Seasonal nutrients retranslocation patterns in needles and twigs of Pinus brutia Ten.

Retranslocation of nutrients from senescing leaves to young and permanent parts of tree bodies is one of the main strategies to confront with nutrient loss from the soil especially in sites with nutrient poor soils. The aim of this study is to investigate retranslocation of nitrogen, phosphorous and potassium in pinus brutia. For this purpose we selected Makhmalkooh afforested forest at Lorestan province and sampling was carried out at 5 times. In each plot, young and senescent needles and twigs were sampled and nutrient retranslocation were measured. Within each plot, we also collected a composed sample of soil and soil physico-chemical properties were measured. Our results showed that net retranslocation was done at two growing seasons (spring and fall) and September to November. Results also highlighted correlations between nutrients concentration in plant tissues and some of the soil properties like electrical conductivity, organic carbon and pH. This emphasis on close relationship between nutrient's soils concentration and plant retranslocation. In conclusion, based on the results of this study, soil properties such as soil fertility, nutrient concentration in the senescent needles, annual precipitation and drought periods at summer are key factors that influence on nutrients retranslocation. The retranslocation results in Makhmalkooh forest reinforced the hypothesis that forest adapted to climate and edaphic condition and can be used as a guide for management plans to assist in nutritional decisions making of forest trees.