Plant Patterning in the Chilean Matorral: Are the Roles of Native and Exotic Mammals Different?1

Professor and Instructor of Biological Sciences, respectively, at Pontificia Universidad Católica de Chile. Casilla 114-D, Santiago, Chile. Abstract: Native and exotic mammals have different effects on the matorral vegetation. (A) Large mammals (guanacos vs goats) differ in that native guanacos are only minor browsers, whereas goats use shrubs more extensively. Differences between goats and shrub-defoliating insects provide additional evidence that goats are a novel perturbation on the matorral vegetation. (B) European rabbits and their native counterparts differ in their effects on shrub seedlings and on native perennial herbs. Native small mammals affect only the periphery of antipredator refuges. Rabbits are infrequently preyed upon, do not exhibit such habitat restriction, and show a more extensive effect. Implications for matorral renewal are discussed.