Bat activity on riparian zones and upper slopes in Australian timber production forests and the effectiveness of riparian buffers

Abstract

Unlogged buffers are used to ameliorate impacts to riparian areas in timber production forests. One function of these buffers is to protect the biodiversity of riparian areas. We measured bat activity in buffered streams with ultrasonic detectors across four different stream orders in logged, regrowth and mature forests (60 sites). Bat activity, foraging rates and species richness were similar in buffered streams surrounded by logged, regrowth and mature forests, suggesting that riparian areas effectively provide habitat for foraging and commuting bats in selectively logged forests. Vespadelus pumilus was the only species that responded to logging history, with decreased activity in mature forests. We found higher activity on larger rather than smaller order streams, a pattern also not affected by logging history. Bat activity along paired forest trail flyways on upper slopes (60 sites) was measured simultaneously with riparian flyway activity (for a total of 120 sites) to determine the importance of riparian areas relative to other available flyways. Activity was higher on upper slopes than on small streams, but similar to levels on larger streams. Total foraging activity was similar between riparian zones and upper slopes. Upper slopes contained higher species diversity, with Chalinolobus gouldii, Miniopterus schreibersii, Mormopterus norfolkensis, Scotorepens sp., Vespadelus pumilus and, to a lesser extent, Vespadelus darlingtoni detected more often than along streams. Other species ( Rhinolophus megaphyllus, Nyctophilus spp. and Miniopterus australis) were not affected by topography. Estimates of total vegetation cover and, in particular, rainforest cover, were negatively associated with bat activity, highlighting the need for management of forest ‘clutter’ in regrowth forests for a suite of bat species. Streams and forest trails provide areas of lower clutter, which assist in maintaining high species diversity in regrowth forests. Our results support the use of riparian buffers, and point to the need for greater recognition of tracks on upper slopes as important habitat.