The impact of a native dominant plant, Euphorbia jolkinii, on plant–flower visitor networks and pollen deposition on stigmas of co‐flowering species in subalpine meadows of Shangri‐La, SW China

Abstract

Anthropogenic activity can modify the distribution of species abundance in a community leading to the appearance of new dominant species. While many studies report that an alien plant species which becomes increasingly dominant can change species composition, plant–pollinator network structure and the reproductive output of native plant species, much less is known about native plant species which become dominant in their communities. Euphorbia jolkinii Boissier (Euphorbia, hereafter) has become a dominant native plant in the over‐grazed meadows of Shangri‐La, SW China. During the flowering season of Euphorbia and over 2 years, we quantified the impact of Euphorbia on plant richness and flower visitor richness in 12 subalpine meadows along a gradient of Euphorbia dominance. We also evaluated the floral preferences of flower visitors, interaction evenness of plant–flower visitor networks and the deposition of pollen on the stigmas of two co‐flowering plant species (Gentiana chungtienensis and Anemone rupestris) in each meadow. The species richness of flower visitors to non‐Euphorbia plants was negatively correlated with Euphorbia dominance. As the proportion of Euphorbia increases, flower visitors to Euphorbia decreased, while flower visitors to other co‐flowering plants increased. Interaction evenness decreased as the proportion of Euphorbia increased. Furthermore, the conspecific pollen deposition of one of the two co‐flowering plant species studied, G. chungtienensis, decreased as the proportion of Euphorbia increased. Synthesis. There appears to be little substantive difference between the impact of a newly dominant native plant and the impacts reported for many alien plants on native plant–pollinator communities. This lack of difference suggests that dominance, in addition to plant origin (alien vs. native), could play an important role in influencing the structure and functioning of native communities. This finding has considerable implications for restoration ecology. Thus, communities where natural dominance order has been changed due to anthropogenic activity may not be considered a problem as all the species are native—in reality though, they may be as damaged as communities invaded by alien species.

Negative impacts of dominance on bee communities: Does the influence of invasive honey bees differ from native bees?

“…Even rarer are examples of dominant native species’ impacts on community composition within guilds, although recent research suggests that this may also happen in plants in response to disturbance (Zhao et al. 2021). In our study, it may be that agricultural management in these systems has sufficiently perturbed local ecosystems such that T. spinipes has become exceedingly dominant, however the dominance effects were independent of land‐use change variables as stated above.…”

Intraspecific divergence in a coastal plant, Euphorbia jolkinii, at a major biogeographic boundary in East Asia

“…Chinese populations of E. jolkinii are predominantly distributed in subalpine regions above 3000 m a.s.l. (Zhao et al, 2021). Moreover, they exhibit morphological characteristics that distinguish them from the coastal populations of E. jolkinii in East Asia (T. Kurosawa, unpublished data).…”

Global change re‐structures alpine plant communities through interacting abiotic and biotic effects

“…Determining the mechanisms that allow species to dominate under novel environmental conditions can serve as proxies for whole community and ecosystem responses to global change (Avolio et al, 2019). In fact, the idea that “super‐dominants,” or overabundant populations of native species, may have similar impacts as non‐native invasive species on community and ecosystem function has begun to gain traction (Regina et al, 2018; Zhao et al, 2021). Conversely, deciphering pathways by which dominant and subordinate species become more evenly distributed is critical for predicting the long‐term maintenance of biodiversity and the preservation of rare species (Csergo et al, 2013; Felton & Smith, 2017).…”