Increasing fire severity alters the species composition and decreases richness of seeds potentially dispersed by small mammals

Abstract

Seed dispersal is a key process that influences the recruitment of plant species, yielding profound consequences on vegetation structure. This process can be affected by environmental disturbances, such as fires, leading to varied impacts on the agents involved, both dispersers and plants. We investigated the potential role of small mammals (rodents and marsupials) as seed dispersers in a Neotropical savanna (Brazilian Cerrado). We also evaluated the impact of fire severity on the seed dispersal services provided by these animals in gallery forests, 3 years after a major fire event. We live-trapped small mammals in 14 sites, 7 of which were located in forests classified in three categories of fire severity (“unburned”, “low severity”, or “moderate severity”). We captured 13 mammal species, finding a total of 11,688 seeds in their feces (collected inside traps or handling bags). These seeds encompassed 28 plant species from at least 8 families. A multivariate analysis (NMDS) revealed differences among small mammal species in terms of potentially dispersed plants, with seeds of 18 plant species being consumed by no more than one small mammal species. An increase in fire severity affected the composition of plant species potentially dispersed, changed the relative role of forest small mammals as seed dispersers, and decreased observed richness of defecated seeds. We conclude that high-severity wildfires affect highly relevant ecological processes, such as seed dispersal by animals. These effects could impact the recruitment dynamics of plant species and, consequently, the vegetation recovery and plant community composition in fire-affected areas.

Abstract in Portuguese is available with online material.