Abstract
Megafaunal frugivores can consume large amounts of fruits whose seeds may be dispersed over long distances, thus, affecting plant regeneration processes and ecosystem functioning. We investigated the role of brown bears (Ursus arctos) as legitimate megafaunal seed dispersers. We assessed the quantity component of seed dispersal by brown bears across its entire distribution based on information about both the relative frequency of occurrence and species composition of fleshy fruits in the diet of brown bears extracted from the literature. We assessed the quality component of seed dispersal based on germination experiments for 11 fleshy-fruited plant species common in temperate and boreal regions and frequently eaten by brown bears. Across its distribution, fleshy fruits, on average, represented 24% of the bear food items and 26% of the total volume consumed. Brown bears consumed seeds from at least 101 fleshy-fruited plant species belonging to 24 families and 42 genera, of which Rubus (Rosaceae) and Vaccinium (Ericaceae) were most commonly eaten. Brown bears inhabiting Mediterranean forests relied the most on fleshy fruits and consumed the largest number of species per study area. Seeds ingested by bears germinated at higher percentages than those from whole fruits, and at similar percentages than manually depulped seeds. We conclude that brown bears are legitimate seed dispersers as they consume large quantities of seeds that remain viable after gut passage. The decline of these megafaunal frugivores may compromise seed dispersal services and plant regeneration processes.
Highlights
Megafaunal frugivores can consume large amounts of fruits whose seeds may be dispersed over long distances, affecting plant regeneration processes and ecosystem functioning
We found that brown bears consumed fleshy fruits in the seven biomes where they were present
At least 101 fleshy-fruited plant species belonging to 42 genera and 24 families were eaten by brown bears across the 96 study areas (Table 1, Fig. 1, Appendix S1)
Summary
Megafaunal frugivores can consume large amounts of fruits whose seeds may be dispersed over long distances, affecting plant regeneration processes and ecosystem functioning. We conclude that brown bears are legitimate seed dispersers as they consume large quantities of seeds that remain viable after gut passage The decline of these megafaunal frugivores may compromise seed dispersal services and plant regeneration processes. Large frugivore species seem to be important in connecting plant populations by increasing gene flow via dispersed s eeds[7,8,9] Beyond differences in their mobility across landscapes, frugivores vary in their seed dispersal effectiveness, which depends on the qualitative and quantitative contribution to seed dispersal s ervices[10,11]. Previous studies have shown that resource availability influences the age of first reproduction, litter size, population density, home range size and habitat selection in Scientific Reports | (2021) 11:1282 |
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