Food security in a perfect storm: using the ecosystem services framework to increase understanding. - Poppy GM; Chiotha S; Eigenbrod F; Harvey CA; Honzák M; Hudson MD; Jarvis A; Madise NJ; Schreckenberg K; Shackleton CM; Villa F; Dawson TP (Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 2014)