Agriculture is one of the major land uses in South Africa. However, the actions of producers can have a great impact on the associated natural environment.
As humans we see ourselves at the top of the food chain, and advanced technology provides endless possibilities in the modern era. Due to our clever ways, we have developed a sense of independence and dominance over all other life forms. We continue to disrupt natural ecosystems, with the global human population that is ever increasing. As our numbers increase, we place a greater strain on the environment.
In this article we look at ecosystems, their sensitivity, human impact and the benefits that one can reap from a balanced ecosystem. The goal of this information is to highlight the sensitivity of these complicated systems.
What is an ecosystem?
The National Environmental Management: Biodiversity Act (Act 10 of 2004) defines an ecosystem, in short, to be the dynamic and complex interaction between animals, plants, micro-organisms and their non-living environment as a functional unit.
There are various examples of ecosystems, such as water ecosystems and forest ecosystems. Even your garden at home can be classified as an ecosystem. Any space where there is interaction and an exchange of energy between living organisms and non-living environmental components, is regarded as an ecosystem.
It is important to maintain a natural balance within an ecosystem. An ecological balance has been defined by various dictionaries as a state of equilibrium within a community of organisms where species, genetics and ecosystem diversity remain relatively stable, subject to gradual changes through natural succession. Others shortly describe the term as a stable balance in the numbers of each species within an ecosystem (WWF, 2020).
Impacts
Humans contribute to various issues that disturb the sensitive balance of an ecosystem. Producers are not excluded from this. An estimated 80% of South Africa’s land surface is in the hands of producers. Agricultural practices are one of the key factors contributing to biodiversity loss (Kotze et al., 2015). Any loss in terms of biodiversity will weaken the structure of the associated ecosystem.
The excessive use and non-targeted applications of pesticides and herbicides can have a devastating impact on the balance of an ecosystem. Pests have also developed a resistance to pesticides in certain cases, which drives the need for stronger and more frequent applications. Many herbicides are toxic to amphibians and soil micro-organisms.
Genetically modified crops that are herbicide resistant have also allowed producers to apply herbicides without much constraint, whilst they are unaware of the damage that is being done over the long term. The increasing use of monoculture species has also resulted in a loss of genetic diversity.
Producers must be aware that every species plays a critical role in the balance of an ecosystem. If any species are removed from that ecosystem, it can have a devastating and often unexpected impact over the long run.
Owls, for example, are often killed by rural communities due to cultural or superstitious beliefs. Owls play an important role in rodent control on farms. Thus, removing them from the associated ecosystem may lead to an overpopulation of rodent numbers, which will lead to other issues such as crop damage. Any sudden significant change in population numbers, including predator species, within an ecosystem will lead to an imbalance.
Benefits
Natural ecosystems provide many free services to the producer. Producers can obtain these benefits by keeping the ecosystem concept in mind. Crop producers, for example, know that multispecies crop rotation is vital to maintain good yields, as it is beneficial for soil organisms and enhances soil fertility.
Another ecosystem benefit for crop producers is pest prevention through biocontrol measures. Ladybird beetles are predators of aphids that damage field crops. A study on soybean aphids (Aphis glycines) found that ladybird beetles can keep these aphid populations below economic thresholds. Without the assistance of ladybird beetles, soybean yields can be suppressed to as much as 40% to 60% of the potential yield (Robertson et al., 2014).
Another example is nitrate, which is very mobile in the soil and can cause all sorts of problems for the water quality (surface water and groundwater). Luckily, wetlands have sediments that can immobilise a significant fraction as organic nitrogen, or it can be denitrified to nitrogen gas by certain microbes. Wetland restoration and conservation are vital for the processing of nitrate. The use of cover crops can also reduce the occurrence of nitrate leaching and improves soil moisture.
Honeybees and various other insects are vital crop pollinators. Scientific studies have shown that by increasing plant species’ richness, pollinator functional diversity will also increase (Isbell et al., 2017). It was also found that the further away the crops were from the bees’ natural habitat, the lower the visitation frequency of these pollinators were within the croplands. Therefore it is a good idea to maintain natural pieces of land in-between croplands.
Conclusion
By now it is quite obvious that the environment will thrive without us, but we will not be able to exist without the environment. Many producers are now starting to realise the importance of farming with the natural ecosystem, instead of against it. All species play an important role in an ecosystem on the farm and it should be looked after to ensure more sustainable crop yields over the long run. Your farm is an ecosystem with natural and commercial components. Always keep this sensitive balance in mind.
References
- Isbell F et al., 2017. Benefits of increasing plant diversity in sustainable agroecosystems. Journal of Ecology, Volume 105, pp. 871 – 879
- Kotze I, Engel W & Nobula S, 2015. Farming facts and futures: Reconnecting South Africa’s food systems to its ecosystems, Cape Town, South Africa: WWF-SA
- Robertson GP et al., 2014. Farming for ecosystem services: An ecological approach to production agriculture. BioScience, 64(5), pp. 404 – 415
- WWF, 2020. wwf.panda.org. https://wwf.panda.org/discover/knowledge_hub/teacher_resources/webfieldtrips/ecological_balance/
[14 May 2021]