Functional Ecology
Appendices
Appendix S1. Soil water content along the topographical gradient, from upper (1) to lower
slope (40). Soil water content was measured twice (May 2013 and May 2014 ) on each quadrat with a
ThetaProbe ML2 sensor and a Theta HH1 Meter (Delta OHM, Caselle di Selvazzano, Italy), and the
two values for each plot averaged. To show the relationship between soil water content (expressed here
as a percentage: 100 m3 m-3), we fitted a linear regression of soil water content on position on the
gradient, which revealed an important increase of soil water content along the studied gradient.
More for less: sampling strategies of plant functional traits across local environmental gradients.
Carmona, CP., Rota, C., Azcárate, F.M. & Peco, B.
Functional Ecology
Appendix S2. Community weighted mean (CWM) and functional diversity (FD) along the topographical gradient, from upper (1) to lower
slope (40). Black dots and lines indicate the values of these parameters obtained considering 10 individuals per species per quadrat (labour-intensive
strategy) and the model fitted to these data, respectively. For each of the considered strategies, we present the envelopes that contain the 95% of the
predicted values (considering 1,000 simulations) for three different sampling strategies. Note that for the GLO and MAX strategies, greater sampling
intensities yielded more precise (i.e. narrower envelopes), but not more accurate (i.e. closer to the regressions estimated using the labor intensive strategy)
predictions.
More for less: sampling strategies of plant functional traits across local environmental gradients.
Carmona, CP., Rota, C., Azcárate, F.M. & Peco, B.
Functional Ecology
Appendix S3. Boxplots representing the error of the different intensities for the LOC strategy. For
each trait and indicator of functional structure (CWM and FD), we calculated the ratio between the
CWM and FD values obtained following the different sampling strategies and the CWMI and FDI of
each quadrat. Error is the absolute difference between 1 and this ratio. Values close to 0 indicate a low
error (i.e. simulated values are very close to the ones attained using the labour-intensive strategy). The
dashed line represents a 10% level of error. Boxplots are ordered from lower (top) to higher (bottom)
sampling intensities. Numbers indicate the number of individuals and species per sampling unit (in
parentheses, the total number of traits measured in the whole gradient for each sampling intensity). Note
that the greatest increases in accuracy between consecutives sampling intensities happened at low levels
of intensity, and successive increases in intensity resulted in smaller improvements.
a) CWM
Height
Leaf Area
SLA
1 (257)
(257)
(257)
2 (514)
(514)
(514)
3 (771)
(771)
(771)
4 (1028)
(1028)
(1028)
5 (1285)
(1285)
(1285)
6 (1542)
(1542)
(1542)
7 (1799)
(1799)
(1799)
8 (2056)
(2056)
(2056)
9 (2313)
(2313)
(2313)
0
5
10
15
0
1
2
3
4
5
6
0
2
4
6
8
10
0
1
2
3
4
5
b) FD
1 (257)
(257)
(257)
2 (514)
(514)
(514)
3 (771)
(771)
(771)
4 (1028)
(1028)
(1028)
5 (1285)
(1285)
(1285)
6 (1542)
(1542)
(1542)
7 (1799)
(1799)
(1799)
8 (2056)
(2056)
(2056)
9 (2313)
(2313)
(2313)
0
2
4
6
8
0
1
2
3
4
More for less: sampling strategies of plant functional traits across local environmental gradients.
Carmona, CP., Rota, C., Azcárate, F.M. & Peco, B.
Functional Ecology
Appendix S4. Boxplots representing the reductions in error attained using the example of EFF
strategy proposed in the main text (2 individuals per species and quadrat if the cover of the
species in the quadrat is <25% and 4 individuals otherwise). This strategy involves the selection of
2.26 individuals per species and sampling unit. We also represent two levels of the LOC strategy (2 and
4 individuals per species and sampling unit). Boxplots are placed in the axis of ordinates according to
decreasing (bottom to top) sampling intensity. Numbers in parentheses indicate the total number of
traits measured in the whole gradient. Dashed grey lines indicate the expected values of error that would
be attained for any given number of individuals measured (vertical axis), assuming a constant rate of
improvement between the two selected intensities of the LOC strategy. Note that, with the exception of
FD for SLA, the EFF strategy yields more accurate values than expected for its intensity level.
a) CWM
Height
Leaf Area
SLA
LOC 2 (514)
(514)
(514)
EFF 2.26 (580)
(580)
(580)
LOC 3 (771)
(771)
(771)
0
5
10
15
20
0
1
2
3
4
5
6
7
0
2
4
6
8
10
12
b) FD
LOC 2 (514)
(514)
(514)
EFF 2.26 (580)
(580)
(580)
LOC 3 (771)
(771)
(771)
0
2
4
6
8
0
1
2
3
4
0
1
2
3
4
5
More for less: sampling strategies of plant functional traits across local environmental gradients.
Carmona, CP., Rota, C., Azcárate, F.M. & Peco, B.