Plant species in peril, report warns

One in five of the world's plant species – the basis of all life on earth – are at risk of extinction, according to a landmark study compiled by the UK's Royal Botanical Gardens at Kew, London and published Wednesday, September 29th, 2010. This is the first ever comprehensive study of plants, from giant rainforests to common snowdrops, and it finds 22% of all species at risk.

The study took five years to complete and used the Royal Botanical Gardens (at right) and London's Natural History Museum archives (which hold around 13 million specimens combined) along with data from the International Union for the Conservation of Nature (IUCN).

At first glance, the 22% figure looks far better than the previous official estimate of almost three-quarters, but the announcement is being greeted with deep concern. (At left: The map shows where major threats to plant life exists with major hotspots in Madagascar, Australia, South America, and Southeast Asia. Click on map image to see larger image.)

The previous estimate that 70% of plants were either critically endangered, endangered or vulnerable was based on what scientists universally acknowledged were studies heavily biased towards species already thought to be under threat.

This new report, "Sampled Red List Index for Plants", is the first ever comprehensive assessment of the threat to more than 380,000 plant species, from giant tropical rainforests to the rarest of delicate orchids, concludes the real figure is at least 22%. It could well be higher because hundreds of species being discovered by scientists each year are likely to be in the "at risk" category

The report says that human activities (81 percent) far outweigh natural threats (19 percent) to plant biodiversity and are being fueled by agriculture, logging, plantations and livestock.

Nearly two-thirds of threatened plant species are found in tropical rainforests, five times the proportion for the nearest other habitats – rocky areas, temperate forests and tropical dry forests. This is because of their huge density of biodiversity and the widespread risks of logging and clearance for other agriculture, said analysts.

Steve Bachman, a plant conservation analyst and one of the lead researchers on the report stated: "It's not just the developing world or the Western world who are mostly to blame. We are all using plants in an unsustainable way. We need to take drastic measures to stop that and we need to understand more about how we utilize them."

The plant study is also considered critical to understanding the level of threat to all the natural world's biodiversity, said Craig Hilton-Taylor of the International Union for the Conservation of Nature (IUCN), which runs the world's official "red list" of threatened species. "Plants are the basis of life, and unless we know what's happening to plants it has many implications," said Hilton-Taylor.

Read a summary of the report here.

Aided by Neil Brummitt, a botanical diversity expert, Bachman and a team of researchers examined around 7,000 plant species randomly drawn from the five major plant groups as a representative sample of the estimated 380,000-400,000 so far known to science. Of these, 3,000 were found to have too little information to begin making an proper assessment – a result that was expected and so built into the selection process.

The remaining 4,000 species were assessed and the level or risk based on a combination of the absolute number of plants estimated in the wild, the known decline, and the total area in which they are thought to live.

The plant groups assessed included bryophytes (mosses and liverworts), pteridophytes (land plants such as ferns), gymnosperms (such as conifers and cycads), monocotyledons (flowering plants including orchids, grass and palm families) and legumes (peas and beans). (At right: example of a gymnosperm)

Of the five plant classifications, gymnosperms were the most endangered group with 36 percent of plants examined being under threat.

Of the 4,000 species assessed, 63% were found to be of "least concern", 10% near threatened, 11% vulnerable, 7% endangered and 4% critically endangered. Another 5% were rated "data deficient".

The proportion of plant species deemed at-risk is similar to that of the IUCN's red list for mammals, worse than that for birds (less than 10% at-risk) and better than the number for amphibians (more than a quarter under threat).

Researchers conceded that over a third of the species in the study's sample were "so poorly known" that a conservation assessment wasn't possible. Nevertheless, they are hopeful the new study will serve as a guide for future plant assessments.

"The point of this project is that we have set the baseline. We will need to do this every five years and see how it changes over time," Brummitt stated.

The report will be presented at next month's United Nations Convention on Biological Diversity in Nagoya, Japan, where representatives from 193 nations are meeting to discuss new measures to tackle the biodiversity crisis.

Stephen Hooper, director of the Royal Botanical Gardens, Kew said: "The 2020 biodiversity target that will be discussed in Nagoya is ambitious, but in a time of increasing loss of biodiversity it is entirely appropriate to scale up our efforts.

"Plants are the foundation of biodiversity and their significance in uncertain climatic, economic and political times has been overlooked for far too long."

At a U.N. summit in New York earlier this month, U.N. Secretary-General Ban Ki-moon urged world leaders "to commit to reducing biodiversity loss."

At the same summit Jose-Manuel Barroso, president of the European Commission, called on countries to agree a strategic plan to "tackle the key drivers of biodiversity loss" and "to prevent ecological tipping points from being reached."

Source:
Cable Network News, "Plant species in peril, report warns", accessed September 29, 2010
The Guardian, "One in five plant species face extinction", assessed September 29, 2010