My Lords, one could argue that what is good enough for Sir David Attenborough is good enough for this Bill. Sir David’s 2020 TV programme “Extinction”, in which he talked about biodiversity, was watched by 4.5 million viewers on its premier. Those people, and the millions more who have watched it subsequently, will have some idea of what biodiversity is.
Although I do not support this amendment for the reasons that my noble and learned friend Lord Hope of Craighead so clearly articulated, I am grateful to the noble Lord, Lord Blencathra, for tabling the amendment, because it provides me with an opportunity, following the noble Baroness, Lady Bennett of Manor Castle, to ask the Minister to clarify precisely what the Government mean when they talk about biodiversity. As my noble and learned friend Lord Hope of Craighead said, words do matter. If the Government are to maintain the term “biodiversity” in this Bill, which I hope they will, please could they explain what it actually means?
I am now going to get a little bit technical. Ecologists recognise a number of different, but interrelated, meanings of the word “biodiversity”. At its simplest, it refers to what is called “species richness”—simply the number of species inhabiting a defined geographical area, such as England. A more sophisticated variant of species richness takes into account the relative abundance of different species. On this measure, an area populated by one extremely common species and, say, five very rare ones will be less biodiverse than if all six species were roughly equally abundant.
As the noble Baroness, Lady Bennett of Manor Castle, has already said, biodiversity can also include genetic diversity within a species. For instance, one might be particularly interested in preserving subspecies that are unique to this island, such as the native pied wagtail, motacilla alba Yarrelli. Furthermore, biodiversity might encompass the genetic distinctiveness of species, by placing a premium on species with no close living relatives on the planet, or on endemic species, such as eudarcia Richardsoni, a micro-moth found only in Dorset.
Finally, biodiversity might encompass the diversity of habitats, such as woodland, heath, peatbog and intertidal marshes, found within a geographical area. Many ecologists distinguish between what they call alpha diversity—species richness within a habitat—and beta diversity, which is diversity between habitats.
I hope that the Minister, in his response, or afterwards in writing, will explain what the Government mean when they talk about biodiversity. At the same time, it would be helpful if he could explain the difference between biodiversity and species abundance, as introduced in Amendment 22, which we will debate later.