Water availability and genetic effects on wood properties of loblolly pine (Pinus taeda)

Abstract

We studied the effect of water availability on basal area growth and wood properties of 11-year-old loblolly pine ( Pinus taeda L.) trees from contrasting Florida (FL) (a mix of half-sib families) and South Carolina coastal plain (SC) (a single, half-sib family) genetic material. Increasing soil water availability via irrigation increased average whole-core specific gravity (SG) and latewood percentage (LW%) by 0.036 and 6.93%, respectively. Irrigation did not affect latewood SG or wood stiffness, but irrigated FL and SC trees had more latewood due to a 29 day longer growing season. Irrigation did not affect the length of corewood production, but irrigated trees had earlier transition ages, producing outerwood ~3 years before rainfed trees. The increase in whole-core SG and LW% was moderate because irrigation promoted earlywood growth in corewood formed before canopy closure, but after year 7, rain-fed and irrigated trees had similar earlywood growth but irrigated trees had more latewood growth, increasing ring SG and LW%. The SC half-sib family had higher SG and greater LW% than trees from FL independent of irrigation due to greater yearly latewood growth. Thus, absence of soil water stress extended seasonal diameter cessation date but did not change latewood SG or wood stiffness.

Wood and Fiber Quality of Plantation-Grown Conifers: A Summary of Research with an Emphasis on Loblolly and Radiata Pine

“…In a loblolly pine irrigation-fertilization trial, an improvement in outerwood LW SG was observed following irrigation [90]. Conversely, in another experiment where trees were only irrigated, whole-core SG increased in the irrigated trees, but latewood SG did not change [91]. In both studies, it was found that irrigation enabled LW formation to continue later into the growing season.…”

Effect of early age woody and herbaceous competition control on wood properties of loblolly pine

“…The derivative method involves fitting a model to the SG profile of each tree (or plot) with ring number as an explanatory variable and taking the first derivative of the fitted function with respect to ring number (Mora et al, 2007;Gonzalez-Benecke et al, 2010). A 4-parameter logistic function was used to explain the change in SG with ring number as presented below …”

Effects of Vegetation Management on Wood Properties and Plant Water Relations of Four Conifer Species in the Pacific Northwest of the USA

“…When there was no moisture limitation, diameter growth continues until late in the season when other factors (temperature or photoperiod) trigger cessation. Gonzalez-Benecke et al (2010) [19] found similar results for loblolly pine and concluded that there was a strong and positive relationship between high soil water availability and gain in ring SG and LW%. During first five growing seasons, competing vegetation cover percent was much larger at the plots without post-planting vegetation control [7], so it can be assumed that in those plots the trees had less soil moisture available due to more competition for water, and thus may have had a shorter latewood growing season due to water limitations.…”

“…On the other hand, when growing conditions are optimal, EW growth is enhanced and the proportion of LW is reduced. When water availability is not limiting during LW formation, higher SG wood is produced due to extended growing season that produced more LW [19]. Barnett et al (2003) [20] came to the same conclusion; increasing water availability can significantly increase the ratio of LW to EW of temperate-zone conifers by delaying the entry of the cambium into dormancy during cambial growth in mid-to late-summer.…”