Phosphorus and water flux dynamics in runoff and plant uptake in forested headwaters

森林源头径流和植物吸收中的磷和水通量动态

• 批准号: 240722219
• 负责人: Professor Dr. Markus Weiler
• 金额: --
• 依托单位: Forstliche Versuchs- und Forschungsanstalt Baden-Württemberg (FVA)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2013
• 资助国家: 德国
• 起止时间: 2012-12-31 至 2017-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/240722219?language=en
• 关键词: Phosphorus; water; flux; dynamics; runoff

Hydrological pathways form the critical link between the source of P mobilization and the P export to streams. The P mobilization processes at the plot scale are comparatively well understood, however, the knowledge of P delivery through hillslopes and headwaters is limited by the complexities of the transport scales and processes involved and the different P detachment mechanisms. Lateral subsurface flow in the soil can contribute large P fluxes to the P export, because P transport is often connected with fast flow processes, and in particular forested hillslopes are landscape units where fast flow typically occurs. Sound process knowledge of hillslope hydrological dynamics including deep seepage and groundwater flow and P uptake to plants is thus highly important when assessing P transport dynamics. In this experimental and modeling study focusing on hillslope and headwater P dynamics, we will study the effects of hydrological runoff processes for the P transport in forested catchments following the general idea of the SPP that the P depletion in soils and geology drives the evolution of forest ecosystems from P-acquiring systems to P-recycling systems. Building on a extensive hillslope observation platform at three sites from the first phase, we will use novel methods and high frequency sampling to capture the high temporal and spatial dynamics of water and P fluxes. We hypothesis that the recovery of P depletion during extreme rainfall events or wet conditions is faster in acquiring systems than in recycling. The uptake of P and water into trees from different soil depths is stronger decoupled in P recycling systems than it is in acquiring systems. And finally, P leaching from the microbial P mineralization in the biologically active soil zone is restricted to conditions with fast soil-internal water flow whilst P from mineral weathering is lost more continuously through deep seepage and groundwater depending on the underlying bedrock geology. These hypotheses will be tested at three core sites of the SPP with a sophisticated, continuous monitoring system for runoff and P transport in the plants, soil and groundwater at high temporal resolution. Event-based and continuous sampling for P species, stable water isotopes and other geogenic tracers will allow us to derive water ages and transit time distributions to be linked with P fluxes and P transport processes. Finally, we will further develop a process-based hillslope model simulating the different flow and transport pathways to link the internal structure and dynamics of runoff and P to the hillslope and catchment properties.

水文途径形成的关键环节之间的来源，磷动员和磷输出流。P动员过程中的情节规模是比较好的理解，但是，通过山坡和源头的知识是有限的运输规模和过程的复杂性和不同的P分离机制。在土壤中的侧向地下流可以贡献大的P通量的P出口，因为P的运输往往与快速流动过程，特别是森林山坡的景观单元，快速流动通常发生。健全的过程知识，山坡水文动力学，包括深层渗流和地下水流和磷吸收到植物，因此，非常重要的磷运输动态评估时。在这个实验和模拟研究的重点是山坡和水源磷动力学，我们将研究水文径流过程的影响，在森林集水区的磷迁移的SPP的一般思想，即土壤和地质的磷耗竭驱动森林生态系统从磷获取系统的磷循环系统的演变。在第一阶段的三个地点建立一个广泛的山坡观测平台，我们将使用新的方法和高频采样来捕获水和磷通量的高时空动态。我们假设，在极端降雨事件或潮湿的条件下，P耗尽的恢复是更快的收购系统比在回收。从不同的土壤深度到树木的吸收磷和水是更强的解耦在磷循环系统比它是在获取系统。最后，从微生物的磷矿化在生物活性土壤区的磷淋失被限制在快速的土壤内部水流的条件下，而从矿物风化的P是通过深层渗流和地下水取决于下面的基岩地质更连续地丢失。这些假设将在三个核心站点的SPP与一个复杂的，连续的监测系统，径流和磷运输的植物，土壤和地下水在高时间分辨率进行测试。基于事件和连续采样的P物种，稳定的水同位素和其他地质示踪剂将使我们能够获得水的年龄和过境时间分布与P通量和P运输过程。最后，我们将进一步开发一个基于过程的山坡模型，模拟不同的流量和运输途径，连接的内部结构和动态的径流和P的山坡和集水性能。