Pinus taeda clones and soil nutrient availability: effects of soil organic matter incorporation and fertilization on biomass partitioning and leaf physiology

Abstract

The combined effects of intensive management and planting of improved seedlings have led to large increases in productivity on intensively managed pine forests in the southeastern United States. To best match clones to particular site conditions, an understanding of how specific clones respond to changes in nutrition in terms of biomass partitioning, leaf physiology and biochemistry will be necessary. This study measured the response of biomass partitioning, light-saturated net photosynthesis (A(Sat)) and photosynthetic capacity to a range in soil fertility and fertilization between two contrasting Pinus taeda L. clone ideotypes: a 'narrow crown' clone (NC) that allocates more resources to stem growth and a 'broad crown' clone (BC) that allocates more resources to leaf area (LA). Under field conditions, we found consistent clone by environment (i.e., varying nutrient regimes) interactions in biomass as well as leaf physiology. Nutrient limitations induced by logging residue incorporation resulted in a 25% loss in stem growth in BC, while NC showed no response. We postulated that the decrease in BC was due to the differences in canopy architecture leading to a reduced canopy CO(2) assimilation, as well as to increased belowground maintenance costs associated with fine-root production. In contrast, N and P additions resulted in a 21% greater increase in stem volume in NC relative to BC. Fertilization increased A(Sat) temporarily in both clones, but A(Sat) eventually decreased below control levels by the end of the study. Although we found a clone by fertilization interaction in leaf physiology, the greatest genotype by environment interaction was found in the LA that appeared to have a greater influence than A(Sat) on growth. This research demonstrates the potential importance of selecting appropriate clonal material and silvicultural prescription when implementing site-specific silviculture to maximize productivity in intensively managed southern pine forests.

Short-term impacts of soil amendments on belowground C cycling and soil nutrition in two contrasting Pinus taeda L. genotypes

“…Fertilizer was applied two times over the course of the experiment. Application rates were selected to maintain consistency with a complimentary field experiment (Tyree et al, 2009a). The first application was on July 28, 2006 in the form of diammonium phosphate (DAP) and ammonium nitrate (AN) at an equivalent rate of 200 kg N and 50 kg P ha À1 .…”

“…ha À1 ), had little effect on overall tree growth (Tyree et al, 2009b). Another study found that contrasting Pinus taeda clones grown in the field responded differently to LR incorporation with one clone being negatively affected while the other clone showed no effect (Tyree et al, 2009a). In addition to possible effects on plant productivity, the incorporation of LR into the mineral soil would likely accelerate decomposition rates possibly negating any possible increases to soil C (LundmarkThelin and Johansson, 1997;Ouro et al, 2001;Perez-Batallon et al, 2001).…”

Short-term changes in biomass partitioning of two full-sib clones of Pinus taeda L. under differing fertilizer regimes over 4 months

“…In order to maximize growth potential in clonal plantations to justify more expensive genetic material at planting, fertilization and other intensive silvicultural practices will need to be applied (Dougherty 2007). However, differences in morphology and development among clones may require different silvicultural prescriptions for different clones (Roth et al 2007;Tyree et al 2009b).…”

Growth and stem quality responses to fertilizer application by 21 loblolly pine clones in the Virginia Piedmont

“…Additionally, variable growth responses to fertilizer application have been observed among a small number of clones (King et al, 2008;Espinoza, 2009;Tyree et al, 2009b). However, we are aware of no information currently available in the literature on clonal fertilizer growth response involving more than eight clones of P. taeda.…”