Carbon storage in tropical forests linked to wildlife conservation

Conserving wildlife can benefit carbon storage in tropical forests across the world and contribute to controlling global warming, says a new study conducted by an international consortium of researchers.

This is because many tropical tree species that have high carbon storage potential depend on large wildlife for seed dispersal.

The study published in Nature Communications on April 25 was conducted by researchers from National Centre for Biological Sciences (NCBS) in Bengaluru, Nature Conservation Foundation (NCF) in Mysuru, University of Leeds (United Kingdom) and 12 other academic and conservation institutions.

Large-seeded tree species which depend on big animals for seed dispersal grow to greater sizes as adults and thus have higher carbon storage potential than species with smaller seeds in tropical forests worldwide, according to the research.

Losses of large seed dispersers can therefore reduce carbon storage by the earth's tropical forests by decreasing the volume of vegetation biomass in these forests.

"Scientists are only just beginning to understand the numerous ways in which animals affect the carbon cycle of tropical forests and the consequences of declines of these animals - also termed defaunation - for terrestrial carbon storage," said Anand M. Osuri, affiliated to NCBS and NCF and also the study's lead author.

The findings say the forests of the Americas, Africa and South Asia, which are primarily composed of tree species dependent on animals for seed dispersal, will face the "most severe reductions of carbon storage" due to declines of large seed dispersers.

In contrast, carbon storage may be "less sensitive" to losses of large seed dispersers in the forests of south east Asia, where a number of large tree species depend on wind and gravity, rather than animals, for seed dispersal.

The study predicts that if 50 percent of all trees dispersed by large animals were replaced over time by trees with other modes of seed dispersal, carbon storage in tropical forests of the Americas, Africa and South Asia would be reduced by two percent, which is roughly equivalent to 14 years' worth of Amazonian deforestation, said Mahesh Sankaran, affiliated to NCBS and University of Leeds.