Carbon Budget of a Spruce Forest Ecosystem

Forest and agricultural land‐use‐dependent CO2 exchange in Thuringia, Germany

“…Soil respiration ( R s ) measurements conducted in the summer of 2003 with an automated system at the spruce site indicate that during sufficient high‐turbulence periods ( u * >0.5 m s −1 ) the ratio of R s to measured eddy covariance night‐time NEE is quite low (∼25%). In contrast, at a spruce site nearby (Waldstein/Weidenbrunnen), soil, wood, and foliage accounted for ∼50%, ∼30%, and ∼20% of ecosystem respiration, respectively (Rebmann et al , 2004a). One potential explanation for the low contribution of soil to ecosystem respiration at the site could be extra heterotrophic respiration from damaged crown tops lying on the ground.…”

Radiation, temperature, and leaf area explain ecosystem carbon fluxes in boreal and temperate European forests

“…Base respiration (R 0 ) (including autotrophic and heterotrophic contributions) could be expressed as the sum of a constant component (R 0,min ) and a component that increased in proportion to assimilative capacity A s (equation (5), Figure 6). The forest at Weidenbrunnen showed considerably higher base respiration rates than the other sites, possibly related to the observed forest decline [Rebmann et al, 2004]. For a number of forests, fitting the two-domain model led to a simpler relationship, either because (1) high (Flakaliden) or low (Aberfeldy) assimilation rates did not occur; (2) variation in fitted assimilation rate was small (Bordeaux) or none (Castelporziano); (3) the data suggested a monotonic increase of R 0 with A s (three of the four deciduous forests, although visual data inspection still suggested two domains; Figure 6); or (4) R 0 did not seem related to assimilative capacity at all (the fourth deciduous forest at Collelongo).…”

“…To this should be added the complex interaction between soil temperature at different depths (affecting soil respiration rate and tree phenology, and through this also aboveground base respiration) and air temperature (affecting aboveground respiration) [Bernhofer et al, 2003]. Part of the unexplained variation in respiration may be attributable to differences in the relative importance of these component fluxes between seasons [Falge et al, 2003;Rebmann et al, 2004] and sites (e.g., related to soil and litter layer characteristics, soil hydrology, and historical and current soil management).…”

“…All four sources are of comparable magnitude, but vary in importance between sites and seasons and can be expected to be driven by the temperature of the corresponding ecosystem compartments [Högberg et al, 2001;Bernhofer et al, 2003;Falge et al, 2003;Janssens et al, 2003;Rebmann et al, 2004]. Because direct, unified, and continuous measurements of the respective fluxes and temperatures at ecosystem scale are not available for the EuroFlux data set, pragmatic choices have to be made in using equation (1).…”

Biological control of the terrestrial carbon sink

“…It still remains unclear if leaves respire during photosynthesis or if respiratory CO 2 is immediately re-assimilated in leaves (Loreto et al, 1999), just as much as soil respiration is being re-assimilated by the canopy or the under-story during the day. Figure 10a shows -comb) and the partitioning into respiration of needles, wood and soil as related to season at the Waldstein site (Rebmann, 2004). (b) Components of soil respiration in a girdled and un-girdled forest at the Wetzstein site.…”