Competitive responses of loblolly pine to radients in loblolly pine, sweetgum, and broomsedge densities

• Published in: Canadian journal of forest research Vol. 23; no. 10
• Main Authors: Perry, M.A, Mitchell, R.J, Zutter, B.R, Glover, G.R, Gjerstad, D.H
• Format: Journal Article
• Language: English
• Published: 01.10.1993
• Subjects: ALTURA; ANDROPOGON VIRGINICUS; COMPETENCIA BIOLOGICA; COMPETITION BIOLOGIQUE; CRECIMIENTO; CROISSANCE; DIAMETRE; DIAMETRO; HAUTEUR; LIQUIDAMBAR STYRACIFLUA; PINUS TAEDA; PLANTULAS; PLANTULE; POBLACION VEGETAL; POPULATION VEGETALE; VOLUME; VOLUMEN
• ISSN: 0045-5067; 1208-6037

A factorial combination of 0, 1, 2, and 4 loblolly pine (Pinus taeda L.) seedlings and sweetgum (Liquidambar styraciflua L.) sprouts, and 0, 4, and 16 broomsedge (Andropogon virginicus L.) seedlings per square meter were used to determine the nature of pine response to competition (competitive response) from multiple life forms during the first season after outplanting. Following adjustment for effects of seedling size and site heterogeneity (soil organic matter), polynomial regression was used to describe pine competitive responses. Patterns in competitive responses varied with time and were dependent upon the particular response variable of interest. Pine response in terms of volume was similar to that for diameter. By early May, pine diameter decreased linearly with increasing sweetgum density but was unrelated to either broomsedge or pine density. Approximately 1 month later, pine diameter response to competition was more complex, being curvilinearly related to both sweetgum and broomsedge density, as well as their interaction. Intraspecific competition effects on diameter response were not detected until mid-September. Height response differed substantively from diameter or volume response. In general, height tended to be less responsive to interspecific competition, although intraspecific competition was more readily detected. Furthermore, pine height response to competition tended to be linear rather than curvilinear, as observed for both diameter and volume. The biologically based reciprocal yield equation produced similar trends in competitive pine volume response, as noted with the polynomial regression equations (i.e., sweetgum and broomsedge density as well as their interaction strongly influenced the inverse of pine stem volume). Removing variation in organic matter and initial seedling size resulted in a considerable increase in the amount of variation in final size accounted for by competition