Abstract:

The soil respiration rate (R_s) and its influential factors of two green landscapes (GL and YZ) were measured using a portable automated CO₂ exchange station (ACE) during the whole growing season in Tianjin. The relationships be-tween soil respiration and its influential factors of soil temperature,soil moisture and soil physicochemical properties have been analyzed. Results show that:(1) There was basically no difference in the seasonal variation of R_s between the two different types of green landscapes,both of them showed an obvious single-peak variation and the peak appeared at the same time. Simultaneously,the variation of R_s was different in different months. In dry season,the R_s was low with few fluctuations,which ranged from (0.20±0.03) to (1.09±0.16) μmol·m^-2·s^-1 for GL,and from (-0.06±0.01) to (0.26±0.05) μmol·m^-2·s^-1 for YZ. Conversely,a relatively higher R_s with more fluctuations was noted in the wet sea-son,it seemed to be varied from (-0.05±0.01) to (3.62±0.26) μmol·m^-2·s^-1 for GL,and from (0.38±0.07) to (3.17±0.27) μmol·m^-2·s^-1 for YZ. In summary,the mean value of R_s in GL was significantly higher than that in YZ; (2) The environmental factors that influence R_s are very complicated in the two green landscapes. The two relatively im-portant factors are soil temperature at 10 cm depth (T₁₀) and soil moisture at 5 cm depth (M₅). In addition,the regression analysis show that the effective degree of T₁₀ and M₅ for R_s were 45.4%-64.8% and 21.1%-52.2%,respectively; (3) There was a certain correlation between soil physicochemical properties and R_s,in which the correlation coefficient between soil organic matter and R_s was highest in all the two green landscapes.

Key words: green landscape, soil respiration rate, soil temperature, soil moisture