Key message

Fine root and litterfall are major contributor of NPP and fine root production may reflect forest productivity in a warm-temperate forest in Japan.

Abstract

Forest ecosystems play an important role as the major carbon sink on land, with fine root dynamics and litterfall representing major carbon fluxes. The objectives of this research were to estimate NPP including annual fine root production values, to investigate fine root dynamics and the relationships between above– and belowground organs in konara oak (Quercus serrata) and hinoki cypress (Chamaecyparis obtusa) forests. Litterfall was collected seasonally for 1 year from June 2013. The ingrowth core method and the sequential soil core method were applied with a root litterbag experiment to estimate fine root (< 2 mm) production (FRP), mortality (FRM), and decomposition (FRD) for 1 year (from 2013 to 2014), using the continuous inflow estimate method and the simplified decision matrix. The total NPP ranged from 8.2 to 13.9 (t ha^− 1 yr^− 1), and the sum of aboveground litterfall and FRP accounted for 60% of the total NPP on average, confirming the significance of above- and belowground litter for the forest NPP as a source of detritus for the decomposer system. In hinoki cypress stand, fine root biomass peaked in the end of winter while fine root necromass showed the highest peak in late summer. In konara oak stand, only very fine root (< 0.05 mm) biomass and necromass demonstrated significant seasonal patterns. The seasonal patterns of fine root production did not differ between forest types and root diameter classes. We found a possible relationship between above- and belowground production and fine root production tended to be high in productive forests. This study improves our understanding of different patterns of carbon dynamics between temperate broadleaved and coniferous forest ecosystems.

中文翻译：

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扁柏（Chamaecyparis obtusa）和konara栎（Quercus serrata）森林细根动态的季节模式及其对净初级生产力的贡献。

关键信息

细根和凋落物是NPP的主要贡献者，细根生产可能反映了日本温带森林的森林生产力。

抽象

森林生态系统作为陆地上的主要碳汇，起着重要的作用，良好的根系动态和凋落物代表主要的碳通量。这项研究的目的是估计包括年细根年产值在内的净初级生产力，调查细根的动态以及在喀纳拉橡树（栎木）和扁柏（Chamaecyparis obtusa）上的和地下的器官之间的关系。）森林。从2013年6月开始，按季节收集凋落物，为期一年，自2013年6月起。采用根垃圾袋试验，采用向内生长核心方法和顺序土壤核心方法，估算细根（<2 mm）产量（FRP），死亡率（FRM）和分解（ （FRD）为1年（从2013年到2014年），使用持续流入估算方法和简化决策矩阵。总NPP在8.2至13.9（t ha ^{− 1} yr ^{− 1}），而地上凋落物和FRP的总和平均占NPP总量的60％，这证实了地上和地下凋落物对于森林NPP作为分解系统碎屑来源的重要性。在扁柏林中，细根生物量在冬季末达到峰值，而细根坏死生物在夏末显示出最高峰。在科纳拉橡木林中，只有非常细的根（<0.05毫米）生物量和坏死生物表现出明显的季节性模式。细根生产的季节性模式在森林类型和根径类别之间没有差异。我们发现地上和地下生产与细根生产之间的可能关系在生产性森林中往往较高。