(6) Biodiversity and managing resources - reducing habitat destruction and over exploitation of natural resources

GCSE level Biology exam study revision notes on biodiversity and managing natural resources, problems with the misuse of land e.g. deforestation versus land conservation, over fishing stocks, indigenous plant and animal species versus the introduction of non-indigenous species

How we use or misuse land and water including deforestation, overfishing and the need for  land and water management conservation

The 'scenario' of habitat destruction

All around you can see how we have impacted on the landscape e.g.  agriculture, buildings, mining, motorways, quarrying, etc.  etc.  !!!

We all want a good standard of living, but the rising populations of the world are putting pressure on the biodiversity of where we live and what we have created from the Earth's resources.

All of this effects the original 'wild' landscape, which we have been reshaping for thousands of years, but never at a faster rate than the present time.

In perusing our developments we have left far too little land for the animals and plants that once lived there.

Asking farmers to leave a 'wild' 3 m strip around the perimeter of field is one small step!

The destruction of habitats and disruption of food chains and food webs, that once made up a complex ecosystem is having pretty negative effect on biodiversity.

The principal causes of habitat destruction

Human activity has considerably reduced biodiversity by extensive building of houses, factories and transport systems; quarrying/surface mining and large scale farming.

The land available for wildlife (animals and plants) is much reduced and the decline in biodiversity follows e.g. biodiverse woodland is cleared for houses or farming - but there is no denying they are needed.

But plant/animal species population numbers decline and animals have to move away to ever deceasing habitat possibilities - migration is one way biodiversity declines in a particular area.

 

Deforestation - why? impacts?

Why deforestation?

One of the most worrying developments is the deforestation of huge areas of the tropical rain forests in South America and Southeast Asia.

This mainly due to the huge scale and pace of deforestation e.g.  in the tropical Amazon forests of Brazil.

The deforestation is to clear the land for farming e.g.

(i) growing crops for food (e.g.  wheat or rice)

(ii) growing crops from which to make biofuels like bioethanol from sugar cane,

(ii) raising great herds of cattle for milk and meat.

Its easy to be critical of countries like Brazil, but many of us who live in well developed countries and enjoy a good standard of living (I live in England), should admit the people in other countries also deserve to have a better standard of living too.

The pressure on the landscape from our natural desires for lifestyle conflicts with what ideally we would like to see in the very landscape we admire but so strongly impact on!

There are no easy answers to this conflict of interests!

Impacts of deforestation on global warming and biodiversity

Deforestation is reducing the rate of photosynthesis taking place so less carbon dioxide is being removed from the air which, theoretically, is going to contribute to rising CO₂ levels and global warming - climate change, which is itself, having a negative effect on biodiversity.

Trees 'store' some of the 'carbon' taken in during photosynthesis for many years and this biomass of e.g.  complex carbohydrates like cellulose, means there would be less carbon dioxide in the atmosphere to contribute to global warming - but not if you cut down huge areas of forest.

To make matters worse:

(i) burning the trees to clear the land, releases large amounts of carbon as carbon dioxide back into the atmosphere,

(ii) and even if the trees are not burned, microorganisms can aerobically decompose rotting wood and also other organic material exposed on uprooting trees, again releasing more carbon dioxide into the atmosphere.

Cutting down lots of trees has led to the destruction of rich complex habitats of plants and animals and an unprecedented decline in biodiversity - many species are under threat and some have become extinct.

The variety of species of plants and animals ('biodiversity') is being considerably reduced by deforestation - destruction of habitats.

We should be planting more trees than we are cutting down to absorb as much carbon dioxide.

 

Peat - another example of an adverse landscape change

A bog or bogland is an acidic waterlogged wetland that accumulates peat, a deposit of dead plant material, usually mosses.

Most peat bogs are in the northern hemisphere - the largest are in Siberia, Russia.

Plants that live in bogs don't completely decay when they die because of a lack of oxygen.

The partially rotted plants build up layer after layer of peat over thousands of years.

This means a vast amount of carbon are stored in the peat, that would otherwise be carbon dioxide in the atmosphere and contribute to global warming.

Again, just like the 'Amazon rain forests', but not involving trees, the pressure for food production has meant that many areas of peat are being drained and converted to farmland.

The peat is sold to gardeners for compost - its a rich source of nutrients.

It is also used as a fuel - even power stations have been run off this semi-fossil fuel.

The result is that we are clearing away and using peat at a much faster rate that it is being formed.

Unfortunately, when peat is drained, the residual organic material comes into contact with air and microorganisms can decompose it aerobically.  In other words they use the oxygen in are to respire and give out carbon dioxide.

This means at the same time, the peat carbon store is released and more carbon dioxide is released into the atmosphere to contribute to global warming.

There is also another issue to do peat bog drying up.

With temperatures rising in the northern hemisphere, bogs are naturally drying out as well as being drained.

This makes then susceptible to burning, just as much as draining them.

This releases more CO₂ into the atmosphere and any residual organic material exposed can also be oxidised too.

As I write this (in August 2019) huge fires are raging across the peatlands and forests of Siberia in Russia releasing huge amounts of carbon dioxide into the atmosphere.

A positive note from Russia

The swamps and bogs surrounding Moscow had been drained in the 1960s for agricultural use and mining of peat as a fuel to generate energy.  In 2002, a series of hard-to-extinguish peat fires led the government to recognize that the peat fields needed to be re-watered to prevent wildfires.

From Wikipedia https://en.wikipedia.org/wiki/2010_Russian_wildfires

Both effects contribute to another example of habitat destruction, disruption of food chains and food webs, and a resulting decline in biodiversity as the 'local' ecosystems are wrecked.

 

Overfishing and fish farms (aquafarming)

Overfishing is the removal of a species of fish from a body of water at such a rate that the species cannot grow to maturity and reproduce in time.  This results in those species either becoming depleted or very underpopulated in that given area of sea.  Overfishing has spread all over the globe and has been going on for centuries and in modern times become even worse as huge trawlers and factory ships are hastening the depletion of fish stocks.

You need policies and regulations that prohibit overfishing and check that fish catches don't exceed a level that causes depletion of fish stocks.

One of the results of overfishing is the rapid development of factory farming methods of raising fish - an example of aquaculture, described next, but this is not without problems of its own.

Aquaculture, also known as aquafarming, is the farming of fish, crustaceans, molluscs, aquatic plants, algae, and other organisms for commercial purposes.   Aquaculture involves cultivating freshwater and saltwater populations of organisms under controlled conditions e.g. fish farming in cages-nets, which is quite different to commercial fishing of open waters, which is the harvesting of wild fish from our lakes, seas and oceans.

Fish farms can be constructed in any area of open water e.g. a large lake or sheltered bay of the sea.  Unfortunately fish farms can reduce biodiversity.

To make farms commercially viable and increase productivity, food is added to the 'net-cages' which produces a lot of waste after digestion. The food and waste can leak into open water causing eutrophication and the death of wild species of organisms.  Fish farms become breeding grounds for large numbers of parasites which can escape and infect wild animals and can kill more healthy wild fish. The fish farms attract predators like seals which get caught in the nets and die.  Farmed fish can escape causing problems for the populations of wild species - they might outcompete them for food, spread disease and interbreed with wild fish of the same species - this dilutes the gene pool of the fish best adapted to survive in 'wild water'.

Some of these problems can be reduced by raising the fish in large tanks rather than enclosed nets in open water.  BUT, this greatly reduces biodiversity because the tanks must be kept free of plants, predators and the parasites have to be killed along with other microorganisms. In some countries, fish farmers add antibiotics to the fish's 'artificial' food or water and chemicals to kill parasites.  Tank fish farms are intensively crowded aquafarms, small fish are bullied and killed by larger fish. Mortality rates are high and disease and parasite infestations are common as is blindness.

 

Indigenous and non-indigenous species

Definitions - apply to plants or animals

An indigenous species is one that occurs naturally in a given habitat area.

Many species can co-exist in an ecosystem that functions with balanced populations of plants and animals.

Indigenous species are also referred to as native plants or animals e.g. the red squirrel is native to parts of the UK.

A non-indigenous species is one that doesn't occur naturally in a given habitat.

This is often due to 'accident' or intentional human introduction for one reason or another - for aesthetic reasons - deer look good in the park, for food, for hunting.

The negative results on biodiversity of introducing a non-indigenous species

Unfortunately introducing a non-indigenous species can cause problems for indigenous species e.g. they may compete with each other for the same food, shelter or water resources.

e.g. the larger and stronger non-indigenous (non-native, introduced to the UK in the 1890s) grey squirrel out-competes the red squirrel for the same food resource. As a result, in the UK, with declining populations, (down to zero in places - 'died out') the native red squirrel is considered an endangered species.

Some non-indigenous species are introduced to diversify our food supply e.g. the signal crayfish, but it has spread into freshwater lakes, streams and rivers where it out-competes many indigenous aquatic species for food, reducing biodiversity.

Signal crayfish also causes further problems by burrowing into river and canal banks causing erosion, bank collapse and sediment pollution.  The 'out-competing' signal crayfish is a voracious predator, feeding on a variety of fish, frogs and invertebrates, as well as plants, and even eating individuals of its own species!
 

Non-indigenous species can bring new diseases to a habitat leading to less biodiversity, because these can infect and kill indigenous species which will not have time e.g. via mutations, to have any protection against the 'invading pathogen'.

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Key points - Summary of ideas

Based on the syllabus-specifications for students taking the AQA, Edexcel and OCR GCSE level biology examinations (~US grades 9-10).

Biodiversity and Managing Resources

• Biodiversity refers to the variety of life in an ecosystem. It ensures ecosystem stability and resilience against environmental changes.

• Human activities such as deforestation, pollution, and climate change threaten biodiversity.

• Sustainable resource management helps maintain biodiversity by reducing habitat destruction and promoting conservation.

Misuse of Land and Deforestation

• Deforestation leads to habitat loss, reduced biodiversity, and increased carbon emissions.

• Urban expansion & agriculture often result in land misuse, affecting ecosystems and soil quality.

• Reforestation & afforestation are strategies to restore lost habitats and combat climate change.

Overfishing and Stock Depletion

• Overfishing reduces fish populations, disrupting marine ecosystems.

• Sustainable fishing practices (e.g., quotas, protected areas) help maintain fish stocks.

• Aquaculture offers an alternative to wild fishing, reducing pressure on natural populations.

Indigenous and Non-Indigenous Species

• Indigenous species are native to an area and contribute to ecosystem balance.

• Non-indigenous species (invasive species) can outcompete native species, leading to biodiversity loss.

• Control measures include monitoring and removal of invasive species to protect native biodiversity.

Land Conservation in the UK

• National parks and nature reserves protect habitats and species.

• Legislation (e.g., Wildlife and Countryside Act) supports conservation efforts.

• Community involvement in conservation projects helps maintain biodiversity.

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Summary of learning objectives and key words or phrases

Be able to describe how to manage resource with the minimum damage to the biodiversity of our environment.

The reasons for and the detrimental effects of deforestation, use of peat - a major carbon store, over fishing and issues with fish farms, the competition between indigenous and non-indigenous species and its effects on biodiversity.

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