The Diversity and Abundance of Small Mammals in Sage-steppe Habitat Fragments within Agricultural and Lava-flow Matrices

Hanser, Steven

Comparison of small mammal communities in sagebrush fragments between agricultural and lava flow matrix (kipukas). Conservation of small mammals in an increasingly fragmented landscape will rely on insights from studies of habitat fragmentation and of the intervening habitat between fragments, the matrix. This study is focused on remnant sage-steppe habitat patches isolated by two different matrices in order to assess the efforts of isolation and matrix habitat on small mammals. Kipukas are patches of naturally occurring sage-steppe habitat surrounded by harsh lava matrix of the Craters of the Moon Lava Flow. Agricultural patches are fragments of sage-steppe habitat that remain within agricultural fields. They trapped small mammals on 11 kipukas and 11 agricultural patches during the summer of 2001. Sage-steppe habitat isolation led to a decline in small mammal species richness. Species composition of patches and the isolation and habitat relationships differed between the lava-flow and agricultural landscapes. Isolation by the lava matrix led to strong relationships between small mammal species richness, Simpson’s Index or density and isolation of habitat characteristics, whereas isolation by the agricultural matrix led to few and only weak relationships.