Better quantification of atmosphere-ecosystem exchange of the isotopologues of CO₂ could substantially improve our ability to probe under­lying physiological and ecological mechanisms controlling ecosystem carbon exchange, but the ability to make long-term continuous measurements of the isotopic composition of exchange fluxes has been limited by measure­ment difficulties. Quantum cascade (QC) lasers are a new generation of infrared light sources that offer increased stability and power for absorption spectroscopy applications (including the measurement of isotope ratios in atmospheric CO₂) and promise substantial improvements over existing instruments: smaller size, increased robustness, and most significantly for remote or long-term field deployments, no need for cryogenic cooling of laser or detectors. 

The Carbon Cycle Data Assimilation System (CCDAS) infers values of the parameters controlling the function of a process model of the terrestrial biosphere using various observations. An obvious restriction of this approach is the limitation by the dynamics of the underlying process model. Careful study of the model-data mismatch and analysis of residuals can alert us to the presence of systematic errors which then candidate processes to extend the terrestrial biosphere model and the assimilation system. In a previous study, Rayner et al. [2005] noticed systematic underestimate of carbon release events in the tropics. The most likely explanation for this was the absence of any model of biomass burning in the biosphere model used in that study. Here, we extend CCDAS to infer the spatial and temporal patterns of biomass burning in the period 1979-1999. In a first attempt we include some flux components to account for missing processes. This so-called weak constraint form avoids biasing the inferences since the underlying model is no longer forced to match data without necessary processes. Also the magnitudes of the extra inferred fluxes quantify the missing processes.

Concentrations of ²²²Rn, CO₂, N₂O and CH₄ were measured in a cold-temperate northern Japanese grassland soil during 1996 to compare the fluxes of CO₂, N₂O and CH₄ calculated by the ²²²Rn method and the static chamber method and to estimate the source strengths of CO₂ and N₂O in the soil using the ²²²Rn method. The ²²²Rn fluxes ranged from 890 to 3400 dpm/m²/h and the average was 1570±310 dpm/m²/h on sandy soil (50% sand). The results of CO₂, N₂O and CH₄ flux-measurements by the ²²²Rn method were in agreement with those by the static chamber method within the observed range of error. The vertical profiles of soil source strengths of CO₂ and N₂O were also calculated from the concentration gradients of ²²²Rn, CO₂ and N₂O to investigate seasonal changes in the soil production rates of CO₂ and N₂O. The production rates of CO₂ and N₂O varied significantly by season, averaging 1650±450 mgC/m³/h and 19±3.2 µgN/m³/h, respectively. These seasonal changes in the source strengths of CO₂ and N₂O in the surface soil corresponded with changes in fluxes of CO₂ and N₂O from the soil.

The contribution of roots to the annual CO₂ emission from gray forest and soddy podzolic soils measured in the field experiments under crops and native vegetation varied in the wide range from 10 to 58% of CO₂ emission from the soil by mean value of 33%. The contribution of roots to the CO₂ emission from soil surface calculated for growth season for all the ecosystems studied was equal to 44%. In agroecosystems the contribution of roots was strongly related to the length of crops growth. CO₂ emission during dormant periods of the year was greatly controlled by the decomposition of surface litter and detritus in the soil than by respiration of roots and soil microorganisms.

The first objective of this paper is to make the link between the seasonality of fine root dynamics and soil respiration in a ponderosa pine (Pinus ponderosa P. & C. Lawson) plantation located in the Sierra Nevada of California. The second objective is to better understand how canopy photosynthesis influences fine root initiation, growth and mortality in this ecosystem. We compared CO₂ flux measurements (NEE, soil CO₂ efflux) with aboveground and belowground root dynamics. Soil respiration was measured in a control and a trenched plot to separate heterotrophic and autotrophic soil respiration.

The present research is an attempt to examine and investigate the impact of land use land cover changes on the environmental sustainability and livelihood security of the local community in the Upper Kullu Valley of the Western Himalaya. Research is based on both the primary as well as secondary data sources. For the primary data were collected through Direct Field Investigation Technique (DFIT) based on Stratified Random Sampling (SRS) Technique. The secondary data were colleted from various Governmental as well nongovernmental offices working in the field of Himalayan environment and sustainability.

In this study, soil CO₂ effluxes determined from CO₂ concentration gradients were compared to effluxes obtained with automated chamber measurements. The CO₂ concentrations showed a diurnal pattern following the soil temperature the concentrations increasing with increasing soil depth. Both methods gave comparable CO₂ effluxes indicating that the gradient method provides an alternative method for monitoring soil CO₂ effluxes.