| Forest fire seriously destroys the structure and function of forest ecosystem,and has an important impact on forest vegetation,soil and regeneration.Pinus tabuliformis is a representative tree species in north China,rich in oil and very flammable.In this study,the Pinus tabulaeformis forest in the burned area of the Liaoheyuan Nature Reserve was divided into the research objects.In October 2014,the forest fire was triggered by burning paper.After the fire,the vegetation,soil and environment in the fire area changed significantly.In September 2018,on the basis of comprehensive inspections,according to the different update way under the heavy fire(natural regeneration,artificial stimulating natural regeneration),natural regeneration under different fire intensity(heavy fire,moderate fire,the fire)and contrast(far)not set 15 20 × 20 m sample area,including natural regeneration under heavy fire sample area and natural regeneration under heavy fire sample to phase in the same way,from Pinus tabuliformis alive,plantation structure(DBH),tree height,crown diameter,height of blackened trunk three aspects analysis community slightly burns stand characteristics,from the aspects of load,calorific value,ash content of three analysis community slightly fuel burns the surface characteristics,from the density and growth traits(base diameter,plant height,crown diameter),the spatial distribution pattern of three aspects of the analysis of characteristics of community slightly fire to be forest regeneration,analysis from the aspects of soil moisture content and soil bulk density of 2community slightly the burns of soil physical property features,using single factor analysis of variance methods are significant differences in analysis of variance/mean method to analysis the spatial distribution pattern,based on principal component analysis and cluster analysis method,selection of forest stand,updating of surface fuel,trees,soil physical properties,four categories,a total of 15 indexes to establish community slightly burns vegetation restoration evaluation index system,scientific evaluation of Liaohe nature reserve community slightly burns vegetation restoration effect,the results can be master community slightly burns law of vegetation restoration,scientific forest management measures to accelerate the burns provides the basis for vegetation restoration.The main findings are as follows:(1)The survival density of Pinus tabuliformis in the Pinus tabuliformis forest in Liaohe source reserve decreased with the increase of the intensity of fire.There was no significant difference in the chest diameter,tree height and crown diameter of Pinus tabuliformis among different fire intensities(P>0.05),and there was a very significant difference in the average blackened height of Pinus tabuliformis trunk(P<0.01).(2)The surface fine combustible load of Pinus tabuliformis increased after fire disturbance.There was no significant difference in surface fuel load,small fuel load and herb fuel calorific value between different renewal modes under severe fire(P>0.05),and there were extremely significant differences in fuel calorific value,ash content and herb fuel ash content with 1h delay(P<0.01).There was no significant difference in surface fuel load,small fuel load and herbaceous fuel calorific value between different fire intensification under natural renewal(P>0.05),and there was very significant difference in fuel calorific value,ash content and herbaceous fuel ash content with 1h delay(P<0.01).(3)In the fourth year after the fire,the regeneration tree species were mainly quercus mongolicus and aspen,and the regeneration of Pinus tabuliformis was only distributed in the lightly burned plots with a large number of small plants.In the fifth year after the fire,the regeneration of Pinus tabuliformis increased significantly and was all clustered.Under severe fire,there were extremely significant differences in the regeneration density and basal diameter of Pinus tabuliformis among different regeneration modes(P<0.01),and significant differences in the regeneration density of other trees(P<0.05).There were no significant differences in the regeneration plant height,crown diameter and basal diameter,plant height and crown diameter of other trees(P>0.05).There was no significant difference in the regeneration density,base diameter,plant height,crown diameter and other tree regeneration density of Pinus tabuliformis under different fire intensities under natural regeneration (P>0.05),and there were extremely significant differences in the basal diameter,plant height and crown diameter of other trees(P<0.01).(4)There was an extremely significant difference in soil moisture content between different regeneration modes under severe fire(P<0.01),while there was no significant difference in soil bulk density(P>0.05).The soil moisture content of the sample plots with different fire intensities under natural renewal showed extremely significant difference(P<0.01),while the soil bulk density showed no significant difference(P>0.05).Soil moisture content had a significant effect on other regeneration density(P<0.05),but had no significant effect on other characteristics of tree regeneration(P>0.05),and soil bulk density had no significant effect on tree regeneration characteristics(P>0.05).(5)According to the stand,updating of surface fuel,trees,soil physical properties,four categories a total of 15 indicators to build community slightly burns vegetation restoration evaluation index system,using principal component analysis and cluster analysis method for evaluation of Liaohe source nature reserve community slightly burns vegetation restoration effect,the evaluation results show that 66.7% of the sample recovery for optimal grade,Liaohe source nature reserve community slightly burns recovery condition overall is good.Low and moderate intensity fire promoted natural regeneration of forest,while severe fire and emergency cutting after fire had poor recovery,so forest tending and management were needed. |
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