Plant Mapping Project Highlights Where Rarest Species Thrive
October 17, 2013

Plant Mapping Project Highlights Where Rarest Species Thrive

Lee Rannals for - Your Universe Online

An international group of researchers has created the most comprehensive map of rare plants to date.

The new map, published in Ecology Letters, shows how climate stability plays a crucial role in the distribution of plants on Earth. It shows that rare species in the Americas are located in California, Mexico, the Caribbean islands, parts of the Andes mountains, the south of South America, and the region around Rio de Janeiro.

"This came as a surprise to us, because the regions are very different in terms of climate and vegetation type. They include habitats such as wet tropical rainforests, dry subtropical regions, and even deserts, tropical mountains, and cool temperate grasslands and forests," Professor Jens-Christian Svenning, Department of Bioscience, said in a statement.

The analysis revealed where rare species in North and South America are found, as well as what factors determined if a region is dominated by widespread or rare species. The study also showed that consistent processes are driving the distribution of the plants.

“There are two factors in particular that are important for the distribution of the rare species," said PhD student Naia Morueta-Holme, who spearheaded the analysis along with Svenning. "Firstly, a stable climate with relatively small seasonal differences, where the climate has remained much the same for tens of thousands of years. Secondly, only small areas of habitat are involved. The species are unable to spread, but the stability nevertheless enables them to survive for long periods of time, and to develop and specialize in the same place."

Seasons vary in large areas in the north of America, and there have been distinct climate changes between ice ages and warm ages. This has enabled widespread species to be dominant here, either because they can withstand a wide range of climate conditions or because they are good at dispersing and can track changes in climate over time.

The team said rare species, which rely on habitat area and a stable climate, are being threatened by human-induced climate changes.

“Even though we’re expecting less climate change in the areas dominated by rare species than in North America, for example, it could well be that future changes may be beyond what the species can tolerate," said Morueta-Holme. "Our results show that climate change will no doubt have serious consequences for some of the most biodiverse areas in the world, which are also threatened by increasing land-use changes of natural areas."

The study resulted in the world's largest data set to date of all the plants in North and South America. The database contains more than 20 million records of about 250,000 species, and more are still being added.

“We’ve finally got a place where we can gather all the records and create an overview of where New World plant species are located. This unique data set provides us with an opportunity to fundamentally understand what determines the current diversity and distribution of plants," the PhD student said. "We’re now better able to predict how species, vegetation and even agricultural crops will react to environmental change. This improves our chances of taking the necessary management measures to avoid negative consequences."