Descriptions of tree root morphology inform design of belowground biomass and carbon inventories and sampling for research. We studied root morphology of tanoak (Notholithocarpus densiflorus), an important component i...Descriptions of tree root morphology inform design of belowground biomass and carbon inventories and sampling for research. We studied root morphology of tanoak (Notholithocarpus densiflorus), an important component in mixed evergreen forests of California and Oregon, USA. Tanoak re-sprouts from belowground lignotubers after disturbances, and stores an unknown amount of carbon in coarse roots underground. We sought to ascribe explanatory nomenclature to roots’ morphological features and to identify models describing tanoak root morphology. Twelve tanoak root systems were excavated, dissected, and measured. Roots tapered according to their circumference and location. Larger roots closer to the lignotuber (located at the base of the tree stem) tapered more rapidly per unit of length. Tanoak roots forked frequently. Root cross-sectional area was preserved after forking events (i.e., the sum of cross-sectional areas for smaller roots on one side of the fork correlated with the adjoining large root). Occurrence and quantity of root branches (small roots branching laterally from larger roots) was dependent upon length of the source root segment. Our models of tanoak root morphology are designed to be organized together to estimate biomass of any segment or collection of lateral roots (e.g., roots lost/missed during excavation, or in lieu of destructive sampling), given root diameter at a known distance from the lignotuber. The taper model gives distal- and proximal-end diameters for calculation of volume for segments of root tapering between forks. Frequency of forking and branching can also be predicted. Summing the predicted mass of each lateral root segment, branch, and forked segment would produce an estimate of mass for a contiguous network of lateral roots.展开更多
目的:探讨40岁以上单根管下颌第二前磨牙根尖段根管直径和锥度。方法:收集40岁以上单根管下颌第二前磨牙52颗,采用显微CT进行扫描,利用3D Med 2.2软件重建后,分别对距离解剖性根尖孔1,2,3,4,5 mm处进行根管颊舌向和近远中向直径测量,并...目的:探讨40岁以上单根管下颌第二前磨牙根尖段根管直径和锥度。方法:收集40岁以上单根管下颌第二前磨牙52颗,采用显微CT进行扫描,利用3D Med 2.2软件重建后,分别对距离解剖性根尖孔1,2,3,4,5 mm处进行根管颊舌向和近远中向直径测量,并计算颊舌向、近远中向锥度和观测根管横截面形态变化。结果:根管根尖段平均直径颊舌向大于近远中向(P<0.05),颊舌径和近远中向平均锥度分别为0.09±0.10,0.05±0.03,根尖段80%根管形态为椭圆形。结论:单根管下颌第二前磨牙根尖段个体差异大,颊舌向直径和锥度均大于近远中向,常用根管器械难以兼顾所有根管,根管预备时需引起注意。展开更多
文摘Descriptions of tree root morphology inform design of belowground biomass and carbon inventories and sampling for research. We studied root morphology of tanoak (Notholithocarpus densiflorus), an important component in mixed evergreen forests of California and Oregon, USA. Tanoak re-sprouts from belowground lignotubers after disturbances, and stores an unknown amount of carbon in coarse roots underground. We sought to ascribe explanatory nomenclature to roots’ morphological features and to identify models describing tanoak root morphology. Twelve tanoak root systems were excavated, dissected, and measured. Roots tapered according to their circumference and location. Larger roots closer to the lignotuber (located at the base of the tree stem) tapered more rapidly per unit of length. Tanoak roots forked frequently. Root cross-sectional area was preserved after forking events (i.e., the sum of cross-sectional areas for smaller roots on one side of the fork correlated with the adjoining large root). Occurrence and quantity of root branches (small roots branching laterally from larger roots) was dependent upon length of the source root segment. Our models of tanoak root morphology are designed to be organized together to estimate biomass of any segment or collection of lateral roots (e.g., roots lost/missed during excavation, or in lieu of destructive sampling), given root diameter at a known distance from the lignotuber. The taper model gives distal- and proximal-end diameters for calculation of volume for segments of root tapering between forks. Frequency of forking and branching can also be predicted. Summing the predicted mass of each lateral root segment, branch, and forked segment would produce an estimate of mass for a contiguous network of lateral roots.
文摘目的:探讨40岁以上单根管下颌第二前磨牙根尖段根管直径和锥度。方法:收集40岁以上单根管下颌第二前磨牙52颗,采用显微CT进行扫描,利用3D Med 2.2软件重建后,分别对距离解剖性根尖孔1,2,3,4,5 mm处进行根管颊舌向和近远中向直径测量,并计算颊舌向、近远中向锥度和观测根管横截面形态变化。结果:根管根尖段平均直径颊舌向大于近远中向(P<0.05),颊舌径和近远中向平均锥度分别为0.09±0.10,0.05±0.03,根尖段80%根管形态为椭圆形。结论:单根管下颌第二前磨牙根尖段个体差异大,颊舌向直径和锥度均大于近远中向,常用根管器械难以兼顾所有根管,根管预备时需引起注意。
