Abstract Ecological communities are stressed by rapid and complex anthropogenic changes, threatening the persistence of biotic interactions and ecosystem functioning. Plant–pollinator communities, for instance, undergo structural transformations as a result of land‐use change, species invasion and climate change. By experimentally investigating changes of interaction networks over time, caused by anthropogenic disturbances, we will be able to better understand the underlying ecology and predict our impact on communities. Here, we used a long‐term community field experiment involving nitrogen (N) addition to investigate the impacts of anthropogenic N enrichment on seasonal dynamics of a N‐limited, fast‐changing ecosystem: alpine meadows on the Tibetan Plateau. Given the brief flowering season and pollinators' phenophase of alpine meadows, we were particularly interested in understanding how N‐induced changes in flowering communities alter plant–pollinator interactions assembly and disassembly over the season, which ultimately shapes network structure and defines ecological resilience of communities. We found that N‐induced declines in floral abundance and richness resulted in an increase in pollinator species turnover over the season. This, in turn, affected natural interaction rewiring processes among temporally persistent species, suggesting a markedly lower seasonal connectivity and persistence of plant–pollinator interactions in meadows with high N input. Importantly, we found that the effects of N on interaction dynamics were particularly strong late in the season, suggesting heightened vulnerability of plant–pollinator interactions to N enrichment during this period. N‐induced changes in plant–pollinator interaction dynamics further disrupted the structure of pollination networks in natural alpine meadows through reduced specialization and modularity, which suggests that pollinators interact with plants more opportunistically over time, resulting in more simplified and homogenized communities under high N input. By considering temporal dimension, our study demonstrates that anthropogenic N enrichment can interrupt seasonal connectivity and stability of plant–pollinator networks, providing novel insights into how and why anthropogenic environmental change affects multi‐trophic interactions in vulnerable alpine ecosystems. Read the free Plain Language Summary for this article on the Journal blog.
Gao et al. (Thu,) studied this question.