Scaling relationships between twig size and leaf size of Pinus hwangshanensis along an altitudinal gradient in Wuyi Mountains, China.

Abstract

To analyze the tradeoff relationship between twigs and leaves, the traits of Pinus hwang-shanensis including leaf area, leaf number, twig length and twig diameter were investigated in Wuyi Mountains along an altitudinal gradient. The results indicated that leaf number, twig length, twig diameter, leafing intensity and twig stem cross-sectional area of P. hwangshanensis increased gra-dually with the increasing altitude, while individual leaf area decreased gradually. Leafing intensity of P. hwangshanensis at different altitudes had significant negative relationships with leaf area. The cross-sectional area of P. hwangshanensis had significant positive relationship with total leaf area. Twig length and twig diameter of P. hwangshanensis correlated negatively with leafing intensity, but positively with leaf area, leaf number and total leaf area. To enhance the competitiveness and resource utilization efficiency, P. hwangshanensis at low altitude tended to have relatively few large leaves on short twigs, and those at high altitude tended to have a large number of small leaves on long twigs. Such tradeoff between twigs and leaves reflected the strategy of resource utilization and the balance of biomass allocation mechanism of P. hwangshanensis responding to the altitudinal change.