Britain's Habitats: a Guide to the Wildlife Habitats of Britain and Ireland 9780691158556, 069115855X, 9781400873197, 1400873193

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Britain's Habitats: a Guide to the Wildlife Habitats of Britain and Ireland
 9780691158556, 069115855X, 9781400873197, 1400873193

Table of contents :
Frontmatter --
CONTENTS --
Preface --
Introduction --
THE HABITATS --
Woodlands --
Scrub --
Heathlands --
Grasslands --
Mountains --
ROCKY HABITATS --
Wetlands --
Freshwaters --
Coastal Habitats --
Other Habitats --
Habitat Correspondence Tables --
Species referred to in the text --
Photographic Credits --
Map Credits --
Acknowledgements --
Index.

Citation preview

BRITAIN’S HABITATS A Guide to the Wildlife Habitats of Britain and Ireland Sophie Lake, Durwyn Liley, Robert Still & Andy Swash

WILDGuides

Published by Princeton University Press, 41 William Street, Princeton, New Jersey 08540 In the United Kingdom: Princeton University Press, 6 Oxford Street, Woodstock, Oxfordshire OX20 1TW nathist.press.princeton.edu Requests for permission to reproduce material from this work should be sent to Permissions, Princeton University Press Copyright © 2015 Sophie Lake and Durwyn Liley Copyright in the photographs remains with the individual photographers. All rights reserved.  No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission of the publishers. British Library Cataloging-in-Publication Data is available Library of Congress Control Number 2014947358 ISBN 978-0-691-15855-6 Production and design by WILDGuides Ltd., Old Basing, Hampshire UK. Printed in China 10 9 8 7 6 5 4 3 2 1

CONTENTS Preface ........................................................................................................................................................................................................................................................................................................................................... 5 Introduction .......................................................................................................................................................................................................................................................................................................................... 7 Types of habitat ...................................................................................................................................................................................................................................................................................................... 10 Factors influencing habitats .................................................................................................................................................................................................................................................................. 12 Natural change – Succession ............................................................................................................................................................................................................................................................... 18 Habitat classification ........................................................................................................................................................................................................................................................................................ 20 Conservation of habitats ............................................................................................................................................................................................................................................................................ 22

THE HABITATS ............................................................................................................................................................................................................................................................................................... 25 WOODLANDS ................................................................................................................................................................................................................................................................................................................ 26 Lowland Mixed Oak and Ash Wood .............................................................................................................................................................................................................................................. 34 Lowland Dry Oak and Birch Wood ................................................................................................................................................................................................................................................. 38 Beech Wood .................................................................................................................................................................................................................................................................................................................... 40 Yew Wood ......................................................................................................................................................................................................................................................................................................................... 42 Wet Woodland ............................................................................................................................................................................................................................................................................................................ 44 Wood Pasture ................................................................................................................................................................................................................................................................................................................ 48 Atlantic Oak Wood ................................................................................................................................................................................................................................................................................................ 52 Upland Mixed Ash Wood ............................................................................................................................................................................................................................................................................. 56 Caledonian Forest ................................................................................................................................................................................................................................................................................................... 58 Atlantic Hazel Wood ........................................................................................................................................................................................................................................................................................... 62 Upland Birch Wood .............................................................................................................................................................................................................................................................................................. 64 Coniferous Plantation ........................................................................................................................................................................................................................................................................................ 66 SCRUB ......................................................................................................................................................................................................................................................................................................................................... 68 Mixed Scrub ................................................................................................................................................................................................................................................................................................................... 72 Hedgerow ........................................................................................................................................................................................................................................................................................................................... 74 Bracken ................................................................................................................................................................................................................................................................................................................................. 78 HEATHLANDS .............................................................................................................................................................................................................................................................................................................. 80 Lowland Dry Heath .............................................................................................................................................................................................................................................................................................. 86 Maritime Heath .......................................................................................................................................................................................................................................................................................................... 90 Dune Heath ..................................................................................................................................................................................................................................................................................................................... 90 Breckland Heath ........................................................................................................................................................................................................................................................................................................ 91 Shingle Heath ................................................................................................................................................................................................................................................................................................................ 91 Limestone Heath ...................................................................................................................................................................................................................................................................................................... 91 Lowland Wet Heath .............................................................................................................................................................................................................................................................................................. 92 Upland Dry Heath .................................................................................................................................................................................................................................................................................................. 94 Upland Wet Heath .................................................................................................................................................................................................................................................................................................. 98 GRASSLANDS ............................................................................................................................................................................................................................................................................................................. 100 Lowland Calcareous Grassland ......................................................................................................................................................................................................................................................... 108 Lowland Dry Acid Grassland ............................................................................................................................................................................................................................................................... 112 Lowland Meadow and Pasture ........................................................................................................................................................................................................................................................... 114 Purple Moor-grass and Rush Pasture ........................................................................................................................................................................................................................................ 116 Coastal and Floodplain Grazing Marsh .................................................................................................................................................................................................................................. 118 Upland Calcareous Grassland ............................................................................................................................................................................................................................................................. 122 Northern Hay Meadow ................................................................................................................................................................................................................................................................................ 124 Upland Rush Pasture ....................................................................................................................................................................................................................................................................................... 126 Upland Acid Grassland ................................................................................................................................................................................................................................................................................ 128 Calaminarian Grassland ............................................................................................................................................................................................................................................................................. 130

MOUNTAINS ................................................................................................................................................................................................................................................................................................................ 132 Montane Dwarf-shrub Heath .............................................................................................................................................................................................................................................................. 136 High Montane Heath and Snow-bed ......................................................................................................................................................................................................................................... 140 Mountain Ledge .................................................................................................................................................................................................................................................................................................... 144 Montane Scrub ........................................................................................................................................................................................................................................................................................................ 146 ROCKY HABITATS .............................................................................................................................................................................................................................................................................................. 148 Rocky Slopes .............................................................................................................................................................................................................................................................................................................. 152 Scree ...................................................................................................................................................................................................................................................................................................................................... 154 Limestone Pavement ....................................................................................................................................................................................................................................................................................... 156 WETLANDS .................................................................................................................................................................................................................................................................................................................... 160 Blanket Bog ................................................................................................................................................................................................................................................................................................................. 168 Raised Bog .................................................................................................................................................................................................................................................................................................................... 172 Upland Spring and Flush ........................................................................................................................................................................................................................................................................... 174 Lowland Fen ............................................................................................................................................................................................................................................................................................................... 176 Valley Mire ................................................................................................................................................................................................................................................................................................................... 180 Reedbed ............................................................................................................................................................................................................................................................................................................................ 184 FRESHWATERS ......................................................................................................................................................................................................................................................................................................... 188 Nutrient-rich (Eutrophic) Lake ......................................................................................................................................................................................................................................................... 196 Upland Lake, Loch and Tarn ................................................................................................................................................................................................................................................................ 198 Peat-stained (Dystrophic) Waters .................................................................................................................................................................................................................................................. 200 Turlough and Fluctuating Mere ........................................................................................................................................................................................................................................................ 202 Mesotrophic Lake ................................................................................................................................................................................................................................................................................................ 204 Marl Lake ....................................................................................................................................................................................................................................................................................................................... 204 Lowland Nutrient-poor Lake ............................................................................................................................................................................................................................................................... 205 Brackish Lake ............................................................................................................................................................................................................................................................................................................ 205 Pond ...................................................................................................................................................................................................................................................................................................................................... 206 Ditch ..................................................................................................................................................................................................................................................................................................................................... 208 Canal .................................................................................................................................................................................................................................................................................................................................... 210 Fast-flowing River and Stream ........................................................................................................................................................................................................................................................... 212 Sluggish River and Stream ....................................................................................................................................................................................................................................................................... 214 Chalk River and Stream ............................................................................................................................................................................................................................................................................... 216 COASTAL HABITATS ...................................................................................................................................................................................................................................................................................... 218 Mudflat and Sandflat ....................................................................................................................................................................................................................................................................................... 224 Saltmarsh ........................................................................................................................................................................................................................................................................................................................ 226 Sand Dune .................................................................................................................................................................................................................................................................................................................... 228 Machair ............................................................................................................................................................................................................................................................................................................................. 232 Coastal Vegetated Shingle ......................................................................................................................................................................................................................................................................... 234 Saline Lagoon ........................................................................................................................................................................................................................................................................................................... 238 Rocky Shore ................................................................................................................................................................................................................................................................................................................ 240 Soft Cliff ........................................................................................................................................................................................................................................................................................................................... 242 Hard Cliff and Cliff Slope .......................................................................................................................................................................................................................................................................... 244 OTHER HABITATS .............................................................................................................................................................................................................................................................................................. 248 Arable .................................................................................................................................................................................................................................................................................................................................. 250 Brownfield ..................................................................................................................................................................................................................................................................................................................... 252 Traditional Orchard .......................................................................................................................................................................................................................................................................................... 254 Habitat Correspondence Tables ...................................................................................................................................................................................................................................................... Species referred to in the text ............................................................................................................................................................................................................................................................ Photographic Credits ...................................................................................................................................................................................................................................................................................... Map Credits .................................................................................................................................................................................................................................................................................................................... Acknowledgements .......................................................................................................................................................................................................................................................................................... Index ........................................................................................................................................................................................................................................................................................................................................

256 266 273 274 275 276

Preface There is a wide diversity of wildlife habitats in Britain and Ireland, ranging from dynamic coastal habitats to remote rocky mountains. They include ancient woodlands, flower-rich grasslands, extensive heathlands, a variety of wetlands and standing and flowing water. In fact, the habitats of Britain and Ireland can be categorised into 64 different types. The aim of this book is to enable you to recognise these different habitats when out and about in the countryside, to understand more about their ecology and conservation, and to appreciate the rich variety of plant and animals species they support. The diversity of habitats found in Britain and Ireland is a consequence of both the varied geology and climate of these islands and the actions of humans. Almost all of our habitats are ‘semi-natural’, having evolved from natural habitats through human intervention (usually in prehistoric times), and have been maintained by humans for thousands of years. A tiny handful of ravine woodlands, inaccessible mountain ledges, unstable cliffs and shifting foreshores are near-natural, although not entirely unaffected by human activities. Such habitats are important because they are places where natural processes function more or

less unhindered and where an element of wilderness still persists. However, semi-natural habitats can be just as important and support very diverse or specialist suites of species, for which they are greatly valued. These species are adapted to relatively open or disturbed conditions, and were probably present within natural clearings, wetlands and in coastal situations when woodland still covered much of Britain and Ireland, expanding into deforested areas in the Neolithic period, around 6,000 years ago. Some of these semi-natural habitats are ancient, and are cherished for their cultural and historical significance as well as their wildlife. This book provides contextual information on the pressures that habitats are experiencing and indicates what is needed to prevent and reverse ongoing degradation and ensure the species to which they are home can flourish. As each human generation becomes accustomed to a progressively impoverished natural environment, it loses sight of the biological richness that previous generations took for granted, a phenomenon that has been called ‘shifting baseline syndrome’ and which results in the gradual diminution of society’s understanding of how rich in wildlife our countryside could be. This book is intended to show how diverse and exciting our habitats can be and what makes them so worth caring about and caring for.

5

Some semi-natural habitats such as lowland meadows (top right, Kingcombe, Dorset) are pastoral in feel, a reminder of a time when our agricultural practices were more accommodating of wildlife; others, such as Upland Dry Heath and Caledonian Forest (centre right, Ryvoan Pass, Cairngorms), are wilder in aspect and less obviously influenced by humans. Machair (below, South Uist, Outer Hebrides) is a unique habitat found only on the coasts of north-west Scotland and western Ireland. Ravine woodlands (bottom, Thirlmere, Lake District), are perhaps amongst the most natural of our habitats.

6

Introduction Habitats are the places where plants and animals live. They are characterised by distinctive combinations of plant and animal communities and their physical environment. This makes it possible to identify individual types of habitat, which is useful in understanding where different species are likely to be found and what their needs are – crucial information for protecting wildlife. Habitats are also valued in their own right as the diverse products of interactions between plants and animals and their environment. For this reason, nature conservation legislation affords protection to habitat types as well as to species. It is fairly easy to separate habitats into broad categories such as woodland, heathland, grassland, wetland and freshwater and many people are familiar with these terms. Yet within each of these categories there is a wide variety of different habitat types. These habitat types have been classified under a range of different systems (see page 20) Some habitats will not fit easily into any one of the accounts given in this book – they might be transitional between different habitats, or a particular local expression of a habitat. For example, this site in Connemara supports a curious patchwork of Machair and Lowland Dry Heath.

that have been designed for a variety of purposes, and are in some cases very technical. This book provides a clear description of each of the wildlife habitats that are likely to be encountered in Britain and Ireland, enabling them to be recognised with confidence. For each habitat type, information is provided on its distribution and extent in Britain and Ireland, its ecology, origins and the way it has developed, and the conservation issues. These ‘habitat accounts’ also indicate the key features and species to look out for and the best times of year to visit. Although most habitats can be recognised quite readily, it is important to remember that they are variable, and that transitions between the different types are common. These transitions (sometimes called ‘ecotones’) may support species typical of both habitats as well as other species that are particularly adapted to the transitional conditions. Sometimes habitats occur in easily distinguishable and often extensive patches with clear boundaries, but in other instances the transition is much more gradual and there is no distinct boundary. In some environments, or under particular management regimes, a variety of different habitat types and transitions between them can be found together in a distinctive combination which can, itself, be considered as a unique habitat. For example, Soft Cliff often contains a mosaic of grassland, wetland and scrub habitats, and Wood Pasture is a combination of woodland and grassland.

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The Habitats of Britain and Ireland Woodlands 7·4% Scrub 2·3% Other 30·8%

Heathlands 7·5%

KEY Coastal 1·6% Freshwaters 1·1% Wetlands 7·1% Rocky 0·2% Mountains 7·5% Improved 34% Semi-natural Grasslands 6·5% 40·5%

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n Woodlands n Scrub n Heathlands n n Grasslands n Mountains n Rocky Habitats n Wetlands n Freshwaters n Coastal Habitats n Other Habitats

page 26 page 68 page 80 page 100 page 132 page 148 page 160 page 188 page 218 page 248

above: Frenchman’s Creek, Helford River, Cornwall. Here the boundary between the different habitats types (Mudflat and

Woodland) is clearly defined. below: In this view of the Lake District several different habitat types can be seen, including Scree (a), Rocky Slope (b), Upland Acid Grassland (c), Bracken (d), Mixed Scrub (e) and Atlantic Oak Wood (f). Individual habitat patches are straightforward to identify, but the edges are in some cases transitional, with one habitat type blending into another.

B

A

C

F E D

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TYPES OF HABITAT When trying to decide on a name for a habitat there is an impressive array of terms to choose from. Whilst some are broad and overarching (e.g. ‘freshwaters’), others are very precise (e.g. ‘Hard oligo-mesotrophic waters with benthic vegetation of Chara spp.’). The titles given to the habitat types included in this book err towards the more specific end of the spectrum as these are generally more informative. Full accounts are given for 64 main habitat types that fall within the broad habitat categories of woodlands, scrub, heathlands, grasslands, mountains, rocky habitats, wetlands, freshwaters, coastal habitats and ‘other habitats’, the latter being a catch-all for anything that did not fit comfortably elsewhere. Summary accounts are provided for a further nine rare habitats (five types of heathland and four types of freshwater lake).

10

Although most of the habitats covered in this book are recognised as UK Priority Habitats (see Habitat Classification page 20), even if their names may vary slightly, there are a few exceptions. This is either because, although not considered a priority for nature conservation, it is still a distinctive semi-natural habitat of some interest for wildlife (e.g. Upland Rush Pasture), or because it is in some way considered to be unique (e.g. Atlantic Hazel Wood). In order to provide a more logical classification from the point of view of identifying habitats in the field, some habitats have not been included within the same broad category that applies to UK Priority Habitats. For example, Calaminarian Grassland and Purple Moor-grass and Rush Pasture are within the grassland section of this book, although they are considered under ‘inland rock’ and ‘fen, marsh and swamp’ respectively as part of the UK Priority Habitat classification system. In addition, for ease of reference, most mountain habitats have been grouped together.

Woodland habitats are those dominated by trees. They include our most structurally diverse and naturalseeming habitats, although almost all are a product of the long-term interaction between people and nature.

Scrub includes habitats dominated by shrub species. Hedgerow and Bracken are included within this category, as they are in many ways ecologically similar.

Heathland includes open habitats dominated by dwarfshrubs such as heathers, Bilberry and Crowberry. Most is semi-natural, a consequence of traditional agricultural practices carried out on poor soils.

Grassland habitats are those dominated by grasses and herbs. Some meadows are enclosed as fields, other grasslands form open landscapes, particularly in the uplands and on downland. Most would eventually revert to woodland without management.

Mountain habitats are found above about 700 m and are primarily influenced by environmental conditions; they are some of our most natural habitats.

Rocky habitats are exposed vegetated rock. Although very typical of mountains, they are also found in the uplands, and even at sea level (although this category does not include maritime cliffs).

Wetlands are a very diverse group of habitats predominantly influenced by the presence of freshwater. Most are transitional, but some have reached an equilibrium due to the wet nature of our climate or ongoing management.

Freshwater habitats include rivers, lakes, streams, ponds and canals; all have open water, which can be either standing or flowing.

Coastal habitats include muddy, sandy and rocky shoreline habitats from the intertidal zone to the point inland where the maritime influence is no longer overriding.

Other habitats include those that are most strongly influenced by humans but can nevertheless still be rich in species, such as Brownfield and Arable.

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FACTORS INFLUENCING HABITATS The habitats we see today owe their origins to a complex range of interacting factors, including geology, geography, topography, climate and the influence of humans.

Geology and soils Britain and Ireland have an incredibly varied geology, which is reflected in the diversity of habitats present and is unusual in such a relatively small area. The bedrock is fundamental in shaping the landscape and habitats present, although in some places its influence is softened by superficial deposits. These are derived through weathering (over geological time scales) or are transported by the wind (as in the case of Sand Dune and Machair), or by glaciers and their melt-waters. Such glacial drift covers much of Britain and Ireland, excluding the south of England. Soil nutrient status and acidity/alkalinity are also key factors in determining the type of habitats present. In some cases,

Rock type

KEY

Igneous rocks such as granite and basalt are formed from molten magma and are usually very hard. They include both volcanic rock (formed by eruptions) and intrusive rock, which is formed deep in the earth’s crust. Patchily distributed, these rocks are slow to erode and form the hard cliffs of Lundy and Strumble Head, Snowdon, parts of the Lake District, Arthur’s Seat in Edinburgh, the highest peaks in Scotland and the tors of Dartmoor.

SEDIMENTARY ROCKS n Eocene, Oligocene, Pliocene and marine Pleistocene n Cretaceous n Jurassic n Triassic n Permian n Carboniferous n Devonian n Silurian n Ordovician n Cambrian n Late Precambrian

Sedimentary rocks dominate across most of England and much of Wales and central Ireland. They are ancient sediments laid down by rivers or on the sea bed, and include limestone, sandstone and shale. Metamorphic rocks are secondary rocks, generated from either igneous or sedimentary rocks through heat and or pressure, deep within the earth’s crust. Limestone metamorphoses into marble, and shale into schist or slate. Metamorphic rocks dominate in the Highlands of Scotland, Tyrone, Londonderry and Donegal.

12

soils can also disguise the character of the bedrock, but the two are usually closely related as soils are derived from weathered rock. The decomposition of vegetation, leaching (whereby soluble substances are carried down through the soil by rainwater and become unobtainable to plants) and climate also influence the soil. On well-drained soils that developed under woodland, leaching is not a strong factor, and the soil, known as brown earth, contains plenty of organic matter incorporated by the activities of earthworms. In colder and wetter climates, leaching is more pronounced, leading to nutrient-poor soils. Where waterlogging occurs, anaerobic gleys form and are widespread in the uplands where they support moorland habitats. Waterlogging can also lead to the formation of peat and wetland habitats. On limestone, the strongly calcareous influence of the bedrock is too pronounced to be leached out and thin, slightly alkaline, free-draining soils (known as rendzinas) support distinctive calcareous grassland habitats.

1

2

METAMORPHIC ROCKS

n Lower Palaeozoic and Proterozoic n Early Precambrian IGNEOUS ROCKS n Intrusive n Volcanic

9 3 8

7

6

5

4

1

2

3

Cul Mor, Assynt. These dramatic peaks are relics of a great sheet of Precambrian sandstone laid down on top of ancient metamorphic gneiss well over 2,000 million years old. Much of the landscape is characterised by Upland Wet Heath and Blanket Bog with mountain habitats found on the peaks.

Meall nan Tarmachan, near Ben Lawers, Perthshire. Rock formed from sands, muds and limestones deposited in an ancient sea ca. 600 million years ago was subsequently subjected to intense heat and pressure. The resulting metamorphic schists are renowned for their Upland Calcareous Grassland and mountain habitats.

Weeting Heath, Norfolk, is found in a gently rolling chalk landscape that has been overlain with wind-blown sands of glacial origins and supports stripes and patchworks of Lowland Dry Acid Grassland and Lowland Calcareous Grassland.

4

5

6

Woolbeding Common, West Sussex, overlies Greensand, a type of greenish sandstone laid down in the Cretaceous period. The area supports Lowland Dry Heath, Lowland Wet Heath and Wood Pasture, and secondary woodland including Lowland Dry Oak and Birch Wood.

Stonehill Down, Purbeck. This quarry was used to excavate chalk, a soft limestone formed in the Cretaceous (less than 100 million years ago) when this area was bathed in a warm, shallow sea. It supports Lowland Calcareous Grassland with Ash-dominated Lowland Mixed Oak and Ash Wood on the northern flank.

Igneous granite outcrops such as Haytor on Dartmoor, Devon are distinctive landmarks formed of hard rocks created around 300 million years ago. They are surrounded by heathland and grassland habitats with Blanket Bog.

7

8

9

Exmoor, Somerset/Devon. The relief is gentle compared to that of the Breacon Beacons (similarly formed of Old Red Sandstone) as the glaciers did not reach this far south in the Pleistocene. Exmoor is characterised by Upland Dry Heath, Upland Wet Heath, Blanket Bog and Atlantic Oak Wood.

The Burren, Co. Clare, has extensive exposures of Carboniferous Limestone, which formed as sediments in a tropical sea from approximately 350 million years ago and support Limestone Pavement, calcareous grasslands and a form of Atlantic Hazel Wood.

The Lake District hills are geologically varied and are composed of differently aged rocks, including volcanic rocks; sedimentary sandstones, siltstones, mudstones and limestone; and granite. They support a variety of upland habitats.

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Climate, topography and geography

Britain and Ireland have an oceanic climate with relatively small differences between the summer and winter temperatures. The moderating influence of the Atlantic Ocean means that the climate is much milder than that of other places at comparable latitudes (i.e. those receiving a similar amount of solar radiation, such as Mongolia), and this shapes the habitats present. However, the climate varies across Britain and Ireland and this is reflected in the types of habitat that can be found in different areas. Oceanic western woodlands receive five times as much rainfall as their south-eastern counterparts, and are characterised by the abundance and diversity of moisture-loving mosses and liverworts (bryophytes). The wind-whipped Hebrides support unique coastal grassland heavily influenced by blown sand. Vast areas of the cool, wet north are blanketed in peatland habitats, while the continental climate of Breckland in East Anglia supports steppe-like grasslands and parched limestone grassland in the south can support Mediterranean plants.

This map shows upland areas of Britain and Ireland defined by climate, soils and altitude. Habitats change in character at about 300 m above sea level, although in more exposed situations the transition can be much lower. Temperature falls around 0·6°C for every 100 m increase in altitude, so only cold-tolerant species are found at higher altitudes. Topography can also accentuate climatic conditions and increase the variety of species and habitats found at different extremes. Corries on the glaciated north and east-facing slopes of mountains support rare montane habitats requiring moist, cool, sheltered conditions; in contrast, warm south-facing well-drained slopes in the south can support Mediterranean species near the limit of their range.

KEY

  Peak over 900 m n Uplands

Humans

Humans have had a profound impact on the habitats of Britain and Ireland since adopting a settled agricultural existence in the Neolithic period, when the process of woodland clearance became widespread (see timeline on page 16). Seven thousand years later the area of woodland had been reduced by more than 95%. During the intervening millennia, open semi-natural habitats came to dominate the landscape as a consequence of agricultural and associated practices. The relative amounts of semi-natural habitat fluctuated through the ages, but it was when these practices began to change radically in the second half of the 20th century that a staggering proportion of habitats was lost to agricultural intensification, afforestation and development. Habitat destruction has now slowed significantly (but not ceased), and deliberate re-creation and restoration is taking place. However, habitats are continuing to deteriorate due, for example, to climate change, pollution, inappropriate management and the affects of habitat fragmentation.

left: Rainfall averages 3,200 mm per year in the higher areas of the Lake District and feeds innumerable small streams. right: In Breckland, an average of 600 mm of rain falls per year and the drought-prone sandy soils support a sparse grassy sward.

14

Climate varies across Britain and Ireland according to latitude, the influence of the Atlantic Ocean and the prevailing south-westerly winds. Western areas are milder, wetter and windier, and show smaller differences in daily and seasonal temperatures. Eastern areas are drier with more extreme temperatures. The south of England can be influenced by the warm air mass from the continent, while northern Scotland is exposed to the polar air mass resulting in a 10–15 °C difference in temperature.

KEY

Mean January minimum temperature (°C) 1981–2011 7 5 4 3 2 1 0 –1 –2 –3 –4

KEY

Mean August maximum temperature (°C) 1981–2011 25 23 21 19 17 15 13 11 9

KEY

Mean Annuall Rainfall (mm) 1981–2011 4,140 3,740 3,380 3,020 2,660 2,300 1,940 1,580 1,220 860 500

Climate change The climate of Britain and Ireland has changed dramatically in the past and is changing rapidly now. Current predictions suggest that summer temperatures will rise and summer rainfall decrease (particularly in the south), winter rainfall will increase and there will be an increase in sea-level rise and extreme weather events. Habitats have adapted to climate change in the past, but the unprecedented rate and scale of change and the degree of fragmentation of many habitats makes climate change one of the biggest challenges for conservation today. Habitats are likely to alter as climatic conditions become unsuitable for some existing species, and climate change may exacerbate the impacts of other factors such as atmospheric pollution or pathogens. However, new species for which conditions become suitable will arrive. Coastal habitats in particular will be impacted by rising sea levels. Action is needed to increase the resilience of habitats by reducing other pressures, by improving habitat management and by ensuring there is space for habitats and species to change in their distribution.

15

YEAR 108000

BC

Start of Devensian/Midlandian Glacial period (ice covers much of Ireland and Britain, north of a line from South Wales to The Wash)

24800

Modern people arrive in Britain and Ireland (a peninsula of Eurasia)

10000 9500

Ireland separated from Britain. Woolly Mammoth and Woolly Rhinocerous extinct Climate warms at end of Devensian/Midlandian Glacial period; tundra-type vegetation; significant movement of people into Britain

8000

Movement of people into Ireland

7000

Scots Pine arrives in north-west Scotland

6000

Britain separated from European mainland

5000

Warmer, more oceanic climate; rain-fed bogs start to form

4000

Woodland reaches fullest extend

3000

Woodland clearance starts by Neolithic peoples using stone axes and ring-barking. First evidence of coppicing; Stonehenge and Newgrange built

1500

First field systems in permanent clearings

1000 500

Auroch extinct in Britain and Ireland Copper mined; use of metal tools expands woodland clearings, heathlands become established

1000 AD 2000

16

EVENT

YEAR 43 500

AD

EVENT Start of Roman Britain, roads, drainage (e.g. Fens) British human population 1·5 million

main picture: Lazy beds

between Clare Island harbour and Portnakilly, Ireland. Lazy beds are a ridge and furrow farming system that can still be seen in parts of western Scotland and Ireland. In these areas seaweed is often applied as a fertilizer and the beds are used to grow potatoes. The field systems in much of Britain would have resembled lazy beds during the post-Roman period in the 5th and 6th centuries.

1086

Normans: 15% of England wooded; medieval open-field farming; Rabbit introduced

1349

Black Death, widespread abandonment of agricultural land

1564

First canal (Exeter)

1614 1621

British human population 4 million Wolf extinct

1637

Start of major drainage works in Fens

1707 1760 1761 1792

Jethro Tull invents seed drill; agricultural revolution about to start Industrial revolution, increase in use of fossil fuels, atmospheric pollution Enclosure Acts: loss of open field systems in Ireland and England ‘Year of the Sheep’: Highland Clearances in Scotland

1845 1850 1919 1950 1958

Irish Potato Famine; Irish population falls by 50% Beaver extinct Woodland cover