INTRODUCTION
The changes of biodiversity with ongoing climate warming have continuously raised public concerns and fascinated scientists and policy makers from all over the world (Grabherr et al., 1994; Lenoir et al., 2008; Chen et al., 2011; Elmendorf et al., 2012; Gottfried et al., 2012; Pecl et al., 2017; Steinbauer et al., 2018). Alpine ecosystems play irreplaceable roles in human well-being (Martin-Lopez et al., 2019) but are quite sensitive to climate change (Grabherr et al., 1994; Lenoir et al., 2008; Gottfried et al., 2012; Steinbauer et al., 2018). Amongst the high diversity of plant life forms displayed in alpine biomes (Körner, 2003), the cold-adapted cushion-forming growth has evolved independently more than 115 times in angiosperm evolutionary history (Boucher et al., 2016) and act as foundation species (Schöb et al., 2012; Kikvidze et al., 2015). Foundation specie are those can modulate ecosystem processes that can greatly affect local conditions experienced by other species and, consequently, re-organize community structure and sustain diversity to a considerable extent (Ellison et al., 2005; Thomsen et al., 2018; Lamy et al., 2020). Therefore, any changes in foundation species populations have consequences for local/regional biodiversity (Ellison et al., 2005), especially in sensitive and/or fragile ecosystems, like alpine and arctic ecosystems. As foundation species, alpine cushion plants can re-organize community structures (Badano et al., 2006), increase and sustain alpine plant diversity (Cavieres & Badano, 2009; Cavieres et al., 2014; Chen et al., 2015a, b), inhibit the loss of phylogenetic diversity (Butterfield et al., 2013) and construct and maintain species interaction networks (Losapio & Schöb, 2017; Losapio et al., 2019), thereby maintaining ecosystem functions and services (Badano et al., 2006; Chen et al., 2015a; Kikvidze et al., 2015). Accordingly, cushion-dominated communities provide ideal model systems to assess potential biodiversity changes with the dynamics of foundation species which are induced by climate warming (Box 1).