Publication Date

2014

Document Type

Honors Thesis

Department

Biological Sciences

Keywords

Climatic change, Endemic plants-Climatic factors, Climate change mitigation, Assisted migration (Plant colonization), Germination, Plant conservation, Assisted colonization, Climate change, Endemic species, Conservation, Seed germination

Abstract

Scientists have already begun to document evidence of range shifts as many species respond to anthropogenic climate change. However, some species with limited dispersal ability or long generation times may not be able to adapt or adjust their distributions as rapid climate change exceeds their migrational capacities. A controversial new conservation technique termed "assisted colonization" or "managed relocation" has been proposed as one solution for protecting climate-threatened, dispersal-limited species by intentionally translocating them to new areas where they have not occurred historically, but where they are expected to survive in the future. In this study, I use the Southern Appalachian endemic plant Umbrella-leaf (Diphylleia cymosa) as a model to explore issues surrounding this unconventional conservation approach. In its native range in the Southern Appalachian Mountains of the eastern United States, D. cymosa is restricted to cool, high elevation forests, a habitat type that is projected to decline in coming decades with climate warming. To test how seed germination rates might be influenced by reduced length of winter cold stratification, I exposed D. cymosa seed to 0, 6, 12, 18 and 24 weeks of cold stratification at ~ 1° C and then measured their germination rates. To place these experimental treatments in a geographic context, GIS spatial analysis was also used to quantify current environmental conditions within the native range of D. cymosa. Results show that D. cymosa seeds require a minimum of 12 weeks cold stratification to germinate, and that germination rates are highest following extended cold stratification of 18 and 24 weeks: 61% and 59%, respectively. These findings indicate that D. cymosa seed performs best under conditions that may already be more typical of northern areas outside the species native range, and that climate warming could significantly impact population dynamics. If such declines become evident, assisted colonization might be a viable conservation option for this species and similar Southern Appalachian endemics.

Language

English

Comments

61 pages : color maps. Honors Project, Smith College, 2014. Includes bibliographical references (p. 52-61)

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