Half of the worlds plants could become extinct this century

Plant species' outlook grim

14.11.2002

Up to half of the world's plants could become extinct this century, according to a new analysis of the true number of endangered species.

Existing studies suggest that about 13 per cent of the known plants in the world are threatened, but the true figure could be far higher, says a study published today in the journal Science.

Nigel Pitman, of Duke University, in Durham, North Carolina, and Peter Jorgensen, of the Missouri Botanical Garden in St Louis, calculate that at least 22 per cent of species should be on the 'Red List' of threatened plants.

The figure of 13 per cent is a 'serious underestimate' because it is based largely on what is known about threatened species in the temperate regions of the world such as Europe and North America, but it is in the tropics, where plant diversity is at its richest and most vulnerable, they say.

'The results suggest that as many as half of the world's plant species may qualify as threatened with extinction under the World Conservation Union classification scheme,' the scientists write. 'Comprehensive Red Lists for plants are available for only a scattering of tropical countries, making it difficult to assess the true scale of the global conservation crisis for plants.'

The two scientists looked at the number of plants that are endemic to nearly 200 countries and used this as a basis for estimating how many are threatened by such things as habitat loss and deforestation.

They say the concentration of endemic plants can be linked to the proportion that would be expected to be threatened with extinction. Globally, this means that between 22 per cent and 47 per cent of plants could become extinct in the foreseeable future. In some countries the figure could be 80 per cent or more of its endemic plants.

There are thought to be from 310,000 to 422,000 species of plants in the world, but Peter Crane, director of the Royal Botanic Gardens at Kew, said fewer than one in 20 had been formally assessed for their conservation status. 'For some plant groups ... at least 50 per cent of the Brazilian species are considered to be threatened,' he said.

Every living thing has natural enemies. We are suppressing those of the human population, so it is out of control. I suggest we stop producing influenza vaccines, and let Mother Nature back in the driver's seat.

This figure seems a little unbelievable to me.

Doesn´t sound too sensible to me. Influenza vaccines are only administered in rich countries. Rich countries are not where the population growth is. The growth is in the poor countries, where they do not have flu vaccines. The simple evidence is that population growth and flu vaccines are negatively correlated.........which might lead you to argue for more vaccines, not fewer, if you wish to restrain pop growth. I think you´ll find similar correlations with other vaccines......it is those areas of the planet with the highest vaccinations rates, the rich countries, that have the lowest pop growth ( and in many cases falling pop ) rates.

Causality is another thing of course.

Tim Worstall

I´m old enough to remember when all life on earth other than the cockroaches was about to become extinct. Remember Reagan ? Nuclear Winter ? Jonathan Schell ? There´s so many ' could be ' ' may be ' ' might ' in this piece to make anyone take it too seriously.

Tim Worstall

How about other vaccines?

Vaccination rates are, of course, different for different vaccines. In the mid - late 1970´s smallpox vaccination was near 100 % worldwide. As it is a disease that only lives in humans, that is how we were able to wipe it out in the wild. We are getting very close to that with polio now.

Measles, mumps, rubella, sorry, I just don´t know the figures.

There is an argument put forward that the number of children desired is closely related to the number one can expect to survive to breed themselves. High child mortality does seem to be related to high birth rates. In those societies where child mortality is almost unknown, ( 10´s per thousand births, like ' the west ' ) birth rates are very low, below relacement. In those places with very high child mortality, 200 , 300 per 1,000 ( measuring to 5 years old, which seems to be how the stats are collected ) there are also very high birth rates, 4 or 5 per woman on average. It has also been noted that a reduction in child mortality seems to take a generation or so to work through to a reduction in birth rates. So one can argue, and I would with caveats, that vaccination against the childhood killers, is a method of, in the long run, reducing pop growth, at the cost of a one generation leap in pop size.

Please note that this is not a conclusive argument. Looking at the two figures, for child mortality and birth rates a generation later, for pretty much any country or society one chooses, does seem to bear it out. But I have not proved causality, and in all such societies there were other things going on as well......usually increased urbanisation, wealth, education, female independence and so on as wel~l. Thus the caveats.

Tim Worstall

But the design of nature is such that the natural enemies keep a population healthy, in addition to controlling the size. That is, the genetic errors, or weaknesses, are weeded out. When you immunize, that doesn't happen