Analysis of soil respiration and influencing factors in a semiarid dune-meadow cascade ecosystem

The characteristics of soil respiration (R_s) in semiarid regions are important with regard to the carbon cycle of complex underlying surfaces and estimation of carbon emissions from regional ecosystems. During the growing season (May-September 2016), in situ observations of R_s were obtained concurrently with measurements of soil bacteria (B_s), soil moisture (M_s), and soil temperature (T_s) at depths of 0-10 cm, in a dune-meadow cascade ecosystem. Results showed that R_s differences among the various ecosystems were significant (P < 0.01), the intensity of R_s in meadows was twice stronger than that in dunes. The average values of R_s presenting a declined trend follows MPA (11.19 μmol m^-2 s^-1) > MAF (7.75) > SSG (6.78) > SMAH (5.02) > SFAH (4.8) > FLC (4.28) > SBG (3.09). An extremely significant (p < 0.01) positive correlated power relationship can be found between R_s and B_s, which could explain 62.41%-86.56% of the variation in R_s in the various ecosystems. Field capacity and the saturated water content were the key demarcation points for the interactive relationship between R_s and M_s, which showing a significant (P < 0.05) positive correlated power relationship in dunes, in contrast, it presenting a significant (P < 0.05) negative correlated exponential relationship in meadows. R_s was positively exponentially correlated with T_s, significant (P < 0.05) in meadows and nonsignificant (P > 0.05) in dunes. Future research should be strengthened to consider multiple growing seasons experiencing various climatic conditions for accurate estimation of terrestrial carbon emissions in arid and semiarid ecosystems.