A magazine study Science warns that the extinction of species capable of dispersing seeds is detrimental to plants, since they lose their ability to migrate to places that climate change has not made inhospitable. “When we lose birds or mammals, we don’t lose just these species. We also lose its important ecological function, which is to disperse seeds,” said Evan Fricke of Rice University.
This study is the first to quantify the problem at a global level, and estimates that the ability of plants that need the collaboration of animals to adapt to climate change has already been reduced by 60%. Tree species present in regions that have become inhospitable due to global warming can, for example, migrate to other areas where it rains more, but they do so in the form of seeds. Half of the plants depend on animals to eat their fruits and transport them further, while others are left to the wind alone.
The Danish researchers used data from thousands of previous studies of animal behavior to build a map of their contribution to seed dispersal. Then, they compared a map that nullifies the effect of human-caused species extinctions and the reduction of their territories.
The results were surprising: the loss in seed dispersal was very pronounced in temperate regions of North and South America, Europe, and Australia, despite only losing a small percentage of mammal and bird species. And it was less in the tropical regions of South America, Africa or Southeast Asia, but it could accelerate if other species such as elephants become extinct.