| Abstract |
- An experimental reintroduction was performed to determine the best method to create new populations of the tuberous species Perideridia erythrorhiza, a rare vascular plant endemic to southern Oregon. Only a handful of sites are currently present, and many of these are subject to other land uses such as urban development and grazing. Before a costly large scale recovery effort is implemented, a stream-lined protocol using smaller, experimental reintroductions
should be created. In this study, different propagule types, sizes, and transplant times were investigated, including large adult tuberous roots, small juvenile tuberous roots, and seeds. Propagules were planted either in the spring or in the fall, and monitored over two growing seasons for emergence, growth, and reproduction. Environmental data were also gathered in an attempt to correlate transplant success with soil moisture and vegetation cover. It was found that large tubers from adult plants transplanted in the fall had the highest probability for survival, produced the most leaves, and exhibited the highest reproductive output. While the small juvenile tubers did poorly, fall planted seed did surprisingly well, but the long-term survival of plants from seed could not be determined in the time frame of this study. While vegetation cover did not appear to have any affect on survival, increasing soil moisture had a negative affect. To provide information useful in the ongoing reintroduction project, the life history
of Perideridia erythrorhiza was examined. Seed germination, juvenile and adult development, reproduction, and breeding system were examined and documented. Of particular interest was the feasibility of rapidly growing large, adult tubers from
seed in a controlled setting, thus avoiding the need to harvest large tubers from extant populations. It was found that by using germination chambers and the greenhouse, plants could reach a size equivalent to a three year old plant - about the stage in development when plants begin to reproduce - in thirteen months. It was also determined that P. erythrorhiza is typically outcrossing. Plants produce fewer seeds when self pollinated, have a high level of inbreeding depression present at the seed production stage, and produce few seeds autogamously, suggesting the need to
incorporate the breeding system of P. erythrorhiza into any future management
protocol. Pollinators will need to be present at reintroduction sites to ensure cross pollination or manual hand pollination will be necessary. If transplants are to be
cultivated, it will be important to ensure that they are not closely related, and that
seed will need to be collected from a number of different individuals.
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