【作者】 王向荣；

【导师】 王政权；

【作者基本信息】 东北林业大学 ， 森林培育， 2005， 硕士

【摘要】 深入了解植物各级根序细根形态和功能,可以为根系动态模型的建立提供科学依据,有助于在生态系统尺度上较精确的估计和预测C和养分的循环动态。在2003年的春、夏、秋(5、7、9月)三个季节,研究了东北林区两个最重要的用材林树种落叶松(Larix gemilini)和水曲柳(Fraxinus mandshurica),土壤表层(A,0～10cm)和亚表层(B,11～20cm)内不同根序的细根的形态参数(直径、长度、比根长)及其季节变化。研究结果表明,随着根序上升,两个树种个体根直径、长度均显著增加(P<0.05),而单位面积细根总长度和比根长明显减小。在同一根序内,细根直径变异范围较大,其寿命可能也具有很大差异,因此,在细根的寿命和周转研究过程中,应该同时考虑直径和根序差异对细根寿命估计的影响。前3级根序细根长度总和分别占水曲柳和落叶松所有五级根序总长度的95.3%和85.7%,而且比根长也显著大于高级根序(4、5级根)细根,因此在水分、养分吸收中具有非常重要的作用。起源于3～5级根的无分支根(1X级)总长度占所有5级根序细根总长度的12%以上,是不可忽略的一部分。各级细根的数量和形态参数在一定程度上受资源有效性的影响,表现出明显的季节和土壤层次变化。数量、长度占较大比例的低级根序细根非常纤细,比较容易受到土壤生物和资源条件的影响而衰老或凋亡,它们的死亡对于植物的养分吸收、土壤养分的归还和植物体内的C分配具有重要意义。更多还原

【Abstract】 It is widely appreciated that a better understanding of the plant root architecture and function variation is a very important research objectives. The study will provide basic scientific data for the root system modular building, and also contribute to the precise evaluation of carbon and nutrient dynamic at the ecosystem scale. We studied architecture characteristics (diameter, length and specific root length etc.) of different fine root branch orders between two tree species Larix gmelini and Fraxinus mandshurica on Maoershan Forest Research Station (45°21’-45°25’N, 127°30’-127°34’E) which owned by Northeast Forestry University, China. Both ash and larch forests were planted in 1986. We collected the fine root samples from two soil depths (i.e., 0-10cm, ll-20cm) in May 15, July 15 and September 15 of 2003. After washing, the root system was dissected into 5 orders, except the 1x order roots from higher order roots. After dissecting, fine root length, diameter and dry weight of a given order were determined. The objective of this study was to examine how root length, diameter, specific root length (SRL) were related to root branching pattern and their variation with different season or soil depth.The results show that mean diameters (p<0.001) and length (P<0.05) of fine root are different significantly from first-order to fifth-order, and increased regularly with increasing root order in both species. But the SRL and total length on a unit area decreased obviously with the increasing root order. The mean diameters of first-order roots were 0.26mm for ash and 0.34mm for larch, and that of the fifth-order roots were 1.54mm and 1.70mm for ash and larch each respectively. When the diameters are smaller than 2mm and 1mm, fine roots of both species include five orders (ash) and four orders (larch) respectively. If the diameters of fine roots are defined as less than 0.5mm, previous three orders for ash roots and two orders for larch roots would be included as fine root population. Within the same root orders, variations of fine root diameter are also obvious. Diameter ranges increased with increasing root orders. These results suggest that both diameter and order cannot be ignored in estimating fine root life span and turnover. Total length of first three order roots constitute 95.3% and 85.7% of all five order root length, and their SRL ware much higher than the 4 and 5 order roots, which are the most important water and nutrients absorb component, 1x order roots from the higher order roots make up 12% of total root length, should not be ignored also. Response to the resource availability, number and architecture of each order roots present clearly season and depth variation. Because finer roots (1-3 orders) were larger in total number and length, therefore, their death had an important influence on the nutrient uptake, soil nutrient cycle and C allocation in plants.更多还原