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‘Roots and branches, the
ancestry of British woodlands’
Native trees and shrubs Alder Alnus glutinosa
Ash Fraxinus excelsior
Aspen Populus tremula
Beech Fagus sylvatica
Downy Birch Betula pubescens
Silver Birch Betula pendula
Blackthorn Prunus spinosa
Box Buxus sempervirens
Alder Buckthorn, Rhamnus frangula
Purging Buckthorn Rhamnus cathartica
Sea-buckthorn, Hippophae rhamnoides
Wild Cherry Prunus avium
Bird Cherry Prunus padus
Crab Apple Malus sylvestris
Dogwood Cornus sanguinea
Elder Sambucus nigra
Wych Elm Ulmus glabra
English Elm Ulmus procera
Smooth-leaf Elm Ulmus minor
Hawthorn Crataegus monogyna
Midland Hawthorn Crataegus leavigata
Hazel Corylus avellana
Holly Ilex aquifolium
Hornbeam Carpinus betulus
Juniper Juniperus communis
Large Leaved Lime Tilia platyphyllos
Small Leaved Lime Tilia cordata
Maple Acer campestre
Pedunculate Oak Quercus robur
Sessile Oak Quercus petraea
Aspen Populus tremula
Black Poplar Populus nigra
Rowan/ Mountain Ash Sorbus aucuparia
Scots Pine Pinus sylvestris
Spindle Euonymus europaeus
Strawberry Tree Arbutus unedo
Whitebeam Sorbus aria
Wild Service Tree Sorbus torminalis
Almond-leaved Willow Salix triandra
Bay Willow Salix pentandra
Goat Willow Salix caprea
White Willow Salix alba
Crack Willow Salix fragilis
Yew Taxus baccata
Suburban woodlands
Park and Street trees Abies nordmanniana Giant fir
Abies numidica Algerian fir
Acer campestre Field maple
Acer cappadocicum Caucasian maple
Acer davidii Pere David's maple
Acer hyrcanum
Acer monspessulanum
Acer negundo Box elder
Acer opalus Italian maple
Acer platanoides Norway maple
Acer pseudoplatanus Sycamore
Acer rubrum Scarlet maple
Acer saccharinum Silver maple
Acer saccharum Sugar maple
Aesculus hippocastanum Horse chestnut
Aesculus x carnea Red horse chestnut
Ailanthus altissima Tree of heaven
Alnus cordata Italian alder
Alnus glutinosa Common alder
Alnus incana Grey alder
Alnus rubra Red alder
Amelanchier canadensis Snowy mespilus
Betula ermanii Erman's birch
Betula lenta Cherry birch
Betula pendula Silver birch
Betula populifolia
Betula pubescens Downy birch
Betula utilis
Betula x aurata
Calocedrus decurrens Incense cedar
Carpinus betulus Hornbeam
Carya tomentosa
Castanea sativa Sweet chestnut
Catalpa bignonioides Indian bean tree
Catalpa ovata Yellow catalpa
Catalpa speciosa Western catalpa
Catalpa x erubescens 'Purpurea' Purple leaved catalpa
Cedrus atlantica Atlas cedar
Cedrus deodara Deodar cedar
Cedrus libani Cedar of Lebanon
Cercidiphyllum japonicum Katsura tree
Chamaecyparis lawsoniana Lawson cypress
Chamaecyparis sp
Cladrastis lutea Yellow wood
Cornus mas Cornelian cherry
Corylus avellana Hazel
Corylus colurna Turkish hazel
Cotinus obovatus American smoke tree
Crataegus arkansana
Crataegus arnoldiana
Crataegus azarolus
Crataegus canbyi
Crataegus champlainensis
Crataegus coccinioides
Crataegus crus-galli Cockspur thorn
Crataegus douglasii
Crataegus ellwangeriana
Crataegus laciniata
Crataegus laevigata Midland hawthorn, May
Crataegus macrantha
Crataegus mollis Red haw
Crataegus monogyna Common hawthorn, May
Crataegus oxycantha
Crataegus pedicellata
Crataegus persimilis 'Prunifolia'
Crataegus phaenopyrum Washington thorn
Crataegus punctata
Crataegus schraderiana
Crataegus sinaica
Crataegus sorbifolia
Crataegus submollis
Crataegus wattiana
Crataegus x dippeliana
Crataegus x lavallei
Crataegus x mordenensis 'Toba'
Cupressus glabra Smooth Arizona cypress
Eucalyptus gunnii Cider gum
Eucalyptus pauciflora subsp niphophila Snow gum
Eucommia ulmoides Gutta-percha tree
Fagus sylvatica Beech
Fraxinus americana White ash
Fraxinus angustifolia Narrow-leaved ash
Fraxinus excelsior Ash
Fraxinus latifolia Oregon ash
Fraxinus ornus Manna ash
Ginkgo biloba Maidenhair tree
Gleditsia triacanthos (inermis) Honey locust
Ilex aquifolium Holly
Ilex x altaclerensis Highclere holly
Juglans regia Walnut
Juniperus scopulorum 'Skyrocket'
Koelreuteria paniculata Golden rain tree
Laburnum anagyroides Laburnum
Larix decidua European larch
Liquidambar styraciflua Sweet gum
Liriodendron tulipifera Tulip tree
Magnolia denudata
Magnolia x soulangeana Magnolia
Malus domestica Apple
Malus floribunda Japanese crab apple
Malus hupehensis
Malus sylvestris
Malus tschonoskii
Malus x eleyi
Metasequoia glyptostroboides Dawn Redwood
Morus alba White mulberry
Morus nigra
Nothofagus obliqua Roble beech
Olea europaea
Ostrya carpinifolia European hop-hornbeam
Parrotia persica Persian ironwood
Picea omorika
Picea pungens 'Glauca'
Pinus halepensis Aleppo pine
Pinus monticola
Pinus nigra
Pinus pinea Umbrella pine, Stone pine
Pinus ponderosa Western yellow pine
Pinus pyramidalis
Pinus sylvestris Scots pine
Pinus x holfordiana
Platanus orientalis
Platanus x hispanica London plane
Populus alba White poplar
Populus balsamifera Balsam poplar
Populus nigra Black poplar
Populus tremula
Populus trichocarpa
Populus x canadensis 'Eugenei' Canadian poplar
Populus x canescens Grey poplar
Prunus avium
Prunus cerasifera 'Pissardii' Purple leaved plum
Prunus dulcis Almond
Prunus padus 'Watereri' Bird cherry
Prunus sargentii Sargent cherry
Prunus serrulata
Prunus speciosa
Prunus x hillieri 'Spire'
Prunus x yedoensis Yoshino cherry
Pseudotsuga menziesii Douglas fir
Ptelea trifoliata Hop tree
Pterocarya fraxinifolia Caucasian wing nut
Pterocarya x rehderiana
Pyrus calleryana
Quercus canariensis Algerian oak
Quercus cerris Turkey oak
Quercus ilex Holm oak
Quercus macrolepis Valonia oak
Quercus palustris Pin oak
Quercus petraea Sessile oak
Quercus robur English oak
Quercus suber Cork oak
Quercus x lucombeana Lucombe oak
Rhamnus cathartica Common buckthorn
Robinia pseudoacacia False acacia
Salix alba White willow
Salix babylonica Willow
Salix daphnoides Violet willow
Salix fragilis Crack willow
Sequoia sempervirens
Sequoiadendron giganteum Wellingtonia, Giant redwood
Sophora japonica Scholar tree, Japanese Pagoda
Sorbus aria 'Lutescens'
Sorbus aucuparia Mountain ash, rowan
Sorbus esserteauana
Sorbus hupehensis
Sorbus intermedia Swedish whitebeam
Sorbus latifolia Service tree of Fontaienbleau
Sorbus pohuashanensis
Sorbus thibetica 'John Mitchell'
Sorbus x thuringiaca
Taxodium distichum Swamp cypress
Taxus baccata Yew
Thuja orientalis
Thuja plicata Western red cedar
Tilia cordata Small leaved lime
Tilia mongolica Mongolian lime
Tilia platyphyllos Large leaved lime
Tilia tomentosa Silver lime
Tilia x europea Common lime
Ulmus carpinifolia var sarniensis Elm
Ulmus glabra 'Nana' Dwarf wych elm
X Cupressocyparis leylandii Leyland cypress
X Cupressocyparis ovensii
Zelkova carpinifolia Caucasian elm
Upper Cretaceous chalk sea
Cope, JCW. 2006. Upper Cretaceous palaeogeography of the British Isles and adjacent Areas. Proceedings of the Geologists' Association, 117, 129-143.
No identifiable plant macrofossils
Tertiary Marked changes in fossil flora in time and space
Warm conditions in the Palaeocene rising to …
…an Eocene climatic optimum
but then … …at the Eocene-Oligocene
boundary a greenhouse to icehouse transition.
The evidence – fossils from named stages
65 Myr-1
Palaeocene Britian
Boreal palaeoarea
• (includes northern Britain, Canada, Scandinavia and much of Russia)
• = Brito-Arctic Igneous or “Thulean” Palaeoprovince
Tethyan palaeoarea
• (includes southern Britain, much of USA, southern and central Europe, Kazakhstan, Central Asia and China)
A European Viewpoint Kvaček Z. 2009.
Forest flora and vegetation of the European early Tertiary
Three zonal vegetation types: 1. Broad-leaved evergreen/semi-evergreen
quasi-paratropical forest with a high diversity of woody angiosperms related to tropical families, ferns and a low diversity of conifers (mostly Doliostrobus)
2. Broad-leaved nothophyllous evergreen forest
with evergreen Fagaceae, Lauraceae, Altingiaceae, Myrtaceae and some conifers (Pinus, Doliostrobus, Cephalotaxus)
3. Polar deciduous to mixed mesophytic forest
with well diversified angiosperms predominantly deciduous and moderate representation of Ginkgo, conifers and ferns.
Doliostrobus An extinct
genus of conifer perhaps
related to Araucaria
Flowering plants are diversifying
Early Tertiary wood anatomy shows feature sets found in living species of several families -Anacardiaceae, Annonaceae, Aquifoliaceae, Apocynaceae, Burseraceae, Caesalpinaceae, Euphorbiaceae, Fagaceae, Flacourtiaceae,
Hamamelidaceae, Meliaceae, Lauraceae, Lecythidaceae, Sapotaceae and Tiliaceae. Anatomical results show increased diversity
by the latest Palaeocene, including the oldest known wood with spiral thickening of the vessels
There is a trend of increasingly warm temperatures with less seasonality with structures more typical of Recent tropical regions by Late Palaeocene/Early Eocene times in the British area.
Brito-Arctic Igneous or Thulean Palaeoprovince
An outlier of a high Arctic coniferous woodland survived for many millions of years
Deciduous conifers – redwood family (Taxodiaceae)
Broad-leafed deciduous angiosperms Hamamelidae (“plane-tree”, “walnut tree”, “beech”, “birch” families)
Ardtun Fossil Leaf Beds
Leaf adpressions in interbasaltic sediments
Leaf features Deciduous
Large broad-leaves
Drip-tip
Taxodiaceous conifer foliage - possibly deciduous
Temperate rain-forest
conditions?
Tethyan Palaeo-area Freshwater mires and woodland
The London Clay Fossil Flora is very largely one of seeds and fruits – some
twigs - preserved in the clay.
London Clay - fruits and seeds
Geographical Affinities
73% Malesian
53% Indo-Malayan
40% Australasian
39% Tropical African
20% American
Palms
Vines
Magnolia
Palms
• 8 genera of palms are represented in London Clay flora including palmetto palm type
• Nipa burtini especially common – its living relative of N. fruticans a prostrate mangrove plant
Nyssa – Tupelo and Taxodium - Bald cypress 2 species of Nyssa are recorded from
the London Clay • Other species of Nyssa
widespread and survive through the European Tertiary into the Pliocene
• 9 living species in North America and Asia.
Taxodium Swamp cypress – 3 living species SE USA to Mexico
BUT WHAT WAS IT LIKE? A MIXTURE OF ELEMENTS WITH
DIFFERENT MODERN AFFINITIES
Temperate elements
(plane, walnut, birch, katsura families) Pinus prestwichii
Subtropical elements
(palms, frankincense, tea, iacina, moonseed, grape and squash families)
Laurocarpum (Cinnnamomum?)
Vitis
Cleyera or Eurya
Symplocos
London Clay ancestors and descendents
1. About one third of fossil taxa can be placed in living genera
Magnolia, Vitis, Oncoba, Dracontomelon
but all are considered extinct species
2. Of the remainder: a) Some can be assigned to a living
family but an unknown genus though closely related to a living genus;
b) Some assigned to a living family but of unknown generic relationship.
3. Others are unknown “Incertae Sedis”
Vitis and Platanus fossils
Uncertain relationships
One species has nutlets like Carpinus or Ostrya, bracts like Corylus and leaves unlike the Betulaceae at all
A ”Platanus” has wood and fruit characteristic of Platanus but leaves unlike any living species
Corylites
Meanwhile important tree species are
evolving into their modern forms
“Modern” temperate broad-leaved deciduous vegetation was established with the diversification of taxa such as Quercus, Fagus.
Some of these may have invaded lower latitudes as high latitude broadleaved deciduous forests were eliminated Tertiary diversification of beech Fagus
Percentage climatic distribution of nearest living relatives of British
Tertiary floras
Palaeocene London clay
Other Lower Eocene
Middle Eocene
Upper Eocene
Oligocene
Number of taxa 38 143 79 60 127 53
% Tropical 70-78 92 89 82 68-78 70
% Subtropical 70-78 60 73 80 69-80 77
% Temperate 68-80 42 73 72 65-85 75
% N. temperate 21-30 12 13 23 22-48 45
Interpreting changing diversities
• Rapid onset of Antarctic glaciation near the Eocene/Oligocene (E/O) boundary (ca. 34 million years ago) – accompanied by sea-level changes
• - 70 m drop and then a brief marine incursion marks the early Oligocene in Europe.
Oligocene
• Major changes during the Oligocene included a global expansion of grasslands, and a regression of tropical broad leaf forests to the equatorial belt.
• The start of the Oligocene is marked by a major extinction event, a faunal replacement of European with Asian fauna.
Bouldnor Cliff, Isle of Wight, 34 Ma-1
Rubus
“Sabal major”
Ilex
Sequoiadendron fordii
Pinus
Quercus
Palaeocene-
Eocene
Miocene
Miocene • St Bees Nest, Derbyshire 5-6 MYa
• Pocket deposits in solution cavities in Carboniferous limestone
Cryptomeria anglica very like C. japonica (Japanese Cedar)
Sciadopitys tertaria (1 extant species S. verticillata – umbrella pine - endemic to Japan)
BUT also fir, spruce and pine
Abies alba, Picea, Pinus
Pliocene - no macro-fossils from Britain
Older Pliocene of Italy • warm temperate climate
oak,
plum,
plane,
alder,
elm,
fig,
laurel,
maple,
walnut,
birch,
buckthorn,
Carya, hickory,
sumach,
Smilax, sarsaparilla,
sassafras,
cinnamon,
Persea,
Oreodaphne/Ocotea
Cassia,
Psoralea
Pinus
Glyptostrobus
Taxodium
Sequoia
Younger Pliocene of Italy
Glyptostrobus europaeus
Glyptostrobus pensilis is now native to native to subtropical south-eastern China and northern Vietnam
From a German museum
Loss of elements Tropical first
then North American and East Asian
Eocene Oligocene Miocene Late Pliocene
Early Pleistocene
Nypa T + - - - -
Other palms T + + - - -
Symplocos T + + + + -
Styrax T & EA + + + + -
Engelhardtia NA & EA + + + - -
Nyssa NA & EA + + + + -
Magnolia NA & EA + + + + +
Phellodendron EA + + + + +
Actinidia EA + + + + +
PLIOCENE PLEISTOCENE
Links between
floras of
North America
and Eastern Asia
Vicariant genera
Wiegela and Diervilla
Tripetaleia and Elliotia
Chionographis and Chamaelirium
Vicariant genera East Asia
• Paulownia
• Deutzia
• Kadsura
North America
• Catalpa
• Philadelphus
• Schizandra
Europe
?
?
?
Acer – the maples (about 129 species)
Includes several vicariant pairs
Acer capillepes/A. rufinerve – A pennsylvanicum
A. henryii/A.cissifolium – A. negundo
A. pycnanthum – A rubrum
96 native 61
endemic species
in China
Others in Taiwan
and Japan
13 species
native to
USA
Others in
Mexico
Native Once native
A. campestre A. pseudoplatanus A. platanoides A. monspessulanum
4-5 other native European species are close relatives of A. monspessulanum
Autumn colour
N. America and East Asia
British Isles and NW Europe
The red autumnal colours are representative of a
more diverse tree flora – rich in Tertiary relicts in N.
America and E. Asia. In contrast the European tree
flora was greatly reduced and modernised Lev-Yadun, S. 2009.
Magnolias and Tulip Trees
Magnolia
80 species in East Asia – 26 in North America
1 species of Liriodendron in each
Liriodendron chinense Liriodendron tulipfera
So what happened to the European element of this Late Tertiary flora?
• Many of these Late Tertiary species have
surviving relatives in the fragments of temperate rainforest trees
Hyrcanian forest and Humid montane forests
• Buxus sempervirens
• Prunus laurocerasus
• Ruscus hyrcanus
• Ilex aquifolium
• Parrotia persica
• Pterocarya fraxinifolia
• Albizzia julibrissin
• Gleditschia caspica
• Fagus orientalis
• Carpinus betulus
• Maples (Acer insigne, A. laetum)
• Wych elm (Ulmus glabra)
• Oak (Quercus macranthera, Quercus castanaefolia)
• Crataegus
• Prunus
• Juniperus
The Europeanisation of the flora
Late Tertiary and
Early Pleistocene
loss of “exotics” and
increasing similarity
to present-day native
flora
The Pleistocene about 2 million years ago to about 10,000 years ago
• Cold (Glacials) and Warm (Interglacials) Periods • Stadials and Interstadials (coldest and warmest stages within the Glacials
Temperature changes correlate with the
oxygen isotope ratio in marine sediments
Hoxn
ian
Ipsw
ichia
n
Cromerian
Ludham borehole east of Wroxham
• A fluctuation from mixed woodland to oceanic heath repeated twice.
• both deciduous trees, and conifers
• Now native:
– Quercus, Alnus, Betula, Carpinus, Pinus
• Some elements of Mid-Tertiary forests no longer native to Europe still hanging on
– Pterocarya and Tsuga.
• Also present and now exotic:
– Picea, Carya, Eucommia, Taxodium/Glyptostrobus
Early Pleistocene of Britain
Early Pleistocene of Britain Unnamed temperate mixed coniferous/deciduous forest
lacking Pterocarya and with only a few traces of Tsuga.
Cromer Forest Beds?
Baventian a “glacial” stage more severe than the Thurnian, with the return of oceanic heaths
Icenian Crag
Antian with temperate mixed coniferous/deciduous forest including Tsuga and Pterocarya
Thurnian a “glacial” stage with an oceanic heath type of vegetation;
Ludhamian, with temperate mixed coniferous/deciduous forest including Tsuga and Pterocarya;
Red Crag s of Suffolk
Eucommia
Tertiary survivor into the Early Pleistocene
Gutta-percha tree – produced from its latex
Only 1 species now
E. ulmoides
Thurnian and Baventian - cold stages without many trees
• extensive oceanic heaths with a high level of non-arboreal pollen mainly composed of the grasses and Ericaceae, particularly Empetrum and Calluna
• cold phases, (e.g. Baventian colder ) evidence of periglacial processes, with solifluction, involutions, and ice wedge casts, perhaps signifying permafrost)
Mid-Pleistocene
onwards
Cromerian (West Runton) Stage interglacial 455-620 kyr-1
Beestonian Stage glacial 620-680 kyr-1
Pastonian Stage interglacial 680 – 800 kyr-1
Pre-Pastonian Stage glacial 800 – 1300 kyr-1
Bramertonian Stage interglacial 1300 – 1550 kyr-1
older
younger
Glacial Refugia
• In Europe the east-west alignment of the Pyrenees-Alps-Carpathians provided a barrier to recolonisation of the north – contrasting with north-south axis of tha Applachians in North America.
Pastonian to Beestonian to West Runton
Beestonian 'arctic beds' - Tsuga appears to have been eliminated by the end
Pastonian temperate flora and fauna. Oak and pine woodland appear to have been present, with Ulmus and Carpinus also represented, and both hemlocks Tsuga canadensis and T.caroliniana were present
older
younger
West Runton (the Cromer Forest Bed sensu stricto)
Only five percent of the flora is not now native to the British Isles
One species, Corema intermedia is now extinct – a kind of Broom Crowberry. (C. conradii is endemic to NE America)
Anglian Glaciation - Britain now becomes an island
• 240,000 years ago glaciers blocked the northern exit from the North Sea, causing the Rhine to break through the chalk ridge linking Britain and the continent.
• The land bridge was periodically re-established as each ice age caused sea levels to drop.
Anglian, absence of thermophilous trees, high N.A.P., together with ice wedge casts and involutions – first full glacial.
Oscillating temperature of the Pleistocene
East Anglian Stage UK Stage
Hunstanton glaciation Devensian
Ipswichian Ipswichian Gipping glaciation Wolstonian
Hoxnian Hoxnian Lowestoft glaciation Anglian
Cromerian Cromerian
Anglian Glaciation
Hoxnian and
Ipswichian Interglacials compared
Pterocarya
reappears briefly
in the Hoxnian
Interglacial (at the
site at Marks
Tey).
Pterocarya - wingnut
Important in “interglacials” throughout the Early Pleistocene
Appears briefly (and for the last time in Hoxnian)
P. fraxinifolia – now native to Caucasus and Elburz mountains of central Asia -reintroduced to western Europe from Iran 1782 by Michaux
There are 5 other species in China and Japan
Abies alba • Hoxnian native
• Not present in Ipswichian, or Holocene as a native
• Fir charcoal from Roman Silchester – perhaps from a burnt vessel
• John Gerard records seeing “Firre” in 16th century Cheshire, Staffordshire and Lancashire but does he mean pine?
Hoxnian interglacial 400,000 years BP
• Homo heidelbergensis
A geographically widespread
open phase possibly
associated by a regionally
extensive forest fire
Gortian interglacial
• The Irish equivalent of the Hoxnian but differs significantly in the later (telocratic) stage with a rise in the importance of Taxus, Abies, Rhododendron, Alnus and Picea – perhaps indicative of an extreme oceanic-temperate rainforest vegetation – with also the strong development of bogs and heaths.
Rhododendron ponticum
Picea abies – Norway spruce
Norway spruce of northern Europe expanded
at the end of the last glacial out of a single
refugium in Russia with two migration routes;
one northwestern over Finland to northern
Scandinavia, and one southwestern across
the Baltic Sea into southern Scandinavia.
Present in both the Hoxnian
and Ipswichian but didn’t
arrive by its own means in
the Holocene
Ipswichian interglacial
Regional variation:
Some places have open
grassland and scrub
Devensian Glaciation
IPSWICHIAN
110-135 ka
CHELFORD
60-65 ka
UPTON
WARREN
40-43 ka
HOLOCENE
0-10 ka
DEVENSIAN
10-110 ka
WRETTON
OR
BEETLEY?
Devensian
Climatic optimum 125,000-120,000 BP
First cooling about 110,000 BP
Then a series of colder stadials and warmer interstadials
Interstadials = Periods of warmth
within the long glacial periods
– warm enough for trees –
with thermophilous herbs and
beetles – but largely treeless
Reaching a climatic minimum from 25,000 BP
Early Devensian Stadials
• Very cold with ice wedge formation (annual mean temperature -8 C – a treeless tundra with dwarf shrubs (Salix herbacea and Betula nana) –
• Arctic Fox, Mammoth, Horse, Bison
• Glaciation in Scotland?
Chelford Interstadial
• Birch, pine and spruce woodland over large areas of central Britain like present-day Finnish boreal forest)
• July mean temp 15°C
• January -10 to -15°C
• Survival of patches of permafrost in places
• Red fox, red deer, spotted hyaena, reindeer, woolly rhinoceros, horse, elk
Upton Warren Interstadial 42,000-43,000 BP
• July mean 18 C (1-2 C higher than today)
• Beetles akin to those found on N.German plain
• Flora a mixture of southern , steppe and halophytic open grassland – includes southern species Najas flexilis (slender Naiad) and Lycopus europaeus (gipsywort)
• An absence of trees (climatic amelioration was very rapid and short-lived – too far for trees to migrate from southern Europe
• Browsing mammals, bison, reindeer woolly rhinoceros and horse may have impeded spread of woodland
Conditions in the period of maximum
glaciation • Mean annual temperature of -6 C
to -7 C
but with a very large annual temperature range
July mean 10 C to January mean -20 C
• a polar desert
• precipitation < 250mm in E. Anglia and Midlands (less than a half or one third of today), less fluvial activity – more rain in southwest
• Widespread permafrost
Pleistocene refuges
The most important
glacial refuge was in
south-eastern Europe
A flickering switch
The Late Devensian
Changing sea-levels
2,000 BP -2 m
5,000 BP -6 m
7,000 BP -8-10 m
9,500 BP -35 m
11,000 BP -40 m
13,000 BP -60 m
14,500 BP -100 m
Entry- points of our native trees
But genetically our trees are
mainly immigrants from
eastern Europe not
southwestern Europe – with
one notable exception
Spread of pine Pinus
sylvestris
The Scots pine, Pinus sylvestris, inhabits mountains in the Iberian Peninsula, usually in the altitudinal range of 1000 to 2000 m. It requires humid conditions, and it cannot withstand droughts. Several subspecies or races have been recognized in its natural distribution,
Although Scots pine survived in the Iberian Peninsula during the Pleistocene glaciations, but most likely did not contribute to the postglacial colonization of northern Europe
Frangula alnus – alder buckthorn
• Warm loving but probably formed part of a tangled wet woodland across the North Sea plain in the early Holocene
Coastal refuges?
The natterjack toad Bufo calamita is relatively thermophilic species requires open, sunny habitats and warm ephemeral ponds for reproduction. mtDNA (control region) analysis demonstrated that the entire north and central European range of this species consists of a single clade that survived somewhere in western Europe, perhaps in coastal regions where the climate was partly ameliorated.
There is also evidence for short-lived northerly refugia during the Younger Dryas cooling, including one that probably provided colonists for south-west Ireland (as one of the ‘Lusitanian’ biota) and north-west England.
Arbutus unedo –
the Killarny
strawberry tree
Oak chloroplast haplotypes
Q. robur may not be native in Scotland Main haplotypes that occur at high frequency in Q. robur and Q. petraea are also sampled from Spain and the western regions of France but Spanish samples are more diverse – Spain probably provide the refuge for oak
Yellow here are
more associated
with Q. robur and
brown with Q.
petraea
GODWIN, H. & TALLANTIRE, P. A.
(1951). Studies of the post-glacial history
of British vegetation. XII. Hockham Mere,
Norfolk. Journal of Ecology, 39, 285-307.
The Post-glacial
succession Hockham
Mere
Competition Hockham Mere vs Stowbedon
This diagram shows the difference in the abundance of each species at two sites at the same radiocarbon date – the sites are about 3km apart but on different soils: sandy soil at the edge of the
Breckland at Hockham Mere;
and on chalky glacial till at Stow Bedon.
Bennett, KD. 1986. Competitive Interactions
Among Forest Tree Populations in Norfolk,
England, During the Last 10000 years. New
Phytol. 103: 603-620.
Tilia cordata Small-leaved lime
Rose to become the
dominant tree species in
south-eastern Britain
Its dominance was originally
not recognised because as
an insect pollinated species
it produces much less pollen
than oak and so is
underrepresented in pollen
diagrams
Its distribution in Britain is
limited because it requires
long summers to set fertile
fruit
Wood pasture or wildwood
Savernake forest
Southwick wood
Climate change and amounts of rainfall and
changes in drainage
Climatic limits – Ilex aquifolium
Temporary clearings
After each clearing a secondary
succession takes – providing an
opportunity for a different outcome
Succession to heath
For example at Iping in West
Sussesx on sandy-soils a
temporary agricultural use seems
to have converted hazel woodland
to heath
The decline of lime and rise of beech
Fagus sylvatica – a late
arrival/introduction or a late expansion?
The Elm decline
An early episode of elm disease
Elm exploited by the Neolithic
people
Dead trees open up the
woodland
Clearing the woodland in the Neolithic period
A managed future?
Some key sources and useful texts
Cleal, CJ. Thomas, DJ., & Collinson, ME. 2001. Mesozoic and Tertiary Palaeobotany of Great Britain. Joint Nature Conservation Committee.
Godwin, H. 1975. History of the British Flora. C.U.P.
Rackham, O. 2001. Trees and Woodland in the British Landscape.
West, RG. 2009. Pleistocene Palaeoecology of Central Norfolk: A Study of Environments through Time. C.U.P.