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

The characteristics of soil respiration (R) 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 were obtained concurrently with measurements of soil bacteria (B), soil moisture (M), and soil temperature (T) at depths of 0-10 cm, in a dune-meadow cascade ecosystem. Results showed that R differences among the various ecosystems were significant (P < 0.01), the intensity of R in meadows was twice stronger than that in dunes. The average values of R presenting a declined trend follows MPA (11.19 μmol m s) > 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 and B, which could explain 62.41%-86.56% of the variation in R in the various ecosystems. Field capacity and the saturated water content were the key demarcation points for the interactive relationship between R and M, 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 was positively exponentially correlated with T, 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.