PNAS:北京大学薛进庄研究组揭示早期维管植物对陆地修饰
2016年8月9日，国际著名学术期刊《美国国家科学院院刊》杂志在线发表了中国北京大学地球与空间科学学院薛进庄研究员的一篇研究论文，研究发现来自一种早期维管植物的痕量的保存下来的植物物质提供了亚洲最早的有根的土壤床的证据。
维管植物在陆地地形上的定植影响了大气和地质过程，但是早期维管植物的地下结构在化石记录中的有限的呈现导致了对早期陆地生态系统的植物-土壤相互作用的不完整的理解。Jinzhuang Xue及其同事研究了来自中国云南的一个地质地层的年代测定为大约4.11亿年到4.08亿年前的早泥盆纪时期的河流沉积物样本。在这些土壤沉积物样本中，这组科研人员发现了复杂的网络样结构，类似于一组已灭绝的早期维管植物的地下根状茎。使用土壤形态学和地球化学对这些沉积物样本进行的分析表明这些植物材料很可能增加了土壤稳定性并且对该地区的土壤积累和形成有贡献。这组作者说，这些早期植物标本早于泥盆纪中期的深根树的出现，这提示维管植物的这些地下结构可能在早期陆地生态系统中出现，而在维管植物陆地定植的一个早期阶段的植物-土壤相互作用对地球景观修饰的贡献可能比此前认为的更早。
原文链接：
Belowground rhizomes in paleosols: The hidden half of an Early Devonian vascular plant
原文摘要：
The colonization of terrestrial environments by rooted vascular plants had far-reaching impacts on the Earth system. However, the belowground structures of early vascular plants are rarely documented, and thus the plant−soil interactions in early terrestrial ecosystems are poorly understood. Here we report the earliest rooted paleosols (fossil soils) in Asia from Early Devonian deposits of Yunnan, China. Plant traces are extensive within the soil and occur as complex network-like structures, which are interpreted as representing long-lived, belowground rhizomes of the basal lycopsid Drepanophycus. The rhizomes produced large clones and helped the plant survive frequent sediment burial in well-drained soils within a seasonal wet−dry climate zone. Rhizome networks contributed to the accumulation and pedogenesis of floodplain sediments and increased the soil stabilizing effects of early plants. Predating the appearance of trees with deep roots in the Middle Devonian, plant rhizomes have long functioned in the belowground soil ecosystem. This study presents strong, direct evidence for plant−soil interactions at an early stage of vascular plant radiation. Soil stabilization by complex rhizome systems was apparently widespread, and contributed to landscape modification at an earlier time than had been appreciated.
作者：薛进庄
