One objective of wetland restoration is to promote soil organic matter (SOM) accumulation, but it may take decades for restored wetlands to accumulate SOM to a level similar to natural wetlands. We designed an in situ field SOM microcosm (9 × 51 cm) of known carbon (C) content (hereafter, SOM microcosm) to test retention of SOM in a natural compared to a restored wetland. Homogenized native wetland soil was used to fill SOM microcosms made of three different types of materials varying in opening size for root in-growth. They were deployed vertically in the soil profiles of a natural wetland (with five habitat types) and a 24-year-old restored wetland (with four habitat types). After 2 years, SOM content differed between natural and restored sites in the top 15 cm. In the natural wetland, microcosm C content did not significantly change over the 2-year period, averaged across habitats and microcosm type, but there was significant loss of soil C in restored wetland SOM microcosms (20 ± 6.7% loss, p < 0.05). The greater loss of SOM generally occurred in microcosms with 3.5-mm than 1-mm mesh sizes. Our findings suggest that although plants contribute C to the soil via root production and exudates, they can also have a negative effect on SOM accumulation due to soil aeration that promotes C mineralization. This microcosm approach may be useful in evaluating the persistence of SOM in restored wetlands compared to natural reference sites.

中文翻译：

---

一种新的原位方法表明，在自然环境中添加的土壤有机质比恢复湿地具有更大的持久性

湿地恢复的一个目标是促进土壤有机质 (SOM) 的积累，但恢复湿地可能需要数十年的时间才能将 SOM 积累到与自然湿地相似的水平。我们设计了一个已知碳 (C) 含量（以下简称 SOM 缩影）的原位现场 SOM 缩影（9 × 51 cm），以测试与恢复湿地相比，SOM 在自然环境中的保留情况。均质的天然湿地土壤被用来填充由三种不同类型的材料制成的 SOM 微观世界，这些材料的开口尺寸不同，用于根系生长。它们被垂直部署在天然湿地（具有五种栖息地类型）和具有 24 年历史的恢复湿地（具有四种栖息地类型）的土壤剖面中。2 年后，顶部 15 厘米的自然和恢复站点之间的 SOM 含量不同。在天然湿地中，p  < 0.05)。SOM 的更大损失通常发生在 3.5 毫米比 1 毫米网孔尺寸的微观世界中。我们的研究结果表明，尽管植物通过根系产生和分泌物向土壤中贡献 C，但由于土壤通气促进 C 矿化，它们也会对 SOM 的积累产生负面影响。与自然参考地点相比，这种微观方法可能有助于评估恢复湿地中 SOM 的持久性。