Effect of Fire Disturbance on Nutrient Content and Soil Microbial Biomass of Two Forest Types
HU Hai-Qing；LI Ying；ZHANG Ran；WU Wei；SUN Long*
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In the burned area of Betula platyphylla and Larix gmelinii forests shortly after the fire in Yichun, we used the chloroform fumigation extraction method to examine the content of soil microbial biomass carbon(Cmic) and soil microbial biomass nitrogen(Nmic) from the two forest types in different months(June, August, October and December). We explored the relationship between Cmic and Nmic, and the influencing factors including soil water content, soil pH, soil temperature, soil organic carbon and soil total nitrogen after the fire. The overall mean Cmic of the burned plots was lower than that in the unburned plots, and the overall mean Nmic was increased after the fire in B.platyphylla. Compared with the unburned plots, Cmic had no significant effect in different months shortly after the fire, the mean Cmic in June, August, October and December in the burned plots(unburned plots) was 1 389.6(1247.2), 886.7(759.0), 1 098.9(1 052.6) and 1 421.4(1 749.7) mg·kg-1, respectively, yet the Nmic was significant higher than that in the unburned plots in June, August and October with the mean Nmic of 214.5(143.4), 101.9(67.5), 119.6(89.4) and 150.2(183.3) mg·kg-1, respectively. The soil microbial biomass was positively correlated to the soil water content, and Nmic was influenced by soil pH significantly. Compared with the unburned plots, the overall mean Cmic and Nmic of the burned plots were lower than those in L.gmelini. The soil microbial biomass had no significant effect throughout different months of L.gmelinii. The mean Cmic in June, August, October and December in the burned plots(unburned plots) was 689.7(695.9), 612.3(910.4), 361.6(474.7) and 1288.5(1353.8) mg·kg-1, respectively, and the mean Nmic was 105.7(124.4), 91.4(111.4), 44.0(76.9) and 118.9(134.5) mg·kg-1, respectively. Cmic and Nmic were significantly positively correlated with soil water content, but negatively with soil pH. The overall mean soil pH ,soil organic carbon and soil total nitrogen of the burned plots were higher than the unburned plots, yet oil water content was decreased in Betula platyphylla. The overall mean soil pH ,soil organic carbon and soil total nitrogen of the burned plots were lower than that in the unburned plots, however, soil water content was increased after the fire in L.gmelinii.