A re-evaluation of our biosphere
AS a bio-geographer, I am in a quandary or ‘caught between the devil and the deep blue sea’. A huge part of my brain votes hard for the conservation and preservation of all species of flora and fauna but another part envisages a more laissez-faire approach to allow nature to take its course. The latter has been triggered in reading a new publication, ‘Inheritors of the Earth’ by Professor Christian D Thomas of the University of York’s Biological Sciences Department in the United Kingdom.
There is no doubt that invasive species of plants and animals can disrupt native ecosystems. That said, as humans most of us are invasive people be we Malaysian or British or any other nationality. It is thought my ancestors, the Celts, came from mid Europe, probably Austro-Hungary, and invaded France and the British Isles. Equally, with climate change, our landscapes, farmscapes, and urbanscapes are also changing the environments in which we live.
Whilst we are all experiencing hotter environments with more or less rainfall inputs, and consequent effects on animal and plant life, we sometimes forget that there have been warmer periods in our planet’s history, even since the end of the last Ice Ages, some 11,000 years ago. In our new Anthropocene age, life has gone on. Thomas maintains that the diversity of species is boosted by climate change as temperatures and precipitation rise or fall locally.
Interestingly, plants from warmer climes colonise new areas, as cold-adapted plant species retreat as the climate warms. How did they get there? Already parakeets and wallabies live freely in England, whilst sparrows fly and rabbits roam freely in Australia. I have seen flocks of parakeets in London Parks and a herd of wallabies in the Peak District National Park. How did they get there? The same question may be asked in regards to the flocks of sparrows and families of rabbits in Australia. The answer is obvious – by human transportation as exotic creatures, which have escaped and bred in their new environments. Many exotic animals have escaped from private collectors or from zoos.
In the summer of 1982 whilst on an evening stroll with my red setter dog in the school grounds of my work place in Berkshire, England I saw a puma dash across the playing fields at high speed before it disappeared into high grass and adjacent woodland. Over the years several pumas have been spotted in these Home Counties of London, having been released into the wild by their owners when new government legislation required all such owners to acquire a Dangerous Wild Animals licence.
As an evolutionary biologist, Thomas explains at length how the number of species living in virtually every country or island has increased during the period of human influence, and the numbers continue to increase. The fauna and flora of Britain are richer today than 11,000 years ago as the result of farming, urbanisation, gardening, climate change and the deliberate introduction of exotic species. Even the net effect of some human disturbances can be more diversity. He claims that “more new plant species have come into hybrid existence in Britain in the last 300 years than are listed as having died out in the whole of Europe”. He does not deny the fact that humans cause problems for wildlife but stresses that we tend to overlook the upside for wildlife in our Anthropocene age. His argument is that “humans must adapt and help direct change, rather than attempt to preserve the world in aspic”. Invasive plants and animals in the UK Japanese knotweed, originally from eastern Asia, was introduced to Victorian gardeners in 1886 as an ornamental plant. It is now widely and wildly growing across most of Britain, forming dense stands which are hard to control. A beautiful, quintessentially British flower meadow alongside my house has its river banks coated with this intrusive plant, which has shaded out more delicate native plants in only five years. Japanese knotweed costs the British economy the equivalent of RM930,000 a year to eliminate – with very limited success.
On acidic soils from silicic rocks in Britain, swathes of wild rhododendrons with their magnificent red blooms have taken over the moorlands. Originally introduced in 1763 from Spain and Portugal as decorative garden plants, rhododendrons have shaded out lower growing plants and have been found to carry diseases fatal to some types of trees. Thus in some areas they have been burned and the roots sprayed with a form of herbicide. Twenty years ago when I visited my birth place in Cornwall, I shed tears as I saw my childhood memories of playing and climbing the rhododendron clumps on an exposed moorland literally going up in flames. However, I treasure the three Asian rhododendrons in my garden.
Invaders from North America such as the grey squirrel, which was released into the wild in 1876, carry a pox virus that has been transmitted to native red squirrels, thus causing a rapid decline in the latter’s population. The ‘greys’ now have a bounty on their heads and are being culled. The American mink arrived in the UK in 1929 for breeding on fur farms. Alas, they have escaped into the wild, preying on water voles. Water voles have seen the most rapid and serious decline in population numbers of any British wild mammal.
Muntjac deer, which came from China and Taiwan in 1831 to originally grace parklands on private estates, are now common across most of England. These deer have a serious impact on woodlands where they clear shrubs and devour tree saplings, thus affecting other wildlife, to include birds and butterflies.
Signal crayfish, a lobsterlike freshwater species, were introduced from America in 1975 to be farmed for food but quickly escaped and have spread rapidly throughout Britain. They prey on the native crayfish which have now been almost totally eradicated. Our ‘global greening’ Surprisingly, Thomas, whilst celebrating the gains from man-made interference with nature, omits to mention the effect of man-made emissions of carbon dioxide (CO2) into our atmosphere leading to ‘global greening’. This increase in CO2, while absorbing the sun’s radiation and hence leading to the Earth’s rise in average temperature, is also absorbed by plant life. This has led to the global vegetation growing greener in the last 33 years. In area this amounts to a patch of green covering the size of the USA with 70 per cent of this attributed to the extra CO2 in the Earth’s atmosphere.
Interference or coexistence
Undoubtedly we have caused the extinction of many large animals, fish and birds when we were first hunter-gatherers. When humans appeared 50,000 or so years ago, there was a rapid disappearance of mammoths, rhinos, giant kangaroos, giant elks and birdlife in the form of giant auks, moas and rocs. It is thought that we caused twice as many extinctions of birds and mammals before the start of the 18th century as we have subsequently caused.
Hybridisation is taking place all around us and the concept that evolution happens very slowly is dispelled by Thomas, who argues that our very existence on the planet has boosted biodiversity. This is to say that the changes we see around us, including those of our doing, are not necessarily for the better or worse. They are merely different. He concludes by asking conservationists and environmentalists to “put aside doom-laden rhetoric … and to shed self-imposed restraints and fear of change and to go on the offensive”. His revolutionary ideas will affect the way I may think and the way I shall continue to study fauna and flora, but I suppose, in my heart of hearts, I shall remain entrenched in the conservation and protection of wildlife. Change, however, is inevitable.
‘The Inheritors of the Earth – How Nature is Thriving in an Age of Extinction’ by Chris D Thomas is published by Allen Lane 2017.