Jen, Cambridge asked:
While on safari in Africa, we saw plants that are favoured by elephants but which they can only eat for fifteen minutes before the plant and all those around it produce tannins to make itself inedible. Is this a common strategy?
John - Yes, plants can do all kinds of things to defend themselves. Of course, some plants produce alkaloids as toxicants, but clever animals like the elephants and I believe also, like ourselves can actually take some enjoyment or entertainment from such plants. So the elephants can become a little dangerous when they've taken some of these alkaloids.
Ben - But does that also mean that you get a sort of patterning in a forest where you have the plant that was attacked, that then creates a ring of protected plant around it and then you have to go a few hundred metres before you get the next plant that gets attacked.
John - Yes, and if you bear in mind the fact that when the plants are being attacked, they can actually signal to plants next to them then you get a very, very complex situation building up. And indeed, Charles Darwin noticed that when plants were living in very complicated ecosystems, they produce generally more biomass than when we grow our traditional monocultures of a row of lettuce or a field of wheat.
Ben - Chris, is that something again that you could model, the way that these responses lead to patterning of vulnerable plants?
Chris - Absolutely, and indeed, we’re looking at other spread of disease in natural systems at present, so this is away from crops where there's a disease called Sudden Oak Death which is threatening very large parts of California and is also causing a lot of damage in the UK. There, we’re looking at what is the heterogeneity - once again, that word comes out very often - in the natural vegetation and how does the invasion by that pathogen actually change that too.