- Title
- Environmental factors affecting the abundance of the threatened shrub Tasmannia glaucifolia (Winteraceae) in Barrington Tops National Park
- Creator
- Voigt, Jenna; Chalmers, Anita
- Relation
- Cunninghamia Vol. 22, p. 1-10
- Relation
- https://www.botanicgardens.org.au/our-science/publications/cunninghamia#volume-22-2022
- Publisher
- The Royal Botanic Garden Sydney
- Resource Type
- journal article
- Date
- 2022
- Description
- Tasmannia glaucifolia (family Winteraceae) (Fragrant Pepperbush) is a rare and threatened shrub endemic to the Northern Tablelands of New South Wales. Reported to be a riparian species, this is the first study to examine the habitat, population structure, health, and potential environmental pressures relating to the Barrington Tops population, and will provide baseline data to increase our understanding of the species. At four study locations in Barrington Tops National Park (one of the three known NSW populations), Polblue swamp, Beean Beean swamp, Edwards swamp and Upper Edwards swamp, 36 quadrats were surveyed across three different habitat types (riparian swamp, riparian woodland, and woodland). Counts, size and health of Tasmannia glaucifolia individuals were recorded, as well as selected environmental and disturbance variables. A total of 491 Tasmannia glaucifolia plants were recorded, lignotuber-style organs on mature individuals noted, and limited seed regeneration confirmed. General linear mixed models (GLMM) showed greatest support for the abundance of Tasmannia glaucifolia depending on habitat type and aspect, and varying with swamp location. The highest numbers of Tasmannia glaucifolia were recorded in riparian woodland habitat (73%) followed by woodland habitat (26%); few individuals were recorded in riparian swamp habitat. An exploratory analysis leads us to hypothesise that aspect has an influence on Tasmannia glaucifolia abundance, with higher counts in this study tending towards southerly aspects. A purple discolouration observed on Tasmannia glaucifolia foliage appears to be more severe in northerly or westerly aspect sites. Moderate support was shown for the GLMM model where Tasmannia glaucifolia abundance depended on habitat type and the cover of exotic Scotch Broom (Cytisus scoparius), with weaker support for Tasmannia glaucifolia abundance depending on habitat type and an indicator of feral horse activity. Scotch Broom and indicators of feral horse activity frequently occurred in the Tasmannia glaucifolia habitats investigated here. Management actions involving feral horse exclusion experiments and removal of Scotch Broom and monitoring over time is needed to evaluate impacts and refine the conservation strategies for this listed Vulnerable species.
- Subject
- threatened shrub endemic; Tasmannia glaucifolia; environmental factors; understanding of the species
- Identifier
- http://hdl.handle.net/1959.13/1495483
- Identifier
- uon:54022
- Identifier
- ISSN:0727-9620
- Language
- eng
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