Soil Carbon Isotope Values and Paleoprecipitation Reconstruction
Soil Carbon Isotope Values and Paleoprecipitation Reconstruction
复制标题
DOI：
10.1029/2020pa004158
复制
发表时间：
2021-03
影响因子：
3.5
通讯作者：
Rebekah A. Stein;N. Sheldon;Selena Y. Smith
中科院分区：
文献类型：
--
作者：
Rebekah A. Stein;N. Sheldon;Selena Y. Smith
人为气候变化在生态系统范围内具有重大影响，包括广泛的干旱、洪水和其他与极端降水有关的自然灾害。为了了解现代气候变化的背景，科学家们经常关注古代气候变化，例如古代降水范围的变化。以往的研究主要采用化石叶有机地球化学和古土壤无机化学作为古降水的代用指标，但在很大程度上忽略了有机土层作为地上生物量和地下无机碳积累之间的桥梁，作为降水的潜在记录者。研究了现代生态系统中土壤有机质稳定碳同位素（δ 13 CSOM）与各种季节和年气候参数之间的关系，发现δ 13 CSOM值与年平均降水量（MAP）之间存在显著的统计学相关性。在测试了现代系统中实际降水量和重建降水量之间的关系之后，我们通过将使用δ 13 CSOM重建的降水量与来自相同古土壤的其他重建古降水量估计值进行比较，来测试地质记录中的这种潜在古降水量代理。这项研究提供了一个很有前途的新代理，可应用于生态系统后泥盆纪（1420 Ma）中新世（1223 Ma），并在混合C3/C4生态系统的地质记录与额外的古植物学和孢粉学信息。它还将古降水重建扩展到更弱发育的古土壤类型，如缺乏B-层的类型，比以前的无机代理，并校准更潮湿的环境。
Anthropogenic climate change has significant impacts at the ecosystem scale including widespread drought, flooding, and other natural disasters related to precipitation extremes. To contextualize modern climate change, scientists often look to ancient climate changes, such as shifts in ancient precipitation ranges. Previous studies have used fossil leaf organic geochemistry and paleosol inorganic chemistry as paleoprecipitation proxies, but have largely ignored the organic soil layer, which acts as a bridge between aboveground biomass and belowground inorganic carbon accumulation, as a potential recorder of precipitation. We investigate the relationship between stable carbon isotope values in soil organic matter (δ13CSOM) and a variety of seasonal and annual climate parameters in modern ecosystems and find a statistically significant relationship between δ13CSOM values and mean annual precipitation (MAP). After testing the relationship between actual and reconstructed precipitation values in modern systems, we test this potential paleoprecipitation proxy in the geologic record by comparing precipitation values reconstructed using δ13CSOM to other reconstructed paleoprecipitation estimates from the same paleosols. This study provides a promising new proxy that can be applied to ecosystems post‐Devonian (∼420 Ma) to the Miocene (∼23 Ma), and in mixed C3/C4 ecosystems in the geologic record with additional paleobotanical and palynological information. It also extends paleoprecipitation reconstruction to more weakly developed paleosol types, such as those lacking B‐ horizons, than previous inorganic proxies and is calibrated for wetter environments.