Wetlands Fen and Raised Bog Characteristics. Threats and Management

Fen

Formation and Characteristics
Fens are an integral stage of ecological succession, the initial development of a fen occurs when freshwater fills a depression in the land surface, soon after a pond or lake has developed, vegetation begins to colonise, this is often a reed swamp. The last ice age created vast changes to the landscape, which majorly influenced the formation of new water bodies and flows, by changing land depressions, forming valleys and transporting base minerals.

The water is fed by mineral rich alkaline groundwater; this provides conditions for typical plant species. As the plants build up and die they create layers of dead organic matter. New vegetation grows on top of the older, slightly decaying matter.
Over time the bed of the lake rises with partially decayed plants. The saturated soils reduce aerobic respiration by bacteria and fungi in the soil, reducing decomposition rates and eventually leading to layers of peat with low mineral content.

At this point the fen is regulated and prevented from turning into a bog by the presence of alkaline ground water passing into the fen. If the water source were to change to rainwater instead of groundwater, the fen would soon convert into a bog and a raised bog can grow on. Once the surface of the peat reaches the water surface it becomes a fen.
Too little rain or seasonal dryness allows air to get into the peat, spurring sudden decomposition, alternatively too much water can wash out hydroxide ions and rainwater acidifies the peat, converting the fen to bog.
Fen development is fragile and can be brief once created as succession continues to Carr and eventually woodland, fen can be maintained where removal of willow and alder by grazing occurs and can often merge into marsh in these areas.

Characteristic Plant Species:

• Flat sedge
• Great fen sedge
• Davall's sedge
• Dioecious sedge; Brown sedge
• Slender sedge
• Flea sedge
• Common spike rush
• Few-flowered spike rush
• Slender spike rush
• Broad-leaved cotton sedge
• Brown bog rush
• Meadow thistle

Rare species:

• Fen Orchid
• Crested buckler

The UK supports a large proportion of fen-land found in Europe, unfortunately fens have declined dramatically over the past century, this is due to several influence factors:

Neglect.
Fens are a stage of ecological succession, without human intervention this habitat would naturally progress to scrub and eventually woodland, drying out in the process.

Loss of habitat from drainage.
Conversion to agriculture and excessive abstraction from aquifers have resulted in a lower water table, subsequently springs and groundwater have a reduced flow and fens do not receive the high water quantities they demand.

Change in water quality.
Abstraction affects the balance of water quality between ground and surface waters, resulting in unstable volumes of chemicals entering the ecosystem and changing the plant community types. This can also occur s from agricultural runoff, (valley fens are increasingly vulnerable to this)

Fragmentation. Continually smaller and more fragmented areas become incredibly vulnerable when several key species are reliant on the habitat.

Fen-lands are dynamic, semi-natural habitats, which require a low level of management (mainly scrub clearance and water level control) to preserve their natural characteristics and to retain an open fen. Fens can support up to 550 different species of plant and in some cases more, they are also an ideal habitat for over half of Britain’s dragonflies, several thousand insects and birds such as bittern, Bearded tit and marsh harrier.

Unsurprisingly most fens have some protective designation, from SSSI/ASSI to the Ramsar Convention and SPA protection from the Birds Directive. Some larger sites are designated NNR and are management with influence from Natural England. Several fen types are listed as priority habitats in the Habitats Directive (transitional mire, poor/rich fen)

Management generally focuses on:

• Restoration of fen to favourable condition
• Reedbed management – prevent over encroachment of reeds that could lead to succession, this often involves “in water” work and aquatic plant removal with hand tools.
• Removal of woody growth can be implemented through mowing and grazing regimes, this prevents invasion of scrub and tree species.
• Management of water levels controls how much water enters and leaves the site, ditches, drains and storage sites allow managers of fens to remove excess water or allow more water in when necessary. The careful balance of water levels keeps the habitat in favourable condition.
• Fen creation is beginning to occur on former abandoned peat workings, this could allow a slow development of new fens to areas where they have ceased to exist in recent years.
• Connection of fragmented fens can occur with the purchase and removal of arable land or forest plantations between two fen sites, these often have extensive drains which could divert water away from the site
• Monitoring and surveys continually provide a deeper understanding of fens and their ecosystems, bird surveys, plant/invertebrate transect counts, water quality testing etc.
• Species recovery for damaged populations with the fen ecology.

Raised Bog

Formation and Characteristics
These bogs form from vegetation which can survive merely on what is provided by rainwater, the raised bogs develop on already existing fens or reed swamps where the peat built up has become deep to the point where vegetations is no longer influenced by alkaline groundwater and develops a more acidic tolerant layer of vegetation: predominantly species of sphagnum moss.

Layers of the sponge like sphagnum moss can hold up to twenty times its own cellular weight in water, providing water for the next generation of moss. As with other waterlogged soils decomposition is reduced and the layers build up increasing the height of the bog over thousands of years. The older sphagnum directly above the fen is well humified and often present with bog cotton, newer layers of peat are relatively un-humified and quite well intact, fresh vegetation continues to grow on the surface.

Raised bogs do not follow the natural contours of the landscape, instead they can be raised, several metres above the local landscape and seem to be domed across its span. The actual surface of the raised bog is an even pattern of hummocks, hollows and pools that harbour microhabitats.

Typical raised bog characteristics

• Water content; Undrained
• Solids: Undrained
• PH: 3.8 – 6.5
• Organic content: 97%
• Inorganic content: 3%
• Peat depth: average of 7.5m (up to 13 metres)
• Annual rainfall: 700-1000mm

Raised bog have declined greatly in recent years with up 94% of natural raised bogs in the UK lost or irreversibly damaged due to the effects of modern life; peat extraction, landfill development, forestry, drainage, pollution, dereliction after previous disruption poor livestock management, built development, atmospheric nitrogen deposition and climate change all contribute to bog destruction and continue to do so.

The mosaic of pools, hummocks and lawns provides habitat a for a variety of flora occurring in micro-habitats, though mostly dominated by sphagnum moss’, undisturbed raised bog surfaces can support species of cross leaved heath, ling, cotton-grass, deer-grass, and sun dews. These tolerant species in waterlogged soils provide a habitat ideal for waders or wildfowl such as Curlew, Hen harrier, Meadow pipit, Skylark and Snipe, invertebrates and other species. The unique wildlife value of raised bogs raises their conservational importance and this has been internationally recognised, as this habitat is now a priority in the UKBAP.

Most bogs are designated or are the process of being designated (SSSI, SAC, SPA, NNR etc) this works to prevent further decline of the habitat. The active management on raised bogs is limited as even slight disturbance, can permanently damage this fragile ecosystem.

Natural Primary Bogs are defined as being sites, which have only received natural disturbance and have reached a natural climatic phase of raised bog. The layered make up of raised bogs has developed over thousands of years to reach this stage, peat removed for whatever use, is irreplaceable.

Raised bogs are affected by three main factors:

Increasing rate of water loss.
A loss of water will result in drying of the bog, accelerated decomposition and shrinking. Managers of bogs need to work towards providing a stable water table and prevent land drainage where it will affect bogs.

Increases in nutrient status.
Nutrient drift or runoff can effect competition between bog species; increased nutrients unbalance the ecosystem, favouring other species over the developed acidic loving plants of a bog. Nutrients can come from fertiliser, pesticide/herbicide, pollutants etc and get into the bogs hydrological cycle.

Loss of vegetation as a natural regulator of water retention.
Raised bogs depend on the layers of living sphagnum to hold water and keep the site continually wet. This is how raised bogs can regularly be higher than the local water table. A loss of this vegetation means water will not be held and the site will eventually dry out, as vegetation becomes less.

Degraded raised bog habitats, occur when active peat formation ceases, this is when no more layers of vegetation are being put down and growth of peat forming vegetation has disappeared. Despite the cease in formation, these sites have an opportunity for restoration with some very careful, long-term management.

If degradation occurs as a result of local forestry and the installation of drains diverting water away from the local hydrological cycle, then removal of trees and blocking of drains could re-wet the site and sphagnum growth may resume. The slow growth of sphagnum makes it very difficult to monitor the success of a rewetting program.

Some species associated with raised bog:

• Dragonflies
• Emerald Damselfly
• Large Red Damselfly
• Blue-tailed Damselfly
• Common Blue Damselfly
• Variable Damselfly
• Azure Damselfly
• Irish Damselfly
• Common Hawker
• Four-spotted Chaser
• Common Darter
• Black Darter

• Moths
• Beautiful Yellow Underwing
• Bordered Grey
• Common Heath
• Drinker
• Emperor moth
• Fox moth
• Grass wave
• Northern Eggar
• Puss moth
• Scallop shell
• Wood tiger

References:
http://www.ukbap.org.uk/UKPlans.aspx?ID=18
http://www.raisedbogrestoration.ie/about/default.asp
http://www.peatlandsni.gov.uk
http://en.wikipedia.org/wiki/Fen
http://www.bnm.ie/files/20061124040538_raised_bogs.pdf.
http://www.greatfen.org.uk/about-management.php

Wetland: Types and General Management Considerations

A wetland is defined as being an area of land where the water table never, drops below 15cm from the surface or exceeds 6 metres depth above the surface of the land. The British climate is suitable for sustaining wetland habitats though climate change could lead to a reduction in habitat size. There are several wetland types and habitats vary even within the habitat. There are six main wetland habitats.


Wetland Types

Marsh
Marshes are often dominated by grasses rushes and sedges, they occur near lakes and rivers where the water table is predominantly high and close to, but rarely above, the surface. Marshes do not contain a layer of peat and are composed on mineral soils. Marshes can be fresh or salt water.

Reed Swamp
Reedbeds/swamps are wetlands dominated by stands of the Common Reed (Phragmites australis), it occurs on mineral soils where the water table is at, or above ground level for most of the year Reed swamps are amongst the most important habitats for birds in the UK, despite this they are largely fragmented.

Wet Meadow
Wet meadows are similar to marshes but receive seasonal flooding rather than continual, this often results is more dominant grasses. They often occur in poorly drained areas such as shallow lake basins, low-lying farmland, and the land between shallow marshes and upland areas.

Fen
Fens develop on alkaline, mineral rich soils, vegetation builds (sedges, grasses and rushes) up and when the plants die, they become caught in amongst the other vegetation, forming layer after layer of dead organic matter, the built up DOA and water saturated soils prevent/ delay the decaying process and eventually peat forms.

Carr
A Carr is a transition to woodland, it is part of the process of ecological succession occurring when the area has developed to being dominated by alder or willows, this succession will continue until the area becomes dry and a new succession will occur.

Bog
A bog is characterised as being an acid mire, vegetation accumulated in waterlogged soils due to a lack of oxygen required for aerobic decomposition. As a result peat accumulates, bogs can accumulate metres and metres of peat in one site, though this forms over thousands of years.
Bogs can be split into different types:

Ombrogenous Mires
These are created by extensive rainfall and rely on a reasonably wet climate to survive as all water replenishment comes from the atmosphere.

There are two forms of ombrogenous mire: blanket bog and raised bog. Blanket bog is so called because its development is mostly independent of basins or topographical features where water collects; it simply covers the landscape like a blanket. Raised bogs develop from a basin or dip in the land where rainwater collects into and builds up layers until the peat sits above the surrounding land.

Topogenous Mires
These are dependant on the formation of the land for existence they are influenced by topography and receive relief water from drainage and seepage. Water rarely comes above the surface or falls far below. Valley bogs receive a flow of water wick keeps the bog continually wet. Basin bogs have no flow of water and water seeps out slowly or evaporates in the basin.

Soligenous Mires
Here the wetness of the ground is maintained by slow lateral gravitational seepage of water through the substrate or the peat. Topography is still the main determining factor but the high water table results not from the concentration of water as in a topogenous mire, but by a sustained, slow flow through the site; usually along some definable drainage or seepage line. As the moving water flowing through the substrate is more oxygenated and hence decomposition is more effective in soligenous mire sites, the depth of peat accumulation is usually less than in topogenous mires, although there are considerable similarities in peat types


Factors Important to the Management of Wetlands
Wetlands are a varied set of habitats with waterlogged soils for some part of the year, the extent of the water-logging varies from habitat to habits and often they overlap and appear in close proximity of each other. Wetlands provide habitat, food, cover for a huge range of invertebrates, wildfowl and waders and so many wetlands are subsequently identified and protected under designation of Ramsar or SPA to prevent decline and work towards improving the quality of the habitat. These important species co-exist with (and often rely upon) specific vegetation present within the community typical to waterlogged soils.

The species found on the wetland should influence the management of the site for example; if wildfowl are present manage for the benefit of waders, who are dependant on winter flooding for feeding opportunities. If waders are present manage for waders etc. In the interest of diversifying a wetland, a mosaic of flooded and non-flooded provides benefits to a wider variety of species.

We have already established that wetlands rely on regular water logging to sustain the habitat; centuries of land drainage have contributed to the loss of wetland sites and their current conservational importance. Any alterations to the habitat will effective the competitive balance between plant species and sudden change could lead to a change of habitat rather rapidly.
The water table should not be altered by draining, or diversion of water into the site from the surrounding area.

Most wetlands rely upon the low nutrient availability that accompanies waterlogged soils; enrichment from agriculture could lead to domination of fewer more competitive species rather than a diverse, rich community that can thrive on low nutrients. This means that no fertilisers, slurry or manure should be used where it can drain into wetlands and pesticide spray must occur away from wetland and surface surrounding it.

Scrub needs to be managed to prevent encroachment and succession towards a climax community, grazing in certain seasons provide vegetation management as well as the removal of nutrients.

Trees and hedges planted near wetlands consume much larger amounts of water and also increase transpiration rates, reducing water and leading to dryer, more successive areas. The seeding of trees and hedges encroaches in to the wet areas and lays down deep layers of litter annually.


Reference:
http://www.envf.port.ac.uk/geog/teaching/ecol/b6notes.htm
http://www.sac.ac.uk/mainrep/pdfs/tn519wetlandswildlife.pdf.

Water. Management, Supply and Demand

Water
Water is an essential component of nearly all life on earth, plants require it for essential functions as do birds, insects, fish, mammals, fungi, bacteria etc.

70% of the earth is covered in water, however only a mere 2.5% of this if freshwater the rest is saltwater in seas and oceans: only 1% of freshwater is actually accessible for direct human use and demand often exceeds sustainable volumes.

There are increasing concerns regarding the sustainability of water across the globe, especially with prolonged reduced levels of precipitation causing droughts in many areas.



Supply
Water is supplied to homes and businesses through water companies; they are responsible for abstraction, distribution and treatment some also deal with sewage treatment as well as returning water to the environment. There are over 20 water companies supplying water to England and Wales but only one company for Scotland and one for Northern Island. The water supplies come from two sources, surface water and ground water and are greatly effected by the levels of rainfall in a particular area, in areas with low annual rainfall rates, stronger measures must be taken to make sure water is available through, water resources plans, drought plans and water efficiency plans.

Surface water is channeled off from fallen rainwater, instead of running into rivers and streams and back into the hydrological cycle it is directed onto storage reservoirs. The reservoirs can hold vast volumes of water for long periods of time, this means that water can be collected during the winter in times of high precipitation and stored until needed during dryer summer weather conditions.

Groundwater comes from underground natural reservoirs known as aquifers, this is where water has managed to penetrate through fractures and pores in geological formations. Naturally the water is released out from the aquifer in the form of springs or rise to the surface creating wetlands. Groundwater is abstracted through the use of wells, which are put in place to actively pump the water up and out. Groundwater is naturally replenished by rainwater but water companies have taken to the habit of artificially re-filling aquifers as a means of storage.

Before water is distributed out to the public it goes through a series of treatments, these are designed to provide users with clean healthy water suitable for a range of needs. Firstly the water is put through a range of processes to remove suspended solids such as clay silts, soils and metal oxides as well as and micro-organisms, this is done by passing the water through fine meshes or the addition coagulants which bind the particles making them easier to remove.

To make water suitable for drinking it needs to possesses some particular chemical properties, oxygen needs to be present some groundwater may be very low in dissolved oxygen and would subsequently be passed through a cascading structure which allows for oxygen to get trapped and dissolve into the water. The pH is also checked and adjusted if too acidic or alkaline as either extreme can cause problems to plumbing and pipes, it can also have an adverse effect on human health. The original pH of the water before treatment will be dependent on its source and the level of adjustment dependent on its intended use.

Finally before water can leaves the treatment center it must be disinfected, this final process removes the last traces of pathogens and means that water is clean through its journey until its use. There are several products used to do this though it is treatment with chlorine tends to be the most popular and effective.

Water consumption is an ever-increasing problem for water providers, the growth of industry and agriculture in the last century demands massive volumes of water each day and so do the millions of washing machines, dishwashers, baths, toilets and hosepipe found in most households today.


Demand
Population size is the main contributing factor to increased demand for water people across the globe already account for the use of 54% of all accessible fresh water on the planet. This is estimated to increase to 70% by 2025 based on population growth alone. The effects of this will be drastic to other species depriving them of access to water, which is as important to their survival as it is to ours.

Water consumption is divided into three main categories, agriculture, industry and domestic use, with agriculture having by far the largest water requirements globally.

Global water consumption distribution:

• 69% - Agriculture
• 23% - Industry
• 8% - Domestic

However distribution varies in different regions and large difference occur between developed and lesser-developed countries, for example:

Africa

• 88% - Agriculture
• 7% - Domestic
• 5% - Industry

Europe

• 54% - Industry
• 33% - Agriculture
• 13% - Domestic

Agriculture causes several problems when it comes to water consumption, large quantities of water are needed for the regular irrigation of crops, the crops are needed to meet demand from the public and pressure on successful production of crops is high. Competition for business in the agricultural sector is high due to strong competition from cheap over-seas exporters; this encourages producers to use excessive amounts of water to increase productivity.

Water used for agriculture is not only removed from the natural water cycle but can create potential pollution problems with the introduction of chemicals back into the water cycle from surface water runoff and groundwater leaching. Nitrates, phosphates and sulphates are all produced naturally by grazing livestock urine and faeces and are commonly found in fertilisers and pest/herbicides; these can easily build up in local waterways and wetlands.

These compounds are essential to supporting plant and aquatic life but high levels can be dangerous, nitrogen encourages dramatic growth of algae species, which then starve other species of light and oxygen. The result of this process known as dentrification is a decline in habitat quality and subsequently a reduction in population and community size as well as the dominance of aggressive invasive plant species.

The use of water in industry has a strong impact on the environment, when we speak of industry we are referring to the production of goods for economic gain. The term industry covers many sectors of production including food and drink production, chemical production, fuel production, paper production and household waste incineration etc. increases in population size and the growth of consumerism attitudes by developed society have lead to an increased demand for millions of products.

The production of products in industry uses large amounts of water daily, nearly every product in the world will use water at some stage, this could be through fabricating, processing, washing, diluting, cooling, or transporting a product; incorporating water into a product; or for sanitation needs within the manufacturing facility.

Industry not only consumes vast quantities of water daily but the bi-products produced in many of these processes can cause severe harm to the environment. Industrial facilities are most commonly recognised by plumes of dark smoke billowing from tall chimneys, this smoke contains many hazardous chemicals such as Sulphur Dioxide (SO2), Carbon Monoxide (CO),
and Nitrogen Dioxide (NO2) as well as many hydrocarbons, heavy metals and toxic organic micro-pollutants. These substances are absorbed by water molecules in the atmosphere and enter water systems through precipitation making, the water is then either cycled through waterways and wetlands or abstracted for human consumption; the polluted water requires heavier treatment and damages natural habitats.

Although domestic consumption of water by volume is far less than agriculture and industry on a global scale, it accounts for high levels of wasted water in local communities. The availability of fresh, clean and hot water on demand has reduced societies appreciation for this essential, life sustaining resource. In areas of high levels of rainfall or areas low on the water table this is not so much of a problem as water is constantly renewed and replenished and there is plenty to meet demand. However in dryer areas, water wastage can be a big problem leading to hose pipe bans and drought situations; normally when there is most need of water.

Wastewater produced by households creates problems of its own, sewage treatments are responsible for treating wastewater to a state where it can be released back into the water cycle. Wastewater is categorised as being either “sullage” (baths, basins, washing machines etc) or “foul waste” (sewage) for water from toilets.

Sewage treatment involves separating water from organic and inorganic material that has been flushed down a toilet, as with livestock earlier human urine and faeces contain high concentrations of ammonium, nitrate and phosphorous, which are damaging to the environment if exposed in the quantities that are produced daily. To be able make the water acceptable for release into rivers, streams and wetlands or for use in groundwater replenishment it must go through a long process of intensive filtrations, chemical treatments and biological treatments; treated water is finally released back into the water cycle.


Main effects of water abstraction from freshwater habitats
The Problems associated with abstraction of water are broad and effect all walks of life, habitats, environments and local and national communities are all affected by possible results of regularly removing large volumes of water from a single source. Over thousands of years the flow and cycle of water has established its own courses and has been a major influence in the success of many habitats heavily influenced by the water flowing through the land. Freshwater in rivers and streams is an important habitat for many species of plant, insect, amphibian, mammal and bird and if its primary requirement for existence (freshwater) is reduced or lost because of abstraction there are going to be significant consequences.

Reduction in habitat size and loss of habitat severely reduces the population density of a species; many species require a certain amount of space or territory to survive. If that space is reduced species will either migrate to another site or if they cannot will probably suffer decline due to over competition for food and a reduction in resources. A reduction in habitat also removes essential cover for predated species making them easier to target, predator species would soon take advantage of the prey’s vulnerable situation and ultimately species could suffer heavy losses.

A reduction of freshwater to a site reduces the waterways effectiveness for self-cleansing and this allows chemicals to build up changing the chemical composition of the water and reducing the suitability of the habitat for a range of species. This change will either result in migration of species or for those who are unable to migrate, most probably death from over contamination. Each species has its own tolerance levels to pollution but even the loss of one species from pollution can have resonating effects throughout this unstable environment.

Groundwater abstraction from aquifers poses some new problems for humans and the environment. Removal of large volumes of water from underground has effects on the local water table and other wells may not be deep enough to reach the lower table and a drop in supply. This reduction in water can also have harsh effects on wetlands that are used to high saturation levels, which become dryer and attract less species of insect and bird, the loss of wetland habitat leads to reduced conservation interest and eventually the land could be completely lost to housing or industry development.

The pumping of groundwater exerts downward pressure onto the surface layers of rock and sediment causing them to compress and lower. Lowering of land can lead to regions sinking to below the water table, increasing the likelihood of flood in the future. The effects to the environment in such a situation would be harsh, areas previously dry are subject to high levels of water saturation, many plant species would be unable to cope with the sudden change in environment and their decline would be felt through the food chain.

The water found in aquifers sits in the pores of rocks helping to stabilise the structure and supports some of the weight from overlying rock, the removal of water and its support can lead to subsidence and sinkholes when the upper rock layers collapse under increased pressure.
In some cases, identified aquifers may have taken thousands of years to reach their currant state with water flowing in to the area slowly or unreliably, the abstraction off water from these sites is a non sustainable resources with very limited supply.


Main effects of pollution to freshwater habitats
Pollution occurs when water is released back into a waterway after abstraction, use and treatment, even though the water has been treated three are still traces of pollutants or higher levels of nutrients than would naturally be present in the water.

Water treatment facilities are monitored by the Environment Agency and have to abide by strict regulations on the quality of water they emit, despite this there is always going to be traces of some substances in water that are higher than they should be and even a slight change in chemical composition or pH can lead to changes within a habitat. General water quality and waterway management has improved in certain areas in recent years especially when water companies make efforts to create and action Biodiversity Action Plans. (BAP)

Anglian Water is one of the largest water providers and treatment facilities in England, providing water to over 4 million people and managing thousands of kilometres of rivers, this company is making efforts towards improving the quality of freshwater habitats both for the environment and recreation in several ways. Anglian Water is currently delivering a 10-year BAP as well of introduction of two new species as part of Water for Wildlife (a project with the Environment Agency and the Wildlife Trusts focused on wetland habitat and species action on the ground). Surveys carried out by the Environment Agency show improvements in the water quality managed by Anglian Water.

Another source of pollution is from the use of water in agriculture and industry. Surface runoff and ground water leaching transport chemicals on and in the soil and into freshwater sites. As discussed earlier the chemicals from livestock waste and fertiliser can damage freshwater habitats by allowing nutrient build up. Runoff and leaching also transport pesticides and herbicides used in modern agriculture directly into the water. These chemicals are designed to kill and impair, they are essentially a poison and can cause the death of flora and fauna in and around the site.






References
http://en.wikipedia.org/wiki/Groundwater
http://www.aeat.co.uk/netcen/airqual/kinetics/#hc
http://www.water-guide.org.uk/companies.html
http://www.anglianwater.co.uk
http://www.globalchange.umich.edu

Heathland Development and Ecology

The lowland heath that is present today across Britain and Europe has evolved as a result of climate change and historical human management, the development of agriculture and land use has effected the vegetation and habitat of lowland heath throughout the ages, affecting both establishment and decline.

Influence of Humans
The first signs of heathland came with the retraction of ice sheets at the end of the last ice age, approximately 14,000 years ago tundra type of vegetation began to establish as ice melted and moved, over the next 4,000 years these species developed and spread over Britain and Europe. Tundra vegetation is typically low and slow growing having adapted to survive the harshest and most hostile of conditions, these characteristics can still be seen today in some heathland plants although adaptations to new climates and soils has changed the vegetation significantly.

As the climate continued to warm new species emerged and the landscape of Britain quickly changed, from 10,000 – 6,000 BP the domination and succession of vegetation to forest over-competed with heath vegetation and soon most of Britain was covered in dense forest; lower growing species were shaded out and only existed in open glades and woodland margins.

The birth of heathlands came during Neolithic times (6,000 – 4,000 BP), Neolithic man turned away from hunter-gatherer survival and began the domestication of plants and animals which lead to management of land and the beginnings of agriculture. During this time large areas of forest and woodland were cleared, most probably by the use of fire, as technology had not yet developed tools suitable for large-scale tree clearance.

The cleared land was used for growing crops for food, in the early days of agriculture man did not have the knowledge to be able to sustain crop growth and so every 20-25 years the soil would be depleted of nutrients and farmers were forced to move to another area and begin the process anew.

The land now became open to succession with the desertion of agriculture and trees began to re-establish, if the area were totally neglected succession would continue to permanent woodland cover. In other cases the land was used to graze livestock such as cattle, sheep and pigs; this prevented the dominance of tree species and allowed for heathland species to establish. Grazing by livestock is a key contributor to the development of heathlands, as we know them today.

By the start of the Bronze Age heathlands had become well established, the growth of population and immigration of people from Europe changed the way that people were living. Human settlements started to appear on more nutrient rich grounds and the development of agriculture there showed a higher productivity and yield of crops than on the previously farmed nutrient poor soils of the Neolithic times. The abandonment of heathland allowed for further domination by heath species.

Despite their reduced popularity, heathlands were still utilised by local people for the resources they could provide and the small scale, low impact management continued to encourage specialised species to develop.

Heathland management continued with little change until the start of the 17th century, by this time much technological advancement allowed for agricultural improvement to take place on barren lands. The enclosure of common lands by the authority of Acts of Parliament in the 17th and 18th Centuries allowed farmers to further develop fields systems and improve agricultural management,

This meant that “waste areas” such as heathlands could now be used for development and reclamation. This lead to a national decline as land is reclaimed for agriculture or abandoned as it became easier to transport and purchase goods rather than self produce, in which case succession to woodland began.

The industrial revolution saw dramatic decline to heathland, as thousands of hectares were lost to other forms of management and industrial growth. Increased agriculture and forestry as well as large-scale extraction of sand and gravel only added to the reduction of lowland heath habitats.

Of all the heathland habitats present in Britain in1800, only 18% still exists today.

The heathland landscape was considered of little importance or interest to the growing economic society that thrived after the industrial revolution, however it was an ideal setting for military manoeuvres and army camps took up residence on heathlands from the late 18th century. Evidence of this can still be seen of this all over lowland Britain today as many of the military stations have continued to exist and grow on heathland sites.

Today heathland is of significant conservational importance due to its decline and continued threat from human activities. Most are now designated SSSI or SAC with some also coming under SPA designation if certain birds are present at the site.

Heathland sites are now more fragmented than ever with small-localised habitats, 82% of all sites designated are considered as being in unfavourable condition. Heathland is a key issue in conservation today and its future hangs in the balance, and it may already be too late as only 58,000 ha exist today in the UK and most of these are in very poor condition. However the Biodiversity Action Plan (BAP) aims to improve existing sites and establish a further 6,000 ha of heathland in lowland Britain.


The Physical Environment
Lowland heath has developed as result of human interference; its survival has also depended on several physical factors that have contributed to its current status. Heathland is restricted by climate, despite it frequenting well drained soils it cannot thrive on continental climates with dry summers and cold winters as water availability is just too low, preferring a more moist “oceanic” climate, of which Britain is ideal. The high precipitation levels in the UK allow heathland to continue and strengthen.

Lowland heath predominantly occurs on acidic, free-draining, sandy soils with poor nutrient availability. The underlying geology varies but in the south and east, heathland soils sit upon sands and gravels and sometimes clays: E.g. heathland found in the Thames Basin is made up of tertiary sands over London clay. The presence of clay can help to trap water, creating microhabitats within the heath and increased moisture spurs an increase in species diversity especially with regard to invertebrates. Although heathland may seem uniform and similar in appearance, variation in geology and soils produces different habitats and communities.

There are three types of heathland, wet, dry and humid; wet heath occurs in areas where the water table is predominantly high throughout the site and water is readily available, dry heath occurs on very well drained soils and underlying rock formations and thus the water table remains consistently low. Humid heath is an intermediate of the two, experiencing both wet and dry conditions throughout the year.

Topography varies from one heathland to another, though predominantly rolling hills and varied mounds and valleys seem to provide the most opportune structure for varied wildlife. The hilly landscape creates high and low points with continual erosion of unstable loose sand deposits on the slope; this helps new species to develop and provides ideal conditions for some specialised species that require base open ground.

Hills and valleys also allow minerals to be washed down from higher ground, possibly creating podzols and iron pans: areas capable of containing water, increasing the diversity of the habitat. Another factor that arises from varied slopes is the amount of light and shade varies depending on which face faces south, this allows for very different types of vegetation to occur in close proximity to one another. Although there is often a lot of slope on lowland heath it can also experience areas of very flat terrain, and even in the hillier areas there it does not compare to the heathland of highland Britain that occurs at high altitudes and on much larger, steeper slopes.


Plants and Animals
Vegetation
Lowland heaths are dominated by the presence of ling heather (Calluna vulgaris); this is the most common heathland plant and is the sole species of its Genus. Ling is a small perennial shrub growing 20-50cm tall. Small scale like leaves have adapted to conserve moisture and reduce transpiration rates. The roots spread radially to absorb moisture quickly and the evergreen leaves allow the plant to produce food all year round. Ling heather also benefits from a symbiotic relationship with mycorrhiza in which the plant is aided with nutrient absorption and the fungi receive sugars.

Ling has developed and adapted to withstand fire, a popular historical form of management and one still practiced today, its ability to withstand controlled fire conditions and show positive regeneration afterwards has contributed to its success on heathlands. The seeds can lay dormant for many years in the soil and fire open up the area to light allowing new growth to commence.

Ling heather is a valuable food resource for a wide range of species including sheep, deer, grouse, heather beetle and the larvae of numerous species of Lepidoptera.

Ling is also accompanied often by Bell Heather (Erica cinerea) a low growing shrub with needle like leaves. It is less woody and more slender than Ling and often uses other heathers and gorse for support and grow tall in close proximity with higher vegetation. Bell Heather forms dense uniformed swards and accompanies other heathers in providing food and protection for heathland animals.

Common Gorse (Ulex europaeus) is a spiny evergreen shrub that can reach up to 2 meters, the stem is hairy and leaves have adapted to low water availability by tuning to spines, which reduce water loss rates. Common Gorse is also a fire climax plant; it burns easily but regenerates well from the roots after a fire.

The bright yellow flowers bloom in mid summer attracting hundreds of invertebrates to feed on the sweet nectar; the plant emits a sweet coconut-like fragrance to attract insects. Stonechats (Saxicola torquata) use the higher branches to sing and Dartford Warblers (Sylvia undata) are attracted by the abundance of insects and will nest when gorse occurs in dense growth with heather. In the south of England you will also find Dwarf Gorse (Ulex minor), which as its name suggests is much smaller than Common Gorse, reaching up to a metre tall.

Invertebrates
5,000 species of invertebrate occur on heathland in the UK, with a variety of butterflies, wasps, bees, beetles, spiders and ants. Digger wasps and solitary bees are common to heathland because of the patches of open sandy ground that occurs throughout.

Sand wasps (Bembix spp) construct tunnels in bare patches of ground in which they lay their eggs, the tunnels are then sealed stocked with food (normally spiders or caterpillars but dependant on prey species choice) which is eaten when the eggs hatch.

Potter Wasps (of which there are over 200 Genera but are most often considered to be of the Subfamily: Eumeninae), construct pots from the soil which they stick to heather branches. The pots are filled with eggs and paralysed prey and then sealed.

The Silver Studded Blue Butterfly (Plebeius argus) is a common inhabitant of heathlands, feeding on ling, Bell Heather and Gorses. Males display bright silvery-blue wings, whilst the females are a dimmer brownish hue, both sexes display the characteristic metallic spots on the hind wing that the species is known for. The butterflies rely on short, sparse vegetation and prefer the open canopy of recently burnt heath.

Birds
Heathland provides food and shelter for both migratory and native birds; there are several species of particular association with heathland over other habitats. Nightjars (Caprimulgus europaeus), are African migratory birds that arrive in spring to nest, they inhabit lowland heaths as well as open woodland and young conifer plantations: theses birds prefer open patches of heath and the small clearings that occur there.

Both sexes are well camouflaged for ground nesting, displaying mottled grey to brown hues, the body is sleek and pointed and well adapted to hunting prey on the wing. Nightjars feed at dusk, dining on the abundant invertebrates that arrive on heathlands over the warmer months.

A popular bird of lowland heath is the Dartford warbler (Sylvia undata), it has suffered decline in past years but populations are slowly begging to rise again with the milder winters that Britain has been experiencing and designative protection from the government (however still confined to southern heaths).

Dartford warblers are small birds with long tails, the coats are brown above with pink below and the both sexes have similar coats with the male exhibiting brighter shades. Most warblers fly to Africa in the autumn, Dartfords survive from the protection provided by dense stands of evergreen heather and gorse, the vegetation provides a barrier from snow, rain and cold winds and the canopy is inhabited by enough insects to make survival possible.

These birds benefit from managed heath with varied ages of stands providing continual protection.

Stonechats (Saxicola torquata) though not restricted to heathland, are frequent inhabitants nesting in dense patches of gorse and heather. The males also require higher local vegetation on which to sit and call this is normally an upper gorse or scrub branch. This species benefits from some scrub present and feeds on fruits as well as insects.

Reptiles
Heathlands can be home to all six native species of reptile, four of them can be found in other habitats around the country, but two species are restricted to heathland and its surrounding boarders.

The Smooth Snake (Coronala austriaca) is a pretty rare species found only in the lowland heath of Dorset, Hampshire and Surrey. The skin is a camouflaged grey-brown colour with two rows of small, dark markings don the length of the body. Smooth snakes grow to 60-70cm long and feed on other heathland reptiles such as common lizards (Lacerta (zootoca) vivipara) and slow worms (Anguis fragilis), as well as small mammals. These snakes will bite to protect themselves but have no venom: they predate through constriction. Smooth snakes rely utterly upon well-managed, mature heathland with plenty of hiding places in which to sun itself.

Sand Lizards (Lacerta agilis) are another heathland dependant and are scarce in the UK occupying small areas in Dorset, Hampshire, Surrey and Lancashire. Their survival is closely linked to managed heathland especially where bare patches of sand are created, on which they can dig tunnels for their eggs. The eggs remain buried for several months and the open sand helps to keep the eggs warm. Sand lizards are distinctively stockier than the common lizard with a deep short head and bulkier frame. Both sexes are marked with a mix of black, brown and cream spots running down the back, in spring males are bright green whilst females remain a pale brown, sandy colour.





References:
http://www.butterfly-conservation.org/species/bdata/butterfly.php?code=sib
http://www.dorsetforyou.com/index.jsp?articleid=336264
http://www.surreycc.gov.uk
http://home.freeuk.com/offwell/whatis.htm
http://www.ukbap.org.uk/ukplans.aspx?ID=15
http://www.surreyheath.gov.uk/tourism/AboutSurreyHeath/heritage.htm#camberley
http://www.wildlifetrust.org.uk/cheshire/heathland.html
http://www.countrysideinfo.co.uk/historic.htm

River Pollution

Rivers are an important part of our landscape; they distribute water all over the country and provide a habitat for wildlife. Over history they have been an essential factor in the survival and growth of man, providing water, food, transport, power and more recently for disposing of waste! Without the presence of rivers our country would be a very different place.

Today they are highly valued for their beauty and attract much tourism. Pollution threatens to spoil and damage the rivers and streams that have been such a large resource to us. Pollution can occur in rivers from various sources. It could come about from direct disposal, surface run off, groundwater drainage, side streams, other water sources and acid rain. All these fall into two general types of pollution direct and indirect. Direct comes from pollution being directly deposited into the water and indirect entering the water from soils and rain runoff from land.

Agriculture has a large role to play in river pollution and as it covers a large part of the country has a lot of influence on how clean rivers can be kept. Farmers will often keep livestock on fields near rivers, of which cattle are most relevant regarding water pollution. The manure passed from these animals washes of the surface of the soil and into the river, as the manure breaks down nutrients leach into the river through ground water. This manure or “silage” is a strong pollutant that can have a massive effect on the quality of the surrounding water and give rise to environmental issues.

Manure produces certain chemicals, some of which are essential to life in a river. The quantities of these chemicals need to be a certain level to sustain a healthy ecosystem; the excessive amounts of these nutrients that manure provides are far too much for a river to cope with.

Nitrates, phosphates and sulphates are all released from manure, they are essential plant nutrients and once in the water will soon cause an abundance of growth in aquatic plants. This excessive growth causes problems for wildlife species that use the river for food, shelter etc. The flow of the river is reduced and as organic matter dies the bed becomes shallower increasing the chances of flood.

In these situations biodiversity is reduced but the overall biomass of the water can be increased this is because only a few species dominate but they are extremely abundant and numerous.

The chemicals not on only increase vegetation but effect species of fish, invertebrates and aquatic mammals that live in or around the river. Each species has its own tolerance levels of nutrients in water, but the numbers of species that can survive in a polluted river decreases as these nutrient levels continue to increase.


Chemical pesticides can have a more direct relationship with pollution simply from the fact that they have direct killing power, this means that certain species who absorb or consume the pesticide will die. This is different to chemicals altering the properties of water, which results in a change of habitat and life in the river. The sudden death of any organisms within the river ecosystem will have a direct impact on other species in the community, through loss of shelter or food. The use of these pesticides also increases the nutrient levels in the water with the same effect as with manure.

Disposal of domestic waste combines both these pollutants with human excrement and grey water from washing machines, baths, sinks etc. Although these waste products are treated there is still high levels of pollutants in the water that is released into rivers by sewage companies. Industry waste dumps massive amounts of chemicals and poisons into rivers regularly which poison and destroy aquatic life.

When fossil fuels are burnt they release sulphur dioxide into the atmosphere, which are absorbed by clouds and falls to the earth as rain. The rain enters the river directly and through soil run off and leaching. The sudden decrease in pH can kill fish and invertebrates and cause the water to be unsuitable for many species. There are few species that tolerate water with a pH lower than 5.

Once the pollution has entered the river it is hard to control, it quickly spreads with the movement of the water to other rivers, streams lakes and ponds. This movement, despite spreading the pollution to other areas is what helps rivers to cleanse themselves. Because of the constant distribution of fresh water the pollution gets diluted and dispersed, lessening its impact on particular areas. Rivers with water falls get a lot more oxygen into the water supply, the oxygen is used by aerobic bacteria to break down dead organic matter, this helps the river to disperse nutrients and clutter on the bed.

If the same levels of pollution were deposited into a still body of water the nutrient levels would rise continuously and provide a habitat suitable only for the most hardy of creatures, such as rat tailed maggots and sludge worms if any life at all.

Ponds and rivers have very different reactions to the same pollutants, pond require a much higher degree of management in relation to pollution due to their ‘closed’ nature, pollution can only be diluted by rainfall or from directed ditches and channels. It cannot cleanse itself through water flow.

Pond and lakes are a much more stable environment because of the lack of flow, plants and animal life can establish and develop easily. In a fast flowing river aquatic life can be reduced to bottom dwelling creatures living in the silt and stones because the force on anything higher is too much for many plants to take root. For this reason changes in nutrient level from pollution can be far more devastating in ponds than in rivers and streams.

In polluted pond water the vegetation ‘blooms’ chocking off oxygen to other species in the water, this unbalances the ecosystem and reduces the ability for diversity, algae blooms dominate shutting out light and consuming lots of oxygen, the growth gets to a point where the water can no longer sustain it and the algae production collapses, this damages the ecosystem even more by sinking to the bottom and building up a layer of organic matter. The reduced oxygen in the water means bacteria and fungi cannot break down the matter and the depth of the pond decreases. Constant pollution accelerates eutrophication resulting in the succession to land with no aquatic life left.

Algae blooms cannot build up in rivers due to the flow, but can in slower parts of the river or small pool off the river, when the matter dies it is more likely to be washed away and distributed more evenly over a wider scale. Lessening the impact of silt build up.

Ponds and rivers can also be affected by oil runoff from roads; the oil creates a film over the surface of the water. In a pond this layer will sit and spread evenly over the surface preventing oxygen dependant species from surfacing to breath resulting in death and reduced diversity. Larva living in the water will not be able to emerge reducing populations for the season; this will affect other species that feed on them by reducing a resource. This causes whole population to dip and without water cleansing disappear from the site all together. In rivers the oil would flow down the course and be deposited in pools and ponds attached creating problems in unique habitats that survive along side the river. The main body of flowing water often recovers well from pollution but at the cost of other habitats.

Another area where flow helps to cleanse pollution is where suspended soils hang in the water, in ponds where water remains generally still, organic matter and clays from surface runoff sit in the water reducing light to vegetation and damaging animals by clogging and chocking breathing and feeding mechanisms. In rivers these soils cannot be suspended but move with the flow and are deposited along the bed and banks when the water slows.

Generally the water in a river can cope well with pollution but the vegetation and land around the river suffers as pollutants are deposited there. These bank sides are vital habitats for many birds, insects and aquatic mammals. When the soil around the water is rich in nutrients, it tends to be dominated by only a few invasive species such as Himalayan balsam, which quickly spreads along the watercourse, out competing species more valuable to wildlife.

The presence of waterfalls and increased gradients along river help with the cleansing process through increased oxygen. I measured the cleanliness of water in three areas along a water course, at one point a water treatment facility deposited treated water back into the river. Even though the water had been treated there are still visible traces of increased nutrients in the water. Several test were done, measuring the cleanliness by chemical tests and species of invertebrates found. The results showed that the water quality decreased immediately after the input of treated water, with higher nutrient values and decreased diversity of invertebrates.

Further down the river after a small waterfall, the water had become cleaner and more abundant. This shows the rivers ability to recover from the effect of pollution through self-cleansing. The oxygen gained from waterfalls and changing gradients helps to defend the river from the effects of plant growth and oxygen reduction that occurs with it. These features also help to increase the speed of the flow dispersing pollutants faster.

Lentic Habitats

Lentic habitats are still water habitats. This means they have no distinct flowing water through them, some examples of lentic habitats are:

• Ponds
• Canals
• Reservoirs
• Ditches
• Dew Ponds
• Moats

As lentic habitats are all land locked they renew their water supplies mainly from rainfall, this can be directly into the water or through draining from the ground; without this the habitat would eventually dry up through evaporation.

Some lentic waters have drains built to draw water from nearby lotic habitats to keep them replenished. The water renewal also plays apart in the level of permanence to the habitat, for example puddles can be classed as lentic habitats but are temporary as they only occur when rain has fallen and evaporate pretty quickly.

Lentic habitats can be classed in three levels of permanence; temporary, semi-permanent and permanent. It all depends on the structure of the habitat and ecological influences such as duration of rainfall and climate.

Areas such as lakes and big ponds will be permanent fixtures in places that have plenty of rainfall and cool temperatures, where as in hot dry climates they would probably be a semi permanent body of water because of the lack of rain and increased levels of evaporation at certain times of year. The depth of the habitat also will affect its level of permanence: the deeper it is the more water it can afford to lose and still be a quality habitat. These permanent habitats are home to creatures all year round.

Semi permanent habitats are often seasonal, places such as ditches will come into this category, they fill up over the wetter seasons and spend the rest of the year drier. Semi permanent habitats are not a constant water habitat and during its dry season will be home to non-water dependant animals. The potential habitat is always there but water renewal rate controls the frequency of it being a water habitat.

Temporary habitats are unreliable habitats for creatures dependent on living in water, they can come and go on a day to day basis, the animals that live in these habitats must be highly adapted or be able to migrate when the need arises. Temporary water habitats can appear in any divot or dip in the landscape and are not constrained by defined margins.


Lentic habitats will vary in their nutritional status; this will affect the diversity of species that inhabit the water. The nutritional status is generally put into four groups

Oligotrophic - Areas of water will very few nutrients and offers little in which to sustain life.
Most of what is found here are bacteria; a creature would have to be very
Specialised to survive in this environment.

Mesotrophic - This is used to describe areas of water with beds of submerged vegetation and medium levels of nutrients. Places like this are more suited to assisting
life than oligotrophic waters.

Eutrophic - Relates to areas of water with rich mineral and nutrient properties, habitats
with these levels of nutrients are often covered with excessive amounts of
algae which can be detrimental to other species inhabiting the water.

Dystrophic - The water has a very acid content and poor in other nutrients, this limits the
vegetation and creatures that can survive in these waters. Often very ‘boggy’
areas.


Zones
Lentic habitats are divided into three zones, littoral, limnetic and profundal. These zones are the layers that support different organisms; each zone has its own special characteristics that certain species will favor over others.

Littoral zones are closest to the shore, they tend to be shallower and hold a lot of vegetation as light can reach all the way to the floor. This zone tends to be abundant with life due to its food source and plenty of shelter. This is where you will tend to find emerging plants, which will increase the diversity of species living here.

The next zone is the limnetic, this is a layer of open water away from the shore, this is the area where most photosynthesis occurs as thw water gets a lot of light and doesn’t run to deep. Floating micro-organisms and swimming creatures dominate this area.

The profundal zone is the deeper level of a body of water more common in lakes than ponds, as this is a deep area with little light. This zone relies on dead organic matter dropping down from the other zones: which is then recycled into nutrients by bacteria and fungi decomposing it. There is less life down in the profundal zone due to its lack of light and cooler temperatures.


Thermocline formation
A thermocline is a layer within a body of water that acts as a barrier between the higher and lower levels. It is formed when sunlight hits the surface layer of the water (epilimnion) and heats the water. Most of the heat is absorbed in the epilimnion and is circulated to warm the rest of the water, however the lower level of water (hypolimnion) is to deep and dark to get heated by the sun, here the temperature is much lower. The area between these two layers where the temperature begins to change rapidly is known as a thermocline. The hypolimnion continues to drop in temp but at a more gradual rate.

The thermocline then acts as a barrier, preventing the two layers from mixing: this means that we end up with two different habitats within the same are of water. The epilimnion is warm with higher levels of oxygen and the longer the thermocline continues the more stable this layer becomes. However the thermocline prevents nutrients from rising to the surface from DOM, which reduces the resources available to this layer.

The hypolimnion at this time is affected by various factors including lack of light and heat and oxygen: which prevents plants from growing, restricting food for organisms living in this layer. The bacteria in this layer will also consume most of the oxygen creating a difficult environment for non-specialised creatures to live in.





References: www.broadwaters.fsnet.co.uk
http://home.comcast.net
http://en.wikipedia.org
www.answers.com

Physical and Chemical Properties of Water

Physical Properties

Lack of Desiccation. All organisms need water to survive; this applies especially to creatures living in water that would die if removed. In water these organisms are kept constantly wet and only survive because of it.

Support. Water has the ability to physically support the weight of life forms, lifting smaller more fragile life forms higher where they can receive light, heat and nutrients. These organisms are often at the base of the food chain and are extremely important for sustaining life in and around the water.

The support provided by water also makes swimming and paddling much easier due to its density. Creatures can push water away to move where as in air they could not. This support also allows plants to float on the surface, this can be in the form of free floating plants or plants rooted to the bottom with the upper most part extending out of the water. These plants provide food and shelter for animals.

Surface Tension. Water has a high surface tension; this means that there is a strong cohesion between water molecules. This allows some life forms to stand and move over the surface of the water because the force of cohesion is stronger than the force put upon it by the life form. This level of tension works in a similar way when trapping small creatures that fall in, because they put such a small force on the water they do not sink, in these cases they will provide food for surface dwelling animals. This tension also helps creatures to hang from the surface to breath, as the molecules force together and hold the creature in place.

Temperature. Water has a reasonably constant water temperature, the change in water temp is a gradual rather than rapid process, and this is because it can absorb large amounts of heat energy before it actually starts to get hot. This provides a consistent environment for life, rather than the swinging temperatures of air. Oxygen dissolves naturally when it comes into contact with air; lower temps of water dissolve greater amounts of oxygen, which is used to sustain life. The lower temps also dissolve more CO2 causing them to have lower pH levels: which tend to provide a greater biodiversity compared to more alkaline waters.

Temperature is also the instigator for thermocline formations (if deep enough), creating separated areas with very different temperatures and this variation in temp causes the habitat to almost become two separate habitats.

Ice. The surface layers of water are affected most dramatically by temperatures dropping, at these times this layer will freeze and become ice, because water is less dense at freezing point it will float and stay at the surface leaving warmer waters deeper down. The water will have no contact with air and wind for fresh circulation of oxygen, which will cause death in organisms that breathe oxygen. Ice will also cause damage to plants putting extra pressure on roots and decreasing its nutrient supply. The total coverage of ice is dependant on how still the water is, (some lakes are large enough to have wave action and this movement can prevent the ice from forming).

Waves. Water can be moved by wind, with strong enough directional force a wave can occur. In areas with regular wind made waves there will be erosion of banks and plants from the continual stress of the heavy water. Waves can also circulate the water spreading oxygen and nutrients.

Transparency. Water is naturally clear, (it is discoloured by chemicals, organisms and sediments). This transparency is what allows photosynthesis and growth to occur in plants beneath the water. Light penetration can be impaired by organisms (algae, water lilies etc), sediments (soils, pollution) and shadow (from boats, trees, walls). Some natural staining can occur from peat, which turns water brown and also iron, turning water red. All this turbidity can have a negative affect on the aquatic plants ability to produce oxygen. There gets to a certain depth and turbidity where plants can only just survive as their oxygen out equals their intake per day. Any lower than this and the plant cannot survive.

Chemical Properties

Dissolved minerals. The level of minerals in a body of water will essentially determine what will live there, as they are essential plant nutrients. These minerals can come from several sources:when manure is put on soil to fertilise bacteria and fungi break it down, this process produces Nitrates. These minerals get in to the soil and when it rains, leach through the soils into the body of water. The plants then use the Nitrate for growth. Phosphates will work in a similar way.

They can also be produced by dead organic matter (DOM) breakdown in the water and from detergents and wastewater being washed in. Sulphates and chlorides are naturally present in water but can also be washed in too. Minerals such as calcium carbonate and magnesium carbonate are also essential to aquatic life and determine water hardness; the more present the harder the water. Water hardness is closely linked with pH levels and so is important for sustaining life. Calcium and magnesium in water will affect alkalinity, certain species will not be able to tolerate alkaline waters and others will thrive, so levels are relevant to biodiversity and the types of species found in the habitat.

These minerals are all dissolved when they come in contact with water, this chemical process make minerals far easier to absorb and for use by plants, this will then benefit the growth and health of the vegetation in and around the water.

With a lot of minerals coming from surface water run off and leached groundwater you tend to find ponds and lakes on lowlands to be very high in these nutrients (eutrophic) and the abundance of algae is usually an indication of this. Ponds or lakes situated on higher ground will often have lower levels of nutrients in varying levels.

Dissolved gases. Oxygen is the most important gas to sustain life in waters, when air and water come in contact oxygen is dissolved into the water. This allows the species living in the water to breath. Oxygen is also produced by plant life in the water from photosynthesis. The temperature of the water greatly affects how much oxygen can be absorbed, the cooler the water the greater the amount of oxygen that can be dissolved. Oxygen is lost at night when plants respire, absorbing oxygen and producing CO2, it can also be lost through an abundance of algae sitting on the surface of the water blocking the light, which then restricts photosynthesis.

There are also varying amounts of CO2 present in water, produced by respiration from plants and animals, too much CO2 in water can be very detrimental to pond life.

Acidity. The pH of water is dependant on various factors; the geology of the area will provide certain types and levels of minerals, which can influence the pH level along with their presence in the surrounding soils. The pH level is directly linked to species found in a pond or lake, high levels of acidity can kill fish or cause so much stress that weight, size, ability to hunt or flee may become impaired and ultimately the species may no longer survive on the site. reducing biodiversity and upsetting the balance of the ecosystem.

Small fluctuations can occur to the pH level at night when plants are producing CO2 but the fluctuations are minimal and the levels are generally quite stable.

Organic matter. The bulk of organic matter found in the water sits at the bottom, it comes from the death of macrophytes (algae) and leaves that have fallen from trees and been blown into the water. All this DOM sinks and eventually gets broken down by bacteria and fungi.

During this process CO2 is given off and oxygen used up and so links directly to the oxygen supply and nutrient values.

Shallower bodies of water will have a rich substrate because of the presence of vegetation at the bottom, compared to this deeper bodies like lakes will have less of this richness because plants cant survive at that depth because of the lack of light. You have to be careful with the shallower pond because this level of organic matter can build up substantially and reduce the water depth over a few years. Organic matter also comes from the breakdown of reedy plants, their structure allows for slower decomposition and produces detritus: which is an essential food for many smaller species living in the water.