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.

Contents1. 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

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

Age in millions of years

Geological formation

Sub-formations Where found

Pleistocene Period 0-2 Clay with

Flints Lies on the chalk in places

Upper Cretaceous Period

65-100 ChalkThe rock formation that forms the North Downs, as at Newlands Corner

Lower Cretaceous Period

100-150

Upper Greensand

Gault ClayA thin band of clay, marked by a line of streams and ponds just to the south of the North Downs

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 Countryside

Age of oil and consumption

Especially since 1945

Chemical agriculture. People more physically and psychologically disconnected from nature

Major reduction in wild flowers and insects. Movement of animals and plants through climate change

Fight to save the countryside

From Late Victorian times

National Trust founded (1895). Green Belt Act (1938)

Nature Reserves (from 1949). Surrey Hills Area of Outstanding National Beauty (1958)

Industrial Revolution

Use of fossil fuel grows. The railways in Godalming (1849)

Growth of suburbia. Country houses built for London businessmen

Surrey seen as a rural idyll within easy reach of London

Agricultural Revolution From 1700 AD

Agricultural improvements (crop rotation, liming, manuring). Some enclosure of fields

Farming of the difficult Greensand and Weald Clay soils made easier

Surrey the workshop of England

1560-1640 ADIron and glass industries powered by wood fuel and watermills

Still little agriculture in the Weald

Anglo-Saxon and Medieval Periods

By 600 AD Anglo-Saxons had colonised the land

Settlements along the line of the Tillingbourne and at Bramley

Summer camps in the Weald used for grazing livestock and cutting timber

Romans 43-410 AD

Iron Age 500 BC-43 AD Hill forts, as at Hascombe Iron tools facilitated farming and forestry

Bronze Age 2000-500 BC Burial mounds (barrows)Heathland replaces forest on poor sandy soils

Neolithic Period 3500-2000 BC

Introduction of agriculture and livestock. Building of Stonehenge

Reduction of the wildwood, first on the chalk

Mesolithic Period 8500-3500 BC Hunter-gatherers,

fisherfolk

Arrival of trees and other warmth-loving plants. English channel formed about 6500 BC

Palaeolithic Period Before 8000 BC Seasonal hunter present

from at least 12,500 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, life-cycles, 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.

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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) SYMPETALAE (joined petals) APETALAE (petals often absent)Ovary superior Ovary inferior Ovary superior Ovary inferior

Actinomorphic flowers (radially symmetrical)

Some parts ∞

NymphaeaceaeWater lilyRanunculaceae Buttercup (stamens ∞)

Rosaceae Rose (carpels ∞) (ovary actually semi-inferior)

Mostly woody plants with unisexual flowers, wind-pollinated Oak

Euphorbiaceae Spurge

(Centrospermae) CaryophyllaceaeStitchwort

Few parts

Brassicaceae Cabbage (4 petals)Geraniacae Geranium (5 petals)

Apiaceae CarrotOnagraceaeWillow herb

Ericaceae HeatherBoraginaceae Forget-me-not

Caprifoliaceae ViburnumAsteraceae Daisy

Zygomorphic flowers (bilaterally symmetrical)

Fabaceae peaRanunculaceae Delphinium

Onagraceae Rosebay willowherb

Ericaceae RhododendronLamiaceae Mint

CaprifoliaceaeHoneysuckle

MONOCOTYLEDONS (1 first leaf, flower parts often in 3s, leaves with parallel venation)WITH CONSPICUOUS FLOWERS FLOWERS INCONSPICUOUS

Actinomorphic flowers (radially symmetrical)

Arecaceae Palm

Liliaceae Snowdrop (6 stamens)Iridaceae Iris (3 stamens)

Liliaceae Bluebell (petals joined near base) Inconspicuous flowers

Juncaceae Rush, Cyperaceae SedgePoaceae GrassZygomorphic

flowers (bilaterally symmetrical)

Zingiberaceae GingerOrchidaceae Orchid