European rabbits versus native rodents in Central Chile: effects on shrub seedlings

Summary

The importance of the introduced rabbit Oryctolagus cuniculus and of the native rodent Octodon degus (=degu) as browsers of shrub seedlings in the Central Chilean evergreen shrublands (=matorral) was experimentally assessed. Seedlings were planted in several spatial arrangements in two open successional stands and in two mature stands of different cover and exposure. The browsing impact of rabbits and degus was evaluated separately after about one year since the start of the experiments. It was found that degus cause important seedling mortality only within a 5 m-radius centered at the border of their retreats. Rabbits, on the other hand, cause heavier seedling mortality, forage more widely, and consequently have a greater impact than do degus. It is speculated that rabbits may be halting the secondary succession process, shifting the matorral composition toward less palatable shrub species, and/or broadening the spacing between shrub clumps.