Human activities such as intensive farming can negatively impact biodiversity. Various practices limit this impact, and can even improve biodiversity. These practices include polyculture rather than monoculture, crop rotation, hedgerow conservation and maintenance, predator strips at field margins, and integrated pest management and biological control.
Polyculture refers to cultivating multiple species of plant in the same area, rather than just one (monoculture). This improves biodiversity and attempts to reproduce the existing biodiversity in the environment.
Cultivating different plants together can also improve their resistance to disease, as shown by growing different rice varieties in China, decreasing disease incidence by 94%. This rendered pesticides unnecessary.
A disadvantage of polyculture versus monoculture is the increased labour needed to carry it out.
Crop rotation refers to cycling the type of plant grown in an area with every season. It prevents the depletion of specific nutrients from the soil.
Additionally, the soil is better structured after growing different crops in it. Pathogens and pests are also disrupted and prevented from building up as a result of prolonged culture of just one species.
A disadvantage of crop rotation is that it is very sensitive to multiple environmental factors such as the weather, and therefore cannot be planned too long in advance. If the rotation isn’t right, rectifying it can take a long time.
Hedgerows are critical habitats and corridors between isolated areas used for farming. They host moths, fungi and insects, and provide key resources for many mammals, birds and insects.
Since hedges would be displaced by trees over time, it is important to maintain them, too.
Implementing field margins where natural prey-predator relationships can continue is a way to maintain biodiversity.
A downside to this is the growth of weeds in these spaces, producing many weed seeds in the habitat that would disperse to the nearby field.
Integrated pest management
Pesticides such as weedkillers (herbicides) and insecticides can be selective (or non-selective) and systemic (or contact). Selective plant protection chemicals only affect certain species, commonly certain weeds. Non-selective chemicals are useful in a large breakout, but risk contaminating wider areas, and weeds as well as other plants.
Systemic chemicals spread through the whole system of an organism, so if the leaves are sprayed, the chemical will reach the roots and other parts. Contact chemicals require application directly onto the target area in order to be effective.
Resulting issues with the use of these protective plant chemicals include leaching into the wider environment and potentially spreading through food chains, toxicity to certain animal species, and providing a strong selection force that results in resistance against the further use of pesticides, similar to the development of antibiotic resistance in pathogenic bacteria.
In order to mitigate these issues and provide the most efficient protection to crops, biological control strategies as well as integrated pest management strategies are employed.
Biological control involves the use of a natural predator of the pest being used to keep its spread in check, while the integrated management (IPM) involves the combination of both chemical control and biological control.
Introducing often exotic species to a new area can successfully result in a drop in the number of their prey. However, it is not a predictable setup, and it can cause unforeseen ecological problems as well as fail to accomplish its goal. By placing a new predator species into a new environment it may target the intended species, but also feed on non-intended species. This can cause an imbalance in the preexisting food chains, and disrupt the ecology of the area.
IPM aims to combine a number of principles and strategies in order to achieve crop protection. It includes responsible pesticide use, biological control methods, preventative measures, monitoring and maintaining a threshold of acceptable levels of pests as opposed to their complete annihilation.
Additionally, in the event of a breakout, mechanical methods of removal such as hand-picking and traps are prioritised over the use of chemicals.
Practices that boost food production at the expense of biodiversity
With the pressure to produce more food, as well as following the economic incentives to do so, various practices are carried out that are unfortunately detrimental to biodiversity.
Clearing land for farming in itself destroys large areas of plant biodiversity, and with it, all the animal biodiversity that relies upon it. Side effects of farming such as leaching of fertilisers into the environment negatively impacts local, or even more distant, biodiversity.
There are many issues (economical, social, ethical) surrounding intensive farming across the globe. Here are a few:
1. Prioritising land – since so much energy is inherently wasted every time plants are used for anything else apart from direct eating by us, it is both an economical and social issue to decide whether so much land should be used for plants grown simply to feed animals which then pass on a tiny fraction of energy onto us; for plants grown to produce biofuel rather than food for us; or for plants grown to end up straight onto our plates so that the energy they pass on is maximised.
2. Controlling the effects of chemicals – artificial compounds used en masse such as antibiotics and pesticides can have far-reaching impacts. For example, if fertilisers leak underground and are transported to a distant lake, they will result in an algal bloom which will cover the entire surface of the lake. All organisms living below will eventually be starved of oxygen and nutrients and die, while other species may colonise the lake and shift the flora and fauna of the area, causing a cascade of events that will radiate outwards.
3. Drawing ethical boundaries – intensive rearing of livestock comes with an array of ethical issues. The range includes forced growth using hormones, captivity in crowded conditions, mass murder for meat, mass torture for cutting off the beads of chicks, and enhancing bacterial resistance by the mass use of antibiotics preventively.
Leaching and eutrophication
This is how fertilisers can reach further areas than planned, by the action of rain and irrigation.
The fertiliser is therefore washed away, out of the control of the plant grower.
Eutrophication is the process of artificial or natural chemicals reaching bodies of water and changing their ecosystem.
Fertilisers will cause the aquatic organism phytoplankton to grow aggressively and cover the surface of the water.
It’s super beautiful, but all the organisms within the body of water are being deprived of oxygen, causing hypoxia. While certain species die and others thrive, the balance of the ecosystem is shifted dramatically. This can have unprecedented and unpredictable effects on the wider community.
Pollution by slurry and silage effluent
Slurry in farming consists of a mixture of organic debris from livestock and other sources, while the silage is the plant feed stored away for winter to feed animals. These are materials highly concentrated in various organic chemicals that are not normally found in the environment, so it is essential that they are stored securely and do not run off into neighbouring land.
In the UK the government has guidelines for managing and storing slurry and silage, such as secure silos (large tanks that may be above ground or underground) and prohibition of storing within 10 m of any inland or coastal waters.
Deforestation for land space for human uses, wood or oil, such as the extensive deforestation in the Amazon, has led to both extinction concerns by the removal of animals’ habitats, as well as the challenge of balancing human production needs with conservation needs.
Attempts to address these issues have been made by organisations including the United Nations and World Bank in cutting emissions and monitoring forest resources. Tools are being developed to help people keep inventories of resources and track developments over time.
Direct payments to conserve forests, and giving land rights to indigenous people also help towards maintaining the balance of production and conservation. In Bolivia, landowners are paid to conserve trees and avoid polluting practices with their livestock, as well as purchase a bee hive. They can then earn money from selling honey.
Land rights in Brazil and China have prevented further deforestation, and in some cases in Brazil, even attained a better conservation status than some National Parks.
Case study: super soya beans
The first genetically modified (GM) soya beans were introduced by Monsanto in 1994. They now occupy the majority of soya land.
The applications of this technology focused on increasing the yield of soya beans at as low a cost as possible. In time, it became apparent that various other elements could also be improved, as the use of soya spans many different products. The soya beans could be made healthier and more valuable by adding several genes foreign to itself, from bacteria and other plants (Roundup Ready Soybean). These can be delivered using a gene gun.
DuPont Pioneer is a company that developed a GM soya bean that makes the resulting soya oil more valuable. Naturally, the soya oil is very susceptible to oxidation and hence making the oil rancid. By silencing or knocking out the delta 9 and delta 12 desaturase enzymes, they made a soya bean with an altered fatty acid composition high in oleic acid and stearic acid, and low in linolenic acid. This different fatty acid profile makes it less susceptible to oxidation.
Although the scientific community has concluded that GM food is equally safe to eat as non-GM food (as tested individually for each new GM food to be marketed), public opinion is still relatively against it. GM food sparked a big debate around its advantages and disadvantages to big agriculture companies, consumers, scientists, farmers and others.
On one hand, GM food improves yield and the overall value extracted from crops. This is significant to the economy as well as areas where people struggle to have enough food to eat. Companies that develop GM food sell seeds and get to make large profits which can be used to further research GM food.
On the other hand, patenting food raises issues for small farmers in developing countries, as well as other ethical concerns of big companies owning the food source of the world. Suspicious consumers also don’t fully trust GM food, so may choose to avoid it in favour of non-GM food.
These concerns that affect multiple parties constantly vie for attention, and form the dynamic of attempting to accomplish balance in this debate.