biodiversity ,

Global warming taking toll on rainforests, too

RICE (US)—Global warming may also be a threat to animal and plant life in biodiversity hot spots like Madagascar, once thought less likely to suffer from climate change.

Most studies of global warming focus on temperate zones, says Amy Dunham, assistant professor of ecology and evolutionary biology at Rice University.

“We all know about the polar bears and their melting sea ice.  But tropical regions are often thought of as refuges during past climate events, so they haven’t been given as much attention until recently.”

Using the lemur as the canary in the coal mine, Dunham found a direct correlation between the frequency of El Niño and a threat to life in Madagascar, a tropical island that acts as a refuge for many unique species that exist nowhere else in the world.

The study appears online in the journal Global Change Biology and will be included in an upcoming print issue.

“We’re starting to realize that not only are these hot spots of biodiversity facing habitat degradation and other anthropogenic effects, but they’re also being affected by the same changes we feel in the temperate zones.”

Dunham set out to learn how El Niño patterns impact rainfall in southeastern Madagascar and how El Niño and cyclones affect the reproductive patterns of the Milne-Edwards’ Sifaka lemur.

The lemur’s mating habits are well-defined, which makes the animal a good candidate for such a study. Female lemurs are sexually responsive to males for only one day a year in the austral summer months of December or January and give birth six months later.

“There aren’t many species that have such long-term demographic data that enable us to look at these kinds of questions,” Dunham explains. “So this was a unique opportunity.”

Dunham found that in Ranomafana, a national park in the southeastern rainforest of Madagascar, El Niño makes wet seasons wetter.

“When it rains heavily, lemurs are not active. They sit there and wait for the rain to stop, huddling for warmth,” Dunham says.

Anecdotal evidence suggested heavy rains knock fruit off the trees when lactating lemurs need it most, and may even kill trees outright. Cyclones making landfall have a direct negative effect on the fecundity, or the potential reproductive capacity of lemurs, Dunham says.

The team also discovered that fecundity was negatively affected when El Niño occurred in the period before conception, perhaps altering ovulation, or during the second six months of life, possibly reducing infant survival during weaning.

“Madagascar’s biodiversity is an ecological treasure,” Dunham says. “But its flora and fauna already face extinction from rapid deforestation and exploitation of natural resources. The additional negative effects of climate change make conservation concerns even more urgent.”

Researchers from Texas State University-San Marcos and Stony Brook University contributed to the research.

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