Pick and Choose
Deciding which species to keep and which to discard? Maybe there’s a simple answer
About ten thousand years ago, a hunter-gatherer nomad tamed some wild plants. It’s unlikely he knew it, but this was the first step of a long technological progression. It allowed our ancestors to settle down and build the foundations for today’s civilization.
And we have never looked back.
Today, croplands and pastures cover about 40 % of the globe’s lands. In those lands, we exploit domesticated plants and animals to gain food, fibres, and fuel. These goods are usually sold by the owner of the land, bringing him some sort of an income.
This give and take forms the basis for much of our society today. And because everything these days seems to centre around money, these biodiversity benefits are measured and valued as well.
Academics such as environmental economists and conservation ecologists have a term for this. They call it “provisioning ecosystem services”. Ecosystem services are defined as “services provided by nature”, which include supplying (“provisioning”) services, regulating services, and cultural services.
The products of agriculture have a clear and obvious value — a value we can see everyday on our shopping and grocery bills. However, other ecosystem services might not be as clearly of value — such as the regulation of carbon and nitrogen cycles, maintenance of soil fertility, and natural pest control, to name a few.
To be clear, these not-so-obvious services do have a very, very high value. An estimate done in 1997 put their worth at somewhere between 16 and 54 trillion American dollars.
The ecosystems provide them for free.
But we’re thinking economically. For the sake of efficiency in conservation, and in trying to optimise agriculture, it’s interesting to know what exactly provides those services, and how we can help the process along.
The first thing to be established is that all these services exist only because of the species in the ecosystem. Intuitively, this make sense, because the ecosystem is the species.
The second is that some species seem to be pretty much useless.
In a study published in 2010 about wild pollinators, Pr. Kleijn showed that almost 80% of the pollination services were done by only 2% of the pollinator species. Moreover, the dominant species were usually abundant and widespread in the landscape. It showed that we could more or less lose most species of pollinators without any large impact on pollination and production of fruits.
Beyond being useless, some species are actually antagonists to ecosystem services. They only serve to make management of the ecosystem more complicated. These species are usually animal pests, plant pathogens, and weeds.
Uncontrolled pests will reduce the quantity and the quality of the crop yield, which further impacts the income of the farmer. People think that up to one third of all cultivated crops are destroyed or damaged by pests.
The other kind of antagonists are actually outright enemies of the system. For example, cuckoo bumblebees lay their eggs in bumblebees’ brood cells. By doing this, they increase the chances of their own children surviving, but they also decrease the growth and reproduction of a key pollinator species.
Losing these kinds of species won’t have any impact on ecosystem services and can even enhance them.
Other species, however, are not so disposable.
The most important species are possibly the ones directly raised and introduced by humankind into the ecosystem. Think of the plants we get food from, for instance.
Obviously, these species need to be conserved because they produce goods with a direct market value. The Food and Agriculture Organization estimated a total production value of 2.55 trillion US dollars for all agriculture production in 2014, including animal and vegetable production.
Along this vein, all the species which help with the growing of edible species should be preserved. The bees pollinating the crops, the nitrogen fixing microorganisms enhancing soil fertility, the pest controllers.
For example, natural pest enemies are actively bred and released in greenhouses in place of chemical pesticides. Unlike chemicals, they have the advantage of the ability to evolve with the pest, so they’ll always be able to do their job.
But sometimes, it’s difficult to know exactly which species provide a given service.
Today, we do not know all the species of flora and fauna that exist on Earth, particularly insects and soil dwellers [Scheffers et al. 2012]. Moreover, even where we do know of a species, we do not know the specific characteristics of every species.
And, as you might be able to guess, it is something of a mammoth task to identify the properties of each species in a given ecosystem.
Funding is often limited. So is workforce. This makes it almost impossible to identify and study each species from the field to understand it’s role, and even harder to judge the value of conserving it.
Most experiments also have their limitations. They are often done in a closed system that cuts off the interactions between species, or don’t consider any movement such as migration and dispersal. We also can’t interfere with the species’ behaviour in natural conditions, so we have to limit predictions to the value of the ecosystem service it might provide.
So far, we’ve been focusing on the “provisioning” and “regulating” services; there are, however, other kinds of services that nature provides, and they’re far less clinical in nature.
Biking in the countryside and observing butterflies around colourful fields is entertaining. A naturalist might make a collection of those butterflies and try to identify all the local species.
This activity and the joy it brings could not possibly exist without a diversity of butterflies and other related species.
Each species which disappears is a part of human culture and heritage flying away. The common names people use to identify species may disappear. The souvenirs, the descriptions, and the stories about species will fade away.
Agricultural landscape managers need to conserve biodiversity in order to conserve all the culture it gives us.
Biodiversity may be useful to us in the future as well. Considering the loss of genetic diversity within and between cultivated species, the capacity to feed the people may someday be threatened.
Historically, genetic erosion within crop has only brought brought famine and misery, like in 1970, when a fungus destroyed more than half of the maize crop in the southern US.
Today, most of our diet depends on only 12 plant species, and any harm to them could greatly hurt the world’s food situation. To ensure nutrition and food security, it is important to introduce a higher diversity of crops in our agriculture.
Of course, species, varieties and in general genetic diversity can be conserved ex-situ in seed banks. But in these cases, the plants don’t have the chance to continue their evolution race against diseases and fast-changing conditions. It’s like leaving one country’s military in suspended animation while the other continues to develop. So it’s probably better to keep those species and varieties in our agricultural landscape.
In the future, a crop genetician may need those species to create genetically modified organisms that are able to cope the consequences of climate change.
From a purely utilitarian point of view, there’s no reason to conserve biodiversity to preserve the ecosystem. Finding those species that are highly active and efficient should be a priority.
But today, we lack the knowledge to identify all the “useful” species, and we must check the influence of the different interactions between all the species, useful and useless.
And now here’s a shortcut: instead of choosing which species to keep, why not keep them all?
We can avoid expensive, time-consuming research by simply conserving biodiversity as a whole. Because, really, who knows what will come in the future? We’re witnessing a high-speed global change which may someday threaten humanity — and if that happens, biodiversity could be our best insurance.
As a bonus, we keep the colourful butterflies and the awesomeness of the German word «schmetterling».
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