Search results for "carbon cycle"
showing 10 items of 106 documents
Scaling carbon fluxes from eddy covariance sites to globe: synthesis and evaluation of the FLUXCOM approach
2020
FLUXNET comprises globally distributed eddy-covariance-based estimates of carbon fluxes between the biosphere and the atmosphere. Since eddy covariance flux towers have a relatively small footprint and are distributed unevenly across the world, upscaling the observations is necessary to obtain global-scale estimates of biosphere–atmosphere exchange. Based on cross-consistency checks with atmospheric inversions, sun-induced fluorescence (SIF) and dynamic global vegetation models (DGVMs), here we provide a systematic assessment of the latest upscaling efforts for gross primary production (GPP) and net ecosystem exchange (NEE) of the FLUXCOM initiative, where different machine learning methods…
Inferring causal relations from observational long-term carbon and water fluxes records
2022
AbstractLand, atmosphere and climate interact constantly and at different spatial and temporal scales. In this paper we rely on causal discovery methods to infer spatial patterns of causal relations between several key variables of the carbon and water cycles: gross primary productivity, latent heat energy flux for evaporation, surface air temperature, precipitation, soil moisture and radiation. We introduce a methodology based on the convergent cross-mapping (CCM) technique. Despite its good performance in general, CCM is sensitive to (even moderate) noise levels and hyper-parameter selection. We present a robust CCM (RCCM) that relies on temporal bootstrapping decision scores and the deri…
Metagenomic insights into strategies of aerobic and anaerobic carbon and nitrogen transformation in boreal lakes
2015
Thousands of net-heterotrophic and strongly stratifying lakes dominate the boreal landscape. Besides their central role as emitters of greenhouse gases, we have only recently begun to understand the microbial systems driving the metabolic processes and elemental cycles in these lakes. Using shotgun metagenomics, we show that the functional potential differs among lake types, with humic lakes being particularly enriched in carbon degradation genes. Most of the metabolic pathways exhibit oxygen- and temperature-dependent stratification over depth, coinciding with shifts in bacterial community composition, implying that stratification is a major factor controlling lake metabolism. In the botto…
Bioindicators and nutrient availability through whole soil profile under orange groves after long-term different organic fertilizations
2019
We investigated long-term (18 years) effects of three organic (cow manure (CM), poultry manure (PM), compost from agro-industry orange wastes (OW)) and one inorganic fertilization (IF) on various soil biological indicators (microbial biomass C, soil respiration, total phospholipid fatty acids (PLFAs), total bacteria, Gram-positive and Gram-negative bacteria and fungi) and nutrient contents (total and extractable organic C, total and mineral N, available P and K) along the profile of a Typic Haplustept under orange Mediterranean orchards. All fertilizers were added on the same N content basis (190 kg N ha−1 per year). Variables related to carbon cycling gradually worsened with depth, regardl…
Effect of catchment characteristics on aquatic carbon export from a boreal catchment and its importance in regional carbon cycling
2013
Inland waters transport and emit into the atmosphere large amounts of carbon (C), which originates from terrestrial ecosystems. The effect of land cover and land-use practises on C export from terrestrial ecosystems to inland waters is not fully understood, especially in heterogeneous landscapes under human influence. We sampled for dissolved C species in five tributaries with well-determined subcatchments (total size 174.5 km(2)), as well as in various points of two of the subcatchments draining to a boreal lake in southern Finland over a full year. Our aim was to find out how land cover and land-use affect C export from the catchments, as well as CH4 and CO2 concentrations of the streams,…
Modelling the Impacts of Climate Change on Dissolved Organic Carbon
2009
Dissolved organic carbon (DOC) from peat soils has implications both for the ecology of receiving waters and for the quality and treatment costs of water used for human consumption. Fluxes of DOC from peat soils are also relevant in the context of the global carbon cycle. Chapter 12 in this volume has reviewed the evidence for the effects of different environmental factors on the decomposition of peat soils and the export of DOC, drawing on literature and long-term data acquired from a number of European sites. The conclusion from this and many other studies is that, although there may be other influences such as land management and recovery from acid deposition, climate factors are a major…
Stable carbon isotopic composition of peat columns, subsoil and vegetation on natural and forestry-drained boreal peatlands.
2018
We studied natural and forestry-drained peatlands to examine the effect of over 34 years lowered water table on the δ13C values of vegetation, bulk peat and subsoil. In the seven studied sites, δ13C in the basal peat layer was 1.1 and 1.2 ‰ lower than that of the middle-layer and surface layer, respectively. Furthermore, there was a positive correlation between the δ13C values of the basal and surface peat layers, possibly due to carbon (C) recycling within the peat column. In the same mire complex, natural fen peat δ13C values were lower than those of the nearby bog, possibly due to the dominance of vascular plants on fen and the generally larger share of recycled C in the fens than in the…
Methanotrophy induces nitrogen fixation during peatland development
2013
Significance In peatlands, the external sources of nitrogen are mainly atmospheric, but the atmospheric nitrogen deposition alone cannot explain the long-term annual nitrogen accumulation rates to these ecosystems. Because of methodological problems, methane-induced fixation of atmospheric dinitrogen gas has been previously overlooked as an additional nitrogen input mechanism. We found that the activity of methane-oxidizing bacteria provides not only carbon but also nitrogen to peat mosses and, thus, contributes to carbon and nitrogen accumulation in peatlands, which store approximately one-third of the global soil carbon pool. Our results imply that nitrogen fixation in wetlands may be str…
Diversity of freshwater Epsilonproteobacteria and dark inorganic carbon fixation in the sulphidic redoxcline of a meromictic karstic lake.
2015
Sulfidic redoxclines are a suitable niche for the growth and activity of different chemo- and photolithotrophic sulphide-oxidizing microbial groups such as the Epsilonproteobacteria and the green sulfur bacteria (GSB). We have investigated the diversity, abundance and contribution to inorganic carbon uptake of Epsilonproteobacteria in a meromictic basin of Lake Banyoles. CARD-FISH counts revealed that Epsilonproteobacteria were prevalent at the redoxcline in winter (maximum abundance of 2 × 10(6) cells mL(-1), ≈60% of total cells) but they were nearly absent in summer, when GSB bloomed. This seasonal trend was supported by 16S rRNA gene pyrotag datasets, which revealed that the epsilonprote…
IoT monitoring of urban tree ecosystem services: Possibilities and challenges
2020
Urban green infrastructure plays an increasingly significant role in sustainable urban development planning as it provides important regulating and cultural ecosystem services. Monitoring of such dynamic and complex systems requires technological solutions which provide easy data collection, processing, and utilization at affordable costs. To meet these challenges a pilot study was conducted using a network of wireless, low cost, and multiparameter monitoring devices, which operate using Internet of Things (IoT) technology, to provide real-time monitoring of regulatory ecosystem services in the form of meaningful indicators for both human health and environmental policies. The pilot study w…