Population dynamics of the rare threatened gooseberry Ribes echinellum Öffentlichkeit

Abstract

The Miccosukee gooseberry, Ribes echinellum, is a federally listed shrub endemic to the Southeastern United States. It has an extremely narrow distribution: only two populations are known to exist, one in McCormick County, South Carolina, and one in Jefferson County, Florida. Reports of a possible decline in abundance in the Florida population have emerged from long-term monitoring efforts; however, these findings are difficult to interpret due to a paucity of information on the biology and ecology of the species. Additionally, comprehensive monitoring efforts ceased a decade ago. We established eight permanent plots in each population for the collection of demographic data over multiple years. We identified differences in the rate of reproduction, growth, and survivorship between the two populations, between local habitats within each population, and between plots that were fenced to control herbivory versus plots that were left open. These vital rates will be used to build a model of overall population dynamics, including population growth rate and long-term viability, using an integrated population model approach. The results of this study will ultimately inform efforts to conserve the species.

Table of Contents

Table of Contents

Introduction ……………………………………………………… 1

Methods …………………………………………………………  18

Results …………………………………………………………… 26

Discussion ………………………………………………………… 42

References ………………………………………………………… 47

Figures and Tables

Figure 1: Photograph of Ribes echinellum………………………………………… 6

Figure 2: Map of study area ……………………………………………………… 19

Figure 3: Experimental design schematic ………………………………………… 23

Table 1: Vital rate effect summary ………………………………………………… 27

Figure 4: Plant height by study plot ………………………………………………  29

Figure 5: Plant height by fate ……………………………………………………… 30

Figure 6: Height of dead plants by treatment ……………………………………… 31

Figure 7: Change in plant height …………………………………………………… 33

Figure 8: Height of flowering plants by treatment ………………………………… 35

Figure 9: Height of flowering plants in South Carolina …………………………… 37

Figure 10: Predicted survival probability  …………………………………………  38

Figure 11: Predicted growth rate …………………………………………………… 39

Figure 12: Predicted reproductive probability ……………………………………… 40

Figure 13: Predicted flower production ……………………………………………… 41

Figure 14: Predicted germination rate  ………………………………………………  42

About this Master's Thesis

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School	Laney Graduate School
Department	Environmental Sciences
Degree	M.S.
Submission	Master's Thesis
Language	English
Research Field	Biology, Conservation Biology, Botany Biology, Ecology
Stichwort	rare species demography
Committee Chair / Thesis Advisor	Emily Coffey, Emory University Lance Gunderson, Emory University
Committee Members	John Wegner, Emory University

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