An ecological classification system for the central hardwoods region: The Hoosier National Forest
Abstract
This study, a multifactor ecological classification system, was developed for the Brown County Hills and Crawford Upland Subsections of the Hoosier National Forest in Southern Indiana. Ecological classifications use the interrelationships between components of ecosystems including vegetation, soils, and physiography as the basis for classifying sites across the landscape. Data for ground flora, saplings, and canopy trees species from selected stands older than 80 years were summarized and subjected to TWINSPAN classification and DECORANA ordination. Physiographic and soil measurements were regressed on ground flora DECORANA scores. Strong relationships were observed between DECORANA scores and slope aspect, soil A-horizon depth, slope position, and soil pH. The vegetation of the Hoosier National Forest is believed to be related to a moisture and nutrient gradient which is influenced by these factors. The landscape was divided into ecological land units on the basis of these relationships. Twelve ecological units for the Brown County Hills subsection, and fifteen units for the Crawford Upland subsection were described. These units ranged from floodplains along large streams to mesic sites on northerly slopes to dry forest on southwesterly slopes. Identification of the vegetation component of the units was aided by ecological species groups, groups of species which tend to occur together across the landscape in response to similar environmental factors. Seven ecological species groups for the Brown County hills and eight groups for the Crawford Upland were identified. Comparison of overstory and understory trees indicated that marked successional trends were evident on many of the 80-120 year-old sample sites. However, these trends varied among ecological units. Significant oak-hickory regeneration occurred on many of the dry ecological units while sugar maple was replacing overstory oak-hickory on moderately dry and mesic units. This classification system can serve both as a framework for future research and as a system on which ecologically sound forest management can be based. It will aid researchers, naturalists and forest land managers as they deal with complex forest resource issues.
Degree
Ph.D.
Advisors
Parker, Purdue University.
Subject Area
Forestry|Ecology|Botany
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.