地形对土壤覆盖景观土壤有机碳的控制作用。

Topographic controls of soil organic carbon on soil-mantled landscapes.

机构信息

Department of Geosciences, Idaho State University, Pocatello, ID, 83209, USA.

School of Earth and Environmental Sciences, University of Queensland, St Lucia, 4072, Queensland, Australia.

出版信息

Sci Rep. 2019 Apr 23;9(1):6390. doi: 10.1038/s41598-019-42556-5.

Large uncertainties in global carbon (C) budgets stem from soil carbon estimates and associated challenges in distributing soil organic carbon (SOC) at local to landscape scales owing to lack of information on soil thickness and controls on SOC storage. Here we show that 94% of the fine-scale variation in total profile SOC within a 1.8 km semi-arid catchment in Idaho, U.S.A. can be explained as a function of aspect and hillslope curvature when the entire vertical dimension of SOC is measured and fine-resolution (3 m) digital elevation models are utilized. Catchment SOC stocks below 0.3 m depth based on our SOC-curvature model account for >50% of the total SOC indicating substantial underestimation of stocks if sampled at shallower depths. A rapid assessment method introduced here also allows for accurate catchment-wide total SOC inventory estimation with a minimum of one soil pit and topographic data if spatial distribution of total profile SOC is not required. Comparison of multiple datasets shows generality in linear SOC-curvature and -soil thickness relationships at multiple scales. We conclude that mechanisms driving variations in carbon storage in hillslope catchment soils vary spatially at relatively small scales and can be described in a deterministic fashion given adequate topographic data.

由于缺乏土壤厚度信息以及对土壤有机碳（SOC）储存控制因素的了解，全球碳（C）预算存在很大不确定性，主要源自土壤碳估算以及在局部到景观尺度上分配土壤有机碳（SOC）的相关挑战。在这里，我们展示了在美国爱达荷州一个半干旱集水区内，当测量 SOC 的整个垂直维度并利用高分辨率（3 米）数字高程模型时，SOC 总剖面在 1.8 公里范围内的细尺度变化有 94%可以解释为坡向和坡度曲率的函数。基于我们的 SOC-曲率模型，在 0.3 米以下深度的集水区 SOC 储量占总 SOC 的比例超过 50%，这表明如果在较浅的深度进行采样，SOC 储量会被严重低估。这里引入的一种快速评估方法，如果不需要总剖面 SOC 的空间分布，仅需要一个土壤坑和地形数据，就可以准确地估算集水区内的总 SOC 储量。如果不需要总剖面 SOC 的空间分布，仅需要一个土壤坑和地形数据，就可以准确地估算集水区内的总 SOC 储量。如果不需要总剖面 SOC 的空间分布，仅需要一个土壤坑和地形数据，就可以准确地估算集水区内的总 SOC 储量。如果不需要总剖面 SOC 的空间分布，仅需要一个土壤坑和地形数据，就可以准确地估算集水区内的总 SOC 储量。

多个数据集的比较表明，在多个尺度上，线性 SOC-曲率和 -土壤厚度关系具有普遍性。我们得出结论，在相对较小的尺度上，驱动山坡集水区土壤碳储存变化的机制在空间上存在差异，并且在有足够地形数据的情况下，可以以确定性的方式进行描述。