![\"2CA2RF4](\"https:\/\/images.newscientist.com\/wp-content\/uploads\/2024\/05\/20114130\/SEI_204387383.jpg?width=1200\")
<\/div>Biodiversity contains several dimensions<\/p>\n
Hans-Joachim Schneider\/Alamy<\/p>\n<\/div>\n<\/figcaption><\/figure>\n<\/p>\n
At first blush, the idea of biodiversity seems simple enough. It is essentially the variety of all life on Earth<\/a>. But making sense of biodiversity<\/a> in a way that can help us halt or even reverse its decline is anything but straightforward.<\/p>\n \u201cPeople often use the word biodiversity just to mean any characteristic of life out there that we might care to protect,\u201d says Mark Vellend<\/a>, a biologist at the University of Sherbrooke in Quebec, Canada. \u201cThat\u2019s not a definition I find useful in science because if it\u2019s everything, it\u2019s nothing.\u201d<\/p>\n For biodiversity to be a valuable concept, he says, it needs to be a measure of biological variety. That way, we can not only assess where we are and where we are headed, but also how best to conserve the biodiversity we have left.<\/p>\n The problem is that variety itself comes in many forms, especially in biology. \u201cYou can\u2019t just come up with a single number for biodiversity in the same way as you can for carbon,\u201d says Andy Hector<\/a> at the University of Oxford. \u201cIt\u2019s way, way more complicated.\u201d<\/p>\n We already have ways to measure biodiversity. That\u2019s how we know it is in steep decline. They boil down to what biologists think of as dimensions of biodiversity. One of the most basic is species richness, which is simply the number of species<\/a> in a given place at a given time. This has been used extensively and can sometimes be a\u2026<\/p>\n<\/p><\/div>\n