[Responses of black soil's microbial respiration and community functional diversity to temperature]

Black soil samples were collected from Lishu (43 degrees 20' N, 124 degrees 28' E), Dehui (44 degrees 12' N, 125 degrees 33' E), Hailun (47 degrees 26' N, 126 degrees 38' E), and Bei' an (48 degrees 17' N, 127 degrees 15' E), and an incubation test was conducted to study their microbial respiration and Biolog metabolic functional diversity at 4 degrees C, 15 degrees C, and 28 degrees C. The soil microbial respiration rate was in the order of Bei' an > Hailun > Dehui > Lishu, irrespective of incubation temperature, but the sensitivity of the respiration to the temperature, i. e., Q10 value, differed. The average value of the Q10 for the soils from Lishu, Dehui, Hailun, and Bei'an was 2.72, 3.26, 3.21, and 3.74 in the range of 4 degrees C-15 degrees C, and was 3.29, 2.36, 2.11, and 1.79 in the range of 15 degrees C to 28 degrees C, respectively. The metabolic quotient (qCO2) also differed with incubation temperature, which was in the order of Lishu > Dehui > Bei' an > Hailun at 28 degrees C and of Bei' an > Dehui > Hailun > Lishu at 15 degrees C, but no significant difference was observed at 4 degrees C. Biolog test showed that the substrate richness and metabolic Shannon diversity index of microbial community were higher for the soils from Hailun and Bei' an at 4 degrees C, but higher for those from Lishu and Dehui at 15 degrees C and 28 degrees C. Principal component analysis with Biolog data suggested that the metabolic function of soil microbial community was similar between Bei' an and Hailun, and between Dehui and Lishu. In sum, the responses of black soil's microbial respiration and community functional diversity to temperature varied with latitude, i. e., more sensitive to low temperature in high latitude region, but more sensitive to high temperature in low latitude region.