Download Godalming nature: an introduction

Godalming nature: influences on local
habitats and some notes on plants
Greening Godalming is a local community group campaigning
to make Godalming a greener town by helping people reduce
their carbon footprints.
Contents
1. Influences on local habitats
1.1. Geology and soils
1.2. Ice-ages and the postglacial
1.3. Human influences over time
2. Notes on plants
2.1. Types and classification of plants
2.2. Plant identification
2.3. Evolution of plants
2.4. Uses of plants
1. Influences on local habitats
1.1. Geology and soils
Rocks are the substrate on which soils develop. Different types of plants prefer different soil
conditions, with major contrasts between those that like limestone or more acidic soils, and
those that prefer wetter or drier conditions.
Godalming has an exceptional range of rocks and soils close at hand (Table 1). The
underlying rocks are between 65 to 150 million years old, dating to the Cretaceous Period of
the Mesozoic Era (when dinosaurs ruled the world). The rocks become older from north to
south, the main types being Chalk (65-100 million years old), Greensand (113-125 millions
years) and Weald Clay (125-136 million years). These are remarkably different rock types –
fairly pure limestone, sandstone and clay respectively, greatly influencing the types of
habitats and plants.
1.2. Ice ages and the postglacial
We are now living in the Quaternary Period (2.5 million years ago to the present),
characterised globally by a series of about 11 major glacial events and many minor ones. The
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last ice age was at its maximum 18,000 years ago, when an ice cap developed over north-west
Europe extending south to the latitude of Liverpool. Surrey has never been glaciated, though
regularly subject to a tundra-like climate causing soil instability through freeze-and-thaw,
which helped to carve out the dry valleys that are features of the chalk and greensand.
The ice age vegetation of Godalming was treeless and composed only of cold-tolerant grasses,
herbs and dwarf shrubs. Tundra covered all of western Europe north of the Alps. The climate
ameliorated at 8000 BC and warmth-loving plants were able to migrate up from ice-age
refugia in the Lusitanian, Italian and Balkan peninsulas. Almost the entire Godalming area
was soon covered by forest, changing in composition as different species arrived from the
south. First birch appeared, then hazel followed by pine, next oak and elm, and finally alder
and lime. Scots pine, such a conspicuous species on heathland today, died out with the arrival
of the broad-leaved trees, its occurrence around Godalming today being due to re-introduction
by people.
Geological
age
Pleistocene
Period
Upper
Cretaceous
Period
Age in
millions
of years
Geological Subformation formations
Where found
0-2
Clay with
Flints
Lies on the chalk in places
Chalk
The rock formation that forms the
North Downs, as at Newlands
Corner
65-100
Upper
Greensand
A thin band of clay, marked by a
line of streams and ponds just to
the south of the North Downs
Gault Clay
Lower
Cretaceous
Period
100-150
Lower
Greensand
Folkstone
and Sandgate
Sands,
Bargate
Stone
Extensively exposed south of the
North Downs, including at
Godalming and Hydon’s Ball and
at Thursley Common
Weald Clay
Mostly south of the above, as at
Chiddingfold
Table 1. Geological formations in the Godalming area.
1.3. Human influences over time
There were ice-age hunters in Britain during the last ice age, hunting mammoth and other
beasts. Mesolithic people came with the appearance of the forest at 8000 BC, pursuing a
hunting, fishing and gathering way of life. Neolithic farmers appeared at 3500 BC,
introducing cattle and other livestock and clearing the forest to grow wheat and barley. These
were still stone-age people, bronze coming with the Bronze Age from 2000 BC and iron with
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the invasion of the Celts (500 BC). The pace of technological development and cultural
change continued to quicken, stimulating growth in the population, itself causing ever greater
impacts on the land.
Period
Date
Economy and culture
Age of oil
Especially since
and
1945
consumption
Chemical agriculture.
People more physically
and psychologically
disconnected from nature
Fight to save
From Late
the
Victorian times
countryside
National Trust founded
(1895). Green Belt Act
(1938)
Industrial
Revolution
Agricultural
Revolution
Surrey the
workshop of
England
AngloSaxon and
Medieval
Periods
Romans
Use of fossil fuel
grows. The
railways in
Godalming (1849)
From 1700 AD
1560-1640 AD
By 600 AD
Anglo-Saxons had
colonised the land
Growth of suburbia.
Country houses built for
London businessmen
Agricultural improvements
(crop rotation, liming,
manuring). Some
enclosure of fields
Iron and glass industries
powered by wood fuel and
watermills
Settlements along the line
of the Tillingbourne and at
Bramley
Countryside
Major reduction in wild
flowers and insects.
Movement of animals
and plants through
climate change
Nature Reserves (from
1949). Surrey Hills
Area of Outstanding
National Beauty (1958)
Surrey seen as a rural
idyll within easy reach
of London
Farming of the difficult
Greensand and Weald
Clay soils made easier
Still little agriculture in
the Weald
Summer camps in the
Weald used for grazing
livestock and cutting
timber
43-410 AD
Iron Age
500 BC-43 AD
Hill forts, as at Hascombe
Bronze Age
2000-500 BC
Burial mounds (barrows)
Neolithic
Period
3500-2000 BC
Introduction of agriculture
and livestock. Building of
Stonehenge
Mesolithic
Period
8500-3500 BC
Hunter-gatherers,
fisherfolk
Palaeolithic
Period
Before 8000 BC
Seasonal hunter present
from at least 12,500 BC
Iron tools facilitated
farming and forestry
Heathland replaces
forest on poor sandy
soils
Reduction of the
wildwood, first on the
chalk
Arrival of trees and
other warmth-loving
plants. English channel
formed about 6500 BC
Open tundra without
trees. England
connected to France
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Table 2. History of human influence on the Godalming countryside.
People have exterminated many of the large animals once found in the Godalming area,
including bear, wolf, lynx, auroch (wild cattle), wild boar and beaver. The effect of this on the
habitats must have been profound. Today, foresters must protect young trees from destruction
by deer, their numbers no longer controlled by natural predators.
Godalming lies on the edge of the Weald, the area contained within the arc of the North and
South Downs in southeast England. Many Wealden soils are sandy or clayey and were
difficult for agriculture before the arrival of improved farming techniques from 1700 AD.
Consequently, the Weald remained heavily wooded until recently, with towns lying on its
northern periphery, like Godalming, exploiting the woodlands and rough grazing to the south.
During the First Industrial Revolution (1560-1640 AD), the Weald was the workshop of
England, smelting local ore using charcoal made from local trees.
The arrival of the railway in Godalming (1849) introduced commuting to Godalming. As
suburbia developed and rich Londoners acquired country houses, so a new view of the
countryside emerged, seen now less as a productive landscape and more as a place to find
peace of mind away from the stresses of urban life. The National Trust was founded (1895),
followed by various measures to protect the landscape and wildlife, such as the establishment
of Nature Reserves (from 1949) and the Surrey Hills Area of Outstanding National Beauty
(1958).
The expansion of chemical agriculture, especially after 1945, has caused large-scale change to
the countryside, contributing to major reductions in wild flowers and insects, now causing
great alarm. Today, more species-rich bits of nature are mostly confined to pockets separated
by tracts of biologically rather sterile land. Invasive species of plants, animals and pathogens
(causing disease) are now arriving at an increasing rate from elsewhere, with major long-term
consequences.
2. Botany
2.1. Types and classification of plants
From an everyday viewpoint, people classify plants into major categories according to their
overall appearance and use. Some of the major types generally recognised are trees, shrubs,
climbers, grasses, ferns, mosses and seaweeds. The amount of knowledge that people have of
plants is strongly related to the importance of plants to them in their daily lines. Few people
can recognise different types of moss, but it fairly normal to know the names of the
commoner trees, such as oak, beech and hazel.
Some of the names applies to plants are ambiguous. Thus, the word ‘herb’ can mean both a
herbaceous plant (contrasting with trees and shrubs) and a medicinal plant. Generally
speaking, our ancestors knew a lot more about plants than we do today, because they
depended on them so immediately for survival. They tended to eat more types of plants than
we do and used many more for medicinal purposes. ‘Wort’ as part of a plant’s name signifies
‘medicinal plant’, the first part of the plant’s name sometimes signalling the disease or
condition for which the plant was used, thus lungwort, birthwort, milkwort, toothwort, etc.
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The scientific way of classifying plants originated in the 18th century, a time when a critical
need arose to catalogue a flood of unknown plants coming into Europe in the Age of
Exploration. The central figure in creating order in plant taxonomy was Carl Von Linné
(Linnaeus) (1707-1778), a Swede who formalised the binomial system for naming plants and
organising species into groups. Under the binomial system, plant species are provided with
two names, a genus and specific epithet. The scientific name of the meadow buttercup is thus
correctly Ranunculus acris L. The L. seen here is not normally added to the name except in
formal scientific publications. It is the name of the person who first described the plant
scientifically, in this case Linnaeus himself (L. is an abbreviation for his name).
Historically, there have been different ways in which scientists have grouped species of plants
(such as the meadow buttercup) into higher groups. Linnaeus classified species into a higher
category (the ‘class’) based largely on the number of stamens (anthers). This was useful in
organising plants into some sort of order, but was highly artificial, since it brought together all
sorts of unrelated species into the same category and separated others which common sense
suggested were basically alike. It was rather like organising goods in a supermarket according
to the first letters of their names (e.g. cabbages with cheese, tomatoes with toilet paper). More
natural systems of classification followed, based on the use of a bundle of characters
considered together, but giving more weight to those thought to be more significant.
The main categories in the hierarchical system of classification used by botanists for plants
are: Plant Kingdom (all plants), Division (e.g. all flowering plants), Class, Family (e.g. the
buttercup family), Genus (e.g. Ranunculus, which includes all types of buttercups) and
species (Ranunculus acris – the meadow buttercup).
At the macro-scale, the main categories of plants are as follows:






Algae (several types, some only distantly related to one another)
Fungi (actually more closely related to animals than plants from an evolutionary
perspective, but generally studied together more with plants than animals)
Bryophytes (mosses and liverworts)
Pteridophytes (ferns and fern allies)
Gymnosperms (pines, cycads, Ginkgo, etc)
Angiosperms (flowering plants)
Most of the plants that we see around us day by day are Angiosperms (flowering plants).
There are two groups of flowering plants, known as Dicotyledons and Monocotyledons, so
named because Dicotyledons have two cotyledons (first leaves) and Monocotyledons one. It
is easy to assign many plants to one or other of these groups by looking at the ways that the
veins are arranged in the leaves and by the number of parts (e.g. petals) in the flowers.
Dicotyledons typically have veins with reticulate (net-like) venation and flowers typically
with parts in 4s or 5s and Monocotyledons typically have leaves with parallel venation (like
grasses) and parts of the flowers typically in 3s. Within both the Dicotyledons and
Monocotyledons there are some species which lack (or have inconspicuous) petals. These are
typically wind-pollinated plants and include some of our commonest trees (such as oak, beech
and hazel) and a number of grass-like Monotyledons (such as grasses, sedges and rushes).
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Other important characters used in classifying the flowering plants include: whether the ovary
is superior or inferior (or in an intermediate position), whether the flowers are radially or
bilaterally symmetrical (actinomorphic versus zygomorphic flowers) and whether the petals
are free or united (Polypetalae and Sympetalae). Table 3 gives a graphic picture of how these
various characters interrelate and some examples of plant families and species.
2.2. Plant identification
The best way to identify plants is in the field, using a book describing the different types of
plants (known as a Flora) and armed with a pocket lens to see finer details (10x
magnification). Plants should not be picked for more detailed examination unless they are
obviously very common. Plants should not be uprooted. For plants that are difficult to
identify, it is recommended taking a photo using a macro-lens for subsequent perusal.
There are many Floras available. The following are recommended:


Fitter, R. Fitter, A, and Blamey, M. Wild flowers of Britain and Northern Europe. Collins.
ISBN 0002112787. This is a pocket guide.
Streeter, D. Hart-Davies, C., Hardcastle, A. Cole, F. and Harper, L. (2010). Collins
Flower Guide. Collins. ISBN 0007183895. This is a ‘proper’ flora, showing how even
very similar looking species can be distinguished from one another.
Floras have many ways of organising plants, e.g. by flower colour, habitat and so on. If you
wish to progress further in scientific knowledge of plants, then you are strongly advised to
become familiar with the main plant families. The above two books organise the plants
according to their families (rather than, for example, according to flower colour).
More detailed floras, like Streeter above, use keys to identify the plants. Keys are ways to
identify plants requiring users to answer a series of logical questions and choosing between
alternatives. For example, one question in a key might ask whether the plant has 5 or 4 petals.
If the answer is 5, then either a particular species will be named, or you go onto the next key,
which might ask (for instance) whether the plant has hairs or is hair-free (glabrous), and so
on.
2.3. Evolution of plants
The evidence for how plants have evolved comes from studies of plant morphology, lifecycles, chemistry, fossils and genetic make-up. The whole subject has been revolutionised
during the last 20 years through DNA research. DNA (the genetic material that defines how
animals and plants are constituted) evolves over time. DNA is a very long molecule. Those
parts subject to very rapid change are the bits of the DNAin which forensic scientists are
interested, because they can allow identification of traces of DNA left at crime scenes to be
identified to individual people with high degrees of confidence. Rapidly evolving DNA is
used in ancestry studies. Studying longer-term relationships between organisms requires
looking at bits of DNA that only change slowly. This is how the evolutionary relationships
between very different looking types of plants and animals have been established.
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DNA evidence shows that flowering plants (Angiosperms) had separated from conifers and
allies (Gymnosperms) before the end of the Devonian geological period (360 million years
ago) and that all flowering plants evolved from a single ancestral species living roughly 150
million years ago. The earliest fossil which unambiguously belongs to a flowering plant is
dated to 130 million years. The appearance of many of the main groups of flowering plants, as
seen today, happened in a burst of evolution that occurred 110 to 125 million years ago. This
is fascinating from a local perspective because this is time period when some of our local
rocks were deposited (Greensand and Weald Clay 113-136 million years ago).
DNA analysis has shown that the big group of plants known as the Monocotyledons (includes
grasses, palms, lilies, etc) is a natural group of plants, is descended from a common ancestor,
but that the Dicotyledons (oak trees, buttercups, dandelions, etc) are not. The burst of
Angiosperm evolution around 120 million years ago is believed to be related to co-evolution
with insects, which also diversified greatly at this time.
2.4. Uses of plants
Plants form the base of life on Earth because of their ability to take inorganic elements
(carbon dioxide from the air, water and minerals from the soil) and create living tissue.
Animals, including ourselves, depend on plants for food, either eating it directly (herbivores)
or indirectly (carnivores). From an evolutionary point of view, the human is an omnivore
(both herbivore and carnivore), with the bulk of its diet usually coming from plants.
Both wild and domesticated plants are used by people – though actually these are intergraded
categories. While popularly we speak of wild and cultivated (or domesticated) plants, in fact
there are virtually no places in the British Isles that have totally escaped the human hand and
few plants that have not been influenced in some way in their genetic make-up by people.
Some of the main categories of use of plants are for food, medicine, fodder, construction
(including house-building and furniture), crafts, fibres, dyes and fuels. Some plants required
for use in large quantities (such as for food) must be domesticated and cultivated to meet the
high levels of present-day demand.
Plants have traditionally been the main ingredients in medicines. The use of plants in
medicines represents by far the largest use of the living world in terms of numbers of species,
with 50,000-70,000 species overall being exploited (about one fifth of all plant species).
Western medicine uses very few (around 100). However, about 40% of pharmaceutical
prescriptions contain ingredients that are either extracted directly from plants or were inspired
in their discovery and development by the chemical properties of plants.
Table 3. CLASSIFICATION OF THE ANGIOSPERMS (FLOWERING PLANTS)
DICOTYLEDONS (2 first leaves, flower parts often in 4s or 5s, leaves with reticulate venation)
POLYPETALAE (with free petals)
Ovary superior
Actinomorphic
flowers
(radially
symmetrical)
Zygomorphic
flowers
(bilaterally
symmetrical)
Actinomorphic
flowers
(radially
symmetrical)
Zygomorphic
flowers
(bilaterally
symmetrical)
Some
parts ∞
Few
parts
Nymphaeaceae
Water lily
Ranunculaceae
Buttercup
(stamens ∞)
Brassicaceae
Cabbage (4 petals)
Geraniacae
Geranium (5
petals)
Fabaceae pea
Ranunculaceae
Delphinium
Ovary inferior
SYMPETALAE (joined petals)
Ovary superior
Ovary inferior
Rosaceae Rose
(carpels ∞) (ovary
actually semiinferior)
APETALAE (petals often absent)
Mostly woody plants with
unisexual flowers, wind-pollinated
Oak
Apiaceae Carrot
Onagraceae
Willow herb
Ericaceae
Heather
Boraginaceae
Forget-me-not
Caprifoliaceae
Viburnum
Asteraceae
Daisy
Onagraceae
Rosebay willowherb
Ericaceae
Caprifoliaceae
Rhododendron
Honeysuckle
Lamiaceae Mint
Euphorbiaceae Spurge
(Centrospermae) Caryophyllaceae
Stitchwort
MONOCOTYLEDONS (1 first leaf, flower parts often in 3s, leaves with parallel venation)
WITH CONSPICUOUS FLOWERS
FLOWERS INCONSPICUOUS
Liliaceae Snowdrop
Liliaceae
(6 stamens)
Arecaceae Palm
Bluebell (petals
Iridaceae Iris (3
joined near base)
Inconspicuous flowers
stamens)
Juncaceae Rush, Cyperaceae Sedge
Zingiberaceae
Poaceae Grass
Ginger
Orchidaceae
Orchid