A lot of attention has been paid to the decrease in bee populations and other pollinators, but a recent review article makes the case that we should be equally alarmed by the declining numbers of seed-dispersing animals, which are crucial for growing healthy forests.<\/p>\n
\u201cBoth are important and should be taken into account in restoration and conservation projects,\u201d study co-author Mauro Galetti, director of S\u00e3o Paulo State University\u2019s Center for Research on Biodiversity Dynamics and Climate Change, said in a press release.<\/p>\n
Pollinators receive more attention because of their known importance for food production and the economy. But roughly half of all plants, including 90% of trees in tropical rainforests, are dependent on seed-dispersing animals for their propagation.<\/p>\n
When frugivorous, or fruit-eating, animals consume seeds, their digestion process prepares the seed to receive water and germinate once they\u2019re deposited, making such animals \u201cunknown heroes,\u201d the press release notes.<\/p>\n
\u201cSeeds consumed by animals will germinate more, faster, and will establish themselves in safer places to grow,\u201d Galetti said.<\/p>\n
Some plants rely on a single species for seed dispersal, as in the case of the Brazil nut and the agouti, an Amazonian rodent. \u201cIf the agouti becomes extinct locally, the Brazil nut\u2019s seed dispersal service will succumb,\u201d Galetti said.<\/p>\n
Birds, bats, monkeys and tapirs are the most common types of seed dispersers, but there are some more surprising animals involved. In Brazil\u2019s Atlantic Forest, for example, certain fish species disperse seeds in riparian forests or those near wetlands. In the Amazon and Brazil\u2019s Pantanal, the piranha-like pacu and tambaqui fish \u201ctravel long distances and eat large quantities of fruit,\u201d Galetti said. In doing so, they spread seeds along the way.<\/p>\n
The review article also noted estimates of forest carbon that can be lost with the decline in seed dispersers. Although the results aren\u2019t yet peer-reviewed, they \u201csuggest that seed dispersal disruption reduces carbon accumulation by multiple tonnes per hectare annually across many tropical regrowth forests,\u201d the researchers note.<\/p>\n
The article also highlighted findings from a 2022 study that showed declines in seed-dispersing animal populations and diversity \u201chas severely reduced long-distance seed dispersal, cutting by more than half the number of seeds dispersed far enough to track climate change.\u201d In other words, fewer animals are carrying seeds into newly suitable habitats, limiting the ability of plants to shift their ranges and adapt to a warming climate.<\/p>\n
The primary causes of declines in seed disperser diversity, population and movement are human-caused habitat loss, landscape fragmentation, invasive species and animal exploitation.<\/p>\n
\u201cProtection, management and restoration of seed dispersers are essential for the success of efforts to address the twin challenges of nature decline and climate change,\u201d the researchers wrote.<\/p>\n