Does understory plant community explain soil organic matter and function in nemo-boreal pine woodland ?

下層植生の群落構造は、亜寒帯松林における土壌有機物や土壌機能に影響を及ぼしうるか?

Mills, R.*; 藤井 一至*; Jassey, V.*; Heffernan, L.*; 小嵐 淳   ; Mattiasen, C.*; Robroek, B.*; Buttler, A.*

Mills, R.*; Fujii, Kazumichi*; Jassey, V.*; Heffernan, L.*; Koarashi, Jun; Mattiasen, C.*; Robroek, B.*; Buttler, A.*

北方林の土壌に対して現在推定されている炭素貯留や循環速度は、下層植生の群落構造やそれが引き起こす空間不均一性を考慮していない。本研究では、下層植生の群落構造が土壌炭素貯留や循環に及ぼす影響を解明するために、亜寒帯松林内の下層植生群落構造の異なる地点において、落葉堆積層の有機物特性や微生物群集構造・機能を調べた。その結果、下層植生の群落構造やバイオマス量と土壌有機物の質との関連性は乏しく、これらの要因と微生物群集構造との明確な関連性も見られなかった。このことから、下層植生の群落構造は、土壌の長期的な炭素貯留に及ぼす影響は小さいことが示唆された。

Currently, estimates of soil carbon stock and turnover in northern forest soils ignore, to a large extent, the variability of understory plant communities, and their contribution to the within-system heterogeneity that might occur. To explore how understory plant communities may explain soil carbon stock and turnover, we analysed podsol O-horizons for organic matter characteristics and microbial communities and functions across contrasting cover of functional groups in a nemo-boreal pine forest in southern Sweden. We found plant community cover and biomass to be a poor predictor of organic matter content and quality, and of the microbial community composition to be poorly related to both. The results imply a disconnection between plant community composition and longer-term soil carbon stores in complex systems on an ecosystem scale.