Pj Dalton

Impact of distance to mature forest on the recolonisation of bryophytes in a regenerating Tasmanian wet eucalypt forest

Forest influence is a type of edge effect that occurs when mature forests affect the recolonisation of adjacent disturbed areas. This can be driven by changes in microclimate conditions near the edge or by an increase in establishment ability with proximity to a propagule source. Bryophyte recolonisation is sensitive to both microclimate and dispersal distance, therefore they are an ideal group to examine how strong forest influence is and over what distance it operates. Responses to forest influence are known to be highly species dependent; therefore, we tested whether distance affects the recolonisation ability of a range of bryophytes. As well as examining a range of species, we tested whether forest influence operated differently on two types of substrate used by bryophytes (logs and ground). For most of the species examined, establishment rates in disturbed forest diminished further away from the mature edge. The influence of unlogged mature forest on bryophyte establishment in harvested forest occurred up to 50 m. Species varied in their response to distance, and the relationships with distance were stronger on the ground compared with log substrates. These results support the concept of forest influence, with areas closer to mature forest experiencing more substantial re-establishment. These findings are relevant to conservation of bryophytes in managed native forests.

Does moisture affect the partitioning of bryophytes between terrestrial and epiphytic substrates within cool temperate rain forests

Abstract Bryophyte communities are highly sensitive to moisture and/or humidity levels. Most studies on the subject focus on bryophytes on either tree or ground habitats and do not consider how bryophytes partition themselves across both ground and epiphytic substrates within the same forest. Sampling mesic temperate forest sites of the same physiognomy from two Tasmanian regions with slightly different moisture levels (a wetter northwest versus a drier northeast region), we examine various aspects of the community structure (overall liverwort and moss cover; species richness; and liverwort to moss ratios) of both tree and ground communities with respects to moisture availability. We then test the hypothesis that a wetter site will exhibit a greater magnitude of bryophytes inhabiting both tree and ground habitats. Results of the analyses show that the ground habitat in the northwest sites exhibited a significantly higher mean species richness, higher overall and mean liverwort to moss ratio, and a higher liverwort cover than the northeast sites. This suggests that the northwest had a more ameliorated ground microclimate than the northeast. In terms of habitat partitioning, a significantly higher percentage of taxa occupied both tree and ground habitats in the northwest, compared to the northeast, which exhibited a higher percentage of taxa restricted to trees. It is proposed that within a single vegetation type, a higher site moisture level may create microclimates conducive to more bryophyte species in both tree and ground habitats, especially the latter, thereby enabling taxa to colonize and coexist on both substrates more freely.

Mosses from Early Pleistocene sediments in western Tasmania

Macrofossils of six terrestrial and epiphytic taxa from five families of moss (Musci) occur in Early Pleistocene sediments at Regatta Point, western Tasmania. These are: Ptychomnion aciculare and Weymouthia mollis, which are clearly the same as modern southern Australian species; Echinodium hispidum and Thuidium sp., which are probably modern species; a species of Papillaria that appears to no longer occur in southeastern Australia; and one unidentified taxon. All are likely to have been species of wet forest or stream sides, and suggest that well-established rainforest occurred locally, at least in riparian areas.

A reconsideration of Pleurophascum (Musci: Pleurophascaceae) and specific status for a New Zealand endemic, Pleurophascum ovalifolium stat. et nom. nov.

Abstract The taxonomy of and relationships between the three taxa described in the genus Pleurophascum are reconsidered. P. grandiglobum is confirmed as a Tasmanian endemic. The New Zealand taxon, heretofore known as P. grandiglobum var. decurrens, differs from the Tasmanian species by numerous morphological characters, including capsule shape, size, and pigmentation; leaf shape; and degree of reflexion of the leaf margins. The New Zealand taxon is given specific status as P. ovalifolium stat. et nom. nov. Both P. grandiglobum and P. ovalifolium have laterally borne sex organs that are not subtended by innovations. Recently discovered fruiting material of the Western Australian endemic P. occidentale differs from both P. grandiglobum and P. ovalifolium by having terminal sex organs, short (c. 1 mm) setae, and nearly sessile, obovoid, and non‐rostrate capsules that lack stomata. Distribution maps and a key to the species are provided. The larger relationships of the genus Pleurophascum cannot yet be resolved.

Distance, environmental and substrate factors impacting recovery of bryophyte communities after harvesting

Aims: Bryophyte re-colonization after disturbance is largely governed by environmental conditions within disturbed forests. In particular, distance to a forest edge is an important predictor of bryophyte community re-colonization, through either direct constraints, such as dispersal limitation, or indirectly by altering environmental conditions. This study examines a range of factors – environmental, distance to an edge, substrate specific environment or local-level environment – to determine which are important in the re-colonization of bryophyte communities after forest harvesting. As bryophyte communities vary with the particular substrate inhabited, responses were examined across four substrates (rock, exposed roots, ground and CWD). Location: Tasmanian southern forests, Australia. Methods: Bryophyte composition was examined on four substrates (ground, coarse wood debris, exposed roots, rocks) within three ages (~7, ~27 and ~45 yr post-disturbance) of harvested wet eucalypt forest. Re-colonization success of bryophyte communities was determined by comparing communities in regeneration forest to mature forest communities using axis scores from one-dimensional constrained ordination. The importance of various environmental conditions for re-colonization success was then modelled. Finally, path analysis was used to determine whether the impact of distance to a forest edge was meditated through its effects on key environmental variables. Results: Multiple environmental factors impacted re-colonization of mature bryophyte communities. Local-level conditions such as microclimate (temperature, humidity and VPD) and LAI were the most important in determining re-colonization across substrates. Path analysis showed that distance to a forest edge had a significant impact on re-colonization success, but only a relatively small part of this was mediated through its impact on environmental factors. Conclusions: Bryophyte re-colonization is driven by a combination of microclimate conditions and factors related to distance from a forest edge (most likely dispersal distance). While some substrate-specific factors impact bryophyte re-colonization success, the consistent impact of local environmental factors across substrates suggests that harvesting management strategies that develop more ‘mature’ microclimate conditions and increase proximity to nearby mature forest patches will be beneficial for all bryophytes communities. As bryophyte re-colonization was correlated with temporally dynamic environmental conditions, we suggest that forest age needs to be considered in future work.

Seligeria cardotii R.Br., a new moss record for Tasmania

Abstract Seligeria cardotii R.Br., a calcicolous moss previously known only from New Zealand, is recorded for the first time in Tasmania. A description and illustration are provided for the species, as well as a discussion of its biogeography.