The study presents a P budget including the P input from the water column, the P burial in the sediments, as well as the P release from the sediments. We found that the P input could not maintain the P release rates. Consideration of other P sources, e.g., terrigenous P and P released from the dissolution of Fe oxyhydroxides, showed that none of these can account for the missing P. Thus, it is likely that abundant sulfide-oxidizing bacteria release the missing P during our measurement period.

This study investigates improvements and uncertainties associated with estimating global inundated area and wetland CH4 emissions using TOPMODEL. Different topographic information and catchment aggregation schemes are evaluated against seasonal and permanently inundated wetland observations. Reducing uncertainty in prognostic wetland dynamics modeling must take into account forcing data as well as topographic scaling schemes.

We present a Bayesian estimation of uncertainty in half-hourly GPP partitioned from flux tower measurements of NEE. The results show that it is possible to do this at any desirable time step. This, in turn, can be used to quantify the propagated uncertainty when validating process-based simulators. We further show the importance of using non-informative priors compared to informative priors of the parameters of flux partitioning model as they speed up calculation without loss of precision.

Lake Ohrid (FYROM/Albania) is the deepest, largest and oldest lake in Europe. To understand the climatic and environmental evolution of its area, a palynological study was undertaken for the last 500 ka. We found a correspondence between forested/non-forested periods and glacial-interglacial cycles of marine isotope stratigraphy. Our record shows a progressive change from cooler and wetter to warmer and dryer interglacial conditions. This shift is also visible in glacial vegetation.

Bowl-shaped ice-wedge polygons in permafrost regions can retain snowmelt water and moisture in their center. On Bylot Island (NU, CA), a rapidly developing thermal erosion gully eroded the polygons' ridges, impacting the polygon centers' ground moisture and temperature, plant cover and species. An intact polygon was homogeneous in its center for the aforementioned elements, whereas eroded polygons had a varying response following the breach, with heterogeneity as their new equilibrium state.

We present stable isotope proxy data and calcification records from fossil reef corals. The corals investigated derive from the Florida carbonate platform and are of middle Pliocene to early Pleistocene age. From the data we infer an environment subject to intermittent upwelling on annual to decadal timescales. Calcification rates were enhanced during periods of upwelling. This is likely an effect of dampened SSTs during the upwelling.

We investigated how today's state-of-the-art terrestrial biosphere models represent biological nitrogen fixation and what the consequences of varying representation are for model predictions under ambient conditions and under scenarios of elevated atmospheric carbon dioxide concentrations. We found that varying global nitrogen fixation rates are simulated under ambient conditions and that the responses of the simulated carbon and nitrogen cycles are significantly affected under perturbation.

We modelled the effects of changes in climate and land management on soil organic carbon (SOC) and dissolved organic carbon (DOC) levels in sandy and loamy soils under forest, grassland, and arable land. Climate change causes a decrease in both SOC and DOC for the agricultural systems, whereas for the forest systems, SOC slightly increases. A reduction in fertilizer application leads to a decrease in SOC and DOC levels under arable land but has a negligible effect under grassland.

The timescales involved in the decay of coarse woody debris (CWD) and related chemical components of spruce and larch in Alpine forests are largely unknown. Dendrochronology and ¹⁴C dating were used to assess time and rates. Distinct differences between tree species occur only at an advanced stage of decay. Larch CWD reaches an age of 210 years and spruce 77 years. Using this approach, the half-lives of cellulose (21 yr for spruce and 50 yr for larch) and lignin (> 100 yr) could be determined.

Predicting biomass correctly at the landscape level in hyperdiverse and structurally complex tropical forests requires the inclusion of predictors that express inherent variations in species architecture. The model of interest should comprise the floristic composition and size-distribution variability of the target forest, implying that even generic global or pantropical biomass estimation models can lead to strong biases.

Monitoring forest carbon stocks requires understanding how resources allocation within trees varies across tree size, species and environmental conditions. Using data on tree dimensions and mass, we show that the average tree shape varies along ontogeny, with large canopy trees having a greater proportion of carbon in their crowns (up to 50 %). This variation pattern generates important bias in carbon predictions at both tree and stand levels, which can be corrected using simple crown metrics.

Origin of suspended sediments in rivers is of crucial importance for optimization of catchment management. Sediment source attribution to a lowland river in central Switzerland with compound specific stable isotopes analysis (CSIA) indicated that 65 % of the suspended sediments originated from agricultural land during base flow, while forest was the dominant source during high flow. We achieved significant differences in CSIA signature from land uses dominated by C3 plant cultivation.

Recent analyses of the global carbon budget found a substantial increase in the land sink in the late 1980s whose origin remains unknown. Consistent with this shift, we find that plant growth increased in the late 1980s especially in Eurasia and northern Africa. There, climatic constraints on plant growth have eased possibly due to linked climate modes in the North Atlantic. Better understanding of North Atlantic climate may be essential for more credible projections of the land carbon sink.

We studied tree and grass litter decomposition across several climates in Europe. Climatic (air temperature, precipitation and soil water content) controls on litter decomposition were quantitatively more important than species or site of origin. The data were used to generate prediction models of remaining litter mass, and carbon and nitrogen contents during the decomposition period. We also observed a significant drop in remaining litter mass after the first couple of days of decomposition.

Our results of this study show that two humic-like C peaks and two protein-like B and T peaks were identified from CDOM using PARAFAC for investigated lakes. The average fluorescence intensity of the components differed seasonally. Components 1 and 2 exhibited strong linear correlation (R² = 0.63). Significantly positive linear relationships, between aCDOM and F_max, and between DOC and salinity (R² = 0.93), were revealed.

This study shows that the phytoplankter Micromonas pusilla alters its lipid composition when the macronutrient phosphate is in low supply. This reduction in phospholipids is directly dependent on the strength of the limitation. Furthermore we show that, when M. pusilla is infected by viruses, lipid remodeling is lower. The study was carried out to investigate how phytoplankton and its viruses are affected by environmental factors and how this affects food web dynamics.

Ocean acidification is likely to affect iron-limited phytoplankton fertilization by desert dust. Short incubations of northeast subarctic Pacific waters enriched with dust and set at pH 8.0 and 7.8 were conducted. Acidification led to a significant reduction (by 16–38 %) of the final concentration of chl a reached after enrichment. These results show that dust deposition events in a low-pH iron-limited ocean are likely to stimulate phytoplankton growth to a lesser extent than in today's ocean.

This ¹³C labeling experiment demonstrates that carbon can be absorbed by the roots, translocated in the plant, and ultimately fixed in organic compounds subject to occlusion in silica particles that form inside plant cells (phytoliths). Plausible forms of carbon absorbed, translocated, and fixed in phytoliths are assessed. Implications for our understanding of the C cycle at the plant-soil-atmosphere interface are discussed.

Nitrous oxide and methane are potent greenhouse gases that are both produced and consumed in soil. Using stable isotope tracers, we found that 68 % of nitrous oxide produced in soil was emitted to the atmosphere throughout the growing season in a cornfield despite variable soil conditions. Gross methane production and consumption were tightly coupled, resulting in near-zero net fluxes. Our results challenge our understanding of controls on nitrous oxide and methane dynamics in upland soils.

In recent years much research has focussed on whether corals will be able to build their skeletons under predicted ocean acidification. One strategy corals may employ is changing the mineralogy of their skeletons from aragonite to the less soluble polymorph of calcium carbonate; calcite. Here we show that newly settled coral recruits are unable to produce calcite in their skeletons under near-future elevations in pCO₂, which may leave them more vulnerable to ocean acidification.