British Landscapes and biodiversity – in a nutshell – some thoughts | Patricia Wiltshire

The word ‘ecosystem’ has crept into many areas of endeavour and is usually used very inappropriately.

An ecosystem consists of the biological community (all plants, animals, fungi, bacteria, and other microbes) living and interacting in a physical place which is termed the habitat. The habitat is the physical and chemical surroundings in which the community lives and operates.

Thus, Community + Habitat = Ecosystem

Virtually every major ecosystem of which you are aware in Britain has been created by man’s activities, and the only truly natural and native ecosystems that have developed and existed since the end of the last glacial period less than 12,000 years ago are:

(a) the woodlands of the New Forest (some of it anyway), the Caledonian Pine Forest, and the upland oak woodlands in Wales,

(b) the vegetation above the tree line on mountains.

(c) coastal and estuarine systems.

All organisms that managed to recolonise and establish in these islands, before the English Channel was formed about 7,500 year ago, may be considered to be truly native. Some, such as the sycamore (introduced in 1500s) and the rabbit (introduced by the Normans after 1066) were brought in later and have become naturalised and, indeed, have become significant role-players in our landscapes and ecology. The rabbit became increasingly important in maintaining some of our diverse grasslands and lowland heaths, especially with the general decline in the massive and extensive sheep rearing of the Middle Ages. The viral disease myxomatosis, and excessive culling of rabbits, has been accompanied by the deterioration of some of our most ancient and beautiful habitats.

Nearly all our woodlands have been felled at least twice, and nearly all ponds and lakes (including the Norfolk Broads) were made by man for his own use, especially as stew ponds, mill ponds, and through gravel extraction. The only natural ones are those where glaciers gouged out lake basins or other glacial activity was involved.

The nature of all habitats depends on gross climate, microclimate, and soil, (thus geological) status. The natural climax vegetation of most of the UK is woodland, and trees are forever trying to invade open spaces. The species composition of those climax woodland ecosystems depends on the soil depth, acidity/alkalinity, wetness, and nutrient status.

Dominant trees: Wherever soils are relatively nutrient-rich and fairly deep, the dominant tree in this part of Surrey would be lime (Tilia species), and not oak as many think; other soils favour oak, beech, and yew. These can all dominate woodland depending on the soils but they are all highly competitive, long-lived trees. Ash, hazel, and birch can also be dominant in woodland, especially after removal of climax species, but these are considered to be ‘woody weeds’ and would always give way to the other species mentioned above. Over time, they would always be out-competed.

Open Habitats: All our heathlands, moorlands, and most grasslands, were created by man’s exploitation and management. Thus, many of our very precious and diverse habitats, such as lowland heath and chalk grassland, are wholly artificial, and without management would undergo succession to woodland again. This is happening on Headley Heath and Box Hill and both are ghosts of their former ecological selves when compared to say, the 1960s.

Friends and Enemies: Virtually every plant has microbial associates and most are in the soil, living in and on the roots (many of our effective medications such as antibiotics have been developed from soil organisms). However, there are many communities of all kinds of microbes growing on and inside the tissues of stems, leaves, and even flowers.

The significance of many of these plant/microbial associations is unknown (particularly ones with bacteria) but so far, we do know that mycorrhizal fungi penetrate roots and provide phosphate, nitrogen, and water to plants while the plants pay the fungi by providing sugar. Mycorrhizal fungi link up many trees in a woodland and there is evidence that sugar produced by one tree can be passed to others via the fungal network. A single plant may have very many different species of fungus associated with it at the same time so the relationships are very complicated. The mycorrhiza is critically important to the health of any plant such that its continued existence will depend on it, and disturbance of surface soils can be so detrimental.

Microbes also form associations with animals and virtually every living thing has its ‘microbiome’ (inside and on the surface). Indeed, the performance and success of any organism (including us) depends on the balance between beneficial and harmful microbes.

The biodiversity of any ecosystem depends to a great extent on microbial communities. Many are free living and exist by feeding the materials shed into the environment by others. All plants, animals (including humans), and microbes, are leaky, and exude carbohydrates, proteins, amino acids, and minerals and these provide food for others. Think about a sweaty armpit – it can emit odour produced by the skin bacteria using the amino acids in the sweat as food.

It is difficult to find any living thing that lives alone. Most form assemblages of associations with others. To give the human as an example, skin, mouth, ears, nose, and all the internal organs (including the brain) have their own associated microorganisms. The human body

consists of a mass of ecosystems though some human bodies are more ecologically diverse than others. Besides bacteria and fungi that are always with us, some people may have lice, mites, worms, and protozoa, and probably don’t even know it.

If the human body is highly biodiverse, just think about your garden (even your lawn), a woodland, grassland, a hedge, a birds’ nest, a pot plant, your dog, a drain, River Mole, and anything else you can think of.

We know more about the galaxies and outer space than we do about the soil in the flowerbed next door. Just think what is being lost when land is covered over with concrete. Compared to the amount of funding given to astrophysics and astronomy, the amount given to soil science is miniscule; our survival depends on soil but not on astrophysics.

Please consider biodiversity in a realistic way. You cannot measure an increase if you have not measured what is there in the first place. The biodiversity metric is an over-simplified device designed for planners so let us apply it carefully and with some common sense.