In any forest it’s the trees that act as a carbon sink, absorbing more carbon dioxide than they emit. But to focus on trees alone is to miss the helping hand provided by forest animals. Though many trees rely on the wind to carry their seeds far and wide, the most carbon-dense trees have larger seeds and are therefore dependent on primates and birds to disperse them. Any dip in the number of these animals means top carbon-sequesters suffer.
Bigger animals also contribute to the carbon sink potential. A recent study of forest elephants published in the academic journal Nature Geoscience found that their seemingly damaging behaviour – tramping though forests, creating paths and openings – actually allows light to reach the ground, again favouring larger, carbon-dense trees.
It was with this in mind that WWF produced its new report, Below the Canopy. Compiled using data from the Living Planet Index (another WWF report released every two years that compiles data from published wildlife studies across the world), Below the Canopy states that forest-dwelling vertebrate populations have shrunk on average by more than half since 1970. The result, it says, are ‘serious consequences for forest integrity and climate change because of the roles that wildlife play in forest regeneration and carbon storage’.
Exactly why forest wildlife is in decline comes down to more than simply the amount of forest available. One of the key findings is that while habitat loss and habitat degradation are certainly major drivers (they accounted for 60 per cent of the threats to forest species identified in the report), changes in tree cover do not always reflect changes in populations of forest animals.
‘In some cases forest cover was increasing, but populations of wildlife weren’t increasing with them,’ says Will Baldwin-Cantello, chief adviser on forests for WWF-UK. The reason for this is that several other issues, including unsustainable hunting and poaching, invasive species, climate change and disease, also contribute to species loss, making the picture particularly complex.
In response to this range of threats, WWF is highlighting the need for a multi-faceted approach to preserving forests, one that prioritises both forest area and forest health – or in other words, both quality and quantity. ‘We want to be promoting restoration and reforestation, but that doesn't mean we should just be putting any tree anywhere,’ says Baldwin-Cantello. ‘It must be the right tree in the right place so that it creates suitable conditions, creating the right kind of habitat for wildlife.’
The organisation is also calling on the international community to implement a more detailed method for measuring forest progress, pointing to the new global biodiversity framework – due to be agreed by UN countries in 2020 – as a prime opportunity to widen the criteria. ‘We really need to do a better job than we did last time at integrating real biodiversity integrators into the framework,’ says Baldwin-Cantello. ‘If, as we did last time, we just measure hectares of forest cover gained or lost then we're really going to miss the point.’
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