TY - JOUR A1 - Uereyen, Soner A1 - Bachofer, Felix A1 - Kuenzer, Claudia T1 - A framework for multivariate analysis of land surface dynamics and driving variables — a case study for Indo-Gangetic river basins JF - Remote Sensing N2 - The analysis of the Earth system and interactions among its spheres is increasingly important to improve the understanding of global environmental change. In this regard, Earth observation (EO) is a valuable tool for monitoring of long term changes over the land surface and its features. Although investigations commonly study environmental change by means of a single EO-based land surface variable, a joint exploitation of multivariate land surface variables covering several spheres is still rarely performed. In this regard, we present a novel methodological framework for both, the automated processing of multisource time series to generate a unified multivariate feature space, as well as the application of statistical time series analysis techniques to quantify land surface change and driving variables. In particular, we unify multivariate time series over the last two decades including vegetation greenness, surface water area, snow cover area, and climatic, as well as hydrological variables. Furthermore, the statistical time series analyses include quantification of trends, changes in seasonality, and evaluation of drivers using the recently proposed causal discovery algorithm Peter and Clark Momentary Conditional Independence (PCMCI). We demonstrate the functionality of our methodological framework using Indo-Gangetic river basins in South Asia as a case study. The time series analyses reveal increasing trends in vegetation greenness being largely dependent on water availability, decreasing trends in snow cover area being mostly negatively coupled to temperature, and trends of surface water area to be spatially heterogeneous and linked to various driving variables. Overall, the obtained results highlight the value and suitability of this methodological framework with respect to global climate change research, enabling multivariate time series preparation, derivation of detailed information on significant trends and seasonality, as well as detection of causal links with minimal user intervention. This study is the first to use multivariate time series including several EO-based variables to analyze land surface dynamics over the last two decades using the causal discovery algorithm PCMCI. KW - time series analysis KW - trends KW - seasonality KW - partial correlation KW - causal networks KW - NDVI KW - snow cover area KW - surface water area KW - Indus-Ganges-Brahmaputra-Meghna KW - Himalaya Karakoram Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-255295 SN - 2072-4292 VL - 14 IS - 1 ER - TY - JOUR A1 - Stein, Katharina A1 - Coulibaly, Drissa A1 - Balima, Larba Hubert A1 - Goetze, Dethardt A1 - Linsenmair, Karl Eduard A1 - Porembski, Stefan A1 - Stenchly, Kathrin A1 - Theodorou, Panagiotis T1 - Plant-pollinator networks in savannas of Burkina Faso, West Africa JF - Diversity N2 - West African savannas are severely threatened with intensified land use and increasing degradation. Bees are important for terrestrial biodiversity as they provide native plant species with pollination services. However, little information is available regarding their mutualistic interactions with woody plant species. In the first network study from sub-Saharan West Africa, we investigated the effects of land-use intensity and climatic seasonality on plant–bee communities and their interaction networks. In total, we recorded 5686 interactions between 53 flowering woody plant species and 100 bee species. Bee-species richness and the number of interactions were higher in the low compared to medium and high land-use intensity sites. Bee- and plant-species richness and the number of interactions were higher in the dry compared to the rainy season. Plant–bee visitation networks were not strongly affected by land-use intensity; however, climatic seasonality had a strong effect on network architecture. Null-model corrected connectance and nestedness were higher in the dry compared to the rainy season. In addition, network specialization and null-model corrected modularity were lower in the dry compared to the rainy season. Our results suggest that in our study region, seasonal effects on mutualistic network architecture are more pronounced compared to land-use change effects. Nonetheless, the decrease in bee-species richness and the number of plant–bee interactions with an increase in land-use intensity highlights the importance of savanna conservation for maintaining bee diversity and the concomitant provision of ecosystem services. KW - bees KW - community composition KW - connectance KW - land-use intensity KW - modularity KW - mutualism KW - number of interactions KW - seasonality KW - woody plant richness Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-220157 SN - 1424-2818 VL - 13 IS - 1 ER - TY - JOUR A1 - Müller, Frank A1 - Hummers, Eva A1 - Hillermann, Nele A1 - Dopfer, Christian A1 - Jablonka, Alexandra A1 - Friede, Tim A1 - Simmenroth, Anne A1 - Wetzke, Martin T1 - Factors influencing the frequency of airway infections in underage refugees: a retrospective, cross sectional study JF - International Journal of Environmental Research and Public Health N2 - Background: Infections are a leading cause of refugee morbidity. Recent data on the rate of airway infections and factors influencing their spread in refugee reception centers is scarce. Methods: A retrospective, cross-sectional study of de-identified medical records with a focus on respiratory infections in underage refugees was conducted at two large German refugee reception centers. Results: In total, medical data from n = 10,431 refugees over an observational period of n = 819 days was analyzed. Among pediatric patients (n = 4289), 55.3% presented at least once to the on-site medical ward with an acute respiratory infection or signs thereof. In 38.4% of pediatric consultations, acute airway infections or signs thereof were present. Airway infections spiked during colder months and were significantly more prevalent amongst preschool and resettled children. Their frequency displayed a positive correlation with the number of refugees housed at the reception centers. Conclusions: We show that respiratory infections are a leading cause for morbidity in young refugees and that their rate is influenced age, season, status, and residential density. This illustrates the need to protect refugee children from contracting airway infections which may also reduce the spread of coronavirus disease 2019 (COVID-19) during the current pandemic. KW - refugees KW - migrants KW - respiratory infection KW - children KW - adolescents KW - seasonality KW - crowded housing KW - COVID-19 KW - containment Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-213134 SN - 1660-4601 VL - 17 IS - 18 ER - TY - JOUR A1 - Bonte, Dries A1 - Travis, Justin M. J. A1 - De Clercq, Nele A1 - Zwertvaegher, Ingrid A1 - Lens, Luc T1 - Thermal conditions during juvenile development affect adult dispersal in a spider N2 - Abstract: Understanding the causes and consequences of dispersal is a prerequisite for the effective management of natural populations. Rather than treating dispersal as a fixed trait, it should be considered a plastic process that responds to both genetic and environmental conditions. Here, we consider how the ambient temperature experienced by juvenile Erigone atra, a spider inhabiting crop habitat, influences adult dispersal. This species exhibits 2 distinct forms of dispersal, ballooning (long distance) and rappelling (short distance). Using a half-sib design we raised individuals under 4 different temperature regimes and quantified the spiders' propensity to balloon and to rappel. Additionally, as an indicator of investment in settlement, we determined the size of the webs build by the spiders following dispersal. The optimal temperature regimes for reproduction and overall dispersal investment were 20 °C and 25 °C. Propensity to perform short-distance movements was lowest at 15 °C, whereas for long-distance dispersal it was lowest at 30 °C. Plasticity in dispersal was in the direction predicted on the basis of the risks associated with seasonal changes in habitat availability; long-distance ballooning occurred more frequently under cooler, spring-like conditions and short-distance rappelling under warmer, summer-like conditions. Based on these findings, we conclude that thermal conditions during development provide juvenile spiders with information about the environmental conditions they are likely to encounter as adults and that this information influences the spider's dispersal strategy. Climate change may result in suboptimal adult dispersal behavior, with potentially deleterious population level consequences. KW - Erigone atra KW - emigration KW - dispersal distance KW - immigration KW - behavior KW - plasticity KW - silk KW - body condition KW - seasonality Y1 - 2008 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-48691 ER -