Growth, defense and herbivory on young leaves of Qualea parviflora (Vochysiaceae) in three different Cerrado habitats

Abstract

Insect herbivory is strongly influenced by the properties of their host leaves. Otherwise, such influence may be mediated by the environment in which the host plant is found. We examined three characteristics that may influence insect herbivory on young leaves of Qualea parviflora Mart. (Vochysiaceae), a widespread tree of the Brazilian Cerrado: leaf expansion rate, sclerophylly (leaf toughness), and tannin concentration during four consecutive months. Herbivory rates were measured on four marked intact leaves in five trees in three different physiognomies of the Cerrado biome: campo sujo (grassland), cerrado sensu stricto (savanna), and cerradão (woodland). Sclerophylly was higher in February while the highest concentration of tannins occurred in November but no variation in the rates of herbivory among months and physiognomies was found. A tendency of higher mean leaf growth rates was observed in the “cerradao” (1.03%) and “cerrado” (1.04%) in comparison with the campo sujo trees (0.86%). Higher sclerophylly and lower expansion rates and leaf size were observed in trees of the campo sujo. There was a tendency for higher herbivory rates in cerrado (10.5%), where the leaves showed lower concentration of tannins (1.5%) than in cerradão (2.1%). New leaves of Q. parviflora showed higher tannins concentration and lower damage than fully expanded leaves. Final leaf area explained 24% of the variation in total herbivory. Leaf size and associated nutritional factors exerted stronger influence on herbivory than defensive compounds on young leaves of Q. parviflora.

Key words: Cerrado, leaf age, leaf growth, Neotropical savanna, plant defenses, sclerophylly.