574 Uruguayan savanna 652 Central Anatolian steppe and woodlands 703 Northern Anatolian conifer and deciduous forests 799 Northeast Spain and Southern France Mediterranean forests 686 Western European broadleaf forests 664 European Atlantic mixed forests 654 Central European mixed forests 647 Baltic mixed forests 651 Celtic broadleaf forests Study sites Litter decomposition in ponds across a large latitudinal gradient Relation to hydroperiod Decomposition rate (A) and stabilization factor (B) were lower in temporal ponds than in permanent ponds. Ecoregions based on Olson et al. 2001 Conclusions 1. In contrast to soils, the results suggest that ponds favor carbon sequestration. 2. Within the studied latitudinal range, the vegetation land cover might be more relevant than latitudinally climate-related factors 3. The existence of drought periods in temporal ponds limits the decomposition process. 4. Total Phosphorus in water positively correlated with k , showing nutrient influence on decomposition dynamics. References Martín, L.1 *, Pastor, A.1, Cuenca-Cambronero, M.2, Antón-Pardo, M.3, Colina, M.4,5, Dede, C.6, Demierre, E.7, Fahy, J.C.7, Girard, L.8, Greaves, H.9, Lemmens, P.10,11, Meerhoff, M.4,12, Mülayim, E.B.6, Patmore, I.R.9, von Plüskow, L.M.10,11, Wijns, R.10, Brucet, S.2,13, Boix, D.1, Romaní, A.M.1 1GRECO, Institute of Aquatic Ecology, University of Girona, Spain; 2Aquatic Ecology Group, University of Vic - Central University of Catalonia, Spain; 3Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Spain; 4Departament of Ecology and Environmental Management, Centro Universitario Regional del Este-Universidad de la República, Uruguay; 5Department of Ecology, Radboud Institute for Biological and Environmental Sciences, Radboud University, The Netherlands; 6Limnology Laboratory, Biological Sciences Department, Middle East Technical University, Turkey; 7Ecology and Aquatic Systems Engineering group, HEPIA, University of Applied Sciences and Arts Western Switzerland, Switzerland; 8Agroecology and Environment Research Unit, France; 9University College London (UCL) Pond Restoration Research Group, Department of Geography, Gower Street, London; 10Laboratory of Freshwater Ecology, Evolution and Conservation, KU Leuven, Belgium; 11Leibniz Institute für Gewasserökologie und Binnenfischerei (IGB), Germany; 12Department of Ecosciences, Aarhus University, Denmark; 13ICREA, Catalan Institution for Research and Advanced Studies, Spain Ponds play an important role in the process of plant litter decomposition, contributing to the carbon cycle. Ponds are highly vulnerable to pollution and climate change, which can affect decomposition. The aim of this project was to quantify the potential for microbial litter decomposition rate in ponds along a latitudinal gradient in different ecoregions, to identify the main drivers of its variability by using the Tea Bag Index (TBI), defined by the different decomposition of a labile tea (green tea) and a recalcitrant tea (rooibos). Introduction Relation to latitude We observed contrasting patterns of decomposition parameters across the latitudinal gradient. While k (A) increased with absolute latitude, S (B) decreased. Relation to nutrients We observed a positive correlation between water total phosphorus (TP) and k (A), indicating the influence of nutrients on decomposition dynamics. In contrast, a negative relations between TP and S (B) was observed, but only with marginal significance. k (decomposition rate) proxy to mass- loss rate of plant litter organic mater. S (stabilization factor) refers to the inhibiting effect of environmental conditions on the decomposition. High values indicate increase carbon sequestration potential. A total of 250 ponds were selected, distributed across eight countries compassing nine ecological regions. The ponds were located at varying latitudes and exhibited diverse land-use intensities, including both permanent and intermittent