Modeling the Impact of Biopores on Root Growth and Root Water Uptake
Modeling the Impact of Biopores on Root Growth and Root Water Uptake
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DOI：
10.2136/vzj2018.11.0196
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发表时间：
2019-03-28
影响因子：
2.8
通讯作者：
Vanderborght, Jan
中科院分区：
文献类型：
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作者：
Landl, Magdalena;Schnepf, Andrea;Vanderborght, Jan
根是已知的使用生物孔隙作为优先生长途径，以克服硬土层和获取底土水资源。本研究评估了根生物孔的相互作用在不同的土壤物理和环境条件下，在根系尺度上使用的机械模拟模型和广泛的实验场数据。在田间试验中，以春小麦（Triticum aestivum L.）生长在生物孔密度大的粉壤土上。X射线计算机断层扫描的土壤柱从现场被用来提供一个现实的生物孔网络作为输入的三维数值R-SWMS模型，然后应用于模拟根结构以及水流在根生物孔土壤连续。通过优化根系生长模型的输入参数，对观测到的根长密度进行了校准。通过将已知的根系生长和土壤渗透阻力之间的相互作用实施到我们的模型中，我们可以模拟根系系统，其对土壤中生物孔隙的响应与文献中描述的实验观察结果相对应，例如增加总根长和增加生根深度。对于所有考虑的土壤物理（土壤质地和体积密度）和环境条件（不同干燥度的年份），我们发现生物孔隙可以通过允许根系从更潮湿和更深的土层中吸收水分来大大减轻干旱时期的蒸腾不足。这甚至是当假设由于有限的根-土接触而减少根在生物孔隙中的吸水时的情况。生物孔隙对根系吸水的有益影响较大，更紧凑，导电性差的土壤。
Roots are known to use biopores as preferential growth pathways to overcome hard soil layers and access subsoil water resources. This study evaluates rootbiopore interactions at the root-system scale under different soil physical and environmental conditions using a mechanistic simulation model and extensive experimental field data. In a field experiment, spring wheat (Triticum aestivum L.) was grown on silt loam with a large biopore density. X-ray computed tomography scans of soil columns from the field site were used to provide a realistic biopore network as input for the three-dimensional numerical R-SWMS model, which was then applied to simulate root architecture as well as water flow in the root-biopore-soil continuum. The model was calibrated against observed root length densities in both the bulk soil and biopores by optimizing root growth model input parameters. By implementing known interactions between root growth and soil penetration resistance into our model, we could simulate root systems whose response to biopores in the soil corresponded well to experimental observations described in the literature, such as increased total root length and increased rooting depth. For all considered soil physical (soil texture and bulk density) and environmental conditions (years of varying dryness), we found biopores to substantially mitigate transpiration deficits in times of drought by allowing roots to take up water from wetter and deeper soil layers. This was even the case when assuming reduced root water uptake in biopores due to limited root-soil contact. The beneficial impact of biopores on root water uptake was larger for more compact and less conductive soils.