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The vegetation was a unique tundra-grassland with sparse arboreal vegetation
( pine, beech, oak) in the form of gallery forests along river valleys (Soffer,
1985). Conditions improved in relative terms between 33 and 24 kyr during the
Briansk Interstadial before the onset of full glacial conditions (Soffer, 1985;
Markova et al., 2002). Tundra, forest“tundra and tundra“steppe were widely
distributed across the Russian Plain during the Briansk Interstadial with the
southern limit of the range of a number of Arctic plants being 1200 km further
south than today (and a further 600 km during OIS 2). Steppe and forest“steppe
predominated in the south, for example around the Black Sea. In the south, the
added topographical heterogeneity (e.g. in Crimea) increased the diversity of
vegetation types (Markova et al., 2002). Climatic improvement is also detected
in northern Siberia from 48“25 kyr, with open larch forest with Alnus fruticosa
and Betula nana in the Taymyr Peninsula (Andreev et al., 2002).
In contrast to the northward migration of trees during warm episodes the ef-
fect of glacials was the extinction of trees except within glacial refugia (Willis,
1996; Tzedakis et al., 2002). By around 13 kyr thermal conditions had improved
in north-western Europe and the tundra and steppe were gradually replaced by
boreal woodland and then by spruce forest and by birch“conifer woodland
(Huntley & Birks, 1983). The cold Younger Dryas Stadial (11“10 kyr) repre-
sented a further deterioration of conditions with tundra once again stretching
from southern Sweden to much of France and the British Isles (Huntley & Birks,
1983). The rapid amelioration leading to the present interglacial (the Holocene)
followed after 10 kyr bp. These changes are re¬‚ected in sites with long pollen
140 Neanderthals and Modern Humans

sequences. At Grand Pile in France the long sequence spanning the past 140 kyr
records signi¬cant changes in arboreal and herbaceous pollen that can be cor-
related with marine isotopic climate signals (Woillard & Mook, 1982).
Sites on the southern fringe of the Eurasian Plain and bordering the Mediter-
ranean lands may re¬‚ect the climatic and environmental changes of the glacial“
interglacial cycles more accurately than those within the Mediterranean or of the
Eurasian Plain. In areas with sharp ecotones vegetation responses are sensitive
and rapid because there is very little migration lag as all the response species
are present within the geographical area, forming a vegetation“climate mosaic
at any given time (Blasi et al., 1999; Peteet, 2000; Roucoux et al., 2001). At
Lago Grande di Monticchio, an Italian lacustrine sequence spanning the past
102 kyr, the mean interval for absolute changes of >20% in total pollen of
woody taxa was 142 yr with decreases being more rapid than increases (Allen
et al., 1999). French Massif Central sites such as Lac du Bouchet and the Pra-
claux Crater, because of their altitude and location relative to refuges and also
the altitudinal vegetation zonation, detect low amplitude climatic ¬‚uctuations
better than Mediterranean sites in which refugia persisted throughout glacial
episodes (Reille & Beaulieu, 1995; Reille et al. 1998). The contrast is a re-
¬‚ection of the reality of the division between the Eurasian Plain and the mid-
latitude belt that I have stressed throughout this book. The Eurasian Plain would
have experienced wider environmental swings in response to climate change
than more southerly areas, not just for reasons of latitude but also on account
of refugial persistence of species. Edge areas, not just on the fringes of the
European peninsulas and the Eurasian Plain but also on similar areas on the
edge of the Russian Plain (Markova et al., 2002) would therefore have exhibited
huge temporal and spatial ecological diversity.


The Mediterranean

Conditions in the Mediterranean would not have changed in the relatively sim-
ple manner described for temperate and boreal Europe. The vegetation of the
Mediterranean would have been controlled, as it is today, by the geography of
the landscape and the local climatic peculiarities of each area (Suc et al., 1994).
The longitudinal width of the Mediterranean and the west“east orientation of the
major mountain masses are barriers for plant movement. High ground extends
far south in peninsulas, particularly in Iberia, the Balkans and Italy, and this
permitted the intrusion of some elements of temperate vegetation well into the
Mediterranean bioclimatic zones (Rivas-Mart´nez, 1981, 1987; Zagwijn, 1992).
±
The double seasonal climatic rhythm is today highly heterogeneous depend-
ing on the variable in¬‚uence of Atlantic air, desert conditions and local relief.
Africa and Eurasia during the last glacial cycle 141

The relative in¬‚uence of wet and arid cycles will have varied during glacial“
interglacial cycles (Narcisi, 2001). In southern Europe, in particular, moisture
is a critical ecoclimatic variable with temperature playing a supporting role
(Tzedakis, 1994) and precipitation was a limiting factor to many plants during
glacials (Willis, 1996). The southward displacement of a weakened Gulf Stream
(Lynch-Stieglitz et al., 1999) to the shores of Portugal (van Andel & Tzedakis,
1996), may nevertheless have at times ameliorated glacial conditions in south-
western Iberia. At other times Heinrich events would have signi¬cantly cooled
these areas (Broecker & Hemming, 2001). Many areas of the western Mediter-
ranean would have experienced harsh conditions during glacials and stadials
(Rose et al., 1999) re¬‚ecting the spatial mosaic characteristic of the region. The
low latitudinal situation would have additionally permitted signi¬cant diurnal
warming, especially in the summer, even during cold phases. The gradual shift
from peak interglacial to early glacial from high to middle latitudes (Kukla
et al., 2002; Shackleton et al., 2002; Tzedakis et al., 2002) is a further indica-
tion of the relatively benign conditions of the Late Pleistocene Mediterranean
in comparison with the Eurasian Plain (Prokopenko et al., 2002).
Patches of Mediterranean vegetation therefore persisted even during the cold-
est and most arid phases and these patches would have varied in distribution
and size in relation to local variations of temperature and humidity (Florschutz
et al., 1971; Pons, 1984; Reille, 1984). These southern refuges maintained a
signi¬cant plant diversity that permitted periodic expansions during interstadi-
als (Carri´ n et al., 2000). The episodic contraction of the geographical range
o
of Mediterranean woodland taxa to southern intra-montane and coastal refu-
gia in response to climatic deterioration is a feature of the Pleistocene of Iberia
(Carri´ n et al., 2000). In Gibraltar the presence of olive Olea europaea, a species
o
considered to be an indicator of maximum interglacial conditions (Tzedakis,
1994; van Andel & Tzedakis, 1996), virtually throughout the sequence span-
ning the last interglacial to the present (Finlayson & Giles Pacheco, 2000)
indicates the refugial nature of southern coastal sites. Inland, climatic ¬‚uctu-
ations varied the extent of tree cover, dominated by Pinus. The coldest and
most arid periods favoured steppe vegetation but Mediterranean taxa persisted.
Woodland replaced open vegetation with climatic warming. The last inter-
glacial, with mean annual temperatures of around 2 —¦ C higher than the present,
saw the development of extensive woodland and the maximal expansion of
olive and evergreen oak across the Mediterranean (Tzedakis, 1994; Rose et al.,
1999). Forest development during interglacials, however, appears to cover only
a fraction of the entire period (Tzedakis, 1994). These patterns are similar in
other parts of Mediterranean Iberia with oscillations in vegetation cover from
woodland to open vegetation and even a breakdown of vegetation cover (Rose
et al., 1999), in the relative abundance of thermophyllous species, and in the
142 Neanderthals and Modern Humans




Figure 6.1. Present distribution of thermo-Mediterranean bioclimate (white) in
relation to other Mediterranean (grey) and Euro-Siberian (black) bioclimates. After
Rivas-Mart´nez (1981, 1987).
±



alternating development of broad-leaved and coniferous woodland (Carri´ n o
et al., 2000).
The development of Mediterranean vegetation and mixed forest during
OIS 3 has been observed in a number of Iberian Mediterranean localities
(Burjachs & Julia, 1994; Carri´ n, 1992; Carri´ n et al. 1995; Carri´ n & Munuera,
o o o
1997). In Italy the forest expands during warm phases but never to the extent
reached during an interglacial, creating a mosaic landscape of forest and grass-
land (Watts et al., 2000). The extent and location of the Iberian refugia were
probably much greater than currently described in European maps based on
limited Iberian pollen sources (van Andel & Tzedakis, 1996, 1998). The evi-
dence instead suggests that there would have existed a large refugium within the
areas currently occupied by the thermo-Mediterranean bioclimatic zones (Fig-
ure 6.1). The apparently contrasting evidence of a succession of cold and tem-
perate environments in the Iberian Peninsula between 50 and 30 kyr (Sanchez
Go˜ i et al., 2000a) is easily reconciled. The location of the marine core, off the
n
coast of Lisbon, strongly indicates that it is sampling material preferentially de-
rived from the continental central mesetas of the Iberian Peninsula, that would
characteristically have exhibited an alternation of deciduous and evergreen oak
woodland with steppic vegetation and periods with the virtual elimination of
Mediterranean vegetation, and the Atlantic Portuguese coast that even today
has a Euro-Siberian vegetation component (Rivas-Mart´nez 1981, 1987). The
±
environments characteristic of the Mediterranean glacial refugia would have
Africa and Eurasia during the last glacial cycle 143

been under-represented or not represented at all in such a core (Figure 6.1). It
is therefore not surprising either that such a sequence should resemble other
continental Mediterranean sites such as Lago Grande di Monticchio (Allen
et al., 1999; Sanchez Go˜ i et al., 2000a). To the north, north-western Iberian
n
patterns of vegetation change between 65 and 9 kyr, alternating between herba-
ceous vegetation with small tree refugia during stadials and discontinuous
woodland during interstadials (Roucoux et al., 2001). These differences over
relatively short distances emphasise the heterogeneous nature of the Iberian
Peninsula (Finlayson et al., 2000a).
There is evidence that in southern Iberia the marine fauna was more sensitive
to climate change than the terrestrial fauna. Levels associated with the end of
OIS 3 in the Gibraltar sites have produced a record of North Atlantic and Arctic
marine mammal (Atlantic grey seal Haliochoerus gryphus) and bird species
(long-tailed duck Clangula hyemalis, little auk Plautus alle, great auk Alca
impennis) that are nowadays rare or absent from these latitudes (Finlayson &
Giles Pacheco, 2000). Such incursions may re¬‚ect southern extensions of polar
water and the presence of icebergs off Portuguese waters on at least six, Heinrich
event-related, occasions between 65 and 9 kyr (Roucoux et al., 2001).
In Greece, Tzedakis (1994) recognises two orders of change in vegetation, a
pattern that is probably typical throughout the Mediterranean. There is one at the
level of open, herbaceous, to forest vegetation that re¬‚ects glacial“interglacial
cycles. The other, of lower order, re¬‚ects changes due to forest succession and
in the character of open vegetation. Importantly, this author recognises that
between glacials and interglacials there are long periods, taking up between 70
and 80% of the cycle, that are intermediate in nature. In his study of the Ioannina
249 core from Greece, Tzedakis (1994) found that these intermediate periods
were characterised by steppe“forest, forest“steppe and steppe vegetation. The
extremes were characterised by desert“steppe or forest. In Italy open and arid
environments were also characteristic of glacial phases, with less open or closed
but humid environments during interglacials (Montuire & Marcolini, 2002). A
study of the micromammal fauna of Italy revealed similar patterns of climate
and environmental change in the north and in the centre“south. Nevertheless,
conditions were always more temperate in the centre“south indicating that there
may have been areas that acted as refuges for micromammals (Montuire &
Marcolini, 2002).
In Greece, as probably over much of the Mediterranean, cold stages are not
uniform within. Instead such periods are characterised by a shifting balance of
open vegetation types, always with a relative abundance of relict tree popula-
tions within the landscape (Tzedakis, 1993; 1994). Interglacials also appear to
have been variable and composed of smaller-scale events (S´ nchez Go˜ i et al.,
a n
1999, 2000b).
144 Neanderthals and Modern Humans

The western Balkans and, in smaller measure, the Alps and the Italian moun-
tains appear to have been the major broadleaved tree refugia during the last
glaciation (Bennett et al., 1991; Zagwijn, 1992; Willis, 1996; Tzedakis et al.,
2002), contrasting with the largely sclerophyllous vegetation of the Iberian
refugium (Carri´ n et al., 2000; Figueiral & Terral, 2002). The Near East and
o
south-west Asia, though warmer than the Mediterranean peninsulas, were also
more arid and were not, therefore, as important as refuges for temperate plants
(Willis, 1996). It is interesting to note, however, that the aridity of Israel was re-
placed by wetter conditions for much of the period between 40 kyr and the LGM
around 20 kyr (Bar-Matthews et al., 1997; Gvirtzman & Wieder, 2001), and that
strong north“south climatic gradients existed, as they do today, due to the de-
creasing in¬‚uence of the Mediterranean towards the south (Goodfriend, 1999).
These crucial differences between each of the major Mediterranean peninsulas
and also the Middle East have been overlooked in past considerations of the
human occupation of Europe.
The north-west African climate was largely in¬‚uenced by the southward
migration of the dry subtropical high pressure zone during glacials that gener-
ated arid conditions (Hooghiemstra et al., 1992; Dupont, 1993). Mediterranean
woodland was signi¬cantly reduced during glacials at the expense of steppe
and semi-desert and regained its importance during interglacials (van Andel &
Tzedakis, 1996). The situation in north-east Africa is discussed in the next
section in relation to the expansion and contraction of the Sahara.


Africa

The shift towards increased cooling and aridity is detected in Africa after 2.8
Myr and the subsequent pattern of African climate was a continuum of wet
and dry conditions (deMenocal, 1995). North-east Africa became progressively
more arid with long dry periods interspersed by short pluvial episodes (Crombie
et al., 1997). After 200 kyr, African glacial stages were more arid than those of
the middle Pleistocene (Jahns et al., 1998).
The complexity of the African climate is the result of the size and heteroge-
neous nature of the continent. Nevertheless links between Northern Hemisphere
climatic conditions and those in tropical Africa are becoming apparent (Johnson
et al., 2002). During the late Pleistocene the development of arid conditions
and the southward shift of West African vegetation zones were synchronous
with the high-latitude glaciations and with correspondingly cold North Atlantic
Sea Surface Temperatures (SSTs) “ the vegetation responded swiftly to these
abrupt changes (deMenocal, 1995; Jahns et al., 1998; Gasse, 2000; Zabel et al.,
2001). During cold and arid phases much of Africa between approximately
Africa and Eurasia during the last glacial cycle 145

5—¦ N and 35—¦ N, as well as eastern and southern Africa, saw a ¬‚ux of shifting
vegetation types from Mediterranean sclerophyll woodland (in the continen-
tal extremes), through temperate semi-desert, temperate desert, tropical desert,
tropical semi-desert, tropical grassland and savanna (Adams & Faure, 1997;
Dupont et al., 2000; Salzmann et al., 2002). Corresponding altitude shifts in
vegetation occurred in the major mountain blocks (Wooller et al., 2003).
The Sahara changed dramatically during these cycles. During the last inter-
glacial, conditions were much wetter than today. There were signi¬cant pluvial
episodes, re¬‚ected by travertine deposition, in the Western Desert of Egypt
(currently one of the driest areas on Earth with a mean annual precipitation
of 1 cm) at that time (Crombie et al., 1997). Atmospheric circulation pat-
terns were signi¬cantly different from today and the Sahara Desert contracted
(Dupont et al., 2000). During the subsequent glacial cycle the desert was even
more extensive than it is today (Grove & Warren, 1968; Gaven et al., 1981;
Swezey, 2001). Superimposed on these cycles are millennial-scale late Quater-
nary cycles, re¬‚ected in lake level and aeolian sediment deposition ¬‚uctuations
(Swezey, 2001).
Tropical rainforest and mangrove vegetation correspondingly expanded and
contracted in central and west Africa (Lezine et al., 1995) and tropical mon-
tane forest responded in similar fashion through changes in elevational distri-
bution (Jahns et al., 1998). In west Africa rainforest and mangrove swamps
were widespread during OIS 5 and 1, but largely reduced in OIS 3 and 4 and
particularly in OIS 2 and 6 when open, grass-rich, vegetation dominated. The
expansion of montane forest during oxygen isotope substages 5d (115“105 kyr)
and 5b (95“85 kyr) is indicative of cool events within this interglacial (Dupont
et al., 2000) and is probably characteristic of the small-scale global climate
variability of the last glacial cycle.


Synthesis

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