Generalized plant–pollinator phenological climate‐driven advances still lead to a decline in phenological overlap

Abstract Climate change is altering the phenology of interacting species, potentially leading to mismatches in the timing of their interactions. This may affect the delivery of key ecosystem services such as pollination. Temperature‐mediated phenological variation has been widely studied at the species level, showing that increased temperatures lead to earlier activity periods for both plant flowering and pollinator emergence. However, some classic examples of tracked interacting pairs show that phenological mismatches can occur between plants and pollinators. Even though plants and pollinators are embedded in complex interaction networks, it remains unclear how phenological shifts scale up to the community level and what role biodiversity may play in buffering negative outcomes. We analyzed an 8‐year time series of plant and pollinator seasonal abundances across 12 Mediterranean scrublands increasingly affected by drought and extreme temperatures, focusing on the subset of common species whose phenology could be reliably described each year. Our aim is to understand how climate change has altered plant–pollinator interactions from the species to the community level. We found that plants and pollinators have been advancing their phenologies over time at similar rates, with an average advance of 5 days per decade. Changes in rainfall and temperature patterns are key drivers of these advances. Despite the congruent shifts and no consistent change in pairwise phenological overlap, total overlap between each species and its potential partners has slightly declined over time. While more diverse communities show higher potential overlap, biodiversity is not directly buffering the reduction in interaction overlap in the studied rich communities. However, in silico experiments show that the buffering effect of biodiversity becomes apparent at lower diversity levels (i.e., fewer than 10 species). In the context of ongoing climate change, protecting diverse communities with high interaction overlap is crucial, as phenological shifts may gradually erode network structure in Mediterranean plant–pollinator systems. Sustained long‐term data collection is also essential to understand the fate of most species, including those whose low abundances may conceal early signs of biodiversity loss.