2.4 Statistics
We categorized the scaling behavior of relationships between cumulative
hyporheic respiration and watershed area for each combination of HEF bin
and basin (n = 20) into four allometric classes: Uncertain, Sublinear,
Linear, and Super-linear. We visually identified an R2threshold of 0.8 where values exhibit a “knee” (Figure S3A), which we
interpret as weak or no allometric scaling. Relationships with mean
R2 values < 0.8 were classified as
”Uncertain”. To classify allometric behavior for relationships with
R2 values >= 0.8, we used 2.5% and
97.5% confidence intervals (CI2.5 and
CI97.5) of slope values as follows: “Linear” for
CI2.5 < 1 and CI97.5> 1, “Sublinear” for CI2.5 < 1
and CI97.5 < 1, and “Super-linear” for
CI2.5 > 1 and CI97.5> 1 (Figure S3C). We capitalize these terms throughout the
rest of this study to clarify when we are referring to these
definitions.
To reveal watershed features explaining variation in the spatial
distributions of hyporheic respiration across each basin, we used mutual
information analysis, which calculates the dependency between two
variables based on Shannon’s entropy. Mutual information analysis was
conducted with the infotheo R package (Meyer 2022), where each
variable was first discretized, then calculated mutual information was
normalized to the maximum information within each analysis. For
statistical tests with significance values, we used a p-threshold of
0.05. All analyses were performed in R (R Core Team 2023) or Python 3.