Small mammals of the Planted Forest Zone of Sarawak, East Malaysia; an assessment of dispersal ability and response to habitat fragmentation

摘要

In recent years a push to establish pulpwood plantation forestry in Sarawak, East Malaysia with Acacia mangium has been identified as a means to relieve pressure on the State’s diminishing natural forest resource whilst providing 1) economic wealth for a developing economy 2) community development, and 3) biodiversity conservation outside the protected area network. In a specially designated 504,000 hectare Planted Forest Zone (PFZ) a range of broad-scale landscape planning initiatives have been implemented in an attempt to conserve a representative sample of biodiversity across the plantation landscape. The effects of forest modification and fragmentation have been widely reported in the literature for mammals, and in this study, non-volant small mammals were fitted with tracking spools and/or radio collars and released into small forest remnants outside of their home ranges to measure response to unfamiliar habitats, forest edges and various scales of habitat fragmentation during simulateddispersal events. Medium sized patches exhibited the greatest species diversity and abundance, whereas the largest forest areas hosted the largest population of brown spiny rat (Maxomys rajah); a species that is identified as vulnerable across its natural range. Small forest patches of c.1.00 ha that had been exempt from clearing during plantation establishment are likely to be species poor and host small populations of extant species only. All species were found to make extensive use of downed woody debris for movement, and showed varied responses to a range of habitat edges including forest roads, acacia plantation compartments, old haul trails, clearings and riparian areas. Two species of treeshrew; long-footed treeshrew (Tupaia longipes) and painted treeshrew (T. picta) were shown to be able to move between the forest patch and the acacia forest while the same edges were shown to pose barriers to the brown spiny rat (M. rajah) and large treeshew (T. tana) illustrating the different ways that species may perceive and use habitat features such as corridors.Despite T. picta being common in the PFZ, comparatively little has been published on its ecology and behaviour compared with the other Bornean tupaiids. Therefore this study also reports on the movement and behaviour of this species within its own home territory as revealed from both radio telemetry and spool-and-line tracking. Home range size, dimension, average daily movement distances and nest site construction was found to be similar to other Tupaiids studied in secondary forests in Sabah, and home ranges were found to be dictated by anthropogenic landscape features such as forest roads and open areas across which no movement was recorded. Painted treeshrews were found to favour logs and fallen woody debris as movement substrates and spend the large majority of their movement at ground level. Camera trapping revealed possible interspecific nest sharing between the painted treeshrew and the three-striped ground squirrel (Lariscus insignis), fuelling the debate on whether or not treeshrews construct their own nests or use nests constructed by squirrels.