Are we a hyperkeystone species?

Are we a part of nature?

Proponents of the Monbiot-esque 'doom view' state that humans have nothing positive to give to the planet. Understandable as there is no other species that has wreaked such havoc and destruction...not even close.

Human activities, including agriculture, have detrimentally simplified many of the Earth's natural systems.

Our activities such as growing food, urban development, over exploitation of natural resources, the spreading of invasive species, changing the course of waterways and catchments, pollution and of course climate change have all had a negative effect on ecosystems BUT what about positive, human created effects...do they exist…are we a keystone species?

It's widely assumed that humans have had nothing but a negative effect on nature's systems but is this always true? Before we discuss let us consider what a exactly a keystone species is.

What is a keystone species?

The concept of the keystone species was introduced in 1969 by zoologist Robert T. Paine, so named because in architecture an arched bridge has a central 'keystone' that provides the support and stability of the structure. Paine made the analogy that in natural systems we can identify individual species that provide this role on the ecosystem as a whole.

 

 

While studying tide pool ecosystems on Washington’s rocky shores, he noticed that a certain species of starfish (Pisaster sp.) were hugely important. Specifically, by feeding on large numbers of mussels, the starfish prevented the mussels from squeezing out other species for space on the rock surface. In intertidal and rocky shorelines, real estate is super hard to come by.

This is because many organisms like barnacles and algae compete to have a place to fasten themselves and utilize nutrients in the water from a firm foothold. When Dr. Paine removed starfish from these pools, mussels took over quickly and wiped out other species. When the starfish were present, they caused a disturbance that kept a larger number of species around.

A well publicised case and a great example of the profound effects a keystone species can bring to an ecosystem is the wolves of Yellowstone National Park in the USA.

Wolves had been absent from the park for 100 years. In 1995 just 41 wolves were reintroduced to the land, the effects on the ecosystem were profoundly positive causing what's called a 'trophic cascade' of ecological change.

In the past, it was largely thought that an ecosystem was built from the bottom up, with plant life as the foundation from which everything else grew. Once healthy plants were established, insects, small rodents, birds, larger herbivores, and finally the top predators would inhabit and provide 'balance'.

Almost all conservation and species reintroduction efforts were based on this theory. In a damaged area, biologists would first try to rebuild the plant life before doing anything else.

This theory proved to be incorrect.

Ecosystems are best managed from the top down, not the bottom up. This insight has profound implications on how we can understand our role in helping to rebalance and in fact increase the complexity of natural systems.

In the case of Yellowstone it worked like this. 

Wolves have this beneficial Trophic Cascade effect for one simple reason: They make elk run.

Consider what elk do when left alone. Entire herds like to go to riversides and eat everything they can find in one place (grasses, bushes, saplings, even small trees) before moving onto another and doing the same thing. After decades without wolf predation, elk had denuded Yellowstone’s landscape and killed many of the smaller trees that line riverbanks.

When wolves were reintroduced, the elk herds could no longer sit in one place and eat everything nearby. They were forced to keep moving in response to wolf predation.

This had myriad benefits. When wolves chase elk during a hunt, the elk are forced to run faster and farther. As the elk run, their hooves aerate the soil, making it prime for water retention and allowing more grasses to grow.

Since the elk cannot remain stationary for too long, aspens and willows in one area are not heavily grazed, and can therefore fully recover between migrations. This meant that songbirds could come back in droves to nest in the new habitat. The trees even shade the rivers, making the water colder. Colder water can hold more oxygen, which provided a boost to fish populations.

This seemingly inconsequential action caused huge change for the better. Even though it was humans who helped fix the problem let's not forget who created it in the first place!

So, can we find examples where humans have acted as keystone species (and not just for repair and recovery) but as an integral part of a complex system?

Holocene to Anthropocene.

You may have heard the term Holocene being used to describe our geological epoch but what does this mean exactly?  

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The Holocene represents the most recent interglacial interval of the Quaternary Period. The preceding and substantially longer sequence of alternating glacial and interglacial ages is the Pleistocene Epoch. Because there is nothing to suggest that the Pleistocene has actually ended, certain authorities prefer to extend the Pleistocene up to the present time; this approach tends to ignore humans and their impact, however. In addition, some geologists have argued that the time characterized by the rise of humanity should be separated from the time characterized by humanity’s domination over the planet’s ecological systems and biogeochemical cycles, and thus they have proposed that the later part of the Holocene should be classified as a new geologic epoch called the Anthropocene.

The Anthropocene is an acknowledgement of the action of humans as a global keystone species - capable of affecting climate change on a global scale.

We are faced with a choice - do we choose to be a beneficial or a destructive force? 

Let's remind ourselves that a keystone species is defined by its ability to create and maintain the ecosystems that allow its own and other species to flourish - we can certainly meet that criteria.

Is the Amazon the most biodiverse ecosystem because of us?

If you were asked to name the most important and precious natural ecosystem on the planet you would probably say the Amazon and with good reason - it is the most biodiverse system on earth. But what you may not know is there is evidence that suggests it's all because of us!

Some geographers, anthropologists, and indigenous people have all rejected the idea that the Americas were an untouched wilderness—“the pristine myth,” as they call this tale—since the early 1990s. (Fifteen years ago, it was the topic of 1491, Charles C. Mann’s article in The Atlantic, later a best-selling book.) But this paper further belies that myth in one of the most biodiverse places in the continent, suggesting that humans did not just farm in the Amazon but helped determine some of its major ecological communities.

Increasing evidence shows that Pre-Columbian civilisations in the Amazon were large and highly developed, containing a bustling network of towns and cities supporting large numbers of indigenous people.

For more than 8000 years the people who lived in the Amazon farmed and built productivity - this increased the abundance and distribution of certain species creating greater biodiversity, not less.

Clearly our current intervention in the Amazon basin is not so positive. The action of deforestation and the subsequent planting of monocultures is utterly devastating - we are removing complexity, not increasing it. This makes the ecosystem easily broken through variations in inputs or conditions - but the important takeaway here is that human action can be positive.

Positive impact

We now have conscious knowledge of our impact, we have the means to communicate this globally and we have the ability to mould the Anthropocene into a steady state, complex utopic paradise where our food production systems are indistinguishable from nature. This is why we support a 'Regenerative Farming Systems' - a method that replicates how animals originally lived in nature.

We are at a crucial point in our development and decision making - we can choose to be the destroyer or the creator.