Soil respiration dynamics in a semi-fixed sand dune under the pioneer shrub Artemisia halodendron Turcz. ex Bess. in the Horqin sandy land, northeastern China

Abstract

Soil respiration is a major pathway by which carbon dioxide (CO2) fixed by terrestrial plants returns to the atmosphere. Studies of the dynamics of soil respiration in sandy land are rare and the contribution (Rc) of plant root respiration to the total soil respiration (Rt) is not well known. In this study, Rt in a semi-fixed dune planted with Artemisia halodendron was separated into autotrophic (root) respiration (Ra) and heterotrophic respiration (Rh) by the root-exclusion method. Rt and its two components were measured or calculated during 2013 on seven dates during the growing season when variation during the day was measured. Both Ra and Rh showed similar dynamics, with the maximum rates observed in July and with large daily variability observed on the earlier dates. Rc ranged from 39.3% to 53.1% during the growing season and exhibited a single peak in early August. Soil temperature at a depth of 20 cm was significantly correlated with soil respiration. Ra was more sensitive to soil temperature than Rh and the temperature sensitivity coefficients (Q10) were 3.39, 2.52, and 2.79 for Ra, Rh, and Rt, respectively. In summary, A. halodendron roots contributed an average of 46% to the total soil respiration, although this contribution varied during the growing season.