Interactions between small mammals and trees according to different forest compositions
PhD Student
Pedro MittelmanResearch Outline
Seed dispersal and predation by small mammals are major factors determining tree population dynamics. However, little is known about how stand compositions affect the fate of seeds removed by small mammals. The relationship between small mammals and tree species can be mutualistic or antagonistic depending on the proportion of seeds cached/eaten, survival of cached seeds, survival of non-removed seeds and their respective probabilities of germination. Ultimately, the rates of seedling establishment with and without small mammals determine if they are beneficial or not to tress.The main question of the 2nd phase of subproject 7 is if a different set of tree species used in forestry practices change where the interactions between small mammals and trees are placed along the mutualism-antagonism continuum.
During the 1st phase of the project it was found that, among other things, there is a high preference by small mammals for removing beech seeds compared to conifer seeds and that there is a difference in relative abundance of mice and voles according to nutrient-poor (northern – more mice) and nutrient-rich (southern – more voles) sites. Also, mice were found to interact more frequently with seeds than voles.
On the second phase we will conduct surveys of small mammal densities and species relative abundance through mark-recapture trapping, assess the fate of seeds removed by small mammals through seed line tracking and evaluate germination rates of seeds cached by small mammals against seeds left intact on the soil using exclusion cages and artificial caches.