Impact Of Management Measure On Larix Principis-Rupprechti Plantation In Qinling Mountains

Larix principis-rupprechtii,belonging to Larix of Panacea,is the main afforestation species in the middle altitude of mountainous areas in China,which has many advantages such as fast-growing,high-yield,of good material,wide application and well decay resistance.Due to the phenomena that wind-blowing,snow-laden and dry shoots seriously affect the quality and growth of Larix principis-rupprechtii and severe pure forestation has led to a sharp decline in biodiversity,systematic study of forest managements and technical measures is urgently needed to change these undesirable phenomena and to improve the stability and productivity of Larix principis-rupprechtii plantation ecosystems.The Larix principis-rupprechtii plantation in Pingheliang area was researched in this study.Different measures that no management(CK),close-to-nature forest management and forest-gap promoting renewal management were implemented in the study area,and the effects of which on the Larix principis-rupprechtii plantation growth,seedling regeneration,the understory plants diversity and the variation of soil physicochemical properties were tested.Through the investigation,we hoped that we can optimize the management technology,put forward constructive suggestions for the follow-up management and provide theoretical and practical basis for the management of Larix principis-rupprechtii plantation in Qinling area.Main conclusions are as followed:(1)Close-to-nature forest management could significantly increase the growth rate of Larix principis-rupprechtii plantations,especially the growth of target trees.Compared with the control group,the retained wood had significantly higher average annual growth rate of the average DBH,individual volume and total volume under close-to-nature forest management,and the target trees under which had significantly higher increase in the DBH and single individual volume,while all trees had little difference in height increase.(2)There were significant differences in the effects of two management measures on the seedlings growth in the understory.After the management,the artificially replanted Betula albosinesis seedlings all died,and the survival rates of Picea asperata and Pinus armandi seedlings were the highest under the close-to-nature forest management,which were 25.9% and 23.4% respectively.The basal diameter size of Picea asperata and Pinus armandi,the amount and growth of natural regenerated seedlings of under different management were as the order of forest gap > close to nature forest management > control.So managements could promote both of the growth of artificial replanted seedlings and the natural regenerated seedlings.(3)Most chemical properties of the soil in the Larix principis-rupprechtii plantations in Qinling Mountains showed an obvious aggregation.With the deepening of the soil,the total potassium content did not change significantly,the soil bulk density and pH value increased gradually,the soil capillary water holding capacity,maximum water-holding capacity,minimum water-holding capacity,soil water content,capillary porosity,non-capillary porosity,total porosity,organic content,total nitrogen,total phosphorus,alkali nitrogen,available phosphorus and available potassium decreased significantly.(4)Management measures can effectively improve the physicochemical properties of the soil.The bulk density,non-capillary porosity,total porosity,water content,maximum water-holding capacity,capillary water-holding capacity and minimum water holding capacity of the soil increased after the management,following the order as: close-to-nature forest management > forest gap > control,and the soil in the layer of 0-20 cm shown the most obvious improving effect.The chemical properties of the soil also improved compared to the control after the management,following the order as: close-to-nature forest management > forest gap > control.The pH value,total phosphorus,hydrolyzed nitrogen,available phosphorus and available potassium content were significantly different among different measures.By affecting the density of forest stand,the management changed the litter and humus in the understory,which forward to affect the physicochemical properties of the soil,improve the soil fertility.(5)Management measures could significantly increase the diversity of shrub and herb plants in the understory.After the management,the types and quantity of understory plants increased significantly,and the proportion of heliophilous plant increased.Management could significantly improve species richness of the plants in the understory of Larix principis-rupprechtii plantation.The amount of shrub and herb species showed an obvious upward trend,especially under the close-to-nature forest management.The common species number and similarity coefficient between the two managements and the control were low,while the similarity coefficient between two managements shown a high value.In summary,close-to-nature forest management could promote the growth of DBH and individual volume of the tree in Larix principis-rupprechtii plantation,effectively improve the soil physical and chemical properties,increase the species richness and plant diversity of the understory plants,and improve the ecological environment in the forest.It’s suggested that close-to-nature forest management could be highly recommended in the other artificial forests in the Qinling Mountains.