Biodiversity loss happens all the time and it always has. Although the diversity of life on earth seems vast, across evolutionary time around 98% of recorded species are extinct.
Death and extinction are inevitable. The laws of nature say organisms cannot live forever. And when all the organisms of a given type die without reproducing successfully, there is a net loss of biodiversity.
Local extinction can occur such as when a parcel of forest is cleared for an oil palm plantation or it can be a global extinction event — the real kind — where all populations of species lost.
This might happen when the majority of forest is cleared for agriculture [think parts of Europe and North America] or when the climate warms and alpine habitat contracts.
It could equally be from dramatic cooling such as when Antarctica broke away from Australia allowing the circumpolar current to suck the heat out of the continent and turn it from temperate forest to a polar desert in as little as 1 million years.
Based on fossil and genetic evidence there have been at least 5 mass extinction events since life began on Earth. The most famous would be 60 million years ago at the end of the Creatceous when the dinosaurs succumbed.
However, there were equally severe events [when the rate of extinction was far greater than the rate of speciation] at 200, 251, 370 and 440 Ma. And all the time there is a steady background rate of biodiversity loss.
rainforest in many parts of the tropics has been cleared and replaced with oil palm plantation | West Papua, Indonesia
Fortunately organisms are superb more making machines. Life is super-efficient at finding, gathering and converting resources to more life — reproduction is everywhere.
Microbes can do it in minutes, elephants take a little longer, but all organisms make copies of themselves from their species blueprint to continue their lineage.
Even the very best photocopier cannot clone the original. So too with organisms, as they reproduce so copies are not exact. There are small but important mistakes in copies of the genetic code. This, the vagaries of the environment on development, and differences in genetic expression is why no two organisms are the same.
Variation in the genetic code is important because it can be passed down. The copy mistake is copied too. If the mistake turns out to benefit its owner — especially if it helps the organism get more resources or mates than its fellows. The the chances of the 'mistake' passing on to the next generation is greater.
If enough of this new variation persists and is consolidated it can result in enough difference from the organism where the original copy error occurred to deliver a new species. In other words biodiversity is made as well as lost.
This process of natural selection has created new diversity throughout evolutionary time. And despite dramatic extinctions, the net result is that diversity has increased — sharply so over the last 100 million years.
It is not just the components of biodiversity — genes, species, ecosystems — that are lost with local and global extinction.
The attributes of biodiversity — diversity, abundance, composition — also change. This often happens before species go extinct. For example, the relative numbers of each species in a forest will change when trees are logged for timber.
Alteration to diversity [how many species are present], abundance [how many individuals are present] and composition [which particular species are present] makes a different to what biodiversity does to how the system functions. Specifically from the human perspective what this does for the flows of goods and services, the natural capital.
If biodiversity is lost all the time — and on occasion dramatically — but always recovers to be greater than in the past, why should it make a list of environmental issues?
There are two reasons, because:
The great variety of life comes about because evolution delivers organisms that are extremely efficient at consistently converting the suns energy into biomass.
The keyword is consistently — energy and matter cycle and recycle between organisms and the environment all the time. Consistency happens because of the efficiency with which organisms gather and use resources even when there is disturbance.
It can sound a little circular given it is the diversity of life that makes natural systems efficient and this efficiency is itself a driver that increases diversity.
Consistency determines the efficiency of plants, animals and microbes in delivering net primary production. This is the difference between the biomass created by plants through photosynthesis [primary production] less the amounts that die and decompose or eaten by animals.
What has happened of course is that around the world humans have steadily appropriated more and more of this net primary production — and as you would expect with nature being what it is, converted it into more humans.
Now we are increasingly dependent on that production.
In fact we have invented many land management, farming, forestry and fisheries practices to improve performance but in doing so we have depleted the biodiversity that helps to supply it.
In our attempts to be more productive than nature, we have lost much of the resilience that nature provides.
the thousands of species and billions of individual organisms that exist just in this teaspoon of soil are all making more thanks to their ability to process resources.
Crucial as net primary production is for humankind it is not the main reason for concern.
Most of the worry over biodiversity loss comes from those who value biodiversity intrinsically. All species have a right to exist and so humans have a moral obligation not to destroy species with which we share the planet.
Conservationists and environmentalists agitate for this view that is labelled environmentalism. And they have a point. Should we allow the destruction of other sentient beings just because we can?
But who do we feed first, the starving human or the starving panda?
People who produce food and consume it tend not to say too much about this sort of thing. At least not loudly. Perhaps because, for the most part , most of us think like engineers and see the world as a place that provides raw materials for us to convert to the things we need and want.
Humans just love to fix things. We cannot stop ourselves from engineering everything around us so that we control the outcome. And although we think of engineering as what we do to build a car, a road, or a bridge, the same idea applies to agriculture. We engineer the environment and the organisms in it to control the outcome — even if this means biodiversity loss.
We even think we can engineer the atmosphere to stop global warming.
We value this ability greatly and not just for the goods and services it provides. The compromise this creates is that our engineering alters nature, often dramatically so, and a major consequence is biodiversity loss.
Quite the conundrum.
highly fertile soil in the highlands of Papua New Guinea have grown vegetables for many generations but forests used to grow here
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