Have you ever wondered how natural Ecosystems that are undisturbed tend to function so well? What processes allow the balance to be maintained in such a system? What happens if something goes wrong?
We can look at a human place of work as an analogy - everyone has a role to play, and as long as everyone plays their role, the balance is maintained. However, if a role is left vacant, the entire system can break down, and compensations must be made to make up for that vacant role. Ecosystem resilience refers to how natural Ecosystems can compensate for missing ecological roles.
With that being said, let's dive into Biodiversity and resilience!
- First, we will look at the meaning of Biodiversity and ecosystem resilience.
- Then, we will talk about biodiversity and ecosystem resilience stability.
- Lastly, we will look at the functions of biodiversity and ecosystem resilience.
The Importance of Biodiversity and Ecosystem Resilience
Let's start by looking at the definition of biodiversity.
Biodiversity refers to the level of diversity among living organisms on Earth. It involves looking at diversity at the genetic, species, and ecosystem levels.
Ecosystems are composed of all biotic (living) components and abiotic (non-living) components within a specific environment. An ecosystem is a level of ecological organization, larger than a community but smaller than a biosphere.
Tropical ecosystems close to the equator tend to have the highest levels of biodiversity and are home to roughly 90% of all living species on Earth, while more northern latitudes have much lower levels of biodiversity. This is known as the latitudinal diversity gradient (LDG).
The latitudinal diversity gradient (LDG) refers to the ecological pattern in which biodiversity levels gradually increase from the poles to the equator.
Ecosystems must be able to withstand or rebound from disturbances in order to stay in equilibrium. These disturbances may include natural occurrences, such as flooding, hurricanes, and some wildfires, as well as anthropogenic disturbances, such as Habitat Destruction, pollution, exploitation, and climate change.
Ecosystem equilibrium is the state in which living organisms and their non-living environment are in balance with each other. When measuring changes in ecosystems, we are concerned with resilience and resistance.
Ecosystem resistance refers to its ability to consistently stay in equilibrium, despite disturbances, while ecosystem resilience refers to its ability to respond to and rebound from these disturbances. Biodiversity plays a vital role in an ecosystem's ability to be resilient.
There are generally considered to be six levels of ecological organization. They are, from smallest to largest: individual organisms, Populations (all individuals of one species), communities (all living species), ecosystems (all living species and their non-living environment), biomes (similar to an ecosystem but much larger), and, finally, the biosphere (all ecosystems on Earth)!
Biodiversity and Ecosystem Resilience stability
Ecosystem equilibrium is kept stable through what is known as the Negative Feedback loop, which is created by interactions between organisms within the ecosystem.
Let's take a look at an example to better understand Negative Feedback loops in ecosystems.
The gray wolf (Canis lupus) is an apex predator that preys upon a variety of other species, particularly ungulates, such as deer and elk. These ungulates feed upon vegetation, especially grasses and shrubs.
An adult male elk (Cervus canadensis), for example, can consume 24 lbs of vegetation per day! The wolves control the population of the ungulates, the ungulates feed the wolves and control the vegetation, and the vegetation feeds the ungulates.
This is known as the negative feedback loop.
Figure 1: The gray wolf is an apex predator that plays a vital role in maintaining ecosystem equilibrium.
If the wolves, for example, were eradicated from the ecosystem, the ungulates would overpopulate, decimate the vegetation, and possibly starve! If the ungulates were to disappear, the wolves would starve, and human-wolf conflict would likely increase due to livestock predation and entering human habitat in search of prey.
If the vegetation were to be removed, the ungulates would starve, and the wolves would be in the same situation as if the ungulates disappeared.
Each of these scenarios involves the breaking of the negative feedback loop, which throws an ecosystem out of equilibrium!
As you can see, removing any species from an ecosystem can have a catastrophic impact, some of which are still not entirely understood.
For example, efforts are being made to eradicate species of mosquito that are capable of spreading diseases, such as dengue fever and Malaria. While most people would likely be on board with eradicating these seemingly irredeemable pests, some ecologists have pointed out that we do not entirely know what negative effect this eradication may have on the ecosystem. Such questions need to be answered and consequences fully understood before implementation.
Biodiversity plays such an important role in ecosystem resilience because the more native species are present in an ecosystem and the healthier their Populations are, the more likely an ecosystem can return to and maintain equilibrium.
Humans are also positively affected by ecosystem equilibrium. A balanced ecosystem means a more productive, cleaner environment. A healthy ecosystem can help to mitigate the effects of anthropogenic climate change, particularly healthy tropical ecosystems, since the removal of tropical rainforests contribute heavily to global warming.
It is also less likely that humans will proliferate diseases associated with the destruction of ecosystems, including diseases related to pollution. Another way it benefits humans is through a reduced need to manage natural ecosystems since they are naturally managed while in equilibrium. Vegetation that may overgrow and causes problems are kept in check by populations of herbivores, and there is no need to cull herbivore populations since they are regulated by carnivores. In this way, ecosystem equilibrium is also financially beneficial.
Biodiversity and Ecosystem Resilience functions
Biodiversity functions as a sort of "safety net" that can make it more likely for an ecosystem to be resilient and return to equilibrium in the face of disturbances. The more species there are in an ecosystem, the higher the probability that one or more of them can adapt to disturbances and fill ecological niches.
Let's look at an example of one species adapting and filling a locally extinct species' niche in its absence.
Historically, the American crocodile (Crocodylus acutus) inhabited the mangroves and the lower sections of rivers along the Gulf Coast of Mexico, from Veracruz to Campeche, with the Morelets crocodile (C. moreletii) inhabiting more inland, freshwater areas. Due to hunting and persecution by humans, the species was eradicated from the Gulf Coast but persists in the eastern Yucatán and in many other areas.
Once the American crocodile was eradicated, the Morelet's crocodile populated the coastal mangroves and estuaries, filling the ecological niche that the American crocodile once held!
A similar situation occurred in northern Australia, with Australian freshwater crocodiles (C. johnstoni) populating the lower, more estuarine sections of rivers when the saltwater crocodile (C. porosus) had become rare, prior to federal protection in the early 1970s. These tropical areas had greater levels of biodiversity (in this case, crocodile diversity), thus allowing similar species to fill vacant ecological niches and maintain some semblance of equilibrium.
Figure 2: When American crocodiles (left) went extinct along the Gulf Coast of Mexico, the Morelets crocodile (right) filled the vacant ecological niche. Source: Brandon Sideleau, own work
Biodiversity and Ecosystem Resilience factors
Two of the most important factors in ecosystem resilience are ecosystem redundancy and modularity.
As was shown above, when American crocodiles were eradicated, Morelets crocodiles moved in and populated the vacant niche. This is ecological redundancy.
Ecological redundancy is the ecological compensation from species that fill a similar ecological role. This is obviously more likely to occur in areas with more biodiversity.
Now, modularity refers to subsets, or modules, consisting of similar species. Some of these modules may have "links" to other modules due to similarities in groups or ecological functions.
If too many of these modules are destroyed or diminished, particularly those containing Keystone Species, an ecosystem may reach a point of no return, known as a critical transition.
Critical transitions are a type of regime shift that occurs when ecosystems may become damaged to such a degree that they can no longer be resilient and is unable to recover.
A regime shift refers to a significant and persistent alteration to an ecosystem.
A Keystone Species is a species that plays such a vital role in an ecosystem that its removal results in extreme changes to it.
Biodiversity and Ecosystem Resilience - Key takeaways
- Ecosystem equilibrium is the state in which living organisms and their non-living environment are in balance with each other. When measuring changes in ecosystems, we are concerned with resilience and resistance.
- Ecosystem resistance refers to its ability to consistently stay in equilibrium, despite disturbances.
- Ecosystem resilience refers to its ability to respond to and rebound from these disturbances. Biodiversity plays a vital role in an ecosystem's ability to be resilient.
- Ecosystem equilibrium is kept stable through what is known as the negative feedback loop, which is created by interactions between organisms within the ecosystem.
- Two of the most important factors in ecosystem resilience are ecosystem redundancy and modularity.
References
- Figure 1: Grey Wolf (https://commons.wikimedia.org/wiki/File:Front_view_of_a_resting_Canis_lupus_ssp.jpg) by Gary Kramer. Public domain.
Explanations 
Exams 
Magazine 
