Understanding seed dormancy and germination aids conservation of rainforest species from tropical montane cloud forest: a case study confirming morphophysiological dormancy in the genus

Abstract

Context. Seed dormancy is one issue hindering implementation of conservation actions for rainforest species. Aims. We studied dormancy and germination in Tasmannia sp. Mt Bellenden Ker and Tasmannia membranea, two tropical montane rainforest species threatened by climate change, to develop a better understanding of dormancy in the species and the genus. Methods. Dormancy was classified for T. sp. Mt Bellenden Ker on the basis of an imbibition test, analysis of embryo to seed length (E:S) ratios and germination in response to the following four dormancy-breaking treatments: (1) scarification of the seedcoat near the micropylar end;(2) removal of the seedcoat; (3) application of 100 mg L −1 or (4) 500 mg L −1 gibberellic acid. The most effective treatment was then tested on T. membranea. The requirement for light for germination was also assessed. Key results. Both scarified and intact seeds imbibed water. Initial E:S ratios were <0.22 for both species and increased up to 0.74 after 40 days, just before radicle emergence, for T. sp. Mt Bellenden Ker. Germination proportions were significantly higher in Treatments 1 and 2 than the remaining treatments for T. sp. Mt Bellenden Ker; T. membranea responded similarly well to Treatment 1. Germination under alternating light/dark conditions was slightly, but not significantly, greater than germination in the dark alone. Conclusions. Both species have morphophysiological dormancy and treatments that remove seedcoat resistance to embryo growth facilitate germination. These treatments may improve germination in other species from the genus Tasmannia. Implications. This knowledge will aid the germination of seeds to implement conservation strategies for Tasmannia spp.

Impacts of anthropogenic climate change on tropical montane forests: an appraisal of the evidence

“…(2023) reported that the genetic health of a tropical montane tree species in Mexico is threatened by human activity and climate change. Research on treeline expansion has also shown that dry conditions in the boundary between TMF and páramo in the Venezuelan Andes support a seedling bank, but with slow growth (Ramírez et al ., 2022); and some species may need treatment, such as scarification, to increase germination rates (Liyanage et al ., 2022). Thus, understanding the genetic adaptations and environmental influence of seeds and seedlings is crucial for conservation efforts.…”

Temperature, nutrient availability, and species traits interact to shape elevation responses of Australian tropical trees

“…not negatively impact growth in situ, with optimal growth of this species occurring at temperatures higher than currently experienced. However, other factors associated with warming, such as increasing atmospheric water stress (Bauman et al, 2022b), and effects on seed bank dynamics (Liyanage et al, 2022), along with biotic interactions, may negatively impact survival of such mountaintop endemic plants (Cheesman and Winter, 2013).…”