Performance of young jack pine trees originating from two different branch angle traits under different intensities of competition

Abstract

-The performance of young jack pine (Pinus banksiana Lamb.) trees, originating from seed orchard trees of two different branch angle traits, was examined under different intensities of competition with morphological measures of crown development and growth efficiency measures. Seedlings were planted under a split-plot design at five initial spacings -0.5 m, 0.75 m, 1.0 m, 1.5 m and 2.0 m -, three blocks, two branching characteristics and four replicates. Relative growth rate for diameter at breast height (dbh) increased by nearly twofold from the closest to the largest spacing. Crown width, crown ratio, needle density ratio and leaf weight ratio decreased significantly with decrease in spacing, which indicated that the efficiency of jack pine crowns to occupy their growing space and the proportion of photosynthesizing biomass relative to respiring biomass were negatively affected by competition. Needle nitrogen concentration decreased with decrease in spacing and was significantly related to leaf weight ratio. Variation with tree size in the ratios of dbh increment to needle biomass and to needle nitrogen content indicated that small trees produced stemwood per unit of photosynthetic tissue and per unit of nitrogen more efficiently than large trees in the absence of severe competition and that this trend was gradually reversed as the intensity of competition increased. Branch angle trait did not constitute a significant advantage for crown development and stem growth. Le taux relatif de croissance en diamètre à hauteur de poitrine (dhp) a presque doublé de l'espacement le plus serré à l'espacement le plus large. La largeur de la cime, le rapport cime-hauteur et les rapports de densité et de masse des aiguilles ont diminué de façon significative avec une diminution de l'espacement initial. Ces résultats indiquent que l'efficacité des couronnes du pin gris à occuper leur espace de croissance et la proportion de tissu assurant la photosynthèse par rapport à la proportion de tissu qui respire a été affectée négativement par la compétition. La concentration en azote des aiguilles, qui a diminué avec une réduction de l'espacement, a été reliée de façon significative au rapport de masse des aiguilles. La variation, en fonction de la taille des arbres, des rapports de croissance en diamètre sur la biomasse foliaire et le contenu en azote des aiguilles indique que, en l'absence de compétition sévère, les petits arbres ont produit plus efficacement de la matière ligneuse par unité de tissu photosynthétique et d'azote que les gros arbres et que cette tendance s'est inversée à mesure que l'espacement diminuait. L'angle de branchaison des arbres ne s'est pas révélé présenter un avantage significatif pour le développement des cimes et la croissance des tiges. compétition / mesures d'efficacité de croissance / angle des branches / azoteAnn. For. Sci. 57 (2000) [635][636][637][638][639][640][641][642][643][644][645][646][647][648][649] 635

Modelling the relationship between canopy projection area and above-ground carbon stock of intermingled canopy trees using high-resolution satellite imagery

“…Another important factor could be the competition or crowding between the trees. Trees crown development was found to be negatively affected by competition from neighbouring tree crowns (Larocque, 2000). It is reasonable to assume that a group of intermingled canopy trees is similar to a stand alone in terms of competition and CPA.…”

Interactions among prescribed fire, herbivore pressure and shortleaf pine (Pinus echinata) regeneration following southern pine beetle (Dendroctonus frontalis) mortality

“…Larger, older seedlings typically experience faster height and diameter growth rates (Cain and Barnett, 1996;Cain and Shelton, 2000), possibly due to more developed root systems. However, the relative height growth rate of the newly planted seedlings was equivalent to that of the natural seedlings, suggesting strong growth potential or competitive ability (Erickson, 1976;Larocque, 2000).…”