Epiphytic ferns and bryophytes of Tasmanian tree‐ferns: A comparison of diversity and composition between two host species

Abstract Ferns, bryophytes and lichens are the most diverse groups of plants in wet forests in south‐eastern Australia. However, management of this diversity is limited by a lack of ecological knowledge of these groups and the difficulty in identifying species for non‐experts. These problems may be alleviated by the identification and characterization of suitable proxies for this diversity. Epiphytic substrates are potential proxies. To evaluate the significance of some epiphytic substrates, fern and bryophyte assemblages on a common tree‐fern species, Dicksonia antarctica (soft tree‐fern), were compared with those on a rare species, Cyathea cunninghamii (slender tree‐fern), in eastern Tasmania, Australia. A total of 97 fern and bryophyte species were recorded on D. antarctica from 120 trunks at 10 sites, and 64 species on C. cunninghamii from 39 trunks at four of these sites. The trunks of C. cunninghamii generally supported fewer species than D. antarctica, but two mosses (particularly Hymenodon pilifer) and one liverwort showed significant associations with this host. Several other bryophytes and epiphytic ferns showed an affinity for the trunks of D. antarctica. Species assemblages differed significantly between both sites and hosts, and the differences between hosts varied significantly among sites. The exceptionally high epiphytic diversity associated with D. antarctica suggests that it plays an important ecological role in Tasmanian forests. Evidently C. cunninghamii also supports a diverse suite of epiphytes, including at least one specialist species.     

4-O-Caffeoylshikimic and 4-O-(p-Coumaroyl)shikimic Acids from the Dwarf Tree Fern,Dicksonia antarctica

Two derivatives of shikimic acid were isolated from croziers of the dwarf tree fern, Dicksonia antarctica, and their structures were elucidated as 4-O-caffeoylshikimic acid and 4-O-(p-coumaroyl)-shikimic acid on the basis of mass spectrometric and NMR spectroscopic evidence.     

Isoprene emissions and photosynthesis in three ferns – The influence of light and temperature

A study was designed to determine the rates of isoprene emission and photosynthesis in three fern species [ Dicksonia antarctica Labill., Thelypteris decursive-pinnata (Van Hall) Ching and Thelypteris kunthii (Desv.) Morton] and the independent influence of light and temperature on these processes. The plants were conditioned in a growth chamber and then transferred to a controlled environment gas-exchange chamber. Samples of the chamber atmosphere were collected; isoprene was concentrated cryo-genically and measured by gas chromatography. Only small amounts of isoprene were detected around the ferns in the dark. Isoprene emissions increased with increasing levels of photosynthetic photon flux density (PPFD) in all three species; 50% of the maximum emission occurred at PPFD levels of 130 to 500 μmol m−² s−¹. Maximum isoprene emissions occurred between 35 and 39°C which is a lower temperature maximum than reported for angiosperms and gymnosperms. The increased emissions with temperature were primarily associated with increased biosynthetic rates for isoprene. Carbon lost through isoprene accounted for 0.02 to 2.6% of the carbon fixed during photosynthesis, depending on the PPFD level, temperature and fern species.     

How old are Wet Forest understories?

Abstract Radiocarbon ages were derived from 12 individuals representing four species of woody understorey plants growing in the Eucalyptus regnans dominated Wet Forests of Victoria's Central Highlands. Cyathea australis, Dicksonia antarctica and Olearia argophylla are common and often dominate the understorey. The fourth species, Persoonia arborea, is a small understorey tree endemic to this region. Field observations and radiocarbon ages for these four species (up to 370 ± 70 years BP) indicate they are capable of surviving fire and are long-lived in this environment.