Responses of biotic interactions of dominant and subordinate species to decadal warming and simulated rotational grazing in Tibetan alpine meadow

Abstract

Warming increases competition among plant species in alpine communities by ameliorating harsh environmental conditions, such as low temperatures. Grazing, as the main human activity, may mitigate the effect of warming, as previously reported. However, it is critical to refine the effects of warming on biotic interactions among species, for example, by taking the competitive ability of species into consideration. Based on a 10-year warming and grazing experiment in a Tibetan alpine meadow, we evaluated interspecific biotic interactions of dominant and subordinate species, using the approach of interspecific spatial associations. Warming significantly increased competition between subordinate and dominant species as well as among subordinate species, but not among dominant species. Moreover, facilitation of dominant-subordinate species also increased under warming. Simulated rotational grazing had similar effects to warming, with increasing interspecific competition. Our results show that, when studying the effects of warming on biotic interactions among species, it is necessary to characterize different species pairs relative to their competitive ability, and that simulated rotational grazing does not mitigate the effects of warming in the long term. Our results also provide evidence that the spatial pattern of species is a critical mechanism in species coexistence.

Ambient climate determines the directional trend of community stability under warming and grazing

“…Notably, decreased species diversity played a primary role in increasing the SD of ANPP response to experimental duration, which, in turn, decreased ANPP stability (Figure 6). This decrease in species diversity might be due to typical shifts in plant composition toward increasing taller and higher density grass with increasing ambient AT in the alpine region (Liu et al, 2018), which shades the forbs and further increases plant competition for light and N (Jiang et al, 2018; Li et al, 2018). In addition, grazing had significant negative effects on species diversity, probably because of the degradation processes which resulted from the decrease in palatable forage (i.e., grass and sedge; Figure 3a,b) under continuous grazing conditions (Wang et al, 2012), but its positive effects on mean ANPP were offset by indirect negative effects of species asynchrony (Figure 6).…”

Richness of plant communities plays a larger role than climate in determining responses of species richness to climate change

“…In reality, species are likely to shift at idiosyncratic rates, depending on their dispersal ability and species traits (Alexander et al, 2015). Evidence suggests that species range Some studies report that environmental change will alter relative cover of species in the community, which may alter plant biotic interactions and species coexistence (Anthelme, Cavieres, & Dangles, 2014;Li et al, 2018). Many of the plant species in our study are long-lived perennials and likely have life spans exceeding 10 years.…”

“…Some studies report that environmental change will alter relative cover of species in the community, which may alter plant biotic interactions and species coexistence (Anthelme, Cavieres, & Dangles, ; Li et al., ). Many of the plant species in our study are long‐lived perennials and likely have life spans exceeding 10 years.…”

“…Many of the plant species in our study are long‐lived perennials and likely have life spans exceeding 10 years. Dominant species usually have a higher potential to acquire resources and to suppress the growth of other species (Mariotte, Buttler, Johnson, Thébault, & Vandenberghe, ), and subordinate species may suffer from increased competition from dominants (Anthelme et al., ; Li et al., ). Although we found effects of our elevational transfers on percent cover of some dominant species in our study communities (i.e.…”