1
Appendix 1. A list of studies used in the current meta-analysis to examine the importance of
2
altitudinal gradients on plant-plant interactions including both nurse-plant and neighbourhood level
3
effects. The numbers of effect size estimate calculated per study are listed (n).
ID
Study
n
505
Badano, E.I., Villarroel, E., Bustamante, R.O., Marquet, P.A. & Cavieres, L.A.
16
(2007) Ecosystem engineering facilitates invasions by exotic plants in highAndean ecosystems. Journal of Ecology 95, 682–688.
510
Quiroz, C.L., Badano, E.I. & Cavieres, L.A. (2009) Floristic changes in alpine
122
plant communities induced by the cushion plant Azorella madreporica (Apiaceae)
in the Andes of central Chile. Revista Chilena de Historia Natural 82, 171–184.
511
Cranston, B.H., Callaway, R.M., Monks, A. & Dickinson, K.J.M. (2012) Gender
8
and abiotic stress affect community-scale intensity of facilitation and its costs
Journal of Ecology 100, 915–922.
512
Eranen, J.K. and Kozlov, M.V. (2008) Increasing intraspecific facilitation in
4
exposed environments: consistent results from mountain birch populations in two
subarctic stress gradients. Oikos 117,1569–1577.
513
Cavieres, L., Arroyo, M.T.K., Penaloza, A., Molina-Montenegro, M.A. & Torres,
4
C. (2002) Nurse effect of Bolax gummifera cushion plants in the alpine vegetation
of the Chilean Patagonian Andes. Journal of Vegetation Science 13, 547–554.
514
Yang, Y., Niu, Y., Cavieres, L.A. & Sun, H. (2010) Positive associations between 152
the cushion plant Arenaria polytrichoides (Caryophyllaceae) and other alpine
plant species increase with altitude in the Sino-Himalayas. Journal of Vegetation
Science 21, 1048–1057.
515
Arroyo, M.T.K., Cavieres, L.A., Penaloza, A. & Arroyo-Kalin, M.A. (2003)
4
Positive associations between the cushion plant Azorella monantha (Apiaceae)
1
and alpine plant species in the Chilean Patagonian Andes. Plant Ecology 169,
121–129.
517
Anthelme, F., Buendia, B., Mazoyer, C. & Dangles, O. (2012) Unexpected
8
mechanisms sustain the stress gradient hypothesis in a tropical alpine
environment. Journal of Vegetation Science 23, 62–72.
518
Cavieres, L.A., Badano, E.I., Sierra-Almeida, A., Gomez-Gonzalez, S. & Molina-
14
Montenegro, M. (2006) Positive interactions between alpine plant species and the
nurse cushion plant Laretia acaulis do not increase with elevation in the Andes of
central Chile. New Phytologist 169, 59–69.
520
Schöb, C., Butterfield, B.J. & Pugnaire, F.I. (2012) Foundation species influence
16
trait-based community assembly. New Phytologist 196, 824–834.
521
Schöb, C., Armas, C., Guler, M., Prieto, I. & Pugnaire, F.I. (2013) Variability in
8
functional traits mediates plant interactions along stress gradients. Journal of
Ecology: in press.
522
Michalet, R., Xiao, S., Touzard, B., Smith, D.S., Cavieres, L.A., Callaway, R.M.
8
& Whitham, T.G. (2011) Phenotypic variation in nurse traits and community
feedbacks define an alpine community. Ecology Letters 14, 433–443.
523
Le Roux, P.C. & McGeoch, M.A. (2010) Interaction intensity and importance
16
along two stress gradients: adding shape to the stress-gradient hypothesis.
Oecologia 162, 733–745.
525
Callaway, R.M., Brooker, R.W., Choler, P., Kikvidze, Z., Lortie, C.J. , Michalet,
518
R., Paolini, L., Pugnaire, F.I., Cook B.J., Aschehoug, E.T., Armas, C. &
Newingham, B. (2002) Interdependence among alpine plants increases with
stress: a global experiment. Nature (London) 417, 844–848.
526
Badano, E.I. & Cavieres, L.A. (2006) Impacts of ecosystem engineers on
24
2
community attributes: effects of cushion plants at different elevations of the
Chilean Andes. Diversity and Distributions 12, 388–396.
527
Liancourt, P., Spence, L.A., Song, D.S., Lkhagva, A., Sharkhuu, A., Boldgiv, B.,
8
Helliker, B.R., Petraitis, P.S. & Casper, B.B. (2013) Plant response to climate
change varies with topography, interactions with neighbors and ecotype. Ecology
(in press).
4
5
6
Appendix 2. A summary of the relative frequency of effect sizes estimates calculated from the
7
available literature on plant-plant interactions on altitudinal gradients.
8
Measure
biomass
count
richness
survival
Total
n
289
328
48
265
930
9
10
Appendix 3. A summary of the relative frequency of effect size estimates calculated from the
11
literature on plant-plant interactions on altitudinal gradients summarized by climatic region and by
12
nurse-plant effects studied or by neighbourhood-level effects.
13
Climatic region
Arctic
Mediterranean
Temperate
Tropical
Type of plant effect
neighbourhood
nurse
neighbourhood
nurse
Neighbourhood
Nurse
Neighbourhood
Nurse
Total
146
28
32
208
308
8
40
160
14
15
3