The long-term effect of non-native earthworm species on forest soil carbon storage is not clear. While initial invasion into earthworm-free soils stimulates carbon losses, there is evidence that carbon stabilization in soil aggregates is enhanced. Fourteen managed forest sites throughout Vermont were sampled to identify and enumerate earthworms, and determine soil aggregate distribution and physically protected carbon. Most of these sites were northern hardwoods reforested in the mid-20th century after agricultural land use. Soil at six 50 × 50 cm subplots at each site was sampled to a depth of 20 cm below the Oe horizon and the mineral soil fractionated into free microaggregates (<250 μm), small macroaggregates (250–2000 μm), and large macroaggregates (>2000 μm). Microaggregates were then isolated from the macroaggregates and organic carbon determined. Mean earthworm numbers below the Oe horizon at each site ranged from 0 to 313 individuals m and ten different species were identified, representing all earthworm ecotypes. Four sites had no earthworms in the soil layer sampled, three sites had earthworms in every subplot with up to six different species, and seven sites had subplots both with and without earthworms. When subplots were grouped by number of species present, there was a trend towards a greater fraction of the mineral soil in macroaggregates containing greater protected carbon, and a lower fraction of free microaggregates. A paired -test of subplots from the seven sites with variable earthworm presence showed significant differences in the same trends and there was significantly greater mineral soil total carbon and protected carbon in the subplots with earthworms. These results are consistent with recent research into earthworm effects on soil carbon stabilization. While initial invasion likely resulted in a negative carbon balance, our findings suggest that earthworms can enhance transfer of carbon into physically protected pools in these forest soils.

中文翻译：

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蚯蚓对美国佛蒙特州管理森林点土壤团聚体分布和保护碳的影响


非本地蚯蚓物种对森林土壤碳储存的长期影响尚不清楚。虽然最初侵入无蚯蚓的土壤会刺激碳损失，但有证据表明土壤团聚体中的碳稳定性得到增强。对佛蒙特州 14 个管理的森林地点进行了采样，以识别和计数蚯蚓，并确定土壤团聚体分布和物理保护的碳。这些地点大多是 20 世纪中叶农业用地利用后重新造林的北方硬木。每个地点的六个 50 × 50 cm 子地块的土壤在大江地平线以下 20 cm 深度处进行采样，并将矿质土壤分为游离微团聚体 (<250 μm)、小大团聚体 (250–2000 μm) 和大大团聚体 (<250 μm)。 >2000微米）。然后从大团聚体中分离出微团聚体并测定有机碳。每个地点 Oe 地平线以下的平均蚯蚓数量范围为 0 至 313 条/米，并鉴定出 10 种不同的物种，代表所有蚯蚓生态型。四个地点的采样土层中没有蚯蚓，三个地点的每个小块中都有蚯蚓，最多有六种不同的物种，七个地点的小块中既有蚯蚓，也没有蚯蚓。当子地块按存在的物种数量进行分组时，存在一种趋势，即含有较多受保护碳的大团聚体中矿质土壤的比例较大，而游离微团聚体比例较低。对七个具有不同蚯蚓存在的地点的子区进行的配对测试显示，相同趋势存在显着差异，并且在有蚯蚓的子区中，矿质土壤总碳和受保护碳显着更高。 这些结果与最近关于蚯蚓对土壤碳稳定作用的研究是一致的。虽然最初的入侵可能导致碳负平衡，但我们的研究结果表明，蚯蚓可以增强碳向这些森林土壤中受物理保护的池的转移。