Changes in the anatomy, morphology and mycorrhizal infection of fine root systems of Cryptomeria japonica in relation to stand ageing
Changes in the anatomy, morphology and mycorrhizal infection of fine root systems of Cryptomeria japonica in relation to stand ageing
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DOI：
10.1093/treephys/tpw076
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发表时间：
2016-09
期刊：
影响因子：
4
通讯作者：
Takuo Hishi;R. Tateno;K. Fukushima;R. Fujimaki;Masami Itoh;N. Tokuchi
中科院分区：
文献类型：
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作者：
Takuo Hishi;R. Tateno;K. Fukushima;R. Fujimaki;Masami Itoh;N. Tokuchi
在土壤养分缺乏的情况下，细根生物量分配往往增加，但在老林分中，即使在养分限制下，细根生物量也不常增加。因此，在老林分中，细根的形态、解剖、分枝结构和菌根化可以有效地补偿低细根生物量对养分的获取。在这项研究中，细根簇的形态，解剖和丛枝菌根感染的变化在每个分支位置的林分年龄进行了评估。本文研究了柳杉（CryptomeriajaponicaD.）这些分析使用Don种植园。随着林龄的增加，细根丛长、根重和根尖数等细根大小参数增加。比根尖长（SRTL）随林龄的增加而减小，表明根系活性部分的分配随林龄的增加而减少。从解剖学观察，随着林分年龄的增长，短暂的根尖增加，这表明在一个根丛根尖周转率高，在老的林分。原生木质部类群在各分枝部位所占的比例表明，老林分的分枝等级生活史比幼龄林分更清晰。老龄林根尖菌根侵染率的增加，可增强根系的吸收功能。SRTL与木/针比相关，表明随着林龄的增加，碳限制可能导致维持活跃根尖的碳分配下降。但在老林分中，短梢和菌根侵染率的增加可以弥补短梢分配的下降。
Biomass allocation to fine roots often increases under soil nutrient deficiency, but the fine root biomass does not often increase in old stands, even under nutrient limitation. Therefore, in old stands, the morphology, anatomy, branching architecture and mycorrhization of fine roots may compensate efficiently for nutrient acquisition by the low fine root biomass. In this study, changes in the morphology, anatomy and arbuscular mycorrhizal infection at each branching position of fine root clusters were evaluated in relation to stand age. A chronosequence (6–90 years of age) of stands in a Cryptomeria japonica D. Don plantation was used for these analyses. The fine root size parameters, such as length, weight and tip numbers of fine root clusters, increased with stand age. The specific root tip length (SRTL) decreased with increasing stand age, suggesting that the allocation to root active portions decreased with stand age. From the anatomical observation, the ephemeral root tips increased with stand age, suggesting that root tip turnover within a root cluster was high in old stands. The proportions of proto-xylem groups among branching positions indicated that the life cycles in branching hierarchy should be clearer in old stands than that in younger stands. The increasing in the mycorrhizal infection of root tips in old stands should enhance the root tip absorptive functions. The SRTL was correlated with the wood/needle ratio, suggesting that carbon limitation as the stand ages may result in decline of carbon allocation to maintain active root tips. However, increasing of the ephemeral tips and mycorrhizal infection rates may compensate the declines of tip allocation in old stands.