TY - JOUR A1 - Schwieder, Marcel A1 - Wesemeyer, Maximilian A1 - Frantz, David A1 - Pfoch, Kira A1 - Erasmi, Stefan A1 - Pickert, Jürgen A1 - Nendel, Claas A1 - Hostert, Patrick T1 - Mapping grassland mowing events across Germany based on combined Sentinel-2 and Landsat 8 time series JF - Remote sensing of environment N2 - Spatially explicit knowledge on grassland extent and management is critical to understand and monitor the impact of grassland use intensity on ecosystem services and biodiversity. While regional studies allow detailed insights into land use and ecosystem service interactions, information on a national scale can aid biodiversity assessments. However, for most European countries this information is not yet widely available. We used an analysis-ready-data cube that contains dense time series of co-registered Sentinel-2 and Landsat 8 data, covering the extent of Germany. We propose an algorithm that detects mowing events in the time series based on residuals from an assumed undisturbed phenology, as an indicator of grassland use intensity. A self-adaptive ruleset enabled to account for regional variations in land surface phenology and non-stationary time series on a pixelbasis. We mapped mowing events for the years from 2017 to 2020 for permanent grassland areas in Germany. The results were validated on a pixel level in four of the main natural regions in Germany based on reported mowing events for a total of 92 (2018) and 78 (2019) grassland parcels. Results for 2020 were evaluated with combined time series of Landsat, Sentinel-2 and PlanetScope data. The mean absolute percentage error between detected and reported mowing events was on average 40% (2018), 36% (2019) and 35% (2020). Mowing events were on average detected 11 days (2018), 7 days (2019) and 6 days (2020) after the reported mowing. Performance measures varied between the different regions of Germany, and lower accuracies were found in areas that are revisited less frequently by Sentinel-2. Thus, we assessed the influence of data availability and found that the detection of mowing events was less influenced by data availability when at least 16 cloud-free observations were available in the grassland season. Still, the distribution of available observations throughout the season appeared to be critical. On a national scale our results revealed overall higher shares of less intensively mown grasslands and smaller shares of highly intensively managed grasslands. Hotspots of the latter were identified in the alpine foreland in Southern Germany as well as in the lowlands in the Northwest of Germany. While these patterns were stable throughout the years, the results revealed a tendency to lower management intensity in the extremely dry year 2018. Our results emphasize the ability of the approach to map the intensity of grassland management throughout large areas despite variations in data availability and environmental conditions. KW - Analysis-ready data KW - Big data KW - Large-area mapping KW - Germany KW - Common agricultural policy KW - Time series KW - Land use intensity KW - Optical remote sensing KW - Multi-spectral data KW - PlanetScope Y1 - 2022 U6 - https://doi.org/10.1016/j.rse.2021.112795 SN - 0034-4257 SN - 1879-0704 VL - 269 PB - Elsevier CY - New York ER - TY - JOUR A1 - Weiß, Lina A1 - Jeltsch, Florian T1 - The response of simulated grassland communities to the cessation of grazing JF - Ecological modelling : international journal on ecological modelling and engineering and systems ecolog N2 - Changes in land-use are supposed to be among the severest prospective threats to plant diversity worldwide. In semi-natural temperate grasslands, the cessation of traditional land use like livestock grazing is considered to be one of the most important drivers of the diversity loss witnessed within the last decades. Despite of the enormous number of studies on successional pathways following grazing abandonment there is no general pattern of how grassland communities are affected in terms of diversity, trait composition and pace of succession. To gain a comprehensive picture is difficult given the heterogeneity of environments and the time and effort needed for long-term investigations. We here use a proven individual- and trait-based grassland community model to analyze short- and long-term consequences of grazing abandonment under different assumptions of resource availability, pre-abandonment grazing intensity and regional isolation of communities. Grazing abandonment led to a decrease of plant functional type (PFT) diversity in all but two scenarios in the long-term. In short-term we also found an increase or no change in Shannon diversity for several scenarios. With grazing abandonment we overall found an increase in maximum plant mass, clonal integration and longer lateral spread, a decrease in rosette plant types and in stress tolerant plants, as well as an increase in grazing tolerant and a decrease in grazing avoiding plant types. Observed changes were highly dependent on the regional configuration of communities, prevalent resource conditions and land use intensity before abandonment. While long-term changes took around 10-20 years in resource rich conditions, new equilibria established in resource poor conditions only after 30-40 years. Our results confirm the potential threats caused by recent land-use changes and the assumption that oligotrophic communities are more resistant than mesotrophic communities also for long-term abandonment. Moreover, results revealed that species-rich systems are not per se more resistant than species-poor grasslands. (C) 2015 Elsevier B.V. All rights reserved. KW - Diversity KW - Individual-based model KW - Land use intensity KW - Seed immigration KW - Abandonment KW - Resistance Y1 - 2015 U6 - https://doi.org/10.1016/j.ecolmodel.2015.02.002 SN - 0304-3800 SN - 1872-7026 VL - 303 SP - 1 EP - 11 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Solly, Emily F. A1 - Schöning, Ingo A1 - Boch, Steffen A1 - Kandeler, Ellen A1 - Marhan, Sven A1 - Michalzik, Beate A1 - Müller, Jörg A1 - Zscheischler, Jakob A1 - Trumbore, Susan E. A1 - Schrumpf, Marion T1 - Factors controlling decomposition rates of fine root litter in temperate forests and grasslands JF - Plant and soil N2 - Fine root decomposition contributes significantly to element cycling in terrestrial ecosystems. However, studies on root decomposition rates and on the factors that potentially influence them are fewer than those on leaf litter decomposition. To study the effects of region and land use intensity on fine root decomposition, we established a large scale study in three German regions with different climate regimes and soil properties. Methods In 150 forest and 150 grassland sites we deployed litterbags (100 mu m mesh size) with standardized litter consisting of fine roots from European beech in forests and from a lowland mesophilous hay meadow in grasslands. In the central study region, we compared decomposition rates of this standardized litter with root litter collected on-site to separate the effect of litter quality from environmental factors. Standardized herbaceous roots in grassland soils decomposed on average significantly faster (24 +/- 6 % mass loss after 12 months, mean +/- SD) than beech roots in forest soils (12 +/- 4 %; p < 0.001). Fine root decomposition varied among the three study regions. Land use intensity, in particular N addition, decreased fine root decomposition in grasslands. The initial lignin:N ratio explained 15 % of the variance in grasslands and 11 % in forests. Soil moisture, soil temperature, and C:N ratios of soils together explained 34 % of the variance of the fine root mass loss in grasslands, and 24 % in forests. Grasslands, which have higher fine root biomass and root turnover compared to forests, also have higher rates of root decomposition. Our results further show that at the regional scale fine root decomposition is influenced by environmental variables such as soil moisture, soil temperature and soil nutrient content. Additional variation is explained by root litter quality. KW - Fine roots KW - Decomposition KW - Land use intensity KW - Lignin: N ratio KW - Temperate ecosystems Y1 - 2014 U6 - https://doi.org/10.1007/s11104-014-2151-4 SN - 0032-079X SN - 1573-5036 VL - 382 IS - 1-2 SP - 203 EP - 218 PB - Springer CY - Dordrecht ER -