Assessing the storage potential of Australian rainforest seeds: a decision-making key to aid rapid conservation

Abstract

Seed banking of rainforest species is hindered by lack of knowledge as to which species are tolerant of desiccation and freezing. We assessed 313 Australian rainforest species for seed banking suitability by comparing the germination percentage of fresh seeds to seeds dried at 15% RH and seeds stored at −20 °C after drying. We then compared desiccation responses to environmental, habit, fruit and seed characteristics to identify the most useful predictors of desiccation sensitivity. Of 162 species with ≥ 50% initial germination, 22% were sensitive to desiccation, 64% were tolerant and 10% were partially tolerant; the responses of 4% were uncertain. Of 107 desiccation tolerant species tested for response to freezing, 24% were freezing sensitive or short-lived in storage at −20 °C. Median values for fresh seed moisture content (SMC), oven dry weight (DW) and the likelihood of desiccation sensitivity (PD-S) were significantly greater for desiccation sensitive than desiccation tolerant seeds. Ninety-four to 97% of seeds with SMC < 29%, DW < 20 mg or PD-S < 0.01 were desiccation tolerant. Ordinal logistic regression of desiccation response against environmental, habit, fruit and seed characteristics indicated that the likelihood of desiccation sensitivity was significantly increased by a tree habit, fleshy fruit, increasing fresh SMC and increasing PD-S. The responses observed in this study were combined with earlier studies to develop a simple decision key to aid prediction of desiccation responses in untested rainforest species.

Restoration seedbanks for mined land restoration

“…2B). When the fresh seed moisture content of M. fraseri is compared against data from a range of desiccation-sensitive rainforest species (Sommerville et al 2021-fig. 7A) the M. fraseri values neatly fall within the interquartile range ($43-58%) of the desiccation-sensitive species.…”

Low availability of functional seed trait data from the tropics could negatively affect global macroecological studies, predictive models and plant conservation

“…Desiccation-sensitive seeds are mainly limited to climax species and/or to habitats where they are not likely to be exposed to drying and/or freezing conditions after dispersal ( Tweddle et al , 2003 ), such as in tropical rainforests. However, seed desiccation sensitivity is a relatively understudied trait, particularly for species from tropical montane forests ( Tweddle et al , 2003 ; Sommerville et al , 2021 ). We show below how this lack of tropical data could reduce the predictive power of global models.…”

Plant Diversity Conservation Challenges and Prospects—The Perspective of Botanic Gardens and the Millennium Seed Bank

“…A major step forward is that requirements to conserve these species ex situ are being progressively understood and workflows have been developed to assist the fast-tracking of conservation efforts. This includes the latest techniques for selection of appropriate germplasm to conserve ex situ, an important step for the success of ex situ conservation of 'exceptional species' which require significant research effort [49]. At the regional level, the European Native Seed Conservation Network (ENSCONET), a consor-tium of organisations interested in native species conservation, created seed collecting and processing manuals for practitioners, available in nine European languages [50,51].…”

“…Efforts have largely focused on dryland species, due to the expectation of desiccation sensitivity of seeds of rainforest. Several studies have explored the seed storage potential of Australian rainforest flora [49,94] and these results were combined with other data sets to develop a key for determining the seed storage potential of untested rainforest species [49]. This key will help us to understand the complex biology of 'exceptional species' and recognise species that need conservation efforts beyond the traditional seed bank.…”