Two holm oak (Quercus ilex L.) sites in Tuscany, Central Italy, were studied in July 2000. One of the sites (Cala Violina) was xeric with low ozone concentration (daily hourly mean for JulyAugust 2000 13.3 nmol mol1). The other site (Colognole) was mesic with a higher ozone concentration (daily hourly mean for JulyAugust 2000 54.2 nmol mol1). Leaf morphological characteristics (area, dry weight, specific dry weight, water content, epicuticular wax amount, stomatal density) and leaf fluorescence were measured. Ozone flux into the leaves was calculated on a stomatal conductance basis. Among the measured parameters, only stomatal density and wax amount significantly differed between the sites. Despite they are usually reported to increase with water stress, both were higher at the mesic and more polluted site than at the xeric one. This response might indicate an adaptation to air pollutants, of which ozone might be of the greatest importance as also stressed by the higher ozone flux into the leaves at the mesic site even if other not measured parameters, such as nitrogen deposition, may also have contributed to the result.
Leaf morphology and gas exchange in holm oak (Quercus ilex L.) trees in different environments.
Paoletti E;
2006
Abstract
Two holm oak (Quercus ilex L.) sites in Tuscany, Central Italy, were studied in July 2000. One of the sites (Cala Violina) was xeric with low ozone concentration (daily hourly mean for JulyAugust 2000 13.3 nmol mol1). The other site (Colognole) was mesic with a higher ozone concentration (daily hourly mean for JulyAugust 2000 54.2 nmol mol1). Leaf morphological characteristics (area, dry weight, specific dry weight, water content, epicuticular wax amount, stomatal density) and leaf fluorescence were measured. Ozone flux into the leaves was calculated on a stomatal conductance basis. Among the measured parameters, only stomatal density and wax amount significantly differed between the sites. Despite they are usually reported to increase with water stress, both were higher at the mesic and more polluted site than at the xeric one. This response might indicate an adaptation to air pollutants, of which ozone might be of the greatest importance as also stressed by the higher ozone flux into the leaves at the mesic site even if other not measured parameters, such as nitrogen deposition, may also have contributed to the result.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
