The long-term fate of deposited nitrogen in temperate forest soils

Increased anthropogenic nitrogen (N) inputs can alter the N cycle and affect forest ecosystem functions. The impact of increased N deposition depends among others on the ultimate fate of N in plant and soil N pools. Short-term studies (3-18 months) have shown that the organic soil layer was the dominant sink for N. However, longer time scales are needed to investigate the long-term fate of N. Therefore, the soils of four experimental forest sites across Europe were re-sampled similar to 2 decades after labelling with(15)N. The sites covered a wide range of ambient N deposition varying from 13 to 58 kg N ha(-1)year(-1). To investigate the effects of different N loads on(15)N recovery, ambient N levels were experimentally increased or decreased. We hypothesized that: (1) the mineral soil would become the dominant(15)N sink after 2 decades, (2) long-term increased N deposition would lead to lower(15)N recovery levels in the soil and (3) variables related to C dynamics would have the largest impact on(15)N recovery in the soil. The results show that large amounts of the added(15)N remain in the soil after 2 decades and at 2 out of 4 sites the(15)N recovery levels are higher in the mineral soil than in the organic soil. The results show no clear responses of the isotopic signature to the changes in N deposition. Several environmental drivers are identified as controlling factors for long-term(15)N recovery. Most drivers that significantly contribute to(15)N recovery are strongly related to the soil organic matter (SOM) content. These findings are consistent with the idea that much of the added(15)N is immobilized in the SOM. In the organic soil layer, we identify C stock, thickness of the organic layer, N-status and mean annual temperature of the forest sites as most important controlling factors. In the mineral soil we identify C stock, C content, pH, moisture content, bulk density, temperature, precipitation and forest stand age as most important controlling factors. Overall, our results show that these temperate forests are capable of retaining long-term increased N inputs preferably when SOM availability is high and SOM turnover and N availability are low.publishedVersio

Agents united:An open platform for multi-agent conversational systems

The development of applications with intelligent virtual agents (IVA) often comes with integration of multiple complex components. In this article we present the Agents United Platform: an open source platform that researchers and developers can use as a starting point to setup their own multi-IVA applications. The new platform provides developers with a set of integrated components in a sense-remember-think-act architecture. Integrated components are a sensor framework, memory component, Topic Selection Engine, interaction manager (Flipper), two dialogue execution engines, and two behaviour realisers (ASAP and GRETA) of which the agents can seamlessly interact with each other. This article discusses the platform and its individual components. It also highlights some of the novelties that arise from the integration of components and elaborates on directions for future work

The long-term fate of deposited nitrogen in temperate forest soils

Increased anthropogenic nitrogen (N) inputs can alter the N cycle and affect forest ecosystem functions. The impact of increased N deposition depends among others on the ultimate fate of N in plant and soil N pools. Short-term studies (3-18 months) have shown that the organic soil layer was the dominant sink for N. However, longer time scales are needed to investigate the long-term fate of N. Therefore, the soils of four experimental forest sites across Europe were re-sampled similar to 2 decades after labelling with(15)N. The sites covered a wide range of ambient N deposition varying from 13 to 58 kg N ha(-1)year(-1). To investigate the effects of different N loads on(15)N recovery, ambient N levels were experimentally increased or decreased. We hypothesized that: (1) the mineral soil would become the dominant(15)N sink after 2 decades, (2) long-term increased N deposition would lead to lower(15)N recovery levels in the soil and (3) variables related to C dynamics would have the largest impact on(15)N recovery in the soil. The results show that large amounts of the added(15)N remain in the soil after 2 decades and at 2 out of 4 sites the(15)N recovery levels are higher in the mineral soil than in the organic soil. The results show no clear responses of the isotopic signature to the changes in N deposition. Several environmental drivers are identified as controlling factors for long-term(15)N recovery. Most drivers that significantly contribute to(15)N recovery are strongly related to the soil organic matter (SOM) content. These findings are consistent with the idea that much of the added(15)N is immobilized in the SOM. In the organic soil layer, we identify C stock, thickness of the organic layer, N-status and mean annual temperature of the forest sites as most important controlling factors. In the mineral soil we identify C stock, C content, pH, moisture content, bulk density, temperature, precipitation and forest stand age as most important controlling factors. Overall, our results show that these temperate forests are capable of retaining long-term increased N inputs preferably when SOM availability is high and SOM turnover and N availability are low

Co-evolution of smart energy products and services: A novel approach towards smart grids

In this paper we present our project on interdisciplinary evaluations of existing smart grid environments regarding (1) the technical performance of smart energy products and services, (2) end users perceptions, (3) stakeholder processes and (4) market aspects. Our evaluations are based on data and information originating from real life pilots and demonstration projects in the field of smart grids in residential areas in the Netherlands and in Austria. The so-called CESEPS project is executed in the European ERA-Net Smart Grids Plus program. CESEPS stands for Co-Evolution of Smart Energy Product and Services. Its main objective is to support the development of smart energy products and services for local smart grids that better respond to the demands and concerns of all stakeholders in terms of performance, cost, reliability, safety and robustness, sustainability and energy-efficiency, and end users' comfort. Besides comparative data analyses and user surveys, this three year project comprises simulation activities to model existing and innovative smart grid energy products to evaluate their feasibility, given the aspects above mentioned. In this paper our approach will be explained and illustrated by several examples of ongoing subtopics of research and knowledge dissemination among stakeholders in the smart grid sector

Co-evolution of smart energy products and services:a novel approach towards smart grids

\u3cp\u3eIn this paper we present our project on interdisciplinary evaluations of existing smart grid environments regarding (1) the technical performance of smart energy products and services, (2) end users perceptions, (3) stakeholder processes and (4) market aspects. Our evaluations are based on data and information originating from real life pilots and demonstration projects in the field of smart grids in residential areas in the Netherlands and in Austria. The so-called CESEPS project is executed in the European ERA-Net Smart Grids Plus program. CESEPS stands for Co-Evolution of Smart Energy Product and Services. Its main objective is to support the development of smart energy products and services for local smart grids that better respond to the demands and concerns of all stakeholders in terms of performance, cost, reliability, safety and robustness, sustainability and energy-efficiency, and end users' comfort. Besides comparative data analyses and user surveys, this three year project comprises simulation activities to model existing and innovative smart grid energy products to evaluate their feasibility, given the aspects above mentioned. In this paper our approach will be explained and illustrated by several examples of ongoing subtopics of research and knowledge dissemination among stakeholders in the smart grid sector.\u3c/p\u3