Responsiveness of Diverse Families of Loblolly Pine to Fertilization: Eight-Year Results from SETRES-2

Loblolly pine is by far the most important forest tree species in the South, with over 1 billion seedlings planted annually by forest industry and non-industrial private forest landowners (McKeand et al. 2003). Genetic gains from tree improvement programs have been large, since geographic and within-provenance variation for growth and adaptive traits in loblolly pine is very large. General trends in productivity variation are that families from southern and eastern coastal sources grow faster than families from northern, western, and interior sources. Contrasting the response to nutrient stress of two very different provenances of loblolly pine such as from the "Lost Pines" region of Texas and the Atlantic Coastal Plain may give us insight into the adaptive significance of different ecophysiological traits.