Retention of dead leaves by grasses as a defense against herbivores. A test on the palatable grass Paspalum dilatatum

• Published in: Oikos 2009-05, Vol.118 (5), p.753-757
• Main Authors: Mingo, Antonio, Oesterheld, Martín
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Biomass; Biomass production; Botany; Ecology; Fundamental and applied biological sciences. Psychology; General aspects; Grasses; Grasslands; Grazing; Herbivores; Leaves; Paspalum dilatatum; Plant growth; Plants; Rotational grazing; Tillers
• ISSN: 0030-1299; 1600-0706
• DOI: 10.1111/j.1600-0706.2008.17293.x

The vast majority of grass species retain their leaves as they become senescent, inducing an accumulation of dead biomass that may limit plant productivity. In this research, we tested the hypothesis that dead leaf retention by grasses act as a defense against large herbivores. In a natural grassland of the Flooding Pampa, we carried out a factorial experiment with dead-leaf removal and grazing as main factors. Dead leaves were removed from the palatable grass Paspalum dilatatum, and growth was measured either in the absence or in the presence of large grazers. In the absence of grazers, dead-leaf removal promoted plant growth. In the presence of grazers, dead-leaf removal increased consumption by cattle, particularly among the largest plants. As a result, in the presence of grazers, plants with dead leaves removed grew less than intact plants. The results indicate that retaining dead leaves is costly for grass species in the absence of grazers, but, as proposed by our hypothesis, that cost is compensated by a corresponding reduction of grazing consumption.