| Chinese FIR (Cunninghamia lanceolata) is excellent material for fast-growing native tree species which unique to South China, plant covers an area of 12.391 million hectares of plantation, 26.55% of the total plantation area in China. In the East South subtropical mountainous areas of Fujian province where is the main commercial forest production bases in China and of Chinese FIR region. With the dramatic increase in demand for wood, large areas of Evergreen broad-leaf forest is replaced by the Chinese FIR plantation, plantated Chinese FIR in the area about burning of after clear cutting forest of Chinese FIR plantation is the update of main silvicultural techniques in China.artificial construct two or three generations of FIR plantations forest after FIRe burning may changes the soil physical and chemical properties of soil microbial activity and Cause issues such as loss of soil fertilizer.Resceachs of the soil respiration, the soil organic carbon and the characteristics of soil microbial communities under different regeneration patterns is less, the relationship between the threand their dynamic change is less. Studies on forest soil respiration are focuse on the characteristics of soil respiration and non-biological factors its response to climate change in the temperate forests, but the research of dynamics of different silvicultural activities on forest which effect the soil respiration and soil components is less, effects on the components of soil respiration and the factos of soil respiratory is not clear. To this end, explore soil microbial characteristics on soil respiration under different update differences update of the subtropical forests and to improve the sustainable management of the theoretical system of Cunninghamia lanceolata plantation is a great significance.This experimental select three forests for research object, located in Fujian province Nanping West celery town (Fujian agriculture and forestry University teaching forest farm), the Background relative consistent One of the three forests we Current is 72 years age, clearcutting FIRe afforestation from the aging Chinese FIR plantation (later known as the age FIR);the other is9 years old on the basis of this aging FIR is part of clearcutting then FIRe afforestation formation of artificial regeneration forest;the last one is 19 years age of natural update forest whitout afforestation and afternatural. Differences in the three ecosystems under different update methods of soil soluble organic carbon, soil respiration, the diversity of microbial communities in different seasons, analysis of samples on a regular basis, reveals a different update type soil dissolved organic carbon and dynamic changes of soil respiration and microbial ecological process of law. Explore in the subtropical regions of the FIR, the impact of the different update on soil respiration, soil organic carbon and microbial community diversity, its variation and mutual relations.Here are the results through this study:1 The age FIR updated will cause changes in soil respiration rate, causes changes in the degree of inconsistency, its variation of a single peak curve, soil respiration increased with increasing temperature, the downward trend in June, July; breathing highest value in July, the lowest value in January. Age FIR the monthly average soil respiration rate changes range 0.78～4.42μmol/m2s, and its variation range is about 5.7 times; Range of natural regenerated forest0.72～5.07μmol/m2s, its variation range is about seven times; artificial regeneration of forest range 0.78 3.40μmol/m2s,its variation range is about 4.4 times. The Ageing FIR average soil respiration rate 2.49μmol/m2s, natural regenerated forestas 2.93μmol/m2s and artificial regeneration forest 2.00 μmol/m2s.compared to the three Chinese FIR forests, natural regeneration and artificial regeneration of forest soil respiration in a forest decline in average rates rose by 17.67%% and 31.74%, Three kinds of soil respiration of forest values have reached significant levels (p<0.05).2 Root respiration rate of average values of three forests are as follows:Age FIR is 0.69umol/m2s, natural regenerated forestis 1.3μmol/m2s and artificial regeneration forest is 0.75μmol/m2s, respectively, representing approximately 27.89%,46.33% and 37.32% of the total soil respiration rate. Differences in performance among the natural regenerated forestand the other two stand a significant difference (P<0.05), the age FIR and artificial regeneration of forest is not significantly different (P> 0.05), aging FIR and artificial regeneration of forestrespiratory rate of change similar.3 Variation of soil heterotrophic respiration in the three forests is in line variation of a single peak curve, the highest respiratory value in June or July, the lowest value in January. The monthly a verage soil respiration rate varied for age FIR is 0.48～3.05μmol/m2s; natural regenerated forest is 0.48～3.0μmol/m2s; artificial regenerated forest is 0.39～2.15μmol/m2s. Annual average soil respiration rate for age FIR is 1.79μmol/m2s, natural regenerated forest is.57μmol/m2s, artificial regenerated forest is 1.25μmol/m2s, Contrast relative to the age FIR, natural regenerated and artificial regeneraed forest soil respiration average rate decreased by 12.30% and 30.17%. Soil respiration in the three forest is in a level of significant difference (p<0.05).4 There is a significant dynamic changes of dissolved organic carbon content of the three forest soils, reduced and then upward in trend. Dissolved organic carbon content in each season are age FIR>natural regenerated forest> artificial regenerated forest. The lowest value of Dissolved organic carbon content in soils apears in July, age FIR forest is 67.54mg/kg, artificial regenerated forest is 65.92 mg/kg, natural regenerated forest is 50.90 mg/kg. Soil microbial biomass carbon content of the three forests showing a trend that rise firstly and then decrease with the seasons, the highest value apears in July, age FIR forest is 251.14mg/kg, artificial regenerated forest is 255.46mg/kg, natural regenerated forest is 250.03mg/kg.Soil microbial biomass carbon content and dissolved organic carbon content exist very significant negative correlation.5 Correlation of Microbial biomass carbon and total soil respiration is a positive significantly correlation or a very significant positive correlation. And the Values about them is 0.91* in the age FIR; 0.97** in the artificial regenerated forest; 0.93*in the natural regenerated forest(* denotes P<0.05;** denotes P<0.01). Micro-organisms are the decomposers of the ecosystem, the process of decomposition of organic matter is the main process of soil emissions of carbon dioxide directly to participate in the carbon cycle, its size is a direct result of soil respiration, the breathing of the factors of the litter layer6 compare with the commercial extraction kit, Soil DNA extraction method used in this experiment, the yield of DNA is about 2 times, PCR products obtain more fragments by digesting with Enzymes, and Average 12 T-RFs more in the last capillary electrophoresis. The experimental soil is the forest soils which contain more humus, so the DNA extraction method used in this study can widely applicable to a variety of soil DNA extraction.7 there may be 3014 microbial community measured in the three forests soil samples, belonging to 19 bhylums. Age FIR is 15 genus throughout the year, artificial regenerated forest is 15 genus, natural regenerated forest is 15 genus. All of these species mostly belongs to Proteobacteria, Actinobacteria, Firmicutes, Spirochaetes, Bacteroidetes. The advantage communities of soil microbial communities in the soil are Proteobacteria, Actinobacteria, Firmicutes.8 The microbial community similarity between the different quarters in the same forest has the highest value 0.794, the lowest value 0.091.Between winter and spring microbial communities in the highest similarity, is respectively0.794,0.710,0.695.In the differences seasonal environmental like autumn and winter, the microbial community of soil, all of the three forests, has a lowest similarity, the similarity values are 0.106,0.079, and 0.067. in the same quarter, January, between age FIR and artificial regenerated forest, microbial community similarity is 0.678, between the age FIR and natural regenerated forest it’s 0.584, and between artificial regenerated forest and natural regeneraed forest it’s 0.643.The similarity of the microbial community in April are 0.683,0.6, 0.637 respectively; in July they are 0.438,0.371,0.481 respectively; in October they are 0.369, 0.34,0.438. In winter and spring, there is a high similarity of the microbial community between forests, and in the summer and fall it’s lower. Microbial community similarity between the age FIR and natural regenerated forest are belower, compare with Microbial community similarity between the age FIR and artificial regenerated forest and between the artificial regenerated forest and natural regenerated forest.9 Soil microbial communities associated the soil respiration in artificial regenerated forest is least, it’s secondly in the age FIR, and it is most in the natural regenerated forest. The composition of the microbial community is very complex, not only contain the floras Participate the geochemical cycle, but also contain pathogen group and probiotic group, The intensity of soil respiration is the result of the interaction of Associated flora. The soil microbial communities positively correlated with soil respiration, is 44 communities in the age forest, including 25 communities participated in the geochemical cycling of carbon,nitrogen, sulfur and other elements; the number of it is 34 and 19 in the artificial regenerated forest; and the number of it is 85 and 53 in the natural regenerated forest.But the soil respiration negatively associated flora is none in the age FIR, it’s 15 communities in the artificial regenerated forest and 5 communities in natural regenerated forest, there is 2 and 5 communities participated in the geochemical cycling. |
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