The effects of large-scale fragmentation on bryophytes in temperate forests.
Abstract
Bryophyte response to landscape fragmentation has not been investigated in replicated studies in temperate forests. Many bryophytes disperse widely but have narrow habitat requirements, suggesting that their responses to fragmentation may differ from other taxa. We studied 16 sites in native eucalypt remnants located within an intensively managed plantation of exotic Pinus radiata. Eight further sites were dominated by exotic pines, and eight more were in large, continuous areas of native eucalypt forest located at the plantation boundary. We investigated how landscape context, remnant size and time since remnant isolation influence the bryophyte assemblage. Rocks, logs, soil, upturned trees and standing dead and live trees were sampled at each site. Eucalypt remnants supported all but six of a total of 58 bryophyte taxa. Radiata pine sites were missing 40% of the species found in native forest, and pine was the only landscape context class not to have unique species. There was little difference in the richness or assemblage composition between the remnants and the unfragmented eucalypt forest. Bryophyte assemblages differed between substrates but were similar across the same substrates even in different landscape context classes (except for rocks). Strip-shaped remnants had more bryophytes in common with continuous forest than patch-shaped remnants, while moss richness increased with remnant size. Synthesis and applications. Native eucalypt remnants surrounded by intensively managed radiata pine plantation appeared to have retained, or regained, much of their bryoflora. Pine plantations were relatively depauperate, although burned eucalypt logs that remained after clearing native forest provided key substrates for many species and were crucial for maintaining bryophyte diversity. Forest managers aiming to retain bryophyte diversity should conserve native remnants of all sizes and retain suitable structural attributes, such as large decayed logs. Our findings support the hypothesis that many bryophytes have the mobility to overcome dispersal problems posed by fragmented landscapes if appropriate habitat or substrate is available.