Comparison of branch biomass relationships for North Caro and Oklahoma/Arkansas loblolly pine seed sources growin in southeastern Oklahoma Michael A.Blazier,Thomas C. Hennessey * , Thomas B. Lynch, Robert F. Wittwer Department of Forestry, Oklahoma State University, Stillwater, OK 74078, USA Received 9 April 2000; accepted 27 December 2000 Abstract Comparison of branch-level foliage and branch (wood þ bark) biomass relationships for North Carolina Coasta Oklahoma/Arkansas (O/A) loblolly pine (Pinus taeda L.)seed sources provided an indication of biomasspartitioning differences between these two seed sources. The objective of this study was to quantify and compare the bran and branch biomass of NCC and O/A provenances on an excessively drained site in southeastern Oklahoma to branch-level biomass partitioning patterns; a modeling process was developed to accomplish this objective. It was found that seed source significantly influenced the amount of foliage per branch. If tree and branch dimensions were NCC branches would carry approximately 30% more foliage per branch than O/A branches. The relationship be branch dimensions and branch production did not differ for the two seed sources. Vertical distributions of branc biomass were found to be similar for the two seed sources as well. Thus, on the droughty site observed in this NCC seed source tended to partition more biomass into the foliage component at the individual branch level th seed source; (2) the two seed sources were similar in their propensity to partition biomass into the branch com branch level, and (3) the two seed sources were similar in the vertical distribution of branch and foliage biomas crown.# 2002 Elsevier Science B.V. All rights reserved. Keywords: Biomass partitioning; Provenance testing; Biomass modeling 1. Introduction Traditional evaluations of the various geographic seed sources of loblolly pine ( Pinus taeda L.) have demonstrated that the sources vary in productivity, but the potential exists for a more comprehensive evalua- tion of seed source growth differences. Tree height growth has been widely used in seed source studies a selection criterion to identify genetic gainsin productivity (McKeand, 1988;Sprintz etal.,1989; Knowe and Foster, 1989).Some authors have noted that height growth is an advantageous selection crite ion since it is correlated with volume production and growth form (Perry et al.,1966;McCutchan, 1983; Sprintz,1987).Measurements of total stem volume have also been used to evaluate the productivity of various loblolly pine provenances (Talbert and Strub, 1987;Buford,1989).Given the importance of tree Forest Ecology and Management 159 (2002) 241–248 * Corresponding author. Tel.: þ1-405-744-5443; fax: þ1-405-744-9693. E-mail address: tomhenn@okstate.edu (T.C. Hennessey). 0378-1127/02/$ – see front matter # 2002 Elsevier Science B.V. All rights reserved. PII: S 0 3 7 8 - 1 1 2 7 ( 0 1 ) 0 0 4 3 7 - 6