[Reader-list] 25% flowering plants face extinction

[Nagraj Adve]

Over 25% of flowers face extinction – many before they are even discovered

Scientists say human activity could spell end for a quarter of all
flowering plants, with huge impact on food chain

    * Juliette Jowit
    * The Guardian, Wednesday 7 July 2010

More than one-in-four of all flowering plants are under threat of
extinction according to the latest report to confirm the ongoing
destruction of much of the natural world by human activity.

As a result, many of nature's most colourful specimens could be lost
to the world before scientists even discover them, claims the
research, published today in the journal Proceedings of the Royal
Society B.

The results reflect similar global studies of other species groups by
the International Union for the Conservation of Nature, which
estimates that one-in-five of all mammals, nearly one-in-three
amphibians and one-in-eight birds are vulnerable to being wiped out
completely. Later this year the results of a huge global analysis of
all the world's estimated up to 400,000 plants by Royal Botanic
Gardens, Kew, is due to be published by the IUCN as part of its
ongoing mission to assess the state of all life on Earth.

"[This year] marks the International Year of Biodiversity," said
Stuart Pimm of Duke University in North Carolina, USA, one of the
authors of the report. "The focus of this celebration has often been
on the species we know of, along with discussions on the unprecedented
challenge of conserving this biodiversity in the face of threats such
as habitat loss. However, by asking just how many species we will lose
before they are even discovered, our study has revealed a figure that
is truly alarming."

The researchers started by carrying out an independent review of how
many flowering plants – which make up most of the plant kingdom –
exist. By considering the rate at which new specimens are being
described to science, adjusted to reflect the growing number of
scientists over the years, and interviewing experts who focus on
different groups such as orchids, irises or grasses, the team
calculated that on top of the existing "best estimate" of 352,282
flowering plants there are another 10-20%, or 35,000-70,000, which
have still to be officially discovered.

The second stage was to assess the level of threats from habitat loss
due to clearing land for planting crops or trees, development, or
indirect causes such as falling groundwater levels and pollution.

They started with a study published in the journal Endangered Species
Research in 2008, which estimated that one-in-five known species were
vulnerable to extinction.

However based on the fact that new species – like recent discoveries –
are likely to be found in "biodiversity hotspots", where there are
huge numbers of endemic species which are not widely distributed
around the world, and a high level of habitat loss, they estimated
that all so-far-undiscovered flowering plants were also at risk.

"If we take the number of species that are currently known to be
threatened, and add to that those that are yet to be discovered, we
can estimate that between 27% and 33% of all flowering plants will be
threatened with extinction," said David Roberts, one of the
co-authors, of the Durrell Institute of Conservation and Ecology at
the University of Kent.

The paper adds: "These estimates are based on immediate threat, and do
not consider further development of destructive factors - including
climate disruption." The paper's third, lead, author was Lucas Joppa
of Microsoft Research in Cambridge.

The warning comes as there is growing international recognition of the
value of the natural world to humans in providing ecosystem services,
from flood protection and medicines to spiritual spaces and enjoyment.

"Plants are the basis for much of life on earth with virtually all
other species depending on them; if you get rid of those you get rid
of a lot of the things above them," added Roberts.