Supporting Information
Appendix S1. Details of the dataset
The dataset use here is presented in Soliveres & Maestre (2014a, 2014b) and Soliveres et al.
(2014). From these datasets, we removed those studies with measures of facilitation other than
occurrences outside/beneath the nurse plant (e.g., Choler et al. 2001) or those sites with
species occurrences not reported or with <10 individuals registered. The studies selected
contain information on 2685 pairwise interactions sampled in 32 community-level studies
spread across 139 sites and all continents except Antarctica (1215 co-occurrences with the
target species having ≥ 10 individuals in a given plot, these were the ones considered here).
The sites varied widely in their vegetation and environmental conditions, with elevations
ranging from 0 to 6000 m.a.s.l., average annual rainfall from 67 to 2000 mm, and with
latitudes and longitudes ranging between 46.4° N–50.8° S and 147.7° E–106.9° W,
respectively. Habitat types were mostly cushion dominated alpine environments or drylands
(grasslands, shrublands and savanna-like systems). Sometimes the study focused on a single
nurse plant species within each community (e.g., Holzapfel et al. 2006) while in others the
study focused on several potential nurse species within a given growth form (e.g., different
species of shrubs: Pugnaire et al. 2004) or different nurse growth forms (e.g., Soliveres et al.
2011). In all cases we pooled all the individuals found beneath all nurses and weighted this
number by the relative sampling effort invested regarding open areas to calculate the cooccurrence metrics. All references are cited either in Table S1 below or in the main text.
Table S1. Studies used to gather the database analysed in this paper. Country where the study
was conducted, main nurse-type beneath which the sampling took place, number of sites
sampled, total number of pairwise interactions reported and the full reference is given. Details
on climate or habitat-type can be found in figshare: Soliveres, S., and Maestre, F. T. 2014.
Data from “Plant-plant interactions, environmental gradients and plant diversity: a global
synthesis of community-level studies”. http://dx.doi.org/10.6084/m9.figshare.963585.
# Sites
# Pairwise
interactions
reported
Country
Nurse_type
Ecuador
cushion
3
107
Chile
cushion
2
64
Chile
cushion
1
18
Chile
cushion
2
62
Chile
cushion
2
89
Chile
cushion
2
64
China
cushion
1
72
India
cushion
1
13
India
cushion
4
140
USA
shrub
1
20
Israel
shrub
4
213
China
shrub
1
167
USA
cushion
2
25
Palestina
shrub
1
43
Chile
cushion
1
27
China
shrub
1
32
Israel
shrub
1
37
Spain
shrub
1
35
Chile
cushion
2
49
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Argentina
shrub
1
47
Spain
cushion
2
43
Spain
shrub
1
66
Spain
cushion
3
78
Spain
Shrub/Grass
10
205
Australia
shrub/tree
18
329
Ecuador
shrub/tree
16
157
Chile
shrub
4
38
Venezuela
grass
6
52
Morocco
grass
10
80
Spain
shrub
23
235
Tunisia
grass
10
41
China
cushion
2
37
139
2685
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Plant Ecology Evolution and Systematics, doi: 10.1016/j.ppees.2014.05.001
Soliveres, S. et al. 2014. Functional traits determine plant co-occurrence more
than environment or evolutionary relatedness in global drylands. Perspectives in
Plant Ecology Evolution and Systematics, doi: 10.1016/j.ppees.2014.05.001
Soliveres, S. et al. 2014. Functional traits determine plant co-occurrence more
than environment or evolutionary relatedness in global drylands. Perspectives in
Plant Ecology Evolution and Systematics, doi: 10.1016/j.ppees.2014.05.001
Soliveres, S. et al. 2014. Functional traits determine plant co-occurrence more
than environment or evolutionary relatedness in global drylands. Perspectives in
Plant Ecology Evolution and Systematics, doi: 10.1016/j.ppees.2014.05.001
Soliveres, S. et al. 2014. Functional traits determine plant co-occurrence more
than environment or evolutionary relatedness in global drylands. Perspectives in
Plant Ecology Evolution and Systematics, doi: 10.1016/j.ppees.2014.05.001
Soliveres, S. et al. 2014. Functional traits determine plant co-occurrence more
than environment or evolutionary relatedness in global drylands. Perspectives in
Plant Ecology Evolution and Systematics, doi: 10.1016/j.ppees.2014.05.001
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