Fire, grazing and the evolution of New Zealand grasses

Less than 4% of the non-bamboo grasses worldwide abscise old leaves, whereas some 18% of New Zealand native grasses do so. Retention of dead or senescing leaves within grass canopies reduces biomass production and encourages fire but also protects against mammalian herbivory. Recently it has been argued that elevated rates of leaf abscission in New Zealand’s native grasses are an evolutionary response to the absence of indigenous herbivorous mammals.