Wilsey Brian, Xu Xia, Polley H Wayne, Hofmockel Kirsten, Hall Steven J
Department of Ecology, Evolution and Organismal Biology, Iowa State University, 251 Bessey Hall, Ames, Iowa, 50011, USA.
USDA-ARS, Grassland, Soil and Water Research Laboratory, 808 East Blackland Road, Temple, Texas, 76502, USA.
Ecology. 2020 Jul;101(7):e03039. doi: 10.1002/ecy.3039. Epub 2020 Apr 17.
Global change includes invasion by exotic (nonnative) plant species and altered precipitation patterns, and these factors may affect terrestrial carbon (C) storage. We measured soil C changes in experimental mixtures of all exotic or all native grassland plant species under two levels of summer drought stress (0 and +128 mm). After 8 yr, soils were sampled in 10-cm increments to 100-cm depth to determine if soil C differed among treatments in deeper soils. Total soil C (organic + inorganic) content was significantly higher under native than exotic plantings, and differences increased with depth. Surprisingly, differences after 8 yr in C were due to carbonate and not organic C fractions, where carbonate was ~250 g C/m lower to 1-m soil depth under exotic than native plantings. Our results indicate that soil carbonate is an active pool and can respond to differences in plant species traits over timescales of years. Significant losses of inorganic C might be avoided by conserving native grasslands in subhumid ecosystems.
全球变化包括外来（非本地）植物物种的入侵和降水模式的改变，这些因素可能会影响陆地碳（C）储存。我们在两种夏季干旱胁迫水平（0和 +128毫米）下，测量了所有外来或所有本地草原植物物种的实验混合物中的土壤碳变化。8年后，以10厘米的增量对土壤进行采样，深度达100厘米，以确定深层土壤中各处理间的土壤碳是否存在差异。总土壤碳（有机 + 无机）含量在本地植物种植下显著高于外来植物种植，且差异随深度增加。令人惊讶的是，8年后碳的差异是由于碳酸盐而非有机碳部分造成的，在外来植物种植下，至1米土壤深度的碳酸盐比本地植物种植下低约250克碳/平方米。我们的结果表明，土壤碳酸盐是一个活跃的库，并且能够在数年的时间尺度上对植物物种特征的差异做出响应。通过在亚湿润生态系统中保护本地草原，可能避免无机碳的大量损失。
