| Fuel is a burning material base of forest fire, and basis for forest fire management. It is a effective method for prevention forest fires to manually interfered and managed. Now, prescribed burning is used to manage fuel in many forest districts. Prescribed burning is controlled and planed to ignite surface fuel which is the area of high fire danger rating and productivity declining period, accelerating fuel into nutrient speed, promoting community renewal, improving ecosystems productivity, while reducing forest fire danger, and elimination fire spread channel. Prescribed burning is intervened forest fire management by human with managing surface fuel to achieve prevention forest fires, and thereby affecting ecosystems. Pinus kesiya Royle ex Gordon var.langbianensis forest in Jinggu county in Yunnan province, Pinus yunnanensis forest in anning city in Yunnan province, meadow, Larix spp. and Betula platyphylla Suk. forest in Daxing’anling in Heilongjiang province were selected as research subject, and effect of different vegetation types, different species and different regions of fire prevention, carbon sequestration benefits, change of soil chemical properties, and forest growth were analysised, then ecological control effects of prescribed burning were evaluated, and outdoor meadow burning experiment and indoor burned experiment field which imitates the situation of a wild forestwere developed, and landscape scale burning experiment were simulated, and fire behavior characteristic of prescribed burning were researched and could be guided prescribed burning work.(1) The great prevention fire effects after prescribed burning showed that the average fuel clearance was up to 77.63% in meadow in Daxing’anling after prescribed burning, and average height decline 81.21%, and average thinkness descending 66.28%, and average painted-face rate was 17.16%. The plot increment of humus layer loads in Pinus Kesiya Forest plot after prescribed burning was 2.696t·hm-2, and higher 24.84% than that of cobtrol plot. After two years, the fuel laods increment in Pinus Kesiya Forest plot after prescribed burning was lower 0.539t·hm-2 than that ofcontrol plot, but increment of humus layer loads higher 0.474t·hm-2 than that of control plot, the increment fuel loads with other methods was about 2t·hm-2, and humus layer little increment.(2) The organic carbon storage under forest Pinus Kesiya Forest after prescribed burning can be increased, it showed that the average organic carbon storage under forest was higher 1.338t·hm-2 than that of control plot, about 10%, humus layer was higher 0.527 cm than that control plot, about 25%, and its average thinkness was 1.593 cm, higher 0.527 cm than that of control plot,about 50%. After two years, the total increment of fuel organic carbon storage was lower 0.382t·hm-2 than that of control plot, but humus layer increment was higher 0.298t·hm-2.(3) The soil organic carbon content and storage in in Pinus Kesiya Forest plot after prescribed burning would increase, it showed that the soil average organic carbon content of 0-60 cm and three level increased highly statistically significant(P<0.01) in Pinus Kesiya Forest plot after prescribed burning, and higher 0.5 than that of control plot. The soil average total organic carbon storage of 0-60 cm increased statistically significant(P<0.05), and higher 49.526t·hm-2 than that of control plot, and 0-20 cm average organic carbon storage increased statistically significant(P<0.05), other level increased highly statistically significant(P<0.01). After two years, average organic carbon content and storage of prescribed burning plot and burying plot were higher 0.0391, 8.734t·hm-2 and 5.569, 363.245t·hm-2 than taht of control plot, and the burying plot was three times higher than that of control plot.(4) After prescribed burning, the effects of soil chemical properties would increase, and it showed:①The typical meadow after prescribed burning and after half a year, PH decreased, and organic matter, available potassium, total nitrogen, total phosphorus and total patassium of 0-5cm level increased statistically significant(P<0.05), available nitrogen and available phosphorus decreased statistically significant, and then increased statistically significant(P<0.05), and available phosphorus, available potassium, total nitrogen, total phosphorus and total patassium of 6-10 cm level decreased statistically significant(P<0.05), organic matter and available nitrogen of 6-10 cm decreased statistically significant and then increased statistically significant(P<0.05), organic matter, available nitrogen, total nitrogen of 11-20 cm increased statistically significant, available phosphorus, available potassium, total phosphorus and total patassium decreased statistically significant(P<0.05). ②The swamp meadow after burning and after half a year, PH of all level decreased, organic matter, available nitrogen, available potassium, total nitrogen and total phosphorus of all level level decreased statistically significant and then increased statistically significant(P<0.05), available phosphorus decreased statistically significant and then 0-5cm level increased statistically significant(P<0.05), total patassium inreased 10%-20% and then decreased in less than 10%. ③The meadow after prescribed burning continuously monitored six months showed that soil PH changed little, and organic matter was higher than control plot except June, and available nitrogen decreased statistically significant(P<0.05), and available phosphorus, available patassium, total nitrogen were lower than control plot except June, and total phosphorus, total patassium were lower than control plot except May. ④The brushwood after prescribed burning continuously monitored six months showed that PH didn’t change, and total patassium decreased 10%-30% except a little higher than control plot in June. ⑤The typical meadow after prescribed burning, amounts of available phosphorus, available patassium and total patassium in 0-20 cm level decreased, other indicators increased, then after half a year, total patassium decreased tatistically significant(P<0.05), but other indicators increased tatistically significant(P<0.05). The swamp meadow after prescribed burning, amounts of total patassium in 0-20 cm increased 10%, other indicators decreased, then after half a year, amounts of total patassium decreased a little, other indicators increased highly statistically significant(P<0.01) except available phosphorus increased a little.The all amounts of meadow in 0-5cm level after prescribed burning from May to September decreased, parts of indicators decreased tatistically significant(P<0.05). The all amounts of brushwood in 0-5cm level after prescribed burning from May to September increased highly statistically significant(P<0.01) except total patassium declined 20%.(5) After prescribed burning, the trees growth would be accelerated, and it showed: average height, average DBH, average dead crown base height, and average live crown base height of Pinus Kesiya, Larch and Birch forest plot were higher than that of control plot, but surface fuel thinkness and loads, brushwood layer loads and height, herb layer loads and height decreased tatistically significant(P<0.05), the thinkness and loads of duff layer and humus layer increased highly tatistically significant(P<0.01). The brush types were more than control plot, but average height, average ground diameter and coverage were smaller than control plot. The herb types, max height, average height and coverage after burning were smaller than control plot.The increment of average height and average DBH after two years in prescribed burning plot increased higher 0.17 m and 0.35 cm than that of control plot. The increment of southern Pinus Kesiya was higher than that of northern Larch and Birch forest.(6) The indoor prescribed burning experiments which imitates the situation of a wild forest showed. Flame height was related to fuel loads, moisture and height. Models of fire spread speed and fire break width predicting on prescribed burning were base on random sampling in non-fixed plot, and datas of indoor simulation burning satisfied normal-distribution check by SPSS software, and then fitting degree were better, and average error were low. The distribution chart of fire break width visually display higher fire danger area that are bigger width.(7) The fire behaviors of prescribed burning are visually displayed by graph to use FARSITE software. The areas of high fireline intensity, long flame length, quick spread speed, high heat, high crown fire activity probability and changing spread direction variation should be carried out relating prevention fire work in advance, avoiding unexpected fire and guarantee safe burning to obtaine a better fire prevention effect and ecological regulation function, and provide theoretical basis for forest management and forest ecosystem management.The prescribed burning is controlled to effective forest fire management method by human ntervention, and can be drastically reduced fuel loads, especially meadow clearance reach above 70%, and reclining fuel height and thinkness, changing fuel three-dimensional structure and continuous distribution, cutting spread channel and reducing fire danger to achieve objective to forest fires of prevention, reducing large area and high intensity. After prescribed burning, ecosystem functions of meadow, brushwood and forest is improved, meadow soil all indicators differently increase and decrease, but after half a year, meadow slash soil all indicators increase except total patassium, brushwood slash all indicators increase tatistically significant in short and long term except total patassium.After prescribed burning, the meadow slash all indicators total imports in five month are less and brushwood slash are more than that of control plot. Forest with prescribed burning, loads and height of herb and brushwood layer decrease, but thinkness,organic content and storage of humus layer increase, and accelerate tree growth, and achieve to forest fire prevention and enhance soil carbon sequestration ability and highlight effect of prescribed burning ecological control. The high fire danger area can be visually displayed with picture to use FARSITE software in prescribed burning, and should be carried out relating prevention fire work in advance, and guarantee prescribed burning and avoiding unexpected fire, so that it can be obtained better ecological control benefits. |
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