“The one process ongoing in the 20th century that will take millions of years to correct is the loss of genetic and species diversity by the destruction of natural habitats. This is the folly our descendants are least likely to forgive us.”
Ecosystems are areas that are consistently influx with the changing environment. As the environment changes (changing fast now due to human impacts), it is important to have biodiversity.
But... what is biodiversity?
Biodiversity can be defined in different ways. Most simply, biodiversity is the variation in life; this could be referring to the actual number of species, the genes, or the ecosystems that are present.
However, humans are starting to do things that decrease biodiversity.
For example: Farming! Farmers are using “mono culture”; they are just planting one thing in one area. Forests, for example, are being cut down to just farm potatoes. When we do that, we’re decreasing the amount of area of life where we can have a diversity and replacing it with just one species of potato. This causes a decrease species and genetic variability.
VIDEO: 5 human impacts on the environment (from 5:03)
In the context of plants, resource exploitation arises from two human industries: mining and logging. Logging, especially the wasteful practice of clear-cutting, reduces biodiversity by simply removing the local ecosystem.
Exploitation can lead to habitat fragmentation...
- The cutting of forest into fragments creates many “edges” where previously there was deep forest. Edges are lighter, warmer, and windier than interior forests. These changes in microclimate may alter plant reproduction. Tree mortality is much greater near edges, and climax species will be replaced by pioneer species. The drier and warmer conditions may also make the fragment more flammable, increasing the frequency of fire.
Connectivity is key
Impacts can be mitigated through effective landscape planning. Patches of suitable habitat need to be connected via corridors to form a habitat network - this allows for immigration and promotes gene flow.
Whether by outcompetition or by physically eliminating other plants in the area, invasive plants are capable of turning severely affected areas into near-monocultures, as well as severely affecting the rest of the ecosystem.
Where do they come from?
Very rarely is a non-indigenous species introduced with the intention of becoming well-established in the local ecosystem. The only times this occurs is with some crops, the notable case of the European Starling (which was released in New York by Eugene Shiffelin, a hardcore Shakespeare fan, to give the New World all the fowl of Shakespeare’s sonnets) and with species intended for biological control of existing invasives.
What can we do about it?
As time passes and the species becomes established, fewer options become available and their associated costs get much higher. The Invasive Alien Species Strategy (IAS) is Canada’s framework to respond to the invasive species crisis - it prioritizes prevention, early detection, and rapid response.
For well established invasives, local management and control becomes the only option. This can involve a number of techniques:
- Physical removal is the most time consuming and resource intensive method
- Controlled burns can also be used - these help to remove the upper seed bank as well. Phragmites australis especially is an apt example: it can only be removed through repeated burns.
- Chemicals can be effective if used responsibly - however there is the potential for pollution and other unexpected negative effects
- Biological controls are also an option. This involves using natural predators/prey relationships to destroy invasives. However, ecological consequences are difficult to predict in advance.
Pollution is also a serious problem for plant diversity. Fertilizer and pesticide runoff from nearby agriculture affects nitrogen balance in the soil, toxic heavy metal runoff from mines poisons the soil, nitrogen oxides and sulphur dioxide reacts in the atmosphere to produce acid rain, and particulate matter from cars and industry clog leaf stomata, reducing plant effectiveness. However, studies have shown that some plants are more resistant to pollution, meaning they have a competitive edge over other plants. As a result of this selection factor, an untamed ecosystem will experience a shift in diversity, in which pollution-resistant plants become dominant.
Mitigation for Pollution
Catalytic scrubbers in industrial smokestacks filter sulphur dioxide from smoke to form a solid calcium sulphate slurry. In addition, all automobiles today are required to carry a catalytic converter as part of the exhaust system, which uses a thin platinum net to remove nitrogen oxides, sulphur dioxide and carbon monoxide.
Climate Change is Bad
We know the causes of climate change, and we're all sick of hearing about them, so let's not bother with it this time. Instead, just know that climate change has the effect of shifting temperatures out of a given species' tolerable range, effectively shifting its range to higher latitudes. This results in habitat shortages, especially since plants are immobile and may have a more difficult time of colonizing an entirely new ecosystem. In addition, parasitic insects, fungi and diseases will be able to move to higher latitudes, where they may have severe effects on local plants.
- Tackk created by Shane Abernethy, Chris Lovell and Roshanak Hedayatmofidi