Keystones species in the functional space of plant traits
We found higher keystone plant species scores in warmer environments
(i.e. 0.41 on average for study sites located <1050 m;
Appendix S1, Table S2) than in colder environments (i.e. 0.26 on average
for sites located >2000 m; Appendix S1, Table S2). The
keystone scores were generally low, with the removal of a single plant
species resulting, on average, in less than one insect secondary
extinction (Appendix S1, Table S2). The top 10 keystones species
retrieved from alpine and lowland trophic networks had same dietary
preferences for botanical groups, as illustrated by their similar
distribution patterns within the functional space of the plant traits
(Fig. 3). In both warm and cold environments, the top 10 keystone
species occupied the functional space characterized by high punch values
(to the maximal extent of this axis; Fig. 3). The top three keystone
species of warm and cold environments all belonged to the Poaceae family
(Appendix S1, Table S2). Forb keystone species were located in the
functional space along the opposing axes of C/N, LDMC vs . SLA in
both low- and high-elevation networks; while legume keystone species
were mostly distributed along the SLA trait axis, at high but not at low
elevation (Fig. 3).