Researches On Characteristics Of Cork And Tree Growth Law Form Different Types Of Quercus Variabilis

Quercus variabils forest is constructive species of the typical zonal vegetation types inwarm-temperate deciduous broad-leaved forest. The core distribution zone of Q. variabils inShaanxi Province is the Qinba Moutains Regions, while there are a few distributed in theLoess Plateau. The paper mainly took Q. variabils natural secondary forests as research object.Sample-plot survey, laboratory experiments and statistical analysis were used to study themicrostructure and characteristics of cork, the growth law of cork and individual, variationcharacteristics of cork growth across environmental gradients from North Slopes, SouthSlopes at Qinling Moutains and Huanglong Moutain in thin and thick types of Q. Variabils.The main results are as follows:(1) Two types of cork cells have the typical features of cork tissues with a regular andradially aligned structure of suberized cells without intercellular void. In the tangential section,cork cells are seen as polygons in a honeycomb-like arrangement, while the radial andtransverse section shows a brick wall-like structure. In the radial section, cork cells arrayedalong a line which was vertical to the tree axial direction. In transverse section, cork cellsarrayed along a radial which emitted by the center of the tree axial direction. The size, cellwall and corrugation of cork cells are affected by growing season. There are corrugations onthe prism height of cell walls, especially during the growth ring and the lignified phellem cells.There are more corrugations during thick type rather than thin type’s. The result shows thecork of thick type of Q. variabilis. is better than thin type’s. More attention should be paid tothe exploitation of cork resources of thick type in the future.(2) There was most significant difference in the periderm thickness between sunny sideand shady side during two types of Q. variabilis. Therefore, appropriated peeling technologyshould be used to protect the tree from harm. While, thinning techniques should be used toimprove the number of forest gap, thereby increasing the heterogeneity of light, temperatureand other environmental resources, provide favorable condition for growth and developmentof the cork of the Q. Variabilis.(3) The cork of thick type was better than the thin type’s, the cork of both of types wereworst during10~20cm DBH (Diameter at breast height). The relationship between peridermthickness and tree’s growth was most significant positive, stepwise regression analysis shows that DBH could instead of age as an important measure index that reflect the peridermthickness and applied to practice. With the increase of cork thickness the cork quality wasrelatively better in two types. The growth of thick type was faster during10~30cm DBH,then become sluggish after40cm DBH; however the growth of thin type was always slow. Inthe future, barks of thick type should be stripped timely when DBH arrived30cm, and thintype should avoid to strip when DBH less than20cm.(4) The growth of cork are affected by environmental factors and hereditary basis. Thethickness of cork in different Regions has significant difference. The result shows the qualityof cork in Shangluo is better than Louguantai and Baimatang, while the cork from Louguantaiis the worst.(5) The maximum of current annual increment of tree height of the thin type of Q.variabilis is during5~20a. The maximum of current annual increment of DBH of thin type isalso during5~25a. While, the growth of current annual increase of volume has nointersection with the growth of average increase before50a. The maximum of current annualincrement of tree height of thick type and thick type is during5~15a.The maximum ofcurrent annual increment of DBH of thick type is during5~30a. While, the growth of currentannual increase of volume has no intersection with the growth of average increase before45a.(6) In the future, barks of thick type should be stripped timely when DBH arrived30cm,and thin type should avoid to strip when DBH less than20cm. Meanwhile, appropriatedthinning techniques should be used to improve the number of forest gap, thereby increasingthe heterogeneity of light, temperature and other environmental resources, provide favorablecondition for growth and development of the cork of the Q. Variabilis. Thick type of Q.Variabilis should be cultivated during the time of tending and intermediate cutting of forest.