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キーワード:
SOM sequestration
Root/rhizosphere
Radiocarbon
C/N
Old-growth-forest
experimental grasslands
central germany
scots pine
radiocarbon
turnover
respiration
dynamics
age
sequestration
climate
要旨:
High carbon uptake of old-growth forests contradict the assumption that old-growth forests are carbon neutral and suggest their Kyoto relevance. As tree biomass is unlikely to store additional carbon in the long term we investigated carbon and nitrogen stock changes in the soil. Therefore we performed paired soil sampling in the years 2000 and 2004 at the National Park Hainich, Germany. In the upper 0-20 cm soil layer 498 g SOC m(-2) was lost in 4 years, but interestingly in 20-60 cm soil depth 1155 g m(-2) of SOC was stored, resulting in an accumulation rate of 164 g m(-2) per year. In the same time nitrogen was accumulated at a rate of 32 g N m(-2) per year. While in 0-20 cm preferential carbon was respired, in the deeper soil layers organic matter with a C/N ratio of microbial organisms was gained. Most interestingly (14)C measurements indicate that gained and lost carbon is of recent carbon age. Our findings suggest that soil organic matter even in deeper soil horizons is very dynamic and that possibly root driven carbon input can significantly change soil organic matter stocks in all depth segments simultaneously. In consequence old growth forests still have a high soil organic matter storage potential as their roots sustain a long-lived permanent storage structure. (C) 2011 Elsevier B.V. All rights reserved.
