Term of Award

Spring 2004

Degree Name

Master of Science

Document Type and Release Option

Thesis (restricted to Georgia Southern)

Department

Department of Biology

Committee Chair

John E. Averett

Committee Member 1

C. Ray Chandler

Committee Member 2

Alan Harvey

Abstract

A mixed evergreen forest exists along the coastline of the Atlantic Ocean and the Gulf of Mexico in the southeastern United States. These maritime forests are dominated by oak trees, pines, and magnolias, which are essential floral components of the maritime forest ecosystem. Because of natural forces like hurricanes and plant pathogens, as well as the forestry practices of humans, these maritime forests are declining. Efforts to restore maritime forests should focus on the restoration of plant species that are key components of the ecosystem. By restoring essential plant species, other native plant and animal species might become reestablished naturally.

This study examined current oak restoration methods by comparing direct seeding to seedling transplantation, as well as the effects of burial depth on seedling recruitment. Live oak (Quercus virginiana) was the species utilized for this study. Restoration methods were compared in Kenan Field on Sapelo Island, Georgia during the winter and autumn of 2003. One hundred fifty acorns were directly sown on the soil surface and 150 acorns were buried at a depth of 6 cm. Acorns were also planted in the lab to produce seedlings that would be used for transplantation. At 6 months of age, seedlings grown in the lab were transplanted (n=50) among seedlings that emerged in the field (n=50).

For all seedlings, measurements for height of the above ground shoot and leaf number were recorded at 6 months of age (before transplant) and 12 months of age (after transplant). Survivorship was recorded after the transplanted seedlings had been in the field for 6 months. There was no significant difference in height between seedlings that emerged from acorns sown on the soil surface and transplanted seedlings that had a head start in the lab. However, seedlings that emerged from buried acorns sown in the field were significantly shorter than seedlings transplanted from the lab and seedlings recruited from surface sown acorns (ANOVA, p = 0.0112, df= 2,98). There was no significant difference in leaf number among the seedlings (ANOVA, p = 0.2581, df = 2,98). The survivorship of seedlings recruited via the direct seeding method was 100% after 12 months in the field. The survivorship ofthe transplanted seedlings was 30% after 6 months in the field. Direct seeding appears to produce significantly more surviving seedlings in the field (G - 68.403, p<0.01, df = 2).

In the lab, the effects of burial depth on live oak seedling emergence, acorn germination, and the viability of non-germinated acorns were examined. Acorns were sown on the soil surface (n-150), at a depth of 3 cm (n=l 50), and at a depth of 6 cm (n=150). Acorns sown on the soil surface produced significantly more fully emerged seedlings than acorns buried at 3 cm and 6 cm (G = 109.306, p<0.01, df= 2). Seedlings that developed from deeply buried acorns took longer to emerge than seedlings from more shallow acorns. Significantly more germination, not resulting in an aboveground seedling, occurred at the 6 cm depth (G = 57.978, p<0.01, df= 2). Of the acorns that did not germinate, tetrazolium chloride testing showed that significantly more acorns were still viable at the 6 cm depth and significantly fewer acorns were viable at the shallow depths (G = 18.594, p<0.01, df= 2).

Overall, direct seeding of a field appears to be a better method for oak restoration to maritime forests. Planting acorns on the surface ofthe soil may be the best way to recruit a larger number of seedlings. Transplanted seedlings would most likely be more successful if they could be watered frequently and protected from predation by large herbivores.

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