‘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.