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Grubb Review

Contributions of Quaternary botany to modern ecology and biogeography

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Pages 189-385 | Received 21 Jun 2018, Accepted 18 Jul 2019, Published online: 06 Dec 2019

Figures & data

Table 1. Selected reviews on Quaternary floristic and vegetational history of different geographical areas. See Birks HJB and Berglund (Citation2018) for further examples.

Table 2. Selected reviews of contributions of Quaternary botany to modern ecology or biogeography.

Figure 1. (a) Mid-elevation belt of Pinus contorta, P. ponderosa, Picea engelmannii, Betula papyrifera, and Populus tremuloides between lowland xeric Artemisia tridentata sagebrush-steppe and high-elevation snow and dry open alpine vegetation, Borah Peak, Idaho, USA. This is a possible modern analogue for a'classical' macrorefugium for trees in the mountains of southern Europe during the last glacial maximum (LGM). Photograph: HJB Birks. (b) Local stands of Picea crassifolia along water seepages at 3600 m on the south-eastern Tibetan Plateau, Sichuan, China. This is a possible modern analogue for a 'microrefugium' for trees in Europe during the LGM. Modern pollen percentages of Picea at this site are less than 3%. Photograph: HJB Birks.

Figure 1. (a) Mid-elevation belt of Pinus contorta, P. ponderosa, Picea engelmannii, Betula papyrifera, and Populus tremuloides between lowland xeric Artemisia tridentata sagebrush-steppe and high-elevation snow and dry open alpine vegetation, Borah Peak, Idaho, USA. This is a possible modern analogue for a'classical' macrorefugium for trees in the mountains of southern Europe during the last glacial maximum (LGM). Photograph: HJB Birks. (b) Local stands of Picea crassifolia along water seepages at 3600 m on the south-eastern Tibetan Plateau, Sichuan, China. This is a possible modern analogue for a 'microrefugium' for trees in Europe during the LGM. Modern pollen percentages of Picea at this site are less than 3%. Photograph: HJB Birks.

Figure 2. The glacial–interglacial cycle for north-west Europe showing the broad changes in biomass (above-ground productivity), soil status, and temperature that take place during a glacial stage (cryocratic – blue) and its associated interglacial stage (protocratic, mesocratic, oligocratic and telocratic – orange). The largest changes in temperature occur at the glacial–interglacial transitions; that is at the beginning and end of the cryocratic phase, particularly at the cryocratic–protocratic transition. There are also fine-scale climatic changes within an interglacial stage and a glacial stage. Based on Iversen (Citation1958), Andersen ST (Citation1994), and Birks HJB and Birks (Citation2004). In the Holocene (present interglacial), the Homo sapiens phase (Birks HJB Citation1986) replaces the oligocratic and telocratic phases at sites with fertile soils (Birks HJB Citation1986).

Figure 2. The glacial–interglacial cycle for north-west Europe showing the broad changes in biomass (above-ground productivity), soil status, and temperature that take place during a glacial stage (cryocratic – blue) and its associated interglacial stage (protocratic, mesocratic, oligocratic and telocratic – orange). The largest changes in temperature occur at the glacial–interglacial transitions; that is at the beginning and end of the cryocratic phase, particularly at the cryocratic–protocratic transition. There are also fine-scale climatic changes within an interglacial stage and a glacial stage. Based on Iversen (Citation1958), Andersen ST (Citation1994), and Birks HJB and Birks (Citation2004). In the Holocene (present interglacial), the Homo sapiens phase (Birks HJB Citation1986) replaces the oligocratic and telocratic phases at sites with fertile soils (Birks HJB Citation1986).

Figure 3. Summary pollen diagram of the composite long pollen sequence from the Velay Plateau in the south-eastern part of the French Massif Central. The interglacial stages are shaded in pale brown and the corresponding marine isotope stages (MIS) are shown. Note the change between interglacial stages with dominant temperate trees and cold, dry glacial stages with dominant Poaceae and steppe taxa. The Holocene is MIS 1, the Ribains interglacial is MIS 5e (= Eemian), the Bouchet I interglacial is MIS 7c, the Landos interglacial is MIS 9e, and the Praclaux interglacial is MIS 11e (= Holsteinian). Redrawn and modified from de Beaulieu et al. (Citation2001).

Figure 3. Summary pollen diagram of the composite long pollen sequence from the Velay Plateau in the south-eastern part of the French Massif Central. The interglacial stages are shaded in pale brown and the corresponding marine isotope stages (MIS) are shown. Note the change between interglacial stages with dominant temperate trees and cold, dry glacial stages with dominant Poaceae and steppe taxa. The Holocene is MIS 1, the Ribains interglacial is MIS 5e (= Eemian), the Bouchet I interglacial is MIS 7c, the Landos interglacial is MIS 9e, and the Praclaux interglacial is MIS 11e (= Holsteinian). Redrawn and modified from de Beaulieu et al. (Citation2001).

Figure 4. Comparison of interglacial tree pollen stratigraphies in five interglacial stages in the composite long pollen sequence from the Velay Plateau in the south-eastern part of the French Massif Central (). Major tree pollen taxa are coloured identically between interglacials. The approximate age of the onset of each interglacial is also shown along with the correlations with marine isotope stages (MIS). Redrawn and modified from de Beaulieu et al. (Citation2006).

Figure 4. Comparison of interglacial tree pollen stratigraphies in five interglacial stages in the composite long pollen sequence from the Velay Plateau in the south-eastern part of the French Massif Central (Figure 3). Major tree pollen taxa are coloured identically between interglacials. The approximate age of the onset of each interglacial is also shown along with the correlations with marine isotope stages (MIS). Redrawn and modified from de Beaulieu et al. (Citation2006).

Figure 5. Schematic diagram summarising the main stages and associated pedological changes (1–4) occurring in the transition from a podsol supporting coniferous forest in the late-glacial (stages 1 and 2) to a brown-earth soil with deciduous forest in the early-mid Holocene (stage 4) at Kis-Mohos Tó (NE Hungary) via an intermediate phase of a podsolic brown-earth with deciduous trees in the early Holocene (stage 3). The chemical record in the lake sediment at Kis-Mohos Tó is summarised. Redrawn from Willis et al. (Citation1997).

Figure 5. Schematic diagram summarising the main stages and associated pedological changes (1–4) occurring in the transition from a podsol supporting coniferous forest in the late-glacial (stages 1 and 2) to a brown-earth soil with deciduous forest in the early-mid Holocene (stage 4) at Kis-Mohos Tó (NE Hungary) via an intermediate phase of a podsolic brown-earth with deciduous trees in the early Holocene (stage 3). The chemical record in the lake sediment at Kis-Mohos Tó is summarised. Redrawn from Willis et al. (Citation1997).

Figure 6. Gerzensee, a kettle-hole lake on the Swiss Plateau at 603 m elevation (46.83°N, 7.55°E). This site has been the focus of detailed studies on rapid warming and associated biotic changes in the late-glacial and early Holocene (Ammann and Oldfield Citation2000; Ammann et al. Citation2013a, Citation2013b, Citation2013c), for example the study summarised in . The Bernese Alps are in the background. Photograph: AF Lotter.

Figure 6. Gerzensee, a kettle-hole lake on the Swiss Plateau at 603 m elevation (46.83°N, 7.55°E). This site has been the focus of detailed studies on rapid warming and associated biotic changes in the late-glacial and early Holocene (Ammann and Oldfield Citation2000; Ammann et al. Citation2013a, Citation2013b, Citation2013c), for example the study summarised in Figure 7. The Bernese Alps are in the background. Photograph: AF Lotter.

Figure 7. Vegetation and soil development around Termination A (Oldest Dryas/Bølling transition) about 14,665 calibrated years ago at Gerzensee, Switzerland (see ). Changes in stable oxygen-isotope ratios (δ18O‰) of bulk carbonate in the lake sediments (A) provide a climate proxy independent of the pollen stratigraphy. The physiognomy of the past vegetation (B) and vegetation type (C) are inferred from pollen (D) and plant-macrofossil data (the nitrogen-fixing shrub Hippophaë rhamnoides is shown in orange in B). Pollen-accumulation rates (grains cm–2 yr–1) (D) reflect vegetation cover and biomass, whereas rates of palynological change (per 70 yr) (E) highlight times of marked change shown by a small or big * that are 50% or 75% greater than the mean rate of change, respectively. Palynological richness (α-diversity) (F) is estimated as number of taxa cm–2 yr–1 to allow for the changes in pollen-accumulation rates (D). The inferred soils (G) are summarised in terms of the extent of the active layer, amount of nitrogen-fixation based on the abundance of nitrogen-fixing plants in the pollen and plant-macrofossil stratigraphies, and general soil types. Inferred changes in the potential nitrogen and phosphorus resources during the vegetation development are also shown (H). All the stratigraphical data are smoothed with a running mean over five samples. Redrawn and modified from Ammann et al. (Citation2013b) and Birks HJB et al. (Citation2016b).

Figure 7. Vegetation and soil development around Termination A (Oldest Dryas/Bølling transition) about 14,665 calibrated years ago at Gerzensee, Switzerland (see Figure 6). Changes in stable oxygen-isotope ratios (δ18O‰) of bulk carbonate in the lake sediments (A) provide a climate proxy independent of the pollen stratigraphy. The physiognomy of the past vegetation (B) and vegetation type (C) are inferred from pollen (D) and plant-macrofossil data (the nitrogen-fixing shrub Hippophaë rhamnoides is shown in orange in B). Pollen-accumulation rates (grains cm–2 yr–1) (D) reflect vegetation cover and biomass, whereas rates of palynological change (per 70 yr) (E) highlight times of marked change shown by a small or big * that are 50% or 75% greater than the mean rate of change, respectively. Palynological richness (α-diversity) (F) is estimated as number of taxa cm–2 yr–1 to allow for the changes in pollen-accumulation rates (D). The inferred soils (G) are summarised in terms of the extent of the active layer, amount of nitrogen-fixation based on the abundance of nitrogen-fixing plants in the pollen and plant-macrofossil stratigraphies, and general soil types. Inferred changes in the potential nitrogen and phosphorus resources during the vegetation development are also shown (H). All the stratigraphical data are smoothed with a running mean over five samples. Redrawn and modified from Ammann et al. (Citation2013b) and Birks HJB et al. (Citation2016b).

Table 3. Possible dominant mycorrhizal types and nitrogen fixers in a north-west European glacial–interglacial cycle and suggested levels of above-ground productivity, available soil phosphorus levels, and amount of nitrogen fixation. This scheme is based on many sources including Harley and Harley (Citation1987), Read (Citation1993a, Citation1993b), Cázares et al. (Citation2005), Kuneš et al. (Citation2011), and Dickie et al. (Citation2013).

Figure 8. The series of pollen diagrams presented by Lennart von Post in his 1916 lecture in Kristiania along a south-west to north-east transect from Zealand (site F), through Skåne and Småland (sites 1–8) and into Västergötland, Östergötland, and Närke on the borders of the north and central Swedish uplands (sites 9–12). The southern limit of Picea abies lies between sites 3 and 4, and the northern limit of Fagus sylvatica is near site 6. The EK-Blandskog + Corylus curve is the combined values of Quercus, Ulmus, Tilia, and Corylus (‘Quercetum Mixtum’). The colours are those that von Post used in his original lecture-chart. As on all his diagrams, von Post has signed it in the bottom right-hand corner. Based on a diagram in Fries M (Citation1967) but extensively modified. This series of pollen diagrams was subsequently published in very different formats by von Post (Citation1924, Citation1926a).

Figure 8. The series of pollen diagrams presented by Lennart von Post in his 1916 lecture in Kristiania along a south-west to north-east transect from Zealand (site F), through Skåne and Småland (sites 1–8) and into Västergötland, Östergötland, and Närke on the borders of the north and central Swedish uplands (sites 9–12). The southern limit of Picea abies lies between sites 3 and 4, and the northern limit of Fagus sylvatica is near site 6. The EK-Blandskog + Corylus curve is the combined values of Quercus, Ulmus, Tilia, and Corylus (‘Quercetum Mixtum’). The colours are those that von Post used in his original lecture-chart. As on all his diagrams, von Post has signed it in the bottom right-hand corner. Based on a diagram in Fries M (Citation1967) but extensively modified. This series of pollen diagrams was subsequently published in very different formats by von Post (Citation1924, Citation1926a).

Figure 9. Picea pollen percentages (expressed as percentages of total tree pollen) at over 250 sites in southern Sweden in the (1) Sub-Boreal, (2) early Sub-Atlantic, (3) middle Sub-Atlantic, and (4) recent times. The native southern range limit (in 1924) is indicated as a solid line on the map for recent times (4). Modified from von Post (Citation1924).

Figure 9. Picea pollen percentages (expressed as percentages of total tree pollen) at over 250 sites in southern Sweden in the (1) Sub-Boreal, (2) early Sub-Atlantic, (3) middle Sub-Atlantic, and (4) recent times. The native southern range limit (in 1924) is indicated as a solid line on the map for recent times (4). Modified from von Post (Citation1924).

Figure 10. Maps of Quercus (deciduous) pollen percentages across Europe for 12,000, 10,000, 8000, 6000, 4000, and 2000 radiocarbon years before present (BP) drawn as isopollen contours representing different percentage values (modified from Huntley and Birks Citation1983), and for 14,000, 11,500, 9000, 7000, 4500, and 2000 calibrated years BP drawn as different sized solid circles representing different pollen percentage values (modified from Brewer et al. Citation2017). The blue shading on the dot maps for 14,000 and 11,500 yr BP shows the likely extent of glacial ice in Fennoscandia. The two sets of maps have been approximately correlated in time using the IntCal13 radiocarbon calibration curve and CalPal (www.calpal-online.de) as the isopollen maps are in radiocarbon years BP and the dot maps are in calibrated years BP.

Figure 10. Maps of Quercus (deciduous) pollen percentages across Europe for 12,000, 10,000, 8000, 6000, 4000, and 2000 radiocarbon years before present (BP) drawn as isopollen contours representing different percentage values (modified from Huntley and Birks Citation1983), and for 14,000, 11,500, 9000, 7000, 4500, and 2000 calibrated years BP drawn as different sized solid circles representing different pollen percentage values (modified from Brewer et al. Citation2017). The blue shading on the dot maps for 14,000 and 11,500 yr BP shows the likely extent of glacial ice in Fennoscandia. The two sets of maps have been approximately correlated in time using the IntCal13 radiocarbon calibration curve and CalPal (www.calpal-online.de) as the isopollen maps are in radiocarbon years BP and the dot maps are in calibrated years BP.

Table 4. Selected examples of Holocene isochrone maps for different geographical areas.

Figure 11. Isochrones (in radiocarbon years BP) for Quercus pollen in Britain and Ireland. Modified from Birks HJB (Citation1989).

Figure 11. Isochrones (in radiocarbon years BP) for Quercus pollen in Britain and Ireland. Modified from Birks HJB (Citation1989).

Table 5. Estimated rates of spread (m yr–1) of trees during the Holocene in Britain and Ireland (Birks Citation1989) and on the European mainland based on Huntley and Birks (Citation1983), Feurdean et al. (Citation2013), Brewer et al. (2017), and Giesecke and Brewer (Citation2018).Citation2017

Figure 12. Possible scenarios for tree spreading across a large area in an interglacial stage. 1. The moving-front or continuous wave hypothesis where trees 'march' across the landscape. 2. Rare far-distance dispersal events form small outlying populations. 3. Populations expand from the outlying populations into locally favourable sites or enclaves. 4. Merging of large and small populations. Small scattered populations expand (as in 3) and are a source for dispersal events, as are the large populations. Scenarios 2, 3, and 4 combined are likely to be most important. Based, in part, on Davis MB (Citation1987) and Giesecke (Citation2013).

Figure 12. Possible scenarios for tree spreading across a large area in an interglacial stage. 1. The moving-front or continuous wave hypothesis where trees 'march' across the landscape. 2. Rare far-distance dispersal events form small outlying populations. 3. Populations expand from the outlying populations into locally favourable sites or enclaves. 4. Merging of large and small populations. Small scattered populations expand (as in 3) and are a source for dispersal events, as are the large populations. Scenarios 2, 3, and 4 combined are likely to be most important. Based, in part, on Davis MB (Citation1987) and Giesecke (Citation2013).

Table 6. Selected examples of range expansions or contractions of taxa that appear to show a ‘stop’ or ‘go’ behaviour during the Holocene.

Figure 13. The changing relative abundance expressed as a percentage of the maximum attained values of tree taxa through time in Britain and Ireland. The top panel (1) shows how relative abundance changes through time in the absence of any detectable dispersal limitation or expansion limitation, as shown by the Holocene behaviour of Corylus, Populus, Salix, or Ulmus. The middle panel (2) shows relative abundance changes for taxa that experience dispersal limitation but little or no expansion limitation (e.g. Betula, Pinus). The bottom panel (3) shows relative abundance changes for taxa that may experience not only dispersal limitation but also prolonged expansion limitation (e.g. Alnus, Carpinus, Fagus) that may extend for 2000–3000 years. Of these, Alnus is the most extreme in its expansion limitation due to the rarity of its 'island-like' wet habitats. There are not enough detailed data to assess the long-term behaviour of Fraxinus, Quercus, or Tilia.

DL = Dispersal limitation; EL = Expansion limitation; EP = Expansion phase.

Figure 13. The changing relative abundance expressed as a percentage of the maximum attained values of tree taxa through time in Britain and Ireland. The top panel (1) shows how relative abundance changes through time in the absence of any detectable dispersal limitation or expansion limitation, as shown by the Holocene behaviour of Corylus, Populus, Salix, or Ulmus. The middle panel (2) shows relative abundance changes for taxa that experience dispersal limitation but little or no expansion limitation (e.g. Betula, Pinus). The bottom panel (3) shows relative abundance changes for taxa that may experience not only dispersal limitation but also prolonged expansion limitation (e.g. Alnus, Carpinus, Fagus) that may extend for 2000–3000 years. Of these, Alnus is the most extreme in its expansion limitation due to the rarity of its 'island-like' wet habitats. There are not enough detailed data to assess the long-term behaviour of Fraxinus, Quercus, or Tilia.DL = Dispersal limitation; EL = Expansion limitation; EP = Expansion phase.

Figure 14. Suggested location of refugial areas for Fagus sylvatica during the last glacial maximum (blue circles) and the major spread into Europe during the Holocene (blue arrows). The green shaded areas are the present native range of F. sylvatica. Modified from Magri et al. (Citation2006).

Figure 14. Suggested location of refugial areas for Fagus sylvatica during the last glacial maximum (blue circles) and the major spread into Europe during the Holocene (blue arrows). The green shaded areas are the present native range of F. sylvatica. Modified from Magri et al. (Citation2006).

Table 7. Numbers of total and species partial extinctions and exterminations of taxa in recently studied Late Pliocene sequences in Belarus and Early or Middle Pleistocene interglacials in Poland along with their assumed correlations with Marine Isotope Stages (MIS) and interglacial stages in western Europe (Lindner et al. Citation2013). (Based on Stachowicz-Rybka Citation2015a and data from Mamakowa and Velichkevich Citation1993a; Velichkevich and Granoszewski Citation1996; Velichkevich and Lesiak Citation1996; Velichkevich and Mamakowa Citation2003; Velichkevich and Zastawniak Citation2003; Velichkevich et al. Citation2004; Stachowicz-Rybka Citation2011, Citation2015a, Citation2015b, Citation2015c; Drzymulska Citation2018).

Table 8. Comparison of modern climatic requirements of cool-temperate tree genera that grew in Europe in the Neogene but had been exterminated by the early Pliocene, that were present in Europe in the Neogene but have relictual disjunct distributions today, and that were present in the Neogene and are widespread in Europe today (based on Svenning Citation2003). Minimum growing degree days and the moisture index (actual evapotranspiration/potential evapotranspiration) are only available for genera in North America.

Table 9. Selected genera or species other than trees that were exterminated from north-west Europe during the Neogene or Pleistocene. See Tralau (Citation1959, Citation1963a), van der Hammen et al. (Citation1971), Huckerby and Oldfield (Citation1976), Watts (Citation1988), Lang (Citation1994), Mai (Citation1995), Drzymulska (Citation2018), and Góis-Marques et al. (Citation2019) for details.

Table 10. Selected examples of publications on the role of persistence, evolutionary adaptation, and of phenotypic plasticity in influencing biodiversity patterns today and in the future.

Figure 15. (1) Fundamental, potential, and realised niches of a species in response to two environmental variables. The realised niche is where populations of the species actually occur and is a subset of the potential niche constrained by biotic, abiotic, and other factors. The potential niche is where the fundamental niche intersects with the realised environmental space at a particular time. (2) A schematic representation of how changes in the realised environmental space between time 1 and time 2 can affect species co-occurrences. At time 1, the potential niches of species 1 and species 2 overlap and the species can potentially co-occur at sites within the intersection. At time 2, the potential niches of the two species do not overlap and hence they will not co-occur in the realised world. (3) The four modes of population response of five species (a-e) to environmental change. Species a mode 1: persistence. Species b modes 1 and 2: shift within local habitat conditions. Species c modes 1, 2, and 3: spread to distant newly-suitable sites and disappear from some former sites. Species d modes 1 and 4: widespread extirpation without colonisation of new areas, thereby changing from being a widespread species to a local or rare species. Species e is the inverse of species d where a formerly rare species colonises extensive new areas. Redrawn from Jackson and Overpeck (Citation2000).

Figure 15. (1) Fundamental, potential, and realised niches of a species in response to two environmental variables. The realised niche is where populations of the species actually occur and is a subset of the potential niche constrained by biotic, abiotic, and other factors. The potential niche is where the fundamental niche intersects with the realised environmental space at a particular time. (2) A schematic representation of how changes in the realised environmental space between time 1 and time 2 can affect species co-occurrences. At time 1, the potential niches of species 1 and species 2 overlap and the species can potentially co-occur at sites within the intersection. At time 2, the potential niches of the two species do not overlap and hence they will not co-occur in the realised world. (3) The four modes of population response of five species (a-e) to environmental change. Species a mode 1: persistence. Species b modes 1 and 2: shift within local habitat conditions. Species c modes 1, 2, and 3: spread to distant newly-suitable sites and disappear from some former sites. Species d modes 1 and 4: widespread extirpation without colonisation of new areas, thereby changing from being a widespread species to a local or rare species. Species e is the inverse of species d where a formerly rare species colonises extensive new areas. Redrawn from Jackson and Overpeck (Citation2000).

Table 11. The frequency of the four modes of response in species populations and species combinations (‘associations’) within Europe and North America during the late-Quaternary.

Table 12. Suggested drivers within the realised environment space (RES) resulting in no-analogue pollen assemblages and possible no-analogue vegetation types during different stages in the late-Quaternary in north-west Europe and eastern North America.

Figure 16. The three major hypotheses (H1–H3) and processes for changes in pollen-assemblage composition and abundance: environmental forcing (H1), biotic interactions (H2), and neutral processes (H3) that can cause ecological drift (Jackson and Blois Citation2015). These processes may interact in the real world. Exogenous environmental change (e.g. climate change) may be a major driver of assemblage properties both directly and indirectly by influencing interactions between taxa and initiating neutral processes. Climate varies continuously and may influence processes within all three hypotheses to modify assemblage properties (Jackson and Blois Citation2015). The three underlying hypotheses H1, H2, and H3 correspond to the hypotheses discussed in the text. Modified from Jackson and Blois (Citation2015).

Figure 16. The three major hypotheses (H1–H3) and processes for changes in pollen-assemblage composition and abundance: environmental forcing (H1), biotic interactions (H2), and neutral processes (H3) that can cause ecological drift (Jackson and Blois Citation2015). These processes may interact in the real world. Exogenous environmental change (e.g. climate change) may be a major driver of assemblage properties both directly and indirectly by influencing interactions between taxa and initiating neutral processes. Climate varies continuously and may influence processes within all three hypotheses to modify assemblage properties (Jackson and Blois Citation2015). The three underlying hypotheses H1, H2, and H3 correspond to the hypotheses discussed in the text. Modified from Jackson and Blois (Citation2015).

Table 13. Estimates of tree-population doubling times (td = logn(2/r); rounded to nearest 5 years) derived from pollen-stratigraphical data (PAR) from North America (Tsukada and Sugita Citation1982; Tsukada Citation1982c, Citation1982d; Bennett Citation1986, Citation1988a; MacDonald and Cwynar Citation1991; MacDonald Citation1993a; Fuller Citation1998; Edwards ME et al. Citation2015), England (Bennett Citation1983, Citation1988b), Central Europe (Giesecke et al. Citation2007; Bradshaw RHW et al. Citation2010), Italy (Magri Citation1989), north-east Australia (Walker and Chen Citation1987; Chen Citation1988), and Japan (Tsukada Citation1981, Citation1982a, Citation1982b, Citation1982c; Tsukada and Sugita Citation1982; Kito and Takimoto Citation1999). Modified from MacDonald (Citation1993a).

Table 14. Estimates of tree-population halving times (th = loge(2/r); rounded to nearest 5 years) derived from pollen-stratigraphical data (PAR) from North America (Tsukada and Sugita Citation1982), England (Peglar Citation1993a; Peglar and Birks Citation1993), and Japan (Tsukada Citation1983).

Table 15. Estimates of tree-population doubling times (td = loge(2/r); rounded to nearest 5 years) derived from pollen-stratigraphical data (PAR) from two sites in southern Ontario after the marked decline of Tsuga canadensis pollen at about 5400 years ago (calculated from data in Fuller Citation1998).

Table 16. Estimates of tree-population doubling times (td = loge(2/r); rounded to nearest 5 years) calculated from the eigenvalue (λ) of the transition matrix where logeλ = r (see Piñero et al. Citation1984). Data from various sources compiled and documented by Bennett (Citation1986).

Figure 17. Generalised pollen-stratigraphical patterns and inferred population processes suggested by Watts (Citation1973) in the establishment and expansion of a tree in the mesocratic phase within an interglacial stage. The very approximate durations of the establishment and expansion intervals are also shown. Modified from Birks HJB and Tinner (Citation2016a).

Figure 17. Generalised pollen-stratigraphical patterns and inferred population processes suggested by Watts (Citation1973) in the establishment and expansion of a tree in the mesocratic phase within an interglacial stage. The very approximate durations of the establishment and expansion intervals are also shown. Modified from Birks HJB and Tinner (Citation2016a).

Figure 18. Hypothetical pollen-stratigraphical reflections of the same climate oscillation in different regions along an imaginary transect from south to north. In the far north, locality A, the climatic oscillation results in a retreat of tundra and expansion of ice. Locality B records the classical Allerød–Younger Dryas–early Holocene pattern of Betula woodland–tundra–Betula woodland. Farther south, the climatic oscillation is recorded by other vegetational and hence pollen-stratigraphical changes. Note that at localities D and F no major pollen-stratigraphical changes are observed as no ecotones are crossed. Based on Fægri and Iversen (Citation1950).

Figure 18. Hypothetical pollen-stratigraphical reflections of the same climate oscillation in different regions along an imaginary transect from south to north. In the far north, locality A, the climatic oscillation results in a retreat of tundra and expansion of ice. Locality B records the classical Allerød–Younger Dryas–early Holocene pattern of Betula woodland–tundra–Betula woodland. Farther south, the climatic oscillation is recorded by other vegetational and hence pollen-stratigraphical changes. Note that at localities D and F no major pollen-stratigraphical changes are observed as no ecotones are crossed. Based on Fægri and Iversen (Citation1950).

Figure 19. Contrasts between an abrupt extrinsically forced ecological change (left panels) with an abrupt intrinsically forced change (right panels). In the extrinsically forced change, a large widespread change in temperature (a), e.g. the Younger Dryas–Holocene transition, causes abrupt ecological changes that are synchronous with or slightly lag behind the climate change at sites 1, 2, and 3 (c), resulting in a strong temporal coherence of change (e). With intrinsically forced change, a long-term progressive trend such as droughts and megadroughts (b) are mediated by site-specific (1–6) thresholds (d). These site-specific thresholds cause abrupt changes across the drought period (f). Clusters of site-level abrupt changes may result from extreme events which may impact many sites simultaneously (f). Modified from Williams et al. (Citation2011a).

Figure 19. Contrasts between an abrupt extrinsically forced ecological change (left panels) with an abrupt intrinsically forced change (right panels). In the extrinsically forced change, a large widespread change in temperature (a), e.g. the Younger Dryas–Holocene transition, causes abrupt ecological changes that are synchronous with or slightly lag behind the climate change at sites 1, 2, and 3 (c), resulting in a strong temporal coherence of change (e). With intrinsically forced change, a long-term progressive trend such as droughts and megadroughts (b) are mediated by site-specific (1–6) thresholds (d). These site-specific thresholds cause abrupt changes across the drought period (f). Clusters of site-level abrupt changes may result from extreme events which may impact many sites simultaneously (f). Modified from Williams et al. (Citation2011a).

Figure 20. (a) The ecological thresholds for the establishment of prairie, oak (Quercus) woodland, and mixed deciduous forest (Bigwoods) in central Minnesota plotted along a climatic gradient (e.g. precipitation) that influences fire frequency. Redrawn from Grimm EC (Citation1983). (b) Schematic representation of ecological thresholds for the establishment of prairie and woodland in central Minnesota. The horizontal axis is time; the vertical axis is a climatic gradient (e.g. mean annual precipitation). In the upper right quadrant (woodland only) above the woodland threshold for annual precipitation (Pw), only woodland will persist as a stable state once it is established. Either of two potentially stable states – woodland or prairie – can persist in areas with climate delimited by the thresholds for woodland (Pw) and prairie (Pp), while only prairie will persist as a stable state below the critical threshold for annual precipitation (Pp) and for increased fire recurrence (lower right quadrant: prairie only). Tw represents the minimum time required for woodland to invade prairie. The vegetation outcomes and pathways are summarised in the right-hand column. Redrawn from Grimm EC (Citation1983) and Delcourt HR and Delcourt (Citation1991).

Figure 20. (a) The ecological thresholds for the establishment of prairie, oak (Quercus) woodland, and mixed deciduous forest (Bigwoods) in central Minnesota plotted along a climatic gradient (e.g. precipitation) that influences fire frequency. Redrawn from Grimm EC (Citation1983). (b) Schematic representation of ecological thresholds for the establishment of prairie and woodland in central Minnesota. The horizontal axis is time; the vertical axis is a climatic gradient (e.g. mean annual precipitation). In the upper right quadrant (woodland only) above the woodland threshold for annual precipitation (Pw), only woodland will persist as a stable state once it is established. Either of two potentially stable states – woodland or prairie – can persist in areas with climate delimited by the thresholds for woodland (Pw) and prairie (Pp), while only prairie will persist as a stable state below the critical threshold for annual precipitation (Pp) and for increased fire recurrence (lower right quadrant: prairie only). Tw represents the minimum time required for woodland to invade prairie. The vegetation outcomes and pathways are summarised in the right-hand column. Redrawn from Grimm EC (Citation1983) and Delcourt HR and Delcourt (Citation1991).

Table 17. Selected examples of detailed fire histories reconstructed from charcoal in Quaternary botanical sequences with emphasis on interactions of fire with other variables, and rapid state shifts and system dynamics.

Table 18. Selected examples of recent theoretical and Quaternary studies on ecosystem dynamics, in particular regime shifts.

Table 19. Approximate age of modern British woodland assemblages inferred from pollen-analytical stratigraphies and macrofossil data. The assemblages are based on the dominant tree taxa as indicated from pollen and/or plant macrofossil taxa. To aid vegetation reconstruction, fossil tree-pollen values have been transformed by Andersen’s (Citation1970) general pollen representation factors as modified for British taxa (Edwards ME Citation1986). The antecedent pollen assemblage or vegetation type are based on available dated pollen data from Britain (Birks HJB Citation1989; Bennett and Birks Citation1990; Fyfe et al. Citation2010, Citation2013; Brewer et al. Citation2017). For details of the NVC types, see Rodwell et al. (Citation1991).

Table 20. Selected examples of prehistoric human activities in the Amazon basin, lowland Congo basin, and Indo-Malaya region detected by palynological and associated palaeoecological studies with the approximate age of the activities and relevant references.

Table 21. Selected examples of publications on the potential contribution of Quaternary or ‘Deep-time’ palaeobiological studies to conservation by providing a historical perspective.

Table 22. Further examples of Quaternary palaeobiological studies that link directly to conservation and management that are not discussed in the text.

Table 23. Selected examples of detailed local- or regional-scale palynological studies on the history of specific vegetation types in Europe, Asia, and United States.

Table 24. Selected examples of palaeoecological studies that contribute to establishing baseline or reference conditions at a particular site or vegetation type.

Figure 21. Vegetation responses at two sites on eastern Madagascar (Fossa and Bassin) to an environmental perturbation (sea-level rise and subsequent drought) about 1000 years ago. Pollen assemblages at Fossa (left) recover towards the previous stable state (high ecological resilience) whereas at Bassin (right) the pollen assemblages continue to diversify (low ecological resilience). Each period shows a time-series of relative pollen proportions (vertical axis) (P continuous line) and a smoothed version (dashed line) based on a robust locally weighted polynomial model (span = 0.25). Heathland is Erica, Asteraceae, and Poaceae pollen, 'Forest' is the sum of pollen of littoral forest tree taxa at Fossa and the sum of pollen of open Uapaca forest tree taxa at Bassin. Recovery refers to a return to forest conditions (see Virah-Sawmy et al. Citation2009a, Citation2010 for details). The small inset panels in each large panel show a phase plot for the smoothed pollen data where the relative pollen abundance (P) is plotted against the local rate-of-change gradient (horizontal axis) (ΔP/Δt). The smoothed data were interpolated and resampled at uniform time intervals for the same number of points as in the original data-sets. The proximity of these points on the phase plots indicate the rate of change in system state, with arrows showing the direction of time from old to young. The dashed ovals enclose the stable forest state prior to the perturbation. The system appears to be moving towards full recovery at Fossa (high ecological resilience) whereas there are no signs of recovery at Bassin (low ecological resilience). Redrawn from Willis et al. (Citation2010a).

Figure 21. Vegetation responses at two sites on eastern Madagascar (Fossa and Bassin) to an environmental perturbation (sea-level rise and subsequent drought) about 1000 years ago. Pollen assemblages at Fossa (left) recover towards the previous stable state (high ecological resilience) whereas at Bassin (right) the pollen assemblages continue to diversify (low ecological resilience). Each period shows a time-series of relative pollen proportions (vertical axis) (P continuous line) and a smoothed version (dashed line) based on a robust locally weighted polynomial model (span = 0.25). Heathland is Erica, Asteraceae, and Poaceae pollen, 'Forest' is the sum of pollen of littoral forest tree taxa at Fossa and the sum of pollen of open Uapaca forest tree taxa at Bassin. Recovery refers to a return to forest conditions (see Virah-Sawmy et al. Citation2009a, Citation2010 for details). The small inset panels in each large panel show a phase plot for the smoothed pollen data where the relative pollen abundance (P) is plotted against the local rate-of-change gradient (horizontal axis) (ΔP/Δt). The smoothed data were interpolated and resampled at uniform time intervals for the same number of points as in the original data-sets. The proximity of these points on the phase plots indicate the rate of change in system state, with arrows showing the direction of time from old to young. The dashed ovals enclose the stable forest state prior to the perturbation. The system appears to be moving towards full recovery at Fossa (high ecological resilience) whereas there are no signs of recovery at Bassin (low ecological resilience). Redrawn from Willis et al. (Citation2010a).

Figure 22. A schematic representation of the glacial legacy or ‘ecological memory’ on interglacial vegetation models of Herzschuh et al. (Citation2016). During interglacials following mild glacial stages (left), NE Asia was colonised by evergreen trees (e.g. Picea, Pinus) from nearby glacial-stage refugia. In contrast, during interglacials following cold glacial stages (right) Larix spp. and deciduous shrubs were dominant in response to the combined effects of permafrost persistence and distant glacial-stage refugia of evergreen trees, and fire. This model implies that vegetation–climate disequilibrium can last for many millennia. Modified from Herzschuh et al. (Citation2016).

Figure 22. A schematic representation of the glacial legacy or ‘ecological memory’ on interglacial vegetation models of Herzschuh et al. (Citation2016). During interglacials following mild glacial stages (left), NE Asia was colonised by evergreen trees (e.g. Picea, Pinus) from nearby glacial-stage refugia. In contrast, during interglacials following cold glacial stages (right) Larix spp. and deciduous shrubs were dominant in response to the combined effects of permafrost persistence and distant glacial-stage refugia of evergreen trees, and fire. This model implies that vegetation–climate disequilibrium can last for many millennia. Modified from Herzschuh et al. (Citation2016).

Table 25. Comparison of ‘proximate’ and ‘ultimate’ diversity and stability on oceanic islands and continental mainlands (modified from Cronk Citation1997).

Table 26. Selected examples of islands or island groups in different oceans where pollen-analytical studies show compositional stability prior to the onset of human impact and ecosystem modification. The approximate duration of the periods with stable pollen composition is given, along with the age for the onset of human activities and an indication of plant extinctions or exterminations of all types on each island. The duration of the stable phases are minimal as the pollen assemblages in some of the sequences may commence within the stable phase.

Figure 23. Summary percentage pollen diagram from Ewing Island (sub-Antarctic Auckland Islands) with selected taxa plotted against depth with a calibrated age scale in years CE. Grey zone shows the time of earliest sealing activity in the region. Redrawn from Wilmshurst et al. (Citation2015).

Figure 23. Summary percentage pollen diagram from Ewing Island (sub-Antarctic Auckland Islands) with selected taxa plotted against depth with a calibrated age scale in years CE. Grey zone shows the time of earliest sealing activity in the region. Redrawn from Wilmshurst et al. (Citation2015).

Figure 24. Mount Roraima, a spectacular tepui in Venezuela. Photograph MM from Switzerland (Wikimedia Commons).

Figure 24. Mount Roraima, a spectacular tepui in Venezuela. Photograph MM from Switzerland (Wikimedia Commons).

Figure 25. Near the summit area of the Eruoda tepui, north-east of the Chimautá massif, Guyana Highlands where Nogué et al. (Citation2009) prepared a pollen sequence covering the last 13,000 years. Photo: Sandra Nogué-Bosch.

Figure 25. Near the summit area of the Eruoda tepui, north-east of the Chimautá massif, Guyana Highlands where Nogué et al. (Citation2009) prepared a pollen sequence covering the last 13,000 years. Photo: Sandra Nogué-Bosch.

Figure 26. Summary pollen and Sporormiella-type (Sporor.) spore stratigraphies (expressed as percentages of upland pollen sum) and charcoal concentrations at Appleman Lake, Indiana between 16,700 and 9000 years ago. The shaded part indicates when the pollen assemblage has no modern pollen analogue. The Sporormiella-type spore record is used as a proxy for megafaunal abundance. Modified from Gill et al. (Citation2009).

Figure 26. Summary pollen and Sporormiella-type (Sporor.) spore stratigraphies (expressed as percentages of upland pollen sum) and charcoal concentrations at Appleman Lake, Indiana between 16,700 and 9000 years ago. The shaded part indicates when the pollen assemblage has no modern pollen analogue. The Sporormiella-type spore record is used as a proxy for megafaunal abundance. Modified from Gill et al. (Citation2009).

Figure 27. Conceptual model of top-down drivers of Late Quaternary vegetation dynamics mediated by biotic interaction. Arrow thickness reflects the hypothesised relative importance of each link. Dashed arrows represent poorly understood or studied relationships. Modified from Gill (Citation2014).

Figure 27. Conceptual model of top-down drivers of Late Quaternary vegetation dynamics mediated by biotic interaction. Arrow thickness reflects the hypothesised relative importance of each link. Dashed arrows represent poorly understood or studied relationships. Modified from Gill (Citation2014).

Table 27. Recent contributions to the debate about the causes of Late Pleistocene and early-Holocene megafaunal extinctions.

Figure 28. Schematic summaries of the general major trends in the four types of diversity proposed by McGill et al. (Citation2015) at the meta-community scale of organisation (sensu McGill et al. Citation2015) within the protocratic, mesocratic, Homo sapiens, and oligocratic phases of the Holocene and the last 200 years ('Anthropocene' and 'Great acceleration') based on terrestrial palynological data from northern and central Europe. The vertical axis for all four diversity types runs from low (L) to high (H). The horizontal axis for the four phases and the last 200 years reflects time from oldest (left) to youngest (right). The trends are schematic trajectories of diversity change with the arrows representing the end-point in the different phases. Redrawn from Birks HJB et al. (Citation2016a).

Figure 28. Schematic summaries of the general major trends in the four types of diversity proposed by McGill et al. (Citation2015) at the meta-community scale of organisation (sensu McGill et al. Citation2015) within the protocratic, mesocratic, Homo sapiens, and oligocratic phases of the Holocene and the last 200 years ('Anthropocene' and 'Great acceleration') based on terrestrial palynological data from northern and central Europe. The vertical axis for all four diversity types runs from low (L) to high (H). The horizontal axis for the four phases and the last 200 years reflects time from oldest (left) to youngest (right). The trends are schematic trajectories of diversity change with the arrows representing the end-point in the different phases. Redrawn from Birks HJB et al. (Citation2016a).
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