Chin J Plan Ecolo ›› 2015, Vol. 39 ›› Issue (2): 197-205.DOI: 10.17521/cjpe.2015.0019

Special Issue: 碳水能量通量

• Orginal Article • Previous Articles     Next Articles

Respiration rates of stems at different heights and their sensitivity to temperature in two broad-leaved trees in Beijing

HAN Feng-Sen, HU Dan*(), WANG Xiao-Lin, ZHOU Hong-Xuan   

  1. Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
  • Received:2014-08-27 Accepted:2014-12-09 Online:2015-02-01 Published:2015-03-10
  • Contact: Dan HU
  • About author:

    # Co-first authors

Abstract: <i>Aims</i>

Woody-tissue respiration (Rw) is well known to be a large component of the terrestrial ecosystem carbon balance. In order to quantify the intra- and inter-specific variations in stem respiration, investigations were made on the temporal and vertical variations in Rw in order to reveal the vertical pattern and the regulatory mechanisms of the temperature-sensitivity coefficient (Q10).


CO2 release rates and stem temperature were measured in two typical deciduous species (Sophora japonica and Salix matsudana) from March through December 2013 in a suburban park in Beijing. All measurements were carried out at three heights (10 cm, 140 cm and 270 cm) corresponding to the base, breast height and first branch of the trees.

<i>Important findings</i>

It was found that the stem respiration differed significantly between the two tree species. The Rw in Sophora japonica was 1.12 (July) to 1.79 (May) times of that in Salix matsudana for the same months except in April. Clear diurnal cycles and strong seasonal variations were found in the stem respiration per unit surface area (RS). The seasonal variation patterns of Rw were unimodal for both species; however, the peak month differed between the two species, i.e. July ((5.13 ± 0.24) μmol·m-2·s-1) for Sophora japonica and August ((3.85 ± 0.17) μmol·m-2·s-1) for Salix matsudana. Stem respiration during the growing season (July and August) was high- er than in the dormant season (November and December); whereas the seasonal variations of Q10 showed opposite trend, i.e. higher in the dormant season than during the growing season. RW increased and the diel patterns of Rw varied with height; the pattern of stem respiration was unimodal for trunk and diauxie for branches, respectively. Stem temperature was found to be the dominant factor regulating the diurnal dynamics of stem respiration at a daily scale. In addition, Q10 higher at the top than at the base. Stem temperature and Q10 collectively determined the temporal and vertical patters of stem respiration. During the growing months, daily accumulated respiration per volume of woody tissue (mmol·m-3·d-1) was linearly related to the inverse of stem diameter measured at breast height. The level of respiration was better expressed on area base (μmol·m-2·s-1) for comparisons among individuals and examination of temporal and spatial variations of the same individual. Therefore, the spatial and temporal variability of Rw should be considered in the construction of city forest carbon budget model so as to reduce the estimation error.

Key words: stem respiration, temporal dynamics, vertical variations, temperature-sensitivity coefficient (Q10), urban ecology