Retranslocation of foliar nutrients of deciduous tree seedlings in different soil condition under free-air O3 enrichment

Abstract

Retranslocation is the amount of an element that is depleted from old plant components and is provided for new growth. Leaf senescence is usually accelerated at elevated O3 (eO3), and leaf shedding is influenced by soil nutrient availability (and acidification). In this study, we focused on the net retranslocation and allocation dynamics of foliar nutrients (N, P, Mg, K, Ca, Mn, Fe and Al) to investigate the effect of eO3 on birch (Betula platyphylla var. japonica), oak (Quercus mongolica var. crispula), and beech (Fagus crenata) seedlings grown in different soil conditions. Seedlings of the 3 species were planted in a free-air O3 enrichment system under 3 soil types (brown forest soil, serpentine soil, volcanic ash soil) for one growing season. All tree species were grown with 3 replications per each plot at elevated O3 (about 80 ppb) and ambient condition (O3 ranging 25-35 ppb). Leaf samples were taken from the top part of seedlings during the growing season in mid-September, and senescing leaves were sampled in mid-November. Both were collected for chemical composition analysis. Retranslocation rate of P was markedly increased by eO3 in birch and significantly differed among soil types in oak seedlings, while was constant across treatments in beech seedlings. Retranslocation of N in oak seedlings was significantly affected by soil type. Retranslocation of other elements was most sensitive to both eO3 and soil type in beech seedlings. The influence of differential growth patterns among species in modulating the physiological response of seedlings to high levels of ozone and different soil conditions are discussed.

Keywords

• Retranslocation
• Foliar Nutrients
• Ozone
• Volcanic Ash Soil
• Serpentine Soil