Changes in stem respiration rate during cambial reactivation can be used to refine estimates of growth and maintenance respiration

Abstract

Summary • To determine if stem respiration (r) varied during cambial reactivation, r was measured during March–July in untreated trees and seedlings, debudded seedlings and girdled seedlings of white ash (Fraxinus americana), red maple (Acer rubrum) and balsam fir (Abies balsamea). • The r was measured using an infrared gas-analysis system. Cambial reactivation was monitored by light microscopy. • After increasing modestly about the time of cambial cell swelling, r declined to a minimum for several weeks and then increased markedly as rapid xylem production (XP) began. Growth respiration (Rg) over the experimental period was positively correlated with XP over the same time span, with differences in wood anatomy and XP-measurement method accounting for differences among species. A weak, positive trend was observed between maintenance respiration (Rm) and XP. Rm varied among species. • The marked springtime increase in r is a nondestructive marker for the onset of rapid XP. Measurements of r made after cambial cell swelling and before rapid XP are appropriate for applying the mature-tissue method to estimate Rg and Rm. Rg reflects XP, particularly the width of differentiating xylem.