科研之友
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摘要
Harvesting forests introduces substantial changes to the ecosystem, including physical and chemical alterations to the soil. In the Northeastern United States, soils account for at least 50% of total ecosystem C storage, with mineral soils comprising the majority of that storage. However, mineral soils are sometimes omitted from whole-system C accounting models due to variability, lack of data, and sample collection challenges. This study aimed to provide a better understanding of how forest harvest affects mineral soil C pools over the century following disturbance. We hypothesized that mineral soil C pools would be lower in forests that had been harvested in the last one hundred years vs. forests that were >100years old. We collected mineral soil cores (to 60cm depth) from 20 forest stands across the Northeastern United States, representing seven geographic areas and a range of times since last harvest. We compared recently harvested forests to >100-year-old forests and used an information theoretic approach to model C pool dynamics over time after disturbance. We found no significant differences between soil C pools in >100-year-old and harvested forests. However, we found a significant negative relationship between time since forest harvest and the size of mineral soil C pools, which suggested a gradual decline in C pools across the region after harvesting. We found a positive trend between C:N ratio and % SOM in harvested forests, but in >100-year-old forests a weak negative trend was found. Our study suggests that forest harvest does cause biogeochemical changes in mineral soil, but that a small change in a C pool may be difficult to detect when comparing large, variable C pools. Our results are consistent with previous studies that found that soil C pools have a gradual and slow response to disturbance, which may last for several decades following harvest.
- 出版日期2015-11
