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Researchers have looked at the numbers again: When a small group of extreme cases is removed, the picture becomes less dark, they say.
– We do not argue that there would be no problems with biodiversity. But this is not a worldwide decline and the situation is not hopeless, Brian Leung, a professor at McGill University in Canada, tells AFP.
Together with research colleagues in the US and UK, he has analyzed the basis of the World Wide Fund for Nature’s large Living Planet Index report, which resulted in dark headlines around the world when it was published. The problem, according to the research group, is that the average figure that should describe the situation of the world’s vertebrates is misleading, since it is strongly influenced by extreme values.
– Compressing the data for all stocks into a single figure can give the impression that everything is in decline, says Brian Leung.
When the researchers removed the populations that decreased most extremely, which were amphibians in South America, which corresponded to about 1 percent of the total of just over 14,000 populations, there was neither an increase nor a decrease in the world average. Their results were recently published in the journal Nature.
– However, this does not mean that the remaining 99 percent of all stocks are fine, notes Leung’s colleague Robin Freeman, who was involved in both the new study in Nature and the original World Wide Fund for Nature report.
If, instead, you remove 10 percent of the populations at both ends, that is, both those that have decreased the most and those that have increased the most, the average shows an overall decrease of 42 percent. And if 2.4 percent of the population is eliminated in the part that decreases the most, you will see a slight increase overall. So what to believe?
“A constructive discussion of species conservation assumes that both the research world and the media resist the temptation to use simple indices,” the research group writes in Nature.
The danger of a nuanced imageBrian Leung and his colleagues believe that it can lead to the perception that nature conservation efforts have no effect and that no matter what we do, it is still running.
– As all stocks continue to fall despite all our efforts in the last decades, that kind of constant negative message can lead to abandonment and reduction of efforts, says Brian Leung.
Olle Forshed, a nature conservation expert at the World Wide Fund for Nature, agrees:
– If you want to understand this better, you need to break down the number of different species groups and regions. So you get a more detailed picture of what it actually looks like.
TT: But then why does the World Wide Fund for Nature present this average value to give a picture of the state of the world’s vertebrates?
– You have to see it as an indication, showing which direction it is leaning. But you are making a mistake if you translate the Living Planet Index directly to apply it to all vertebrate populations individually. It’s not possible, says Olle Forshed.
A more nuanced picture, he explains, shows, for example, that the situation is more alarming for, among other things, amphibians in South and Central America, bird populations in much of Asia and for many of the large mammals of the world. African continent.
I Europe and North America however, it appears brighter. There, some stocks are even on the rise again, but from very low levels.
– There is a clear connection with reducing hunting pressure and nature conservation efforts. Unsustainable hunting has been very strictly regulated. In addition, we have overcome various types of environmental toxins. So many trends can be reversed with the right efforts. It is important knowledge that it is possible to change the situation of many vertebrates, says Olle Forshed.
