Abstract Detail

Extreme conservation measures for plants at the extremes in the Hawaiian archipelago model system

Wolkis, Dustin [1], Deans, Susan [2].

Assessing the use of herbarium specimens as an untapped source for ‘ōhi‘a seed preservation.

‘Ōhi‘a, or Metrosideros polymorpha, is one of the most common trees in Hawaii’s native forest, serving as an ecological backbone that also has significant cultural importance. Newly described fungal pathogens, Ceratocystis lukuohia and C. huliohia, cause the disease known as rapid ‘ōhi‘a death (ROD), emerging as a serious threat to ‘ōhi‘a. Efforts to mitigate the damage of these pathogens include securing ‘ōhi‘a seeds ex situ for potential restoration. Seed banks are one promising resource, as they contain previously collected seeds in optimal conditions to maintain viability, and are a repository for ongoing collection efforts. We investigated a potential alternative source of ‘ōhi‘a seeds that are incidentally collected and preserved for another purpose—herbarium voucher specimens. Because ‘ōhi‘a seeds are orthodox, or able to remain viable in long term storage following conventional drying and freezing protocols, we asked whether seeds found on herbarium voucher specimens maintain viability following entry and storage in herbaria, to serve as another source of genetic diversity for restoration in the face of ROD.  We investigated three topics: 1) how long ‘ōhi‘a seeds maintain viability on herbarium sheets, 2) how herbarium curation practices affect seed viability of ohia, and 3) how long ‘ōhi‘a seeds survive in conventional seed banks. We collected fresh ‘ōhi‘a seeds and placed them in an herbarium dryer (57°C/5% relative humidity) for 5 days, followed by 2 weeks in the freezer (−18°C/95% RH) to mimic conditions herbarium vouchers experience before storage, and compared their viability to fresh seeds. We compared these herbarium treatment seeds to seeds that were harvested from a chronosequence of herbarium specimens, and seeds stored with conventional seed banking methods between 3.75 and 6.5 years old. Viability was assessed using germination trials. There was no difference in the proportion germinated among treatments and controls for herbarium entry (p = 0.56). Although no seeds from herbarium specimens germinated, freshly collected dried and frozen seeds germinated at proportions equivalent to the control (p = 0.76). For seeds stored using conventional storage methods at 3.75 and 6.5 years, germination was equivalent to fresh seeds. While these results suggest that ‘ōhi‘a seeds may be able to survive conventional herbarium entry methods, they likely lose viability in 4 years or less in storage. Conservation practitioners should not rely on herbaria as a seed source for ‘ōhi‘a, and instead should use traditional seed banks and other ex situ conservation methods for restoration.

1 - National Tropical Botanical Garden, Science & Conservation, 3530 Papalina Rd, Kalaheo, HI, 96741, United States
2 - Plant Extinction Prevention Program, 3060 Eiwa St. , Lihue, HI, 96766, USA

none specified

Presentation Type: Colloquium Presentations
Session: COL05, Extreme conservation measures for plants at the extremes in the Hawaiian archipelago model system
Location: Virtual/Virtual
Date: Wednesday, July 29th, 2020
Time: 3:45 PM
Number: COL05011
Abstract ID:846
Candidate for Awards:None

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