July 2 (UPI) -- Madagascar's largest tree species are under threat. So are the island nation's iconic primates, its lemurs.
Healthy forests are essential to Madagascar's lemurs, and new research suggests the trees need healthy lemur populations to survive. They rely on each other.
"Forest loss is a huge problem in Madagascar right now, but our study suggests that just saving the trees is not enough," Amy Dunham, associate professor of biosciences at Rice University, said in a news release.
Lemurs disperse the seeds of Madagascar's largest hardwood species. And as the new research showed, lemurs are the only animals on the island large enough to ingest the seeds found inside the fruits of Madagascar's largest tree species.
During a previous survey, scientists tracked the diets of 24 groups of lemurs and their dispersal of large seeds for three years. The data showed seeds that were digested and dispersed by lemurs were more likely to sprout and develop into a sapling than seeds that simply fell from the tree.
The latest study, published this week in the International Journal of Primatology, builds on the earlier findings.
Using previous survey results, scientists built a model to simulate the process of tree regeneration in the forests of Madagascar. The models allowed scientists to measure how the loss of primate populations would impact large tree species.
"We found that lemurs are the primary seed dispersers of the largest canopy trees," said researcher Anecia Gentles, who graduated from Rice in May. "The models suggested that the loss of lemurs and the trees they disperse could lead to increasing abundances of smaller, fast-growing tree species with lighter wood."
The largest tree species with the largest seeds would be most negatively impacted by the loss of lemurs. As a result, the ability of Madagascar's forests to sequester carbon would be diminished by the primates' decline.
The research confirms the importance of integrative conservation programs -- efforts that look to conserve important ecological relationships.
"Tropical forest ecosystems globally are threatened by the loss of large fruit-eating animals, and there's growing evidence that we need to think more holistically about conserving functioning ecosystems in order to save forests," Dunham said.