Fire influences the structure of plant-bee networks

Abstract

Fire represents a frequent disturbance in many ecosystems, which can affect plant–pollinator assemblages and hence the services they provide. Furthermore, fire events could affect the architecture of plant–pollinator interaction networks, modifying the structure and function of communities. Some pollinators, such as wood-nesting bees, may be particularly affected by fire events due to damage to the nesting material and its long regeneration time. However, it remains unclear whether fire influences the structure of bee–plant interactions. Here, we used quantitative plant–wood-nesting bee interaction networks sampled across four different post-fire age categories (from freshly-burnt to unburnt sites) in an arid ecosystem to test whether the abundance of wood-nesting bees, the breadth of resource use and the plant–bee community structure change along a post-fire age gradient. We demonstrate that freshly-burnt sites present higher abundances of generalist than specialist wood-nesting bees and that this translates into lower network modularity than that of sites with greater post-fire ages. Bees do not seem to change their feeding behaviour across the post-fire age gradient despite changes in floral resource availability. Despite the effects of fire on plant–bee interaction network structure, these mutualistic networks seem to be able to recover a few years after the fire event. This result suggests that these interactions might be highly resilient to this type of disturbance.