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Simple climate solution: Stop hunting elephants and fruit-eating animals

A recent study led by the Wildlife Conservation Society (WCS) has found that, in order to curb climate change, a simple yet surprising approach could be protecting elephants, gorillas, and other large-bodied fruit-eating animals like tapirs or hornbills. The overhunting of these species reduces the ability of forests to sequester carbon.

These frequently hunted animals, many of which are at risk due to both illegal and commercial hunting practices, are primarily fruit eaters that spread large seeds. Such seeds come from tree species known for their high carbon storage capacities. 

Empty forests

According to the researchers, the disappearance of these significant frugivores – including primates, hornbills and toucans – alters the forest composition over time. This leads to an increase in trees that rely on wind dispersal or have small seeds. These trees typically have lower wood density and, consequently, store less carbon.

“Many tropical forests have been described as ‘empty’ owing to loss of animals, often as a result of unsustainable subsistence or market hunting,” said lead author Elizabeth Bennett, the Vice President of Species Conservation at WCS. 

“Such hunting is known to have detrimental effects on target species, broader biodiversity, and the livelihoods and well-being of local communities.” 

“Less appreciated is the adverse impact of defaunation on the capacity of tropical forests to sequester and store carbon, which has implications for climate change.”

Loss of large frugivores 

The researchers point out that in regions like the Neotropics, the loss of large primates and tapirs, responsible for dispersing seeds from large-seeded trees with denser wood, is estimated to cause long-term reductions in above-ground tree biomass. 

This reduction ranges from an average of three to six percent. In extreme cases, it could reach nearly 40 percent. 

In places such as central Thailand, trees relying on seed dispersal by sizable frugivores represent almost a third of the total carbon biomass.

Restoration efforts 

Interestingly, current restoration efforts to counteract emissions usually involve planting seeds and seedlings of mostly small-seeded, largely second-growth species. Reforestation projects often overlook large-seeded species dispersed by animals.

Once these animals become extinct or severely reduced, repopulating them becomes challenging, particularly without their primary food sources. This factor further impedes the restored forests’ potential to capture and store carbon efficiently.

Ecologically intact forests

The study also highlights the critical role of ecologically intact forests. Such forests, which are vast, uninterrupted by significant human-induced damages, and home to diverse wildlife, are vital. They estimate to remove around 3.6 billion tons of CO2 annually.

“Animals have a vital role in maintaining the integrity of such forests; those forests with their full complement of faunal species, at healthy population densities, sequester and store more carbon than those that have lost components of their fauna,” said co-author John Robinson.

“Maintaining intact faunas is therefore a critical component of any strategy to conserve forests to address climate change.”

Beyond forest dynamics

Additionally, hunting’s detrimental effects on climate go beyond forest dynamics. Hunting causes the loss of carbon stored in the bodies of wildlife.

For instance, an adult forest elephant holds approximately 720 kg (1,587 pounds) of carbon (2.64 tons of CO2e). Thus, the tragic loss of 11,000 elephants from 2004 to 2012 in a single Gabonese national park equates to a loss of 7,920 tons of carbon storage or 29,040 tons of CO2e.

Study implications 

The study emphasizes that markets like REDD+ (Reduced Emissions from Deforestation and forest Degradation) already recognize the carbon sequestration and storage capacities of forests. 

However, these markets primarily focus on the trees’ carbon and thus on preventing deforestation and forest degradation. 

Given that the loss of large fauna can reduce forest carbon content, there is a chance to enhance the carbon storage value of intact fauna. This can strengthen biodiversity evaluations by showcasing the complete ecological integrity of protected fauna.

“Explicitly valuing wildlife for its role in the sequestration and storage of carbon in tropical forests, and creating a market for intact faunal assemblages, can potentially generate significant revenues for forest and hunting management,” said Bennett.

“Such a market is one way to pay for the multi-faceted programs needed to conserve forests with their full complement of large faunal species, while also ensuring the nutritional health and well-being of local communities in carbon-friendly ways.”

The study is published in the journal PLoS Biology.

By Andrei Ionescu, Staff Writer

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