The germination requirements of 19 herbs in the Australian Alps were investigated
to determine which species may be sensitive to predicted climate changes.
Seeds were subjected to factorial treatments of cold stratification for
0, 4, 8 and 12 weeks, followed by incubation at constant temperatures
of 10, 15, 20 and 25 °C and alternating temperatures of 20/5 and 20/10
°C. Germination responses were used to identify stratification-dependent
species, to classify dormancy and to determine optimum conditions for
laboratory germination. Ordinal logistic regression was used to determine
whether the duration of stratification required for at least 50% germination
could be predicted by seed weight, seed length, embryo : seed ratio or
species distribution (latitudinal range, altitudinal range and maximum
altitude). The Kruskal–Wallis test was used to determine any significant
differences in stratification requirement between endospermic and non-endospermic
seeds. Species varied considerably in their response to the treatment
combinations, and therefore their dormancy class. No significant predictors
of stratification requirement were identified by ordinal logistic regression
(P > 0.9); however, there was a significant difference in stratification
requirement between endospermic and non-endospermic seeds (P = 0.003).
Species with non-endospermic seeds did not require any stratification
to germinate well over a range of temperatures, and appear most likely
to remain stable or expand in range in response to climate warming. Conversely,
the need for at least 8 weeks of cold stratification was associated with
the presence of endosperm and either a restricted distribution or upland
ecotypes of widely distributed species. Alpine species with endospermic
seed and a restricted distribution are most likely to contract in range
under climate change and would be appropriate to prioritize for ex situ
conservation. © 2013 The Linnean Society of London,, Botanical Journal
of the Linnean Society, 2013, 172, 187–204.
ADDITIONAL KEYWORDS: alpine – climate – dormancy – germination – plant conservation – seed structure – temperature requirement.