How many tropical plant species are threatened by climate change? Which plants have big enough ranges to survive a warming world, not to mention deforestation? How likely is it that the tropics are undergoing a current mass extinction? These questions may appear straight forward, but a new study in Global Change Biology finds that researchers lack the hard data necessary to come to any confident conclusions. According to the study, nine out of ten tropical plants from Africa, Asia, and South America lack the minimum number of collections needed (at least 20) to determine the species’ range, and therefore predict the impact of climate change.
“The problem isn’t that there are so few records—there are about a millions records—the problem is that the species diversity is so high. When you look at the way those records are distributed among the species, you find that most species are known from 1 or 2 collections,” co-author Miles Silman of Wake Forest University told mongabay.com.
For its part, mongabay.com has hundreds of photos of tropical plants that it has been unable to identify such as this unidentified flower in Tabin Wildlife Reserve, Sabah, Malaysia. Photo by: Jeremy Hance.
Silman’s co-author, Kenneth Feeley of the Florida International University and the Fairchild Tropical Botanic Garden explains says in order to confidently map a plant’s distribution researchers needs more than 20 collections, i.e. plant specimens collected from the field and referenced geographically.
“Estimates put the total plant diversity for the Neotropics at more than 85,000 species. In order to have just 20 collections of each we would need close to 2 million records. Add in Africa, Asia, India, and the islands, and maybe half a billion records are called for. As a comparison, in the United States we have fewer than 20,000 native vascular plant species,” Feeley says, adding that “we don’t know the true distribution of any tropical plant species. Almost any inventory conducted will uncover some species well outside their documented ranges. Many species that we think are rare or endemic may be better described as undercollected and understudied,” Feeley says.
Such a lack of data makes predicting climate change’s impact on tropical plants practically impossible.
“If we don’t know where a species is now how can we hope to know where it will be in the future?” Feeley asks.
A dearth in data may cause researchers to believe that a plant is only capable of handling certain temperatures when in fact it may be able to survive farther afield, but simply remains uncollected. The reverse can occur as well “lulling us into a false sense of security,” as Feeley says, about the plant’s long-term survival.
Rainforest canopy from the air in Panama. Photo by: Rhett A. Butler.
“The solution is very simple in theory and but hard in practice: we need more and better collections. Getting these collections means that we need to continue training and funding botanists, collectors
and biological explorers. We also need more taxonomic experts that can identify what gets brought into the herbariums from the field.” says Feeley.
Silman adds that “most people would be surprised to learn that for a lot of the major taxa of tropical plants, there is just one person dedicated to studying them. Or, in some cases, no one.”
In addition the study argues that herbaria and natural history collections need to better valued around the world. Even the smallest collections need to be integrated into global databases, and efforts to create a freely available digital biodiversity collection should continue.
For Silman the gap between raw data on record and the startling richness of tropical plant biodiversity hit home during an expedition ten years ago.
“We cored a lake on the east slope of the Andes and got a beautiful record of forests in the Andes biodiversity hotspot that extended back 50,000 yrs. When I went to look for data on modern distributions for the species found [as fossils…] there was precious little data on nearly all the taxa. We knew more about many of the species from their fossil pollen in a lake than we did from them living in nature. ”
CITATION: Feeley, K.J. and M. R. Silman. 2010. The data void in modeling current and future distributions of tropical species. Global Change Biology. doi: 10.1111/j.1365-2486.2010.02239.x
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