Comparison of Growth Efficiency of Mature Longleaf and Slash Pine Trees

Abstract

Variation in aboveground biomass partitioning (between the stem, branches, and foliage) of mature trees is a key determinant of growth potential. Investment of photosynthate in crown components generally results in greater overall biomass production of longer duration. The increased production of crown components may be an investment in longterm aboveground production and can result in increased growth efficiency (defined as biomass increment per unit leaf area). This study was initiated to compare the relationships of crown structure to aboveground allocation and stemwood growth for matureplanted slash pine (Pinus elliottii Engelm.) and naturally regenerated longleaf pine (P. palustris Mill.) trees. Total tree height, diameter at breast height, height to base of the live crown, and bark thickness were measured and increment cores taken from longleaf and slash pine trees of similar ages growing on similar sites. These data were used with allometric equations, developed previously for each species from destructive sampling procedures at these sites, to predict projected leaf area and 5-year stem biomass production. Growth efficiency for trees was calculated as 5-year stemwood biomass increment per unit projected leaf area. Average (per tree) stem biomass production was not statistically different between longleaf pine and slash pine, nor were average projected leaf areas. Average growth efficiency of longleaf pine was significantly greater than that of slash pine (P < 0.10); graphical examination of individual tree data, however, did not indicate strong or significant differences in growth efficiency between species when comparing trees of equal size. These findings suggest that greater investment in crown structural components by longleaf pine may, at the stand-level, help to maintain stemwood production over a longer lifespan relative to slash pine, but individual tree results are less clear.

Citation

Jack, Steven B.; Sheffield, Mary Carol P.; McConville, Daniel J. 2002. Comparison of Growth Efficiency of Mature Longleaf and Slash Pine Trees. In: Gen. Tech. Rep. SRS-48. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. pg. 81-85