不同林龄杉木人工林细根形态性状的变化特征分析

    Analysis of the Variation Characteristics of Fine Root Morphological Traits in Cunninghamia lanceolata Plantation Forests at Different Forest Ages

    • 摘要: 为了探究杉木Cunninghamia lanceolata细根觅食能力随林龄和土层深度的变化特征,研究了福建省龙岩市白砂国有林场7、10、23、29和42年生杉木人工林60 cm土层内杉木细根形态性状(包括比根长、比表面积、组织密度和根平均直径)的变化特征。结果表明:(1)对于0~60 cm土层内总细根形态性状,比根长、比表面积均为7年生最大,29年生最低;组织密度7年生最小,29年生最大;根平均直径在各林龄间无显著差异。(2)杉木细根比根长、比表面积在各土层内随林龄的变化特征相似,均为7或10年生最大,29年生最低。(3)对于各林龄细根形态性状在同一土层内的平均值,杉木细根的比根长和比表面积均随着土层深度的增加而呈现先下降后增加的趋势;而且区分不同林龄时可以发现这一变化趋势在7年生时尤为明显。(4)7年生细根形态性状在各土层间的差异显著,塑性变化较为活跃;而29和42年生细根形态性状在各土层间的差异均不显著,塑性变化相对较弱。因此,在林分发育的后期,杉木细根自身觅食能力的下降,以及形态性状在各土层间可塑性的降低可能会导致杉木细根在林分发育后期的资源获取潜力下降,这可能会是导致杉木地上净初级生产力在林分发育后期下降的一个因素,这为揭示杉木人工林生产力变化机理以及杉木人工林的合理经营提供了科学依据。

       

      Abstract: In order to explore the variation characteristics of foraging ability of Cunninghamia lanceolata fine roots with forest age and soil depth, the variation characteristics of morphological traits (including specific root length, specific surface area, tissue density and average root diameter) of Cunninghamia lanceolata fine roots in 60 cm soil layer of 7, 10, 23, 29 and 42-year-old Cunninghamia lanceolata plantation forest in Baisha State-owned Forest Farm of Longyan City in Fujian Province were studied. The results showed that: (1) For the total fine root morphological traits in the 0~60 cm soil layer, the specific root length and specific surface area were the largest at 7 years old and the lowest at 29 years old. The tissue density was the smallest at 7 years old and the largest at 29 years old. There was no significant difference in the average diameter of roots among forest ages. (2) The specific root length and specific surface area of fine roots of Cunninghamia lanceolata were similar with the changes of forest ages in each soil layer, which were both the highest at 7 or 10 years old and the lowest at 29 years old. (3) For the average values of fine root morphological traits in the same soil layer for different stand ages, the specific root length and specific surface area of Cunninghamia lanceolata fine roots both showed a trend of decreasing first and then increasing with the increase of soil depth. Moreover, it could be found that this change trend was particularly obvious at 7 years old when distinguishing different forest ages. (4) The morphological traits of 7-year-old Cunninghamia lanceolata fine roots were significantly different among different soil layers, and the plastic changes were more active. However, there was no significant difference in the morphological traits of fine roots at 29 and 42 years old among different soil layers, and the plastic change was relatively weak. Therefore, in the late stage of stand development, the decrease of self-foraging ability of Cunninghamia lanceolata fine roots and the decrease of plasticity of the morphological traits among various soil layers may lead to the decrease of resource acquisition potential of Cunninghamia lanceolata fine roots in the late stage of stand development, which may be one factor leading to the decline of aboveground net primary productivity of Cunninghamia lanceolata in the later stage of stand development. This provided scientific basis for revealing the mechanism of productivity change of Cunninghamia lanceolata plantation forests and the rational management of Cunninghamia lanceolata plantation forests.

       

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