-46 -Multifunctional Grasslands in a Changing World Volume I Grasslands/Rangelands Resources and Ecology--Ecology of Grasslands/Rangelands

Key Points: The use of stable isotope analysis in grassland science has increased enormously in the last two decades. It is providing insight into the functioning of grassland systems, including aspects such as the biogeochemical cycles of carbon, nitrogen and water, C 3 :C 4 vegetation dynamics, the nutritional ecology of grassland fauna, and the (agro)ecology of cattle production systems. This paper deals with the natural stable isotope compositions of three major bioelements (carbon, nitrogen and oxygen) and how they behave in organisms and ecosystems, and it describes examples of recent research progress in the ecology of grassland systems, which were made with the help of stable isotope analysis. Introduction Until 1990 stable isotope analysis was used only sporadically in grassland research. Today, more than 6% of all 'grassland' publications appearing in the ISI Web of Science data base employ stable isotope analysis. Several reviews and books have been published in the last years, which covered various aspects of the application of natural stable isotope analysis in ecology and in the study of stable isotope behaviour in the environment and in organisms (e.g

Pristine levels of suspended sediment in large German river channels during the Anthropocene?

Suspended sediment is an integral part of riverine transport and functioning that has been strongly altered during the Anthropocene due to the overwhelming human pressure on soils, sediments, and the water cycle. Understanding the controls of changing suspended sediment in rivers is therefore vital for effective management strategies. Here we present results from a trend analysis of suspended sediments covering 62 monitoring stations along the German waterways (catchment sizes range between 2000 and 160 000 km2) with more than 440 000 water samples taken between 1990 and 2010. Based on daily monitoring of suspended sediment concentration (SSC), we found significant declines in mean annual SSC and annual suspended sediment loads (SSLs) at 49 of 62 monitoring stations totaling −0.92 mg L−1 yr−1. At some stations decreases during the 20 years represent up to 50 % of the long-term average SSC. Significant decreases in SSC are associated with declining SSL despite an increase in sheet and rill erosion by almost 150 % derived from modeling due to changes in land use and management as well as rainfall erosivity. The contemporary suspended sediment loads of the Rhine at the German–Dutch border are approaching the natural base level of ∼1 Mt yr−1, which was reached by the Rhine during the mid-Holocene when the suspended sediment load was adjusted to the Holocene climatic conditions and before the onset of increased loads due to human-induced land use changes in the Rhine catchment. At this point we can only speculate regarding potential reasons for a decline in sediment transport in larger rivers despite erosion increase. We argue that increased sediment retention in upstream headwaters is presumably the major reason for declining SSC in the large river channels studied.</p

Comment on "Rainfall erosivity in Europe" by Panagos et al. (Sci. Total Environ., 511, 801–814, 2015)

Recently a rainfall erosivity map has been published. We show that the values of this map contain considerable bias because (i) the temporal resolution of the rain data was insufficient, which likely underestimates rain erosivity by about 20%, (ii) no attempt had been included to account for the different time periods that were used for different countries, which can modify rain erosivity by more than 50%, (iii) and likely precipitation data had been used instead of rain data and thus rain erosivity is overestimated in areas with significant snowfall. Furthermore, the seasonal distribution of rain erosivity is not provided, which does not allow using the erosivity map for erosion prediction in many cases. Although a rain erosivity map for Europe would be highly desirable, we recommend using the national erosivity maps until these problems have been solved. Such maps are available for many European countries. (C) 2015 Elsevier B.V. All rights reserved

The 18O ecohydrology of a grassland ecosystem - predictions and observations

This research has been supported by the Deutsche Forschungsgemeinschaft (grant no. SCHN 557/9-1), the Agence Nationale de la Recherche (grant no. ANR-13-BS06-0005), and the European Commission (grant no. SOLCA 338264). This work was supported by the German Research Foundation (DFG) and the Technical University of Munich (TUM) in the framework of the Open Access Publishing Program.Peer reviewedPublisher PD