Using advances in stable water isotopy to quantify species- and interspecific ecohydrological feedback processes and water transit times of different tree stands

利用稳定水同位素的进展来量化物种和种间生态水文反馈过程以及不同林分的水传输时间

• 批准号: 444110369
• 负责人: Dr. Natalie Orlowski
• 金额: --
• 依托单位: Global Institute for Water Security
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/444110369?language=en
• 关键词: Using; advances; stable; water; isotopy

Significant changes in hydrological extreme events are predicted to increase in occurrence and severity in the future. Understanding the complex linkages and interactions between precipitation inputs, water storage in the soil and groundwater, as well as catchment output water fluxes is still a major challenge in ecohydrology. Vegetation plays a pivotal role in the hydrological cycle controlling 50-70 % of terrestrial evapotranspiration. Distinct plant species differ significantly in their water use strategies. Integrating such information on species-specific alterations of soil infiltration, hydraulic redistribution, and root-water uptake dynamics delivers first hints on how trees may funnel water towards their active root zones. This will become important under future climatic conditions and the development of adaptation strategies for a sustainable forest ecosystem management.The concept of water ages by means of water isotopes is used to assess how different flow paths contribute to runoff and how these contributions change over time. Water ages provide a different dimension in addition to hydrometric responses, helping to better understand the hydrological processes and improve the realism of hydrological models. This concept mostly has been used to focus on individual compartments of the (eco-)hydrological cycle or the whole catchment. However, recent developments in transit time estimations, demonstrate that we need to consider the interfaces among the compartments (e.g., soil-atmosphere or soil-roots) for a more holistic understanding of the ecohydrological cycle. Therefore, species-specific differences and complementary resource utilization of trees in mixed stands might alter water transit times and ages in the ecohydrological cycle.Our central hypothesis is that species identity and water competition between tree species is a major driver for ecohydrological soil-tree feedback processes. We will investigate our central hypothesis on pure and mixed stands of fir and beech trees in a combined experimental (work packages (WPs) 1-3) and modelling approach (WP 4), where high spatial resolution of isotopic, hydrometric, classical and novel plant eco-physiological measurements will be combined with continuous long-term monitoring to quantify all compartments of the ecosystem’s water cycle. Isotopic signatures of water fluxes and pools on a natural abundance level will be observed via a novel in-situ isotope monitoring platform (SWIP) for one year (WP 1) to validate the SWIP system for the specific tree species and soil types. In WP 2, we will conduct an isotope labelling experiment to quantify stand specific temporal heterogeneity of the ecosystem compartment’s response times. WP 3 will focus on unravelling transit times and water ages of the distinct ecosystem compartments. In WP 4, we will apply the acquired data to model ecohydrological processes using SWIS. We will improve and adapt the model structure to the different tree stands.

据预测，未来水文极端事件的重大变化将增加发生次数和严重程度。了解降水输入、土壤和地下水中的储水量以及流域输出水通量之间的复杂联系和相互作用，仍然是生态水文学的一大挑战。植被在水文循环中起着举足轻重的作用，控制着陆地蒸散量的50-70%。不同的植物物种在其水分利用策略上有很大的不同。综合这些关于土壤入渗、水力再分配和根系水分吸收动态的物种特定变化的信息，可以提供关于树木如何向活跃的根区输送水分的第一线索。这在未来的气候条件和制定可持续森林生态系统管理的适应战略时将变得重要。通过水同位素的水龄概念被用来评估不同的流动路径如何对径流做出贡献，以及这些贡献如何随着时间的推移而变化。除了水文反应外，水年龄还提供了不同的维度，有助于更好地了解水文过程，提高水文模型的真实性。这一概念主要被用来侧重于(生态)水循环或整个集水区的个别隔间。然而，运输时间估算的最新发展表明，我们需要考虑隔层(例如，土壤-大气或土壤-根部)之间的界面，以便更全面地了解生态水文循环。因此，混交林中树木的种属差异和资源互补利用可能会改变生态水文循环中的水分传递时间和年龄。我们的中心假设是，树种间的物种同一性和水分竞争是生态水文土壤-树木反馈过程的主要驱动力。我们将在实验(工作包(WPS)1-3)和建模方法(WP 4)相结合的实验(工作包(WPS)1-3)和建模方法(WP 4)中研究我们对冷杉和山毛榉纯林和混交林的中心假设，其中高空间分辨率的同位素、水文、经典和新型植物生态生理测量将与连续的长期监测相结合，以量化生态系统水循环的所有分区。将通过一个为期一年的新的原位同位素监测平台(SWIP)观察自然丰度水平上的水通量和水池的同位素特征，以验证针对特定树种和土壤类型的SWIP系统。在WP 2中，我们将进行同位素标记实验，以量化生态系统区块响应时间的林分特定时间异质性。WP3将侧重于解开不同生态系统隔间的运输时间和水龄。在WP 4中，我们将使用SWIS将所获得的数据应用于生态水文过程模型。我们将改进和调整模型结构，以适应不同的树种。