Geoscience Reference
In-Depth Information
III. SCALE DEPENDENCE OF PREDATOR-PREY
MASS RATIO
A. Methods and Results
The four types of PPMR were calculated using the data from all 21 sites to
study the scale dependence of PPMR. The calculation of PPMRs requires
information on predator and prey body masses, predator species identity,
and prey category. The mean and median values were selected as representa-
tive values for each PPMR definition.
Our analysis showed that different values are obtained depending on the
definition of PPMR (
Figure 2
), in agreement with
Woodward and Warren
(2007)
. However, closer investigation showed two major differences in the
pattern found in our analysis compared to this earlier study. First, individual-
link PPMR was higher by about one order of magnitude than link-averaged
PPMR, which is in sharp contrast with the pattern reported by
Woodward
8
6
4
2
0
-2
Species-averaged
Link-averaged
Individual-predator
Individual-link
Figure 2
Scale dependence of PPMR estimation. In the boxplots, thick solid and
thin dashed lines represent the median and mean values of PPMR, respectively.
