Dark respiration rate increases with plant size in saplings of three temperate tree species despite decreasing tissue nitrogen and nonstructural carbohydrates

JOSé-LUISMACHADO and PETER B. REICH

Tree Physiology26, 915–923

In shaded environments, minimizing dark respiration during growth could be an important aspect of maintaining a positive whole-plant net carbon balance. Changes with plant size in both biomass distribution to different tissue types and mass-specific respiration rates (Rd) of those tissues would have an impact on whole-plant respiration. In this paper, we evaluated size-related variation inRd, biomass distribution, and nitrogen (N) and total nonstructural carbohydrate (TNC) concentrations of leaves, stems and roots of three cold-temperate tree species (Abies balsamea  (L.) Mill, Acer rubrum  L. and Pinus strobus L.) in a forest understory. We sampled individuals varying in age (6 to 24 years old) and in size (from 2 to 500 g dry mass), and growing across a range of irradiances (from 1 to 13% of full sun) in northern Minnesota, USA. Within each species, we found small changes in Rd, N and TNC when comparing  plants  growing across  this  range of  light  availability。Consistent     with   our   hypotheses,   as  plants   grew    larger, whole-plant N and TNC concentrations in all species declined as a result of a combination of changes in tissue N and shifts in biomass distribution  patterns.  However,  contrary  to  our  hy potheses, whole-plant and tissue Rd increased with plant size in the three species。

Keywords: Abies balsamea,Acer rubrum,balsam fir,biomass allocation, carbohydrates, deeply shaded, low light, Pinus strobus, red maple, root excavation, white pine, whole plant respiration.

Tree size存在的另类问题，器官养分浓度问题---划为专题中...