Biomass partitioning and nitrogen dynamics of four eastern tree species receiving irrigation and fertilization
Cobb, William Russ
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To determine how water and nutrient additions alter growth, biomass partitioning, and nitrogen use efficiency of pine and hardwood species, stand growth, biomass, nitrogen concentrations and contents of aboveground organs of Pinus taeda, Pinus elliottii, Liquidambar styraciflua, and Platanus occidentalis were measured in stands receiving irrigation and varying levels of fertilization. Hardwood growth responded to treatments more than pine growth (stem wood growth of sweetgum and sycamore was 1,082% and 1,835% respectively vs. 173% and 178% in loblolly and slash pine respectively). Treatments increased hardwood stem biomass growth relative to foliage biomass growth, while partitioning of the pines did not change. Unlike the pines, the hardwoods increased stem biomass growth per unit of foliar [N] with irrigation and fertilization. This suggests increased foliar efficiency in hardwoods while pine growth likely results from increased foliage mass and also that hardwoods are more plastic in their response to increasing resource availability.