Stem and branch respiration of beech: from tree measurements to estimations at the stand level

Abstract

Summary• Stem and branch respiration of 30-yr-old Fagus sylvatica trees was measured in a temperate forest for 1 yr to estimate the annual flux at the stand level.• The seasonal response of respiration to air temperature was determined using infra-red gas analysis (IRGA) systems. Annual respiration was derived from half-hourly temperature recording and allometric relations established for the same forest.• The basal respiration rate at 15 ° C (R15) increased greatly during the growing season. On a volume basis, monthly means of R 15 were higher for branches than for stems. For stems, Q 10 was relatively constant throughout the year, with an annual average of 1.7. Estimated annual respiration was approx. 325 g C m -2 ground surface area yr -1 with 50% of this amount attributed to growth respiration.• Stem and branch respiration played a major role in the annual carbon balance of the beech stand. It represented approx. one third of the ecosystem-level carbon loss from respiration. The magnitude of crown respiration makes it obvious that information on branch respiration characteristics is required for reliable estimations at the stand level.

Spatial and seasonal variations in stem respiration of beech trees (Fagus sylvatica)

“…This fact is critical, since the proportion of organs in the crown (stem and branches) compared to the total amount of wood is large in beech trees (11% in volume and 53% in area in [8]). Further investigations concerning the variation in respiration rates within the crown, especially for branches in the lower part of the canopy, would be needed in order to assess the relationships between R M , diameter and age of the organs.…”

“…For both methods, we used a wood density value of 636 kg m -3 [8], and we assumed that the carbon content of the woody tissues was 0.49 g C / g dry wood [31]. In June 1997, after a strong storm the upper and lower cuvettes installed in the crown slightly moved from their original location on the stem.…”

“…Because of the smaller diameter of the organs, the stem tissues also warm faster at the top than at the base of the stem. Indeed, Q 10 , the factor expressing respiration increase for a temperature increase of 10 o C, can vary with height along the stem [8] or with the organ in question, stem or branch [28].…”

“…Thus estimates of the growth respiration coefficient (r G ) and biomass increments, of standing biomass and maintenance respiration rate (r M ), are required to estimate stem respiration at stand level. Usually, r G and r M are derived from measurements at breast height (1.3 m), but some studies have shown that respiration varies with stem and branch diameter or height [4,5,8,18,32,40,41,49], or with the woody organ (stem or branch) considered [5,28,32,41,49].…”

Allométrie du bois de cœur et de l’aubier pour sept espèces d’arbres tempérées chinoises

“…Transpiration and stem respiration are tightly correlated to sapwood area (SA) for individual trees and stands (e.g., Damesin et al, 2002;Meinzer et al, 2001). A power function model for scaling SA from stem diameter has been widely accepted, but the universal exponent of 7/3 of the power function proposed by Enquist (2002) has been challenged.…”