Hydrologic regulation of plant rooting depth
Hydrologic regulation of plant rooting depth
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DOI：
10.1073/pnas.1712381114
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发表时间：
2017-10-03
影响因子：
11.1
通讯作者：
Otero-Casal, Carlos
中科院分区：
文献类型：
--
作者：
Fan, Ying;Miguez-Macho, Gonzalo;Otero-Casal, Carlos
植物生根深度影响生态系统对干旱等环境胁迫的恢复力。深根将深层土壤/地下水与大气相连，从而影响水文循环和气候。深根增强了基岩风化，从而调节了长期的碳循环。然而，我们对根的深度和原因知之甚少。在这里，我们提出了一个全球综合的2,200根观察沿着生物（生活型，属）和非生物（降水，土壤，排水）梯度> 1,000种。结果表明，根深的强烈敏感性，以当地土壤水分剖面确定降水渗透深度从顶部（反映气候和土壤），地下水位深度从下面（反映地形驱动的土地排水）。在排水良好的高地，生根深度跟随渗透深度;在积水的低地，根保持浅，避免地下水位以下的氧气压力;在两者之间，高生产力和干旱可以将根送到地下水毛细边缘许多米。这个框架解释了在相同的气候条件下观察到的不同的生根深度，但在不同的地形位置相同的物种。我们评估这些水文机制的全球意义，估计根吸水深度使用逆模型，根据观测到的生产力和大气，在30。（类似于1公里）全球网格，以捕捉对土壤水文至关重要的地形。由此产生的植物生根深度的模式承担了强大的地形和水文签名在景观全球尺度。它们强调了一个基本的植物-水反馈途径，这可能对理解植物介导的全球变化至关重要。
Plant rooting depth affects ecosystem resilience to environmental stress such as drought. Deep roots connect deep soil/groundwater to the atmosphere, thus influencing the hydrologic cycle and climate. Deep roots enhance bedrock weathering, thus regulating the long-term carbon cycle. However, we know little about how deep roots go and why. Here, we present a global synthesis of 2,200 root observations of > 1,000 species along biotic (life form, genus) and abiotic (precipitation, soil, drainage) gradients. Results reveal strong sensitivities of rooting depth to local soil water profiles determined by precipitation infiltration depth from the top (reflecting climate and soil), and groundwater table depth from below (reflecting topography-driven land drainage). In well-drained uplands, rooting depth follows infiltration depth; in waterlogged lowlands, roots stay shallow, avoiding oxygen stress below the water table; in between, high productivity and drought can send roots many meters down to the groundwater capillary fringe. This framework explains the contrasting rooting depths observed under the same climate for the same species but at distinct topographic positions. We assess the global significance of these hydrologic mechanisms by estimating root water-uptake depths using an inverse model, based on observed productivity and atmosphere, at 30. (similar to 1-km) global grids to capture the topography critical to soil hydrology. The resulting patterns of plant rooting depth bear a strong topographic and hydrologic signature at landscape to global scales. They underscore a fundamental plant-water feedback pathway that may be critical to understanding plant-mediated global change.