Sclerophylly in Qualea Parviflora (Vochysiaceae): Influence of Herbivory, Mineral Nutrients, and Water Status

Abstract

Qualea parviflora Mart. (Vochysiaceae) is a deciduous tree, commonly observed in campo sujo, cerrado sensu stricto and cerradao vegetation types in Brazilian cerrado (savannas). In this study we investigated herbivory, nutritional, and water status effects on leaf sclerophylly of Q. parviflora. Twenty fully expanded leaves were taken from 10 plants in each vegetation type four times a year. Mean leaf concentration of N, P, K, Ca, C, Al, Si, and percentage of total phenols, herbivory and tannins were measured on a plant basis. Leaf specific mass (LSM) (g m 2 ), a sclerophylly index, and pre-dawn leaf water potential (MPa) were also recorded. Soil samples below each tree were collected to quantify N-NO3, N-NH4, P, K, Mn, soil moisture, organic matter, Si, and Al. Qualea parviflora showed a LSM from 69 to 202 g m 2 and leaves were younger and less sclerophyllous in November (beginning of rainy season). Q. parviflora inhabiting the cerradao had leaves with higher concentration of nutrients and lower sclerophylly while trees in campo sujo and cerrado sensu stricto did not show significant differences in leaf sclerophylly. The concentrations of N, P, K and tannins had an inverse relationship with leaf age. Concentration of phenols, Al, C, Ca, Si, C/N and Ca/K increased with leaf age. The concentrations of P and Ca/K ratio in leaves explained 60% of variation observed in leaf sclerophylly. We did not find any significant relationship between the level of sclerophylly and water potential or herbivory. Our results corroborate the hypothesis that predicts lower concentrations of essential macronutrients would be the main factors influencing higher sclerophylly in leaves of Q. parviflora plants in Cerrado.