Human Influences on Biodiversity

Human Influences on Biodiversity - SQA Key definitions: 

• Base flow - The discharge of a river during prolonged dry periods, where there is no additional flow due to precipitation.

• Diffuse pollution - Pollution with no specific point of discharge, and is the result of activities spread across large areas, e.g. smog caused by vehicle exhaust over a city. 

• Environmental assessment - An evaluation of the potential environmental, social, and economic effects of a proposed project before a decision is made.

• Environmental impact assessment (EIA) - An assessment made to protect the environment by ensuring that a local planning authority has full knowledge of possible significant environmental effects of a proposed development, and mitigation for these, which are taken into account in the decision-making process. 

• Environmental monitoring - The processes and activities that need to take place to characterise and assess the quality of an environment over time.

• Groundwater - Water located beneath the Earth's surface in the soil pore spaces and in the fractures of rock formations.

• Habitat - The place where an organism lives. 

• Habitat destruction - The destruction of an ecosystem, leaving natural habitats unable to support species and communities within them. This reduces biodiversity, sometimes to the point of extinction.

• Habitat fragmentation - The reduction of a large habitat area into smaller, scattered remnants, which can have implications for biodiversity, including ecosystem diversity, species diversity, and genetic diversity.

• Hydrograph -  A graphical representation of water flow (or discharge) over time at a specific point on a river, stream, or channel.

• Initiative - Actions implemented by the government to achieve the goals of a strategy.  

• Invasive non-native species (INNS) - Any non-native animal or plant that can spread and cause damage to the environment, the economy, our health or the way we live. 

• Keystone species - A species which defines an entire ecosystem, having an effect on all parts of it. 

• Lag time - The time interval between the peak rainfall and the peak discharge of a river.

• Legislation -  A law or set of laws that has been formally enacted by the government to achieve a strategy.

• Marine protected area (MPA) - An area where potentially destructive human activities are regulated to protect natural and cultural features.

• Native species - A species within its natural distribution. 

• Non-native species - A species introduced through human action (accidental or deliberate) outside its native distribution. 

• Peak discharge - The maximum rate of flow of a river, due to additional water from a weather event such as precipitation or snowmelt. 

• Peak rainfall - The maximum intensity of precipitation (rain, snow, etc.) during a weather event. 

• Plagioclimax - An alternative climax community, which occurs when human influence has prevented progression to the natural climax community.

• Point pollution - Pollution discharged from a single location, e.g. pipe or chimney; individually minor but can combine to form diffuse pollution.

• Policy - A plan of action that focuses on a specific target. 

• Pollution - The introduction of contaminants into the natural environment that cause negative changes to the ecosystem. 

• Reforestation - The process of replanting trees and forests that have been cut down. 

• Rewilding - The implementation of activities that initiate or accelerate the recovery of habitats or ecosystems with respect to their health, integrity and sustainability. 

• Runoff - Chemicals entering a waterway such as a loch or river, from farmland, forestry activities, urban areas, roads and sealed surfaces, or industrial premises. 

• Site of special scientific interest (SSSI) - Areas of land and water that are considered to best represent the natural heritage of Scotland. 

• Strategic environmental assessment (SEA) - An assessment made to provide a high level of protection of the environment from development. It is mandatory for plans and/or programmes that relate to large-scale changes in land use

• Strategy  - The methods and principles needed to achieve a policy.

Human Impacts

Humans have throughout history had huge impacts on the natural world.  These impacts can be both positive and negative in effect; however, the vast majority of impacts that Humans have had are negative. The impacts are usually accidental (not intentional), but that does not make them any less impactful. The unintended effect of all of these negative influences is to reduce biodiversity, reduce or increase species population or cause extinctions. 

However, we are working to enact and support positive impacts on biodiversity, locally, nationally, and globally. 

Human influences on Biodiversity include:- 

• Habitat destruction

• Habitat fragmentation

• Rewilding 

• Harvesting practices 

• Reintroduction of nationally extinct species

• Point and diffuse pollution of air, land and water 

• Plagioclimax 

• Conservation practices

Habitat Destruction

Habitat destruction leaves natural habitats unable to support species and communities within them. This reduces biodiversity, sometimes to the point of extinction.  The most common form of habitat destruction is deforestation, but other forms include : Dam construction and flooding, filling in or draining of wetlands, unsustainable fishing practices, pollution, desertification due to climate change, etc. 

Deforestation is the large-scale removal of trees and forests, which occurs for a variety of reasons. 

These reasons include:-  

• Clearing land for farming 

• Clearing land to make space for settlements 

• Industrial use of wood (making paper, timber for construction, etc.)

• Clearing land for transportation reasons (road building, etc.)

• Use of wood as a fuel source

These reasons have been used for thousands of years on a small scale, but due to increases in population and technology, deforestation has increased rapidly over the last century, with clearing land for food being the main reason. 

The graph below shows the drivers of forest loss across the Brazilian Amazon rainforest in a single year (2013). As can be seen, clearing land for farming (especially cattle farming) makes up more than 75% of the deforestation:-

Deforestation has a huge impact on biodiversity by destroying habitats completely and therefore reducing the available land that species can thrive in. It is estimated that several hundred species of plants, animals and insects are lost each day, partly as a result of deforestation, and this rate is increasing. 

Deforestation Case Study : The Caledonian Forest

The Caledonian Forest was once a vast woodland that covered Scotland. The forest consisted mainly of Scots Pine, Birch, Rowan, Aspen, Juniper, Oak and a few other hardy species. On the west coast, however, Oak and Birch formed a temperate rainforest ecosystem rich in ferns, mosses and lichens.

The Caledonian Forest formed at the end of the last ice age, around 7,000 years ago, but by the 1600s had been almost completely destroyed through deforestation.  It remains now only in very small pockets of ancient woodland in remote parts of Scotland, which are now protected by law to preserve these remaining areas.

This unique ecosystem is home to some of Scotland's rarest species of plants and animals:-

Habitat Fragmentation

Even if the destruction of an ecosystem is not complete, Habitats can become isolated from each other, known as 'Habitat Fragmentation'. 

Habitat fragmentation results in the reduction of a large habitat area into smaller, scattered remnants and can have implications for biodiversity, including ecosystem diversity, species diversity, and genetic diversity. Loss of keystone species, in particular, can have a disproportionate impact on an ecosystem. 

Fragmentation impacts can include a reduction in the total area of the habitat, a reduction in the average size of each patch of habitat, and isolation of fragments. 

An example of habitat fragmentation can be seen between Humans and Elephants in India and South-East Asia. Elephants are found across South-East Asia, and where their habitats intersect with Human communities, due to the Elephants' large size and foraging habits, conflict can occur. 

Due to deforestation for either timber or additional farmland, the habitat of the Elephant is being greatly reduced over the last 100 years. This has led to more Elephants entering populated areas in search of food, coming into conflict with the people present.  

A single Elephant can eat up to 450kg of plant material a day, so with an average herd size of around 7, a family group can consume over 3 tonnes of food per day. This means that a group of Elephants can quickly consume entire smallholder farms in they enter the farmland. 

Farmer's livelihoods depend on their farms, so they defend them vigorously. As Elephants are huge animals, they can overcome most barriers put in their way, so noise defenses (such as banging metal sheets) or fire are used to drive Elephants away from farmland.

This has led to further losses to the Elephant population due to injuries sustained in physical conflicts with humans. Every year, people are injured and killed due to conflict with Elephants across South East Asia, with 100s killed in India annually. 

However, even though the number of Elephants has remained fairly constant over the last decade, the number of human fatalities due to Elephants in India has dropped by more than a third:- 

This is due to work being done between the farmers, government agencies, charities and other stakeholders to tackle the issue of human-elephant conflict.

Changes that have been made at the local farming level include:- 

• Increased natural (such as chilli-based) deterrent use instead of fire. 

• 'Buzzing Wall' defences using beehives (utilising the elephant's natural fear of Bees as a deterrent).

• Changing farming practices to make the farms easier to defend.

• Growing crops that Elephants are less likely to eat.

• Education of local populations in humane deterrent strategies and safe Elephant interaction strategies.

• Diversification schemes using the Elephants as a source of income (tourism etc.).

• Introduction of 'Elephant corridors' to allow seasonal movement through the farmland without causing damage. 

Rewilding

Rewilding involves activities that initiate or accelerate the recovery of habitats or ecosystems with respect to their health, integrity and sustainability. 

Rewilding involves:- 

• Erosion control

• Reforestation

• The use of local native species

• Removal of non-native species

• Removal of invasive plants

• Reintroduction of native species and keystone species

• The creation of wildlife or habitat corridors to link habitat fragments. 

An example of rewilding in Scotland can be seen within Creag Meagaidh National Nature Reserve in Northern Scotland. 

This region of Scotland had been overexploited for forestry, Deer and Sheep farming for centuries. The ecosystem had lost almost all of its native tree cover due to overgrazing, and the loss of habitats had severely reduced biodiversity. Without natural predators, the Deer population was too large, leading to over-grazing and other environmental damage. 

In the mid 1980s, a program of Deer Control measures were put in place to reduce deer numbers within the area. These control measures included Deer Fencing to prevent access, issuing Deer Stalking permits and in some cases systematic Deer Culling to directly reduce numbers. 

Over the last 40 years, the reduction in Deer population has allowed the recovery of the native plant species, with tree coverage increasing without the need for planting, as well as the return of many plant species that used to be present. The increased plant and tree cover has allowed an increases in the variety of habitats  and therefore has shown a marked increase in local biodiversity. 

Rewilding : Removal of Non-Native and Invasive Species

For native plants and animals to thrive, non native and invasive species are removed from an area that is being rewilded, allowing the native organisms to flourish.  

Rewilding : Reforestation

Reforestation is the process of replanting trees and forests that have been cut down. There are two main types of reforestation activity:-

Reforestation supports the biodiversity of an ecosystem by replacing lost habitats and preventing the felling of virgin forests by providing a more sustainable source of wood for industry. 

However, just like other forms of rewilding, if reforestation is not fully thought out and well implemented, it can cause further issues:- 

Agroforesters plan and plant land to have a mix of agriculture and forest for improved crop yields and promote a healthier environment. The idea behind agroforestry is to use trees and shrubs to complement the plants being grown in agricultural practice. For example, some crops grow better when in the shade, such as leafy greens and some herbs.

An Agroforester will plant crops that work well together in a natural environment, and that will benefit ecology in an area, such as trees providing habitats for animal species. Crops and trees or shrubs can also be planted to repair where the soil may have become exhausted of nutrients due to over-farming. As the effects of climate change increase and soils experience change or damage, this is expected to be a major area in which Agroforesters will work in the future.

Key Environmental Agencies : 'Forestry and Land Scotland' & 'Scottish Forestry'

In Scotland, there are two main organisations with a remit covering Scotland's forested areas : 

Harvesting Practices

Over-exploitation occurs when a plant, animal or physical resource is harvested at a rate that exceeds the reproduction of the plant and animal species or the replacement of the physical resource. 

By over-exploiting a species, that species will show a rapid decline in numbers and, in severe cases, become extinct. 

Harvesting Practices Case Study : North American Bison

Before the arrival of Europeans, there were an estimated 60 million Bison, being sustainably managed by the Indigenous American population. 

By the end of the 19th century, however, this Bison population had crashed to only 512 individuals due to a combination of market demand for meat, as well as a deliberate effort by the US Government to wipe out the bison in order to exert control over the Indigenous population (due to their heavy reliance on Bison). 

By 2016, due to conservation efforts, the number of Bison in North American had gradually climbed up to about 20,000 individuals. 

Bison conservation is important as the Plains Bison is a 'Keystone Species'. A keystone species is a species which define an entire ecosystem, having an effect on all parts of it. 

When the Bison grazes on grasses, they do this to a range of sizes, creating a range of habitats for small mammals, insects and birds. Through their dung, seeds of plants are spread and existing plants are fertilised. The hooves of the Bison break up the soil, allowing oxygen to penetrate deeper and cycling nutrients to the surface. 

The Bison also roll to clean themselves, causing depressions called wallows to form. The soil in these wallows is compacted and water cannot pass through it, so when it rains these wallows fill with water. These water filled wallows provide additional habitats for amphibians and birds as well as drinking water for a range of species.

Harvesting Practices Case Study : Northern Atlantic Cod

The Grand Banks of Newfoundland are a series of underwater plateaus found off the northeast coast of Canada. For centuries the Grand Banks produced a seemingly endless supply of cod and other commercially valuable fish. 

However, overfishing and mismanagement of stocks in the second half of the 20th century saw the number of cod shrink and then ultimately collapse, leading to a moratorium on fishing for Cod in the Grand Banks in 1992.

This moratorium (the total ban on commercial fishing for cod), devastated the local economy and caused significant social issues for the people of Newfoundland, with 37,000 people losing their livelihoods. 

Studies of the Northern Atlantic Cod have show since that the moratorium came too late, and Cod in large numbers may never return to the Grand Banks. 

The graph below shows the amount of Cod landed in Newfoundland since the 1960's:-

The population crash of Cod in the late 1970's can clearly be seen, as well as the impact of the moratorium in 1992. In recent years, some limited fishing has been allowed again, but at severely reduced numbers.

Reintroduction of nationally extinct species

When a species is absent from an area due to human interactions, it can be reintroduced by transplanting populations from elsewhere. The aim of this is to allow the restoration of the complex ecosystem that used to be present. This is especially important if a keystone species is reintroduced, as these define an entire ecosystem, affecting all parts of it. 

The reintroduction of species must be carefully managed, however, as there is a large range of impacts that could be caused by the careless introduction of a species into an area, especially if it is an apex predator. 

Human Influences : Point and diffuse pollution

As human populations have increased, so has the amount of pollution that is entering the environment. Pollution can come from many sources and cause damage to a wide variety of ecosystems, sometimes thousands of miles from its source. 

Pollution can be categorised in two ways :  

• Point Pollution - Point source pollution is discharged from a single location, e.g. pipe or chimney; individually minor but can combine to form diffuse pollution.

• Diffuse Pollution - No specific point of discharge, and is the result of activities spread across large areas, e.g. smog caused by vehicle exhaust over a city.

The diagram below shows some sources of pollution :-

Pollution Case Study : Eutrophication

Eutrophication occurs when fertilisers or sewage enter a waterway such as a loch or river (known as runoff), and causes excessive plant and algal growth, causing major changes in the balance of the ecosystem. In severe cases, eutrophication can cause the complete collapse of an ecosystem. 

As can be seen in the above graph, as the nutrient levels in a loch increase, a huge increase in Algae growth comes at the expense of all other aquatic plant life. 

This thick blanket of Algae prevents sunlight from reaching the plant life below the surface, preventing photosynthesis and therefore killing the Pond Grasses and Phytoplankton present. 

When the algae die, their remains are decomposed by bacteria in the water, depleting the oxygen levels in the water, killing aquatic life such as fish.

This completely disrupts the Food Web, with the potential to cause a collapse of the entire ecosystem, leaving behind a dead, empty loch. 

The process of eutrophication can also occur in marine environments:-

Human Influences : Plagioclimax 

An alternative climax community, which occurs when human influence has prevented progression to the natural climax community, is known as a Plagioclimax. These Palgioclimax communities can be either accidental or intentional : 

Plagioclimax Case Study : Muirburn 

Muirburn is the process of controlled and intentional burning of moorland vegetation, most commonly heather, to promote a community best suited for grouse or grazing animals. The primary aim is to create a mosaic of vegetation patches of different ages and heights across the moor. 

Small, carefully managed strips or patches of older, woody heather are burnt on a rotation (typically every 10 - 20 years). The fire aims to be a "cool burn," removing the canopy without igniting the underlying peat or deep soil, resulting in the older, tougher, less nutritious heather being replaced by young, vigorously regenerating shoots. 

The mosaic provides a mix of habitats essential for Red Grouse, as young, nutritious shoots are food for chicks and adults, while older, taller patches provide cover and nesting sites. The fresh growth of grasses and heather is also more palatable and nutritious for grazing animals like sheep, cattle, and deer.

Plagioclimax Case Study : Conservation Grazing

An alternative to Muirburn that is available to landowners is 'Conservation Grazing'. Conservation grazing uses low-intensity grazing by livestock (such as sheep or cattle) to manage the biodiversity of an area. 

Unlike intensive commercial farming, where the aim is to maximise livestock production, the goal of conservation grazing is purely ecological, the animals are used as a tool to achieve specific conservation outcomes. Their selective feeding, trampling, and digging create a patchwork of different vegetation heights and structures, improving biodiversity. 

Conservation practices

There is a wide range of conservation practices that can be used to protect and enhance biodiversity. 

These include :  

• Embedding consideration of biodiversity in policy, governance and decision-making 

• Environmental Monitoring

• Protecting wildlife sites

• Targeting action on priority species and habitats

• Engaging people and encouraging behaviour change. 

Conservation Practices : policy, governance and decision-making

The Scottish Government has also put in place a policy for the direct governance of biodiversity in Scotland. Known as the 'Scottish Biodiversity Strategy to 2045', the policy puts in place ambitious statutory (legally binding) targets and goals of the Scottish Government for the next 20 years. 

These goals include : 

• Accelerating restoration and regeneration.

• The protection of nature on land and at sea, both within and beyond protected areas.

• Embedding nature-positive farming, fishing, and forestry by ensuring these sectors are managed more sustainably.

• Recover and protect vulnerable and important species and habitats, making every effort to prevent the extinction of globally threatened species.

• Investing in nature, requiring both public and private funding to deliver the Strategy's aims and developing a values-led market for responsible investment.

• Taking action on the indirect drivers of biodiversity loss, such as production and consumption patterns, demographic trends, and socio-cultural values.

The language used by government to describe the work they do can be quite complicated. The diagram below gives a summary of governmental terms, with an example of their use : 

Key Environmental Agencies

In order to monitor, assess and regulate the human influences on Biodiversity, countries around the world have dedicated organisations that are responsible for overseeing this. 

In Scotland, there are two main organisations with a remit for this :

• The Scottish Environment Protection Agency (SEPA) 

• NatureScot (NS) 

Key Environmental Agencies : Environmental Monitoring

As part of their roles in governing Scottish biodiversity, both SEPA and NatureScot conduct environmental monitoring. 'Environmental monitoring' is the systematic and repeated measurement and observation of an area to assess the state of an area over time, and provide the data necessary for informed management and conservation decisions.

One of the key roles of SEPA is to perform 'environmental monitoring' of Scotland's waterways - its lochs, streams and rivers. Through monitoring, SEPA can determine that all legislation relating to the protection of the waterways is being followed. This includes rules on water abstraction by farmers, field runoff, outflows from industry and water treatment plants, or the impact of leisure uses such as boating or fishing. A key aspect is the use and interpretation of hydrographs. 

A hydrograph is a graphical representation of water flow (or discharge) over time at a specific point on a river, stream, or channel. By comparing a natural hydrograph to a modified hydrograph (e.g., from a dam, reservoir, or other potential change), ecologists can assess the environmental impact of human activities. SEPA then publishes this data at this link. 

Below are two examples of Hydrographs based on data gathered by SEPA : 

The above hydrographs show typical patterns for their locations: a repeating high-low cycle of the tides of the sea, or the approximately constant flow of a river. The discharge of a river during prolonged dry periods is known as the 'Base Flow'. The water of the base flow comes from groundwater runoff, water that moves laterally (sideways) through the soil and rock layers until it eventually discharges into the river channel. 

When precipitation (rain, snow, sleet, etc.) occurs, this additional water will enter the waterway and increase the flow above the base flow level. The hydrograph below shows an example of this : 

The above hydrograph shows the typical pattern seen in water levels after heavy rain. The rain that caused the change in flow occurred on the morning of November 22nd, labelled above as 'point of peak rainfall'. This is caused by rain falling directly into the river, giving a small increase in the flow at the time the rain actually fell. 

The maximum rate of flow of the river, known as the 'peak discharge', occurred approximately 24 hours later, on November 23rd. The time interval between the peak rainfall and the peak discharge of a river is known as the 'Lag Time'. This is caused by it taking time for the water that fell on the surrounding land to enter the river itself. This includes factors such as : 

• Vegetation cover - Trees and plants intercept rainfall, hold water, and promote infiltration into the soil. This prevents rapid surface runoff, increasing the lag time. 

• Soil Permeability - If the underlying soil and rock are highly permeable (e.g., sand, chalk), more rainwater will infiltrate the ground and travel slowly as groundwater flow, increasing the lag time. If the ground is impermeable (e.g., Granite or asphalt), the rainwater will travel as surface runoff, entering the river faster. 

• Ground gradient - A gentle slope means water flows more slowly both overland and through the soil, significantly increasing the lag time, whereas steep areas will have shorter lag times.

Environmental Monitoring : Environmental Assessment

As part of planning for construction and other projects, the environment must be taken into account. This is in the form of legislation, requiring that environmental assessments be performed prior to planning permission being given : 

Conservation Practices : Protecting Wildlife Sites

NatureScot is responsible for designating and protecting 'Sites of Special Scientific Interest' (SSSIs). SSSIs are areas of land and water that are considered to best represent the natural heritage of Scotland. 

This can be in terms of:

• Flora (Plants)

• Fauna (Animals)

• Geology

• Geomorphology (Landforms)

• Mixtures of these natural features 

It is an offence for anyone to intentionally or recklessly damage the protected natural features of an SSSI, and it is one of the roles of NatureScot to monitor and enforce this through prosecutions where necessary.

Key Environmental Agencies : Marine Scotland ( MS )

Marine Scotland is the directorate (department) of the Scottish Government that holds responsibility for the management of Scotland’s seas and is responsible for the marine environment, fisheries, and aquaculture. Marine Scotland is also responsible for designating and protecting the 'Marine Protected Area (MPA)' network. 

The Marine Protected Area network involves 231 sites covering 22% of Scotland’s marine environment. MPAs are areas where potentially destructive human activities are regulated to protect natural and cultural features. MPAs can also be beneficial to fisheries, creating safe havens for commercial species to reproduce, often followed by a spill over into surrounding areas.

Zoning aims to protect wildlife and to reduce conflicts of activities by designating what activities can occur in which locations. People carrying out activities not permitted in a particular zone will be fined; for example, a zone may permit Creel fishing but prohibit Dredging. This controls the use of the locations to reduce overall damage to fish stocks and ecosystems. 

The map below shows how the waters around Scotland are zoned. Fishing is either restricted or banned in all coloured areas:-

Protecting Wildlife Sites Case Study : Lamlash Bay No-Take Zone

Lamlash Bay No Take Zone (NTZ) is the first Community-led Marine Reserve of its kind in Scotland and was established in 2008 off the coast of the Isle of Arran, Ayrshire. Within the NTZ, no fish or shellfish can be taken from its waters or seabed, including the shore area.

It covers 2.67 sq km and was the result of 13 years of campaigning by the Community of Arran Seabed Trust (COAST).

Despite being such a small area, during the past 10 years researchers have found that the size, fertility and abundance of commercial species such as lobsters and scallops is significantly better within the No-Take Zone. Seabed biodiversity is also found to be increasing by 50% and anecdotal observations from divers, fishermen and anglers indicate that the seabed and fish are recovering. 

Note - for an article covering the progress of the Lamlash Bay No-Take Zone, please see - This Link

Conservation Practices : Targeting Action on priority species and habitats

By targeting action on specific species or habitats, an improvement for entire communities or ecosystems can be accomplished. 

Highly visible, popular, or culturally significant species (like the Scottish Wildcat or Golden Eagle) are often chosen as "priority species." Their charisma helps secure political will, raise funding, and engage the public. 

Targeting a priority habitat (e.g., Caledonian Pine Forest, Blanket Bog, or coastal machair) provides an 'umbrella' of protection for all the species that live within it, giving benefits at all levels of the ecosystem.

Conservation Practices : Engaging people and encouraging behaviour change

Governments, environmental agencies and charities are not capable of achieving their goals alone - they must have public support. A significant portion of the work involves raising public awareness and encouraging the public to follow guidance, donate time, or contribute money.