Relative stable interannual variation in plant‒plant pollen transfer rather than the plant‒pollinator network of a subalpine meadow

Previous studies have shown that plant–pollinator mutualistic interactions experience highly interannual variation. Given that pollinators often move across multiple plant species, the plant‒plant interactions that take place via heterospecific pollen (HP) transfer may also vary temporally, which could have important implications for floral evolution and community assembly. Here, we evaluated the interannual variation in plant–pollinator networks and plant‒plant heterospecific pollen transfer (HPT) networks of a subalpine meadow community in Southwest China for three consecutive years. The interactions largely varied between years for both network types. The composition of donor-species HP deposited on the plants varied less than did the visit composition of the pollinators, which suggested that HP could be transferred from identical donor species to recipient species through different shared pollinators between years. The plant species were at more similar positions in the HPT network than they were in the plant–pollinator network across years. Moreover, the more generalized plant species in the plant–pollinator network tended to export their pollen grains and more strongly influence HPT. We evaluated the relatively stable structure of the HPT network compared with the plant–pollinator network, which represents an important step in the integration of plant–pollinator and plant‒plant interactions.