This paper briefly reviews data assimilation techniques in carbon cycle data assimilation and the requirements of data assimilation systems on observations. We provide a non-exhaustive overview of current observations and their uncertainties for use in terrestrial carbon cycle data assimilation, focussing on relevant space-based observations.

Few researchers have investigated post-photosynthetic ¹³C fractionation happening in leaves. Potted saplings were cultivated under orthogonal treatments of CO₂ concentration and soil water content. The ¹³C fractionation from mesophyll conductance and post-carboxylation both contributed to the total ¹³C fractionation that was determined by δ¹³C of water-soluble compounds and gas-exchange measurements.

Our analyses showed that soil biogeochemistry could distinguish two forest ecosystems that coexist in Quebec: open lichen woodlands and closed-canopy black spruce–moss forests. Variations in carbon stocks, base cation concentrations and crystallinity of aluminium and iron were related to the different vegetation covers. This research was carried out as a first step to identify geochemical indicators of canopy cover types that could be useful in further palaeoecological studies.

Previous studies have mainly focused on the effects of N deposition on tree growth in temperate and tropical forests, however, the responses of different trees and understory plants in subtropical forests to N deposition remain unknown. We conducted a 3.4-year experimentally simulated N enrichment and found that small trees were hindered while medium and large trees were not significantly affected by N fertilization. Additionally, the growth of understories was suppressed by N fertilization.

A surface summer plankton bloom in the western tropical South Pacific was sampled during the Oligotrophy to UlTra-oligotrophy PACific Experiment (OUTPACE) cruise. We characterize the bloom's properties and the circulation responsible for its evolution. Nitrogen fixation helped sustain the bloom, and larger-scale flows, rather than the smaller ones, explain its movements. Future studies of blooms in this region can make use of these findings to track the horizontal export of plankton production.

CO₂ and N₂O are two prominent GHGs contributing to global warming. We combined measurement and modelling to quantify GHG emissions from adjacent arable, forest and grassland sites in Germany. Measured emissions reveal seasonal patterns and management effects like fertilizer application, tillage, harvest and grazing. Modelling helps to estimate the magnitude and uncertainty of not measurable C and N fluxes and indicates missing input source, e.g. nitrate uptake from groundwater.

We present 1 to 2 years of greenhouse gas flux field measurements (CO₂, CH₄, N₂O and NO) in the tropical forest soils of Panama. Fluxes were measured in five sites along the orthogonal gradients of precipitation and fertility. Using these natural gradients, our results highlight the importance of both short-term (climate) and long-term (soil and site characteristics) factors in predicting soil trace gas fluxes and provide information for modeling trace gases under future climate scenarios.

To improve predictions of future forest productivity, we introduce an analytical approach that uses data from numerous research experiments that have occurred across the southeastern US to calibrate a mathematical forest model and estimate uncertainty in predictions. As a result, predictions using the model are consistent with a rich history of forest research in a region that supplies a large fraction of wood products to the world.

Here we investigate how CO₂ enrichment affects the relationships light–production and light–calcification in coral reef communities. For the three communities tested, CO₂ did not affect the light–production relationships, while calcification was lower at elevated CO₂ for all light levels. Our result indicates that CO₂ can modify the balance between net calcification and net photosynthesis of reef communities by depressing community calcification without affecting community photosynthesis.

We collected peat porewaters across a 640 km latitudinal transect of sporadic to continuous permafrost zone and analyzed organic carbon and trace metals. There was no distinct decrease in concentration along the latitudinal transect from 62.2° N to 67.4° N. The northward migration of the permafrost boundary or the change of hydrological regime is unlikely to modify chemical composition of peat porewater fluids larger than their natural variation within different micro-landscapes.

Phosphorus (P) has accumulated in sediments due to past human activities. The re-release of this P to water contributes to the growth of harmful algal blooms. Our research improves our mechanistic understanding of how P is partitioned between different chemical forms and between sediment and water under dynamic conditions. We demonstrate that P trapped within iron minerals may be less mobile during anoxic conditions than previously thought due to reversible changes to P forms within sediment.

The main goal of this study was to understand if, similarly to the fossil record, high quantities of toxic metals induce coccolith dwarfism in coccolithophore species. We investigated, for the first time, the effects of trace metals on coccolithophore species other than E. huxleyi and on coccolith morphology and size. Our data show a species-specific sensitivity to trace metal concentration, allowing the recognition of the most-, intermediate- and least-tolerant taxa to trace metal enrichments.