Animals that disperse plant or fungal propagules following perturbations such as timber harvests play an important role by directionally dispersing seeds or spores from intact communities to disturbed sites. Understanding how animal species contribute to dispersal dynamics can inform management practices that help promote these vital ecosystem functions and the services they provide. Here we examine the temporal, functional, and spatial components of mycorrhizal fungal spore dispersal by small mammals following timber harvests in northern New Hampshire, USA. We tracked the interactions of seven mammal species and over 40 mycorrhizal taxa composed of two functional types (ecto- and arbuscular) during a two-year period directly following the harvest of 11 patch cuts (0.4 ha) distributed across three forest types. We measured potential spore dispersal in patch cuts and adjacent forests, along with microhabitat associations of mammals.
Results/Conclusions
With the exception of two early successional specialists, which only occupied patch cuts, all mammal species occurred in both the patch cuts and adjacent forest. However, mammal species differed greatly in their relative capacity to disperse mycorrhizal fungi due to species-specific differences in consumption of ecto- or arbuscular mycorrhizal spores, along with marked idiosyncratic population fluctuations between years. For arbuscular mycorrhizal fungi, Peromyscus maniculatus was the primary disperser in the first year and Napaeozapus insignis was the primary disperser in the second year; whereas, for ectomycorrhizal fungi, Myodes gapperi and Tamias striatus were the primary dispersers in the first year, along with N. insignis in the second year. Mammal species also differed in their microhabitat selection, indicating that they were depositing spores in different locations. Our results suggest that mammals are highly complementary in their temporal, functional, and spatial ability to disperse mycorrhizal spores. Furthermore, preserving microhabitats associated with small mammal species within and surrounding timber harvests may be important for maintaining critical dispersal of mycorrhizal fungi by mammals.