation rates in ‘well-behaved’
simple lakes approximate catchment biomass (Seppä et
al. 2009)
Using 120+ pollen diagrams from Fennoscandia,
Britain, and Ireland, can derive generalised trends for
these four biodiversity components. However,
Holocene is not ecologically uniform, so we have
produced biodiversity trends for four phases (Iversen
1958; Birks 1986)
Protocratic – early-Holocene forest development
Mesocratic – mid-Holocene forest maximum
Homo sapiens – human impact
Oligocratic – acid heath and bog phase
Birks et al. (2015)
Protocratic –
diversity , biomass 
Mesocratic –
diversity –, biomass –
Homo sapiens –
diversity , biomass 
Oligocratic –
diversity , biomass 
Last 200 years ‘Anthropocene’ – little change
In last 200 years in
Homo sapiens phase
sites, small decrease in
- and spatial diversity and biomass,
and small increase in
temporal -diversity
Oligocratic sites show
little change in - and
temporal -diversity,
small decrease in spatial
-diversity, and slight
rise in biomass (?N
deposition)
Meta-community ‘regional’ scale
Palaeodata
Homo sapiens Oligocratic
McGill et al.
-diversity

–

Spatial -diversity

 (very small)

Temporal -diversity

–
?
Biomass

 (very small)

Differences between palaeodata and McGill et al. (2015)
for trends in -diversity
See that at this regional
scale, and sites on fertile
soils in NW Europe,
changes in last 200 years
are not a simple
continuation of trends
initiated in the Homo
sapiens phase.
At oligocratic acid sites, recent
trends in - and -diversity
are primarily a continuation
of trends started in the
oligocratic phase, with the exception of small decrease in
spatial -diversity (‘biotic homogenisation’) and small
increase in biomass.
Do not expect same biodiversity trends in the Holocene
in, for example, central Europe, Alps, Mediterranean, the
tropics, or North America – different modern biota and
environments, Holocene biotic and vegetational histories,
and environmental and ecological changes.
Potentially interesting to explore Holocene and
‘Anthropocene’ trends in biodiversity in aquatic systems
-diversity
Hill’s N0 (rarefaction or repeated
resampling without replacement to a
constant base-sum), N1, and N2
Temporal -diversity
PCA, DCA, DCCA, principal curves, rateof-change analysis
Spatial -diversity
? Not relevant in the limnological context
Biomass
Biovolumes and accumulation rates
Biodiversity trends in the Holocene and ‘Anthropocene’
relevant to discussions about planetary boundaries
especially the Dearing et al. (2014) ‘safe’ and ‘justoperating’ spaces or boundaries for regional socioecological systems. Palaeoecological data can provide
an evidence-base for defining environmental limits to
ensure sustainability and human well-being at the
regional or local scale.
Encourage the increasing number of ecologists and
biogeographers writing about ‘Anthropocene’
biodiversity to extend their time-scales to include
trends in the Quaternary (Q-time). Biodiversity trends
simply did not begin in the ‘Anthropocene’.
Acknowledgements
Hilary Birks
Cathy Jenks
Anne Bjune
Triin Reitalu
Thomas Giesecke
Willy Tinner