Carbon uptake by the terrestrial biosphere depends on supplies of new nitrogen (N) from symbiotic N fixation, but we lack a framework for scaling fixation accurately and predicting its response to global change. We scaled individual fixers (i.e. plants that host N-fixing bacteria), quantifying three key parameters—the abundance fixers, whether they are fixing their rates. apply this black locus...

With Chlorella ellipsoidea cells, the effect of oxygen was investigated on the products of enhanced dark (14)CO(2) fixation immediately following preillumination in the absence of CO(2). When the reaction mixture was made aerobic by bubbling air (CO(2)-free) throughout preillumination and the following dark (14)CO(2) fixation periods, the initial fixation product was mainly 3-phosphoglyceric ac...

An ongoing field study of the effects of elevated atmospheric CO2 on a brackish wetland on Chesapeake Bay, started in 1987, is unique as the longest continually running investigation of the effects of elevated CO2 on an ecosystem. Since the beginning of the study, atmospheric CO2 increased 18%, sea level rose 20 cm, and growing season temperature varied with approximately the same range as pred...

The relationship between phytoplankton cell size and abundance has long been known to follow regular, predictable patterns in near steady-state ecosystems, but its origin has remained elusive. To explore the linkage between the size-scaling of metabolic rate and the size abundance distribution of natural phytoplankton communities, we determined simultaneously phytoplankton carbon fixation rates...

[1] The remarkable correspondence between glacialinterglacial changes in atmospheric CO2 levels and global climate over much of the Pleistocene suggests that CO2 is also a key climate change driver. However, there is as yet no widely accepted explanation of the low glacial CO2 levels. Here I use an intermediate-complexity climate model to show that glacial cooling, acting on the rates of organi...

Increasing the concentration of atmospheric carbon dioxide is the main factor for the climatic change having some harmful consequences for the human health while there is no considerable effort for decreasing this accelerated global problem, yet. Kermanshah province located in the west of Iran has about 1,200,000 ha rangeland which is dominated by Astragalus sppas the more frequent shrub beinga...

observations, to constrain the pattern of N2 fixation across the Pacific Ocean. N2 fixation introduces isotopically light atmospheric N2 from to the ocean (d N = 0‰) relative to the oceanic average near 5‰, which makes nitrogen isotopes suitable to infer patterns of N2 fixation. Including atmospheric iron limitation of diazotrophy in the model shifts the pattern of simulated N2 fixation from th...

We examined the physiological responses of steady-state iron (Fe)-replete and Fe-limited cultures of the biogeochemically critical marine unicellular diazotrophic cyanobacterium Crocosphaera at glacial (19 Pa; 190 ppm), current (39 Pa; 380 ppm), and projected year 2100 (76 Pa; 750 ppm) CO2 levels. Rates of N2 and CO2 fixation and growth increased in step with increasing partial pressure of CO2 ...