Study systems
This study was conducted in the Himalaya-Hengduan Mountains (HHM) in SW
China, where is one of the richest and most complex floras in the
temperate zone of the Northern Hemisphere (Sun et al., 2017). See Text
S1 for the details. Field experiments were conducted in northwestern
Yunnan province (Figure S1), which is in the core area of alpine plant
diversity of the HHM (Zhang et al., 2021). We selected eight communities
dominated by the typical cushion plantArenaria
polytrichoides Edgew. (Caryophyllaceae) as our study systems. As
foundation species, A. polytrichoides plays key roles in the
alpine ecosystem functions in this region (Text S2). Specifically, we
selected four populations along an altitudinal gradient in Pujin pasture
of the Baima Snow Mountains (Figure S1) to elucidate the cushion plant’s
population dynamics, the associated plant diversity changes and the
underlying mechanisms. In addition, another four populations in
different mountain ranges were also selected to assess and compare
current population dynamics at larger scale and predict potential
biodiversity changes in alpine ecosystems more broadly (Figure S1). See
Text S3 for the details.