Spatial Structure Characteristics And Operational Urgency Evaluation Of Main Forest Types In Jiufeng Forest Park

Based on the study conducted in Jiufeng Experimental Forest Farm of the Beijing Forestry University,this paper analyzes the spatial and unstructured characteristics of five different dominant tree species,namely Robinia pseudoacacia,acuteserrata,Quercus variabilis,Platycladus orientalis and Sophora japonica.It also explains the effect of slope position and the analysis of different types of forests,to withstand the pressure of competition,combined with the management of the urgency,the evaluation index of different forest evaluations,get the operating urgency level and to give management recommendations.The findings are as follows:(1)The results show that the effect of slope position on the mixed forest of Robinia pseudoacacia is not significant.In the herbaceous layer,the plant diversity is better than the uphill position,and shows a downward trend with the elevation.The structure of the stand diameter of the mixed forest of Robinia pseudoacacia is inverted "J" type,which is typical mixed-age hybrid forest structure.The high structure of the mixed forest of Robinia pseudoacacia at different slope was first increased and then decreased gradually.There are several young tree stands in the forest or there are several new mixed tree stands in the forest.(2)The characteristics of forest space in the mixed forests of Robinia pseudoacacia,Acuteserrata,Quercus variabilis,Platycladus orientalis and Sophora japonica were analyzed by structural factors such as aggregation index,angular scale,mingling degree and size ratio.The spatial distribution pattern of forest trees showed that the Acuteserrata mixed forests tended to be randomly distributed,and the mixed forests of Quercus variabilis were clustered and distributed;the isolation degree of tree species was further verified that the Acuteserrata mixed forest was in the transition state of mixed intensity mixed to polar intensity,and the stability of the forest structure was strong.0.538,in moderate mixed,the appropriate increase in forest mixed degree is conducive to the health and stability of the Forest Division to the direction of healthy and stable development;the average size of the stands shows that the average scale of different types of mixed forests is 0.484?0.522.(3)Selecting the Hegyi Competition index to analyze the competition pressure of the forest of different dominant tree species.Results show that the mixed forests of Quercus variabilis,Platycladus orientalis,Sophora japonica mixed with Acuteserrata forests.In the forest,the cluster distribution of forest trees will aggravate the competition intensity of the species,and the appropriate adjustment of the forest space distribution pattern is beneficial to improve the competition pressure of the stand.(4)The assessment of the urgency of stand management is based on the 9 indexes of the forest structure and the spatial space factor.The results showed that the management urgency rating of Acuteserrata,Sophora japonica,Robinia pseudoacacia and Platycladus orientalis in different types of forest was urgent,the operating urgency index of the mixed forest of Quercus variabilis was 0.44,and the urgency evaluation grade was imperative.The main reasons for the low health level of individual trees are the poor natural regeneration of the seedlings and the stratification of the forest layer is not obvious.