Publication Date

Summer 2024

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Studies

Advisor

Rachel O’Malley; Lynne Trulio; Benjamin Carter

Abstract

Human actions directly damage habitat for native plants; restoration ecology facilitates successful plant re-establishment in these environments. Open-pit mines leave behind steep, rocky, and nutrient-deficient habitats that are some of the most degraded ecosystems on the planet. Dudleya or ‘live-forevers’— a genus of native California succulent plants that contains many rare, threatened, or endangered species — grow on rocky cliffs and may create a successful reclamation-restoration story. However, Dudleya germination is poorly understood. Much of the literature on Dudleya cites a single field report suggesting that bryophytes facilitate germination, but no previous experiments have evaluated this proposal. In this study, I used germination trials to see whether the bryophyte subgroup mosses facilitate Dudleya germination in nutrient-poor quarry soils. In a two x three factorial design, I planted 11 replicants of 10 Dudleya cymosa subspecies cymosa seeds in pots with potting or quarry soil and one of three soil covers: bare soil, the moss Anacolia baueri, or the moss Homalothecium pinnatifidum. Overall, D. cymosa subsp. cymosa germination was low in quarry soil, regardless of soil cover, and higher in potting soil. This means that the addition of mosses did not facilitate Dudleya germination by serving as early succession nurse species, rather mosses displayed allelopathic traits. These findings underscore the value of interrogating field observations through careful manipulative experiments. While Dudleya did germinate on quarry soil the rate was low and further specific studies should be conducted to determine best practices for establishing new populations in quarries.

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