Table 1.
Pigment concentrations and soil chemistry and gene abundance of nifH and amoA in different BSCs types of the Great Basin and Chihuahuan Desert (mean ± s.e., n = 3).
Fig 1.
Nitrogen fixation (Acetylene reduction) rates of dark (solid black symbols), light (grey symbols) and lichen (solid black symbols) BSCs in the Great Basin and Chihuahuan Desert.
Symbols show the mean of n = 8 determinations and error bars depict standard errors. Different lowercase letters indicated significant differences (p < 0.05) for comparisons among temperatures within single BSC type. An asterisk indicates significant differences between dark and light BSCs for a single temperature.
Table 2.
Responsivity of N transformations to T among the BSCs studied, gauged by estimates of the slope of a regression between the natural logarithm of the process rates and the inverse of temperature (Arrhenius plots; see full data in S1 Fig).
Only the portion of any dataset where rates increased with T was used. Slopes that were not significantly different at the 95% were assigned same letter in the multi-comparison column. Q10s, giving the average fold increase in rate for an increase of 10°C, are also included, calculated from regression curves of the same datasets.
Fig 2.
Potential AO fixation rates of dark (solid black symbols) and light (grey symbols) and lichen (solid black symbols) BSCs in the Great Basin and Chihuahuan deserts.
Symbols show the mean of n = 5 determinations, anderror bars depict standard errors. Different lowercase letters indicated significant differences (p < 0.05) for comparisons among temperatures within a single BSC type. An asterisk indicates significant differences between dark/lichen and light BSCs for a single temperature.
Table 3.
Diazotrophic growth capability as a function of temperature in cultured cyanobacteria isolated from the Great Basin and the Chihuahuan deserts.
Fig 3.
Trend of the balance between Nitrogen fixation (acetylene reduction) and AO rates, as the net difference for each BSC type an origin, according to the legend inserted.
Columns show the mean of n = 40 determinations (differences between 8 ARA value and 5 AO value), and error bars depict standard errors. Different lowercase letters indicated significant differences (p < 0.05) for comparisons among temperatures within a single BSC type.