Natural and man-made habitats in Stockport

There is no easy way to describe how a ‘habitat’ looks; it is simply that which allows something to feed, breed or shelter from the elements. This could be grassland, woodland, a pond, a pile of rubble or the roof of your house. It is usually the case that the natural environment offers more opportunities for wildlife than the built environment, but both have their own place and nothing should ever be ruled out as having no importance for birds, mammals, insects or plants.

Grassland

Woodland, scrub and hedgerows

Ponds, rivers and canals

Parks and greenspace

The built environment (including private gardens)

Grassland

In the UK, this is a successional stage between bare ground and woodland, and without some sort of external influence would normally soon become scrub and ultimately tree covered. This influence can be grazing (as in a pasture) or mowing (as in a hay-meadow or a lawn). In prehistoric times grassland would have been a natural component of a dynamic landscape, forever changing as areas of woodland were cleared by storms or fires allowing light demanding species to maintain a foothold until scrub and trees took over again. Herds of grazing animals may well have helped to keep some areas as grassland on an almost permanent basis.

Until the 1940s, most farm fields supported a very rich variety of plant species and consequently huge numbers of insects, mammals and birds. Schemes aimed at boosting food production intensified agriculture and many old meadows and pastures were ploughed up and sown with protein rich but wildlife unfriendly rye-grass. The introduction of artificial fertilisers and weedkillers and the shift from haymaking to silage production have all had serious impacts too. In recent times various organisations have tried to halt and even reverse a lot of this damage by protecting the important grasslands and recreating new species rich meadows wherever possible.

The best time of year to explore the rich abundance of life in a grassland is May, June or July, when birds and insects are at their peaks and the grasses and wildflowers are in full bloom. Take along an identification guide and see how many species you can recognise. There are excellent examples of species rich grasslands at Bruntwood Park in Cheadle and Chadkirk Country Estate in Romiley. Both of these are open to members of the public.

Maintaining botanical diversity is dependent upon management. Here is a list of the positive and negative things that can be done:

P The grass needs to be controlled in some way to prevent succession and loss of diversity. This can be through annual mowing or grazing.

P An early cut, just after the start of the growing season can further aid diversity.

P Removing all cut material can reduce nutrient levels which will aid less competitive species.

O Using any form of herbicide will reduce the numbers of plant species growing. It may be worth making exceptions for problem species such as docks or thistles though.

O The use of fertiliser or slurry will encourage the more dominant species, such as rye grass.

O Mechanical operations (e.g. harrowing, rolling etc) in early spring can affect ground nesting birds.

Woodland, scrub and hedgerows

Apart from mountain tops and open standing water, most of England would eventually develop into some sort of woodland environment. In fact it is often referred to as the climax community, meaning it is the final stage of succession. Woodland comes in many guises, ranging from willow and alder woods on waterlogged ground to oak woods on clays and acid soils and ash wood on lime rich soils. In all its forms, it is one of our richest habitats. The vast arrays of plants, fungi, birds, insects and mammals that all rely on woodland for at least part of their life cycle are attracted by the range of niches available and of course the cover and three dimensional element to the structure. The height of the trees substantially increases the amount of space for things to live! The original woodland that colonised Britain after the last ice age is referred to as the wildwood; there is none of this left anywhere in Stockport, or even in the United Kingdom as it has all been affected by man’s activities to some degree.

· Primary woodland is that which has existed continuously since the time of the wildwood, albeit subject to management or otherwise influenced by man.

· Secondary woodland exists where at some point the land has been ploughed or put to some other use before being replanted with trees or allowed to revert naturally. This can be either recent (post 1600) or ancient (pre 1600)

· Semi-natural woodland is that which has developed with no (or very limited) input from man

· Ancient woodland is that which has existed continuously since at least 1600. Obviously this cannot be recreated if lost!

· All primary woodland is ancient by definition

Scrub can exist for several reasons; where there are factors that prevent the development of normal woodland, such as very poor soils or extremes of climate or as an intermediate stage between grassland and woodland. It is worth defining the varying types of scrub:

· Seral scrub – ephemeral vegetation existing as a successional stage between grassland and woodland

· Sub-seral scrub – factors such as grazing, burning or cutting prevent the development of trees but allow scrub to persist. This exists as a deflected successional stage or plagioclimax.

· Climax scrub – factors such as salt spray, strong winds, skeletal soils or substrate instability may not allow succession beyond the scrub stage. Examples may be found on cliff-tops, small islands and in the sub-alpine regions of Scotland.

The addition of a vertical element when compared to herbaceous vegetation offers greater opportunities to invertebrate colonisers. Many non-phytophagous insects take advantage of the increased shelter, basking, prey capture and breeding opportunities afforded by the structural complexity of scrub. The phytophagous species tend to be associated with particular plant families, with willow and hawthorn being especially valuable in this respect. The build of leaf litter and increase in humidity provide opportunities for primitive groups such as springtails and other epigeal invertebrates.

Scrub has a great potential for birds; both insectivores and frugivores are well catered for and species most strongly associated with this habitat are warblers, thrushes, pigeons, starlings, robins, tits and finches. It is also worth noting the differences in structure requirements among birds. Some, such as the yellowhammer and whitethroat require low and open scrub, whereas the garden warbler and blackcap are associated with denser, more closed scrub.

Hedgerows are an important part of the landscape, both in character and biological terms. Many miles were planted as a direct result of the Enclosure Acts (1760-1830) as field boundary markers, although some exist as linear remnants of primary woodland. These are usually typified by a diversity of woody species (usually more than five) and certain plants known as indicator species. These include wood sorrel, bluebell, dog’s mercury and yellow pimpernel. Managed sympathetically, hedges allow connectivity between other habitats, acting as wildlife corridors. Birds, mammals and insects may all use these for food, shelter, breeding and hunting. Hedgerows and the headlands next to them often support herb species that have been lost to intensification from the rest of the field.

Ponds, Rivers and Canals

Ponds may be naturally occurring or man-made although most with any permanence are probably not natural. Whatever their origins though, they are of great value for wildlife. This value varies significantly as parameters such as nutrient level, shading, disturbance, acidity and altitude are altered. As with many situations, structural variety will give rise to the greatest diversity of species, although not necessarily the greatest productivity. A combination of marginal vegetation, submerged aquatic plants, open water and marshy margins will ensure that many of the commoner taxa are allowed to proper. Important species associated with ponds in Stockport include the great crested newt, water vole, shining ram’s-horn snail and the lesser silver diving beetle. A common problem in ponds is eutrophication, when an excess of nutrients causes a rapid expansion in algae or bacteria populations which place huge demands on dissolved oxygen which in turn can lead to the suffocation of fish or anything relying on gills to breathe. Eutrophication can be caused by sewage spills, fertiliser run-off or leachate from agricultural land.

Canals and rivers vary most obviously in that canals are man made and have very limited water flow, whereas of course rivers occur naturally and flow freely. Rivers may be canalised in urban environments to fit into development schemes. Between them they provide some of the richest habitats in our area as well as acting as linkages between other existing biodiverse areas. Linear waterbodies are susceptible to the same threats from pollution as ponds, but in addition their nature may facilitate the spread of invasive species such as Japanese knotweed, Himalayan balsam and the American mink. All of these spread rapidly and displace native wildlife in so doing.

There is, however, more to these habitats than the aquatic elements. Ponds often have boggy margins or areas of wet grassland associated with them which offer opportunities for wildlife in their own right. Rivers and canals provide corridors of significant importance in the landscape, with often herb-rich banks or strips of linear woodland that provide feeding, breeding and migration opportunities for insects, birds and mammals.

Parks and greenspace

Much of the publicly accessible greenspace in Stockport has excellent value for biodiversity, and all of it is important in some way. Some parks, such as Etherow Country Park or Bruntwood Park have nationally or regionally important habitats or assemblages of species, whereas others have species that are relatively common yet important to the people who encounter them on their visits or perhaps are unusual with Stockport, despite being common in other areas.

Stockport Nature Network has reached an agreement with Stockport Metropolitan Borough Council to secure the creation of 300 hectares of land designated as Local Nature Reserve; roughly one hectare for every thousand people resident within the Borough. This is based on Natural England’s (formerly English Nature) recommendations for accessible greenspace. The figure currently stands at 233 ha (April 2006) with a further 30+ ha planned for designation by 2007. Local Nature Reserves have statutory protection, and are designated either for their high degree of natural interest, or a combination of reasonable natural interest and high value for environmental education. The commitment to management for nature conservation and access by members of the public is central to their designation.

There are many habitats within the Borough’s parks, including all of those listed above. Some are more ‘natural’ than others, and opportunities for improvement exist in many. With Council ownership, alternatives to existing management may be sought which benefit wildlife even further as there is no requirement to make profit, as is the case on most other land. Groups such as Stockport Nature Network are vital in assisting the Council to secure funding to allow project work to continue, surveying sites to establish which areas are most in need of work and recording important species such as badgers and bats.

The built environment (including private gardens)

Houses, commercial buildings, the road network and derelict land can all have a lot to offer wildlife. Bats, many bird species and numerous wildflower species are able to capitalise on the niches created within built structures and their immediate surroundings.

It is well known that bats will roost in roof spaces and under the eaves of domestic houses, and many species of birds enjoy greater breeding success when their food supply is supplemented by the efforts of people who feed them. In these days of agricultural intensification, road verges may be strongholds of plants that have shown declines in meadows and pastures. Grass that isn’t mown every year tends to have higher populations of small mammals which is why kestrels are often seen hovering near motorways and other trunk roads, scanning the ground for voles or other prey.

‘Waste’ ground is often anything but waste when it comes to wildlife. The combination of low fertility, unstable substrates and unusually high or low pH often found on these sites leads to colonisation by specialist plants not always abundant elsewhere. As these plants are specially adapted for colonising they have evolved to produce vast numbers of seed which provide important food sources for finches and other birds. They also support healthy populations of invertebrates which benefit the non seed eating bird species. Although there is usually pressure to develop or ‘tidy up’ these sites, their qualities can be replicated in associated landscaping schemes and make a refreshing alternative to turf and ornamental trees.

Domestic gardens, when viewed as a whole, make up an enormous area and make a significant contribution to the amount of land that can be managed for the benefit of wildlife. There is a vast amount of information concerning wildlife gardening on the internet, and a good starting place is The BBC http://www.bbc.co.uk/gardening/basics/techniques/organic_wildgardens.shtml . Although suburban gardens may not be associated with the most important species from a conservation perspective, those which have shown serious declines in recent years or are very vulnerable to loss of habitat such as badgers, bats and great crested newts can all be found in gardens around Stockport. Bird numbers can easily be boosted by feeding all year round, and advice on this is available here http://www.rspb.org.uk/gardens/whatyoucando/Gardeningwithwildlife/feeding_birds.asp .

Canalised – of a river, having had its course ‘improved’ to allow a smoother flow of water, often by straightening, dredging or removal of obstacles

Climax Community – the community that exists when an ecosystem is in equilibrium; when succession has reached its natural conclusion. It is best applied at a landscape scale to dynamic systems in flux

Epigeal – living or occurring on or near the surface of the ground

Eutrophication - the enrichment of water by nutrients especially compounds of nitrogen and phosphorus, causing an accelerated growth of algae and higher forms of plant life to produce an undesirable disturbance to the balance of organisms and the quality of the water concerned

Frugivores – animals that eat fruit (not necessarily exclusively)

Indicator Species – plants or animals whose presence (or absence) indicates certain environmental conditions

Phytophagous – feeding on plants, including trees. Usually used in reference to insects

Plagioclimax – when external factors such as burning or grazing deflect a community from its natural climax, the result is a plagioclimax

Productivity – in simple terms is the capability of a system to produce food; the amount photo- (or chemo-) synthesis that can take place. Measured in energy per unit area per year

Successional – relating to the predictable and relatively orderly changes in the structure and composition of an ecological community

Wildlife Corridors – linear tracts of land joining fragmented habitats

Wildwood – the woodland that covered Britain after the last ice age before human influence began to shape its composition. No wildwood exists in Britain today