John Barron from ABC News Radio asked a fair question today. After listening to me explain how important it was that had a seedbank as an insurance policy for species loss and to restore habitats, he pointed out quite rightly that species have always gone extinct. Of course they will continue to do so but there are a few good arguments for protecting what we have living with us today.
Firstly we don't know what the real effect is of losing a particular species from an ecosystem - it might be critical for the survial of other species, for the ability of that habitat to stop errosion or help water collection into rivers and lakes, and all sorts of other things. While species have gone extinct right through evolution, the species we live with today are the ones we have evolved with as humans so it's a little risky to knock them off one by one on the assumption things will just balance out in some way (of course they may 'balance out' without humans...).
Then there is the fact that each species represents a unique outcome of evolution, a kind of Mona Lisa painting as Steve Hopper from Royal Botanic Gardens Kew puts it, that can never be replaced. Why would we want to knowingly destroy these amazing things that can't be replaced - it's the 'knowingly' that is important because we actually have the chance to stop them going extinct in most cases.
So the arguments can be practical - what is the cost of destroying a species (in most cases we don't know but wouldn't it be wiser to leave ourselves with more 'opportunities' in the future) - or passionate - these species are such amazing things that it would be obscene to willingly let them go extinct. There are other arguments but they usually fall into these two categories.
The seedbank, then, is a good way to store all this plant genetic diversity. Given the benefits of each species - the opportunity cost or the value of a Mona Lisa - the cost is minimal. The best thing for all of us is of course to retain the plants in their natural habitats, where they interdepend and flourish along with other plants, animals and microorganisms. Restoring individual species is difficult, restoring entire habitats extremely difficult (if possible). But a seedbank is part of a considered and sensible approach to conserving our plant diversity in a changing world.