Australian Alpine seeds and seedlings: Can they cope with change?

Background/Question/Methods

The Australian Alps have been identified as critically vulnerable to climate change by the International Panel on Climate Change. Alpine environments occupy ca. 5200 km² of Australia’s south-east mainland. This alpine ecosystem is Heritage listed, a centre of plant diversity within Australia and one of the world’s biodiversity hotspots. Australian alpine species are being forced to move into cooler, wetter areas as their native environments experience reduced snow cover/depth, increased summer temperatures and elevated CO₂ . Little is known about Australian alpine seed germination strategies or the resilience of alpine seeds and seedlings to future climate scenarios. Experiments are currently underway to investigate: 1) Which alpine seeds germinate at dispersal and which postpone germination? 2) Which alpine plants form persistent soil seed banks? and 3) How do alpine plant, seed and seedling traits vary with altitude?

Mature seeds of 44 alpine forb species were collected for ex situ seed germination tests. Alpine soil collected post spring germination was examined for seed bank content under glasshouse temperature regimes designed to mimic current and future climate scenarios. Plant data and seeds from > 30 individual plants from each of 8 species were collected along altitudinal gradients to assess patterns of variation with altitude.

Results/Conclusions

Preliminary data suggests that the majority of Asteraceae, Poaceae and Caryophylaceae seeds tested will germinate immediately post-dispersal in situ. In contrast, most Apiaceae and Cyperaceae seeds tested did not germinate under ‘summer’ or autumn’ conditions despite high viability. Dormancy mechanisms that postpone germination until during or after the winter may enable these species to maximize the short alpine growing season.

Preliminary results suggest greater germination from the soil seed bank in ‘cool’ compared to ‘warm’ conditions suggesting fewer seedlings emerging from such soil under future, warmer climate scenarios. Species vary in the effects of altitude on seed production, seed characteristics and vegetative traits.

Our protocols for reliable seed germination and plant propagation will contribute to effective future management of alpine flora. Ex situ, our work will improve conservation of alpine flora at the Australian Alpine Seed Bank and increase public awareness of both climate change and the challenges facing the Alpine region in particular.