Drought limits tropical plant distributions, scientists report

May 02, 2007
Drought Seedling
Severely wilted tropical tree seedling. Credit: Bettina Engelbrecht

Drought tolerance is a critical determinant of tropical plant distributions, researchers working at the Smithsonian Tropical Research Institute in Panama report in the journal Nature, May 3. In a novel coupling of experimental measurements and observed plant distributions across a tropical landscape, drought tolerance predicted plant distributions at both local and regional scales. This mechanism to explain a common observation will contribute significantly to models of land use and climate change.

Tropical forest, often called rainforest, conjures up images of verdant, evergreen landscapes. Whereas temperatures may be relatively constant in the tropics, rainfall and water availability often vary dramatically across small distances.

"The Isthmus of Panama is the ideal place to test the idea that the distribution of plant species is influenced by their ability to tolerate a lack of water," said researcher and article author Bettina Engelbrecht of the University of Kaiserslautern in Germany and STRI.

After measuring the drought tolerance of 48 plant species experimentally, scientists looked at the plants’ regional distributions across 122 tropical forest plots set up by the Center for Tropical Forest Science. The plots are distributed over a rainfall gradient from the wet Caribbean slope to the drier Pacific slope.

"It was a surprise that even in humid tropical forests, traditionally viewed as water saturated, plants growing at dry sites were more drought-tolerant than plants growing at wet sites," Engelbrecht said.

The team also evaluated the local distributions of both seedlings and older trees on STRI’s 50-hectare Forest Dynamics plot on Barro Colorado Island, roughly in the middle of the rainfall gradient. Drought tolerance was a stronger predictor of species distributions for saplings and adult trees than for seedlings, implying that plant community composition adjusts in accordance to environmental constraints.

Researchers ruled out several other potential predictors of plant distribution that could be associated with drought tolerance, such as shade tolerance and nutrient availability.

Identifying drought tolerance as a cause of plant distribution patterns significantly advances the understanding of tropical plant diversity and implies that changes in rainfall patterns—a predicted consequence of climate change in the tropics—may give rise to dramatic changes in tropical plant communities.

"In the tropics, climate change does not just mean temperature change—dramatic shifts in rainfall patterns also are expected to occur," said Ben Turner, STRI staff scientist and co-author. "Our research shows that changes in rainfall patterns will have considerable consequences for tropical forests."

Source: Smithsonian Tropical Research Institute

Explore further: Researchers collect soil samples from around the globe in effort to conduct fungi survey

add to favorites email to friend print save as pdf

Related Stories

What do wildfires have to do with climate change?

Oct 14, 2014

As the western U.S. faces its third year of severe drought, firefighters are still battling two large fires in California. The state, which is experiencing its worst drought since record keeping began in ...

Drought response identified in potential biofuel plant

Jul 15, 2013

Drought resistance is the key to large-scale production of Jatropha, a potential biofuel plant—and an international group of scientists has identified the first step toward engineering a hardier variety.

Recommended for you

Parasitic worm genomes: largest-ever dataset released

5 hours ago

The largest collection of helminth genomic data ever assembled has been published in the new, open-access WormBase-ParaSite. Developed jointly by EMBL-EBI and the Wellcome Trust Sanger Institute, this new ...

Male sex organ distinguishes 30 millipede species

5 hours ago

The unique shapes of male sex organs have helped describe thirty new millipede species from the Great Western Woodlands in the Goldfields, the largest area of relatively undisturbed Mediterranean climate ...

How can we avoid kelp beds turning into barren grounds?

9 hours ago

Urchins are marine invertebrates that mould the biological richness of marine grounds. However, an excessive proliferation of urchins may also have severe ecological consequences on marine grounds as they ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.