New Maps of Plant Diversity Show Global Richness Patterns

SAN DIEGO, California, March 20, 2007 (ENS) - A new global set of maps of plant diversity offers clues to the likely impact of climate change on the services plants provide to humans. With several hundred thousand plant species plotted, the scientists who created the maps say they are the most extensive to date.

Dr. Walter Jetz of the University of California-San Diego and Holger Kreft of the University of Bonn sought in their mapping study to determine how well the diversity, or the "richness," of plant species could be predicted from environmental conditions alone.

The maps depict the species richness patterns of plants in 1,032 geographic regions worldwide.

"Climate change may drive to extinction plants that hold important cures before we find them," says Kreft, a biologist at the Nees Institute for Biodiversity of Plants at the University of Bonn.


Maps of plant richness produced by Walter Jetz and Holger Kreft. The kriging noted on the maps is a geostatistical approach to modeling. (Photo courtesy UCSD)
"Ecological research like ours that captures complex diversity - environment relationships on a global scale may assist in a small, but important way so that such a fatal potential failure can be averted," said Kreft.

"Given that we are far off from knowing the individual distributions of the world's 300,000 odd plant species," says Jetz. "Holger Kreft and I investigated how well the richness of plants can be predicted from environmental conditions alone."

The maps, which accompany the study, "Global patterns and determinants of vascular plant diversity" published in this week's early online issue of the journal "Proceedings of the National Academy of Sciences," highlight areas where conservation efforts are especially important.

Kreft said, "The global map of estimated plant species richness highlights areas of particular concern for conservation and provides much needed assistance in gauging the likely impact of climate change on the services plants provide to humans."


Dr. Walter Jetz earned his PhD in zoology from Oxford University. (Photo courtesy UCSD)
Combining field-survey based species counts from over a thousand regions worldwide with high-resolution environmental data, the scientists were able to capture the factors that promote high species richness of plants.

"This allowed us to estimate the richness of yet unsurveyed parts of the world," says Jetz, an assistant professor of biology at UCSD and the senior author of the paper.

The scientists expect the maps to help pinpoint areas that deserve further attention for the discovery of plants or drugs that are as yet unknown to humanity.

"Plants provide important services to humans - such as ornaments, structure, food and bio-molecules that can be used for the development of drugs or alternative fuels - that increase in value with their richness," says Jetz.


Common across temperate latitudes, feverfew, Tanacetum parthenium, was known to medieval herbalists as a remedy for headache and fever. How many plants still unidentified could cure stubborn diseases? (Photo credit unknown)
"Tropical countries such as Ecuador or Colombia harbor by a factor 10 to 100 higher plant species richness than most parts of the United States or Europe. The question is, Why?"

An enthusiastic field ornithologist, Jetz has also participated in similar studies of the richness of bird distribution, and also that of terrestrial mammals and amphibians.

"I am interested in the way environment, evolutionary history and chance affect ecological patterns at the level of the individual, population and community," he said, "and how these then combine to form patterns at the scale of continents or the whole globe."