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细根对生态系统养分、水分和碳循环至关重要。然而,目前关于森林生态系统细根可塑性的研究多集中于乔木树种,对灌木少有研究。本研究以杉木(乔木)和檵木(灌木)为研究对象,采用根袋法研究种内竞争和残落物覆盖对2物种1级和2级细根形态特征(比根长、直径和分枝比)及养分吸收能力的影响,揭示种内竞争和林下管理措施(残落物覆盖)对2物种细根塑性和养分吸收策略的影响机制。结果表明:残落物覆盖、种内竞争及二者的交互作用对杉木细根形态特征各指标均无显著影响。残落物覆盖显著提高了檵木1、2级根分枝比,残落物覆盖、种内竞争及二者的交互作用均显著降低了檵木1级根的直径。檵木细根属性的这些变化增加了其细根的养分吸收速率。因此,增加杉木林残落物覆盖使林下檵木细根形态特征的变化更利于土壤养分的高效吸收,进而可能会与同土层中塑性差的杉木细根产生养分竞争。
Fine roots are vital to ecosystem nutrients, moisture and carbon cycling. However, the current researches on the fine root plasticity of forest ecosystems mostly focus on arbor species and few researches on shrubs. In this study, fir (arbor) and alder (shrub) were used as research objects. Root-bag method was used to study the effects of intraspecific competition and litter coverage on the morphological characteristics of primary and secondary fine roots (specific root length, diameter, Branch ratio) and nutrient absorption capacity, and revealed the mechanism of influence of intraspecific competition and under-management measures (debris cover) on fine root plasticity and nutrient uptake strategies of two species. The results showed that: the coverage of debris, intraspecific competition and the interaction between the two had no significant effect on the morphological characteristics of Chinese fir. The coverage of alfalfa significantly increased the root branching ratio, alluvial cover, intraspecific competition and interaction between Alnus mandshurica and Alnus cremastogyne altar. These changes in fine root properties of alder increase the nutrient uptake rate of its fine roots. Therefore, increasing the coverage of Cunninghamia lanceolata forest residues makes the change of morphological characteristics of fine roots of Alnus cremastogyne more conducive to the efficient absorption of soil nutrients, which may result in nutrient competition with fine roots of poor plasticity in the soil layer.