Spatial Variation Of Vessel Characteristics In Quercus Mongolica

Vessel is the moisture transport organization in hardwood, and connect to the efficacy and safety of the hydraulic characteristics of trees. In order to investigate the s patial distributionof vessel characteristics in Quercus mongolica, seven sample trees were logged from the Maoershan experimental forest farm. Microtome sections were sliced from the roots, trunk, branches, and were taken pictures with Mshot (MD50) digital imaging system. The vessel diameter, the tissue proportion, vessel density, and morphology of roundness were measured by wood anatomical measurement system (TDY-5.2). The conductivity and theory brittleness index were calculated according to the vessel diameter and density. To evaluate the efficacy and safety of the hydraulic characteristics, the anatomical characteristics, the radial and axial variation of vessel characteristics were analysized in this paper. The results show that:(1) Q. mongolica is typical ring-porous wood with clearly heartwood. Secondary xylem is consist of vessel, wood fiber, wood ray, loop control of cell and axial parenchyma cells. In the trunk and branches, the xylem perform for ring-porous wood. In roots, the vessels string radial alignment within the growth ring, and are characterized by diffuse-porous wood features. Through the secondary xylem, single nitrate vessel perforation type are found. For single perforation, most are tail and more incline on both ends of the vessel.(2) From pith to bark, the vessel diameter and tissue proportion increased, the vessel density and roundness decreased. However, the variation trend is not the same. Roundness reduced linearly in the roots. In the trunk, roundness decrease first, and then increase after reach a certain age. In the branches, the roundnes deviate from the circular and then change at a certain age. On the whole, Roundness are correlated negatively with cambium age. Ks and VI have a trend of increase with the increased age.(3) Because of the different environment and site conditions, the vessel diameter of root is largest in north and minimum in south. The vessel diameter of the canopy is largest in east and west.(4) With the increasing of moisture transport distance, the vessel diameter became smaller, density increased, roundness and hydraulic characteristics have a slight trend. The variation trend is small before8m, and is obvious after8m.Q. mongolica is out of sync. Vessel characteristics of Q. mongolica is different between age, location, and heights. This is due to the interaction of the intrinsic factor auxin concentration and the external environment factors sunlight. The vessel with greater diameter have a higher moisture conductivity but low security. Spatial variation of vessel characteristic reflects the balance between the moisture conduction efficiency and safety.