Effects of nutritional status and seedling size on field performance of Pinus halepensis planted on former arable land in the Mediterranean basin

Seedling size and nutrient concentration of nine Aleppo pine (Pinus halepensis Mill.) seedling sets, which differed in nursery fertilization, were measured before being planted out. Height and survival were monitored for 3 years after planting. Transplant stress indexes (TSI), defined as the relationships between initial height and growth were analysed for five growth periods: December 1998 (planting date) to June 1999, June 1999 to November 1999, November 1999 to November 2000, November 2000 to November 2001, and December 1998 to November 2001. Analyses of covariance were performed to separate set effects on growth from initial height effects, obtaining a TSI adjusted for set effects (TSI(adj)). Analysis of covariance revealed a negative TSI(adj) for the first period. Nitrogen and phosphorus concentrations were related to height growth in this initial period. For subsequent periods, only seedling height influenced growth. Therefore, large seedlings (root-collar diameter >2.3 mm) are recommended for afforestation purposes. In addition, high nutrient content (>20 mg N seedling(-1)) is also desirable to enhance early growth of Aleppo pine after planting in the Mediterranean basin.