Date of Award

Spring 5-1-2002

Document Type

Thesis

Degree Name

Master of Arts (MA)

Department

Geography, Geology, and Anthropology

First Advisor

Greg Bierly

Second Advisor

C. Mark Cowell

Third Advisor

Jay Gatrell

Abstract

Thirty-five permanent plots were reexamined to identify and describe the spatial and temporal characteristics of Dobbs Park, an isolated old-growth forest stand in westcentral Indiana. The 3.6 ha stand was resurveyed in summer 2000, with all stems greater than 10 cm dbh measured, and accessions and deaths recorded. The results are compared to original data collected in summer 1974, with compositional and spatial patterns identified via GIS and spatial analysis. The stand has declined slightly in density from 342 stems/ha to 333.15 stems/hectare (-2.6%) while basal area (dominance) for the stand has increased from 23.6 m2/ha to 25.8 m2/ha (+8.8%) over the twenty-six years. Along with the decreases in density and basal area is a notable shift in species composition. Originally considered an elm-ash community in 1974, the stand has experienced high elm mortality and a deficiency in oaks and hickories in early stem sizes. Coupled with the lack of disturbance, alterations in drainage patterns and the increasing role of gap succession, mesophytic species like Acer saccharum (sugar maple) and Fagus grandifolia (beech) currently dominate the stand in overall importance. Sugar maple has the highest overall density (62 stems/ha) and importance (10.2%) in the stand, and is experiencing high reproductive success. Beech is ranked second in importance (8.1 % ) and has a similar monotonic size-class distribution as sugar maple. Shade intolerant species like black walnut, shellbark hickory and white oak are showing little (if any) IV recruitment in species. Statistical analysis using Poisson distribution and chi-square difference tests suggest that patterns of mortality (VMR=l.38) and accessions (VMR=l.82) are not random, but clustered, indicating that gap dynamics are the primary mode of disturbance within the stand. Changes in distribution patterns and the success of shade tolerant species are attributed to localized ponding, autogenic responses, and the modifications ofland surrounding the stand. Dobbs Park is a "bio-island" within areas of human development, and as a result, fails to maintain the historical stand composition due to its isolation and internal dynamics.

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