Biodiversity – Habitat Diversity and Size Matter

Marine biodiversity, and ocean coral reefs in particular, are threatened by acidification, illegal fishing, legal overfishing, agricultural runoff, the spread of algae, excessive silt flowing in the seas and oceans caused by deforestation and dynamite fishing. In fact most of marine life will be long gone before acidification would have wiped it out. Author Elizabeth Kolbert calls climate change the equally evil twin of acidification. Climate change is causing the oceans to warm up. Similarly to terrestrial environments, the seas and oceans do not have a uniform temperature. Each marine ecosystems sustains different species of marine plants and animals within a temperature range. As all chemistry functions within given temperature ranges, the rise in temperatures across the planetary marine ecosystems causes the symbiotic relationship between the various plant and animal species to fall apart. This causes a devastation of animal populations and biodiversity.

Image showing Dynamite fishing - biodiversity loss

The temperature changes predicted for this century are no different to the temperature swings of the ice ages, not that this is any comfort. It gets worse. Although the extent of the changes may be similar, the rate is not and the rate is critical. The warming we are experiencing today is happening at a rate that is ten times faster than all previous glaciation periods in the history of the planet. To keep up with this, species will have to migrate or adapt ten times more quickly. Those species or populations that can neither adapt nor move fast enough will die. Climate change will also see mass migrations of peoples, like never experienced before in living memory, moving away from arid lands, coastal areas or unwelcoming temperatures and climate. Millions of human beings will be on the move causing social disruption and upheaval across the globe or worse. This is what is expected to unfold in the coming decades.

There is one golden rule in ecology and that is that biodiversity needs space, natural, pristine and uninterrupted space. The larger the area the greater the diversity of plants and animals. Humanity’s encroachment on natural terrestrial and marine habitats is the fundamental reason for the collapse of species populations and biodiversity worldwide. In 2004 a group of scientists carried out a study using a thousand plant and animal species. Comparing the species to area relationships they estimated that, if humanity continued to contaminate and disrupt nature at the current increasing rate, there would be a loss of 22% to 31% of species by 2050 in the optimistic scenario and a loss of 38% to 52% in the pessimistic scenario.  Some of the species may not be fully extinct but they would be irreversibly going in that direction. Following publication these findings had been challenged on a number of grounds. However, it has to be said that subsequent studies using other criteria and extensive observation on the ground as well as more recent research in 2017 and 2018 by member of the US Natural Academy of Sciences, the WWF and Birdlife International have confirmed that the situation is indeed as dire as was predicted way back in 2004.

Image of shark caught in fishing net - biodiversity loss

We have to go back to the mid-Miocene epoch of Earth’s history, fifteen million years ago, to find carbon dioxide levels and therefore temperature levels that are as warm as today. If humanity continues with this ‘business as usual’ myopic attitude it is more than likely that by the end of the century the carbon dioxide and temperature levels will reach those that have not been experienced on Earth since the Eocene Epoch, fifty million years ago, that saw palm trees growing in the Antarctic. We cannot know whether species today, including our own, possess the physical immunities and features that allowed their and our ancestors to thrive in the Eocene. The question is…do we really want to find out?

There are 130 million square kilometres of land on Earth that is ice-free. Of this 70 million square kilometres has been converted by agriculture and pastures, by cities, reservoirs and malls, by logging, mining and quarrying. 36 million square kilometres is covered by forest that is generally speaking natural but not exactly. The rest is tundra, mountains or desert.

This classification into biomes (land and marine areas of similar weather, temperature, animals and plants) that we have grown up with no longer makes sense. Rather scientists and researcher are now classifying the Earth’s ecology by using Anthromes, or human biomes, to reflect the way that humans have reshaped the planet’s ecological patterns and processes, e.g. urban, irrigated croplands or populated forests. Analysed in this way the wildlands that are mostly devoid of people are 30 million square kilometres. Even these wildlands however are not virgin land. They are crossed by roads, pipelines and seismic lines. The latter are lines of geophones that are used to detect ground structure and movement. No part of the Earth is safe from humans, we are everywhere. We are the ultimate invasive species.

Image of forest burning - biodiversity loss

Reserve 1202 is located in the middle of the Amazon in the State of Amazonas in Brazil. Reserve 1202 is a perfect square, ten hectares of pristine rainforest surrounded on all sides by corridors of scrub that isolate it from the rest of the rainforest. This and similar forest fragments, differing in size, are part of the Biological Dynamics of Forest Fragmentation Project. This project has been running since 1979. It was previously known as the Minimum Critical Size of Ecosystems Project that better reflects what the project is about. Numerous scientists have been observing and recording for forty years the effects that the dissecting a large forest mass with human infrastructure into many smaller islands of forest, has on the population size and diversity of species in the area.

The results are incontrovertible. First the obvious. Size matters – the larger the forest the greater the biodiversity and population sizes of species. Secondly, once a forest fragment becomes physically separated from the greater forest mass, in the first year the diversity and population size increase as species from the disturbed areas move to it. However, after the first year, both the diversity and populations begin to decrease year on year eventually resulting in a collapse of the ecosystem in the forest fragment and most of the population species there becoming extinct. Herein now lies the seed of extinction.

Image of forest fragmentation - biodiversity loss

Populations of animals living in wild habitats that are isolated by natural causes, such as rising sea levels, may become extinct by a sequence of unfortunate events such as migrating predators or a virus. If the surrounding areas are still pristine and large enough, members of the same species from another nearby population may wonder into the isolated habitat and the population of the species will be re-established. If however the wild habitat has been isolated by human infrastructure and is surrounded by similar habitat fragments the extinction will become regional and ultimately global. The extinction process is ruthless, each member of a species dying a lonely and unacknowledged death.

We should not delude ourselves that planting trees on the sides of roads and in gardens or parks safeguards biodiversity in any way. Biodiversity needs very large swaths of wild lands that are at least hundreds of years old and that are undisturbed by humans or human infrastructure.

Main source: Book ‘The Sixth Extinction – An Unnatural History’ by Elizabeth Kolbert

Article published in the Sunday Times of Malta, 23rd June 2019