Masters Theses

Date of Award

8-2001

Degree Type

Thesis

Degree Name

Master of Science

Major

Forestry

Major Professor

David S. Buckley

Committee Members

Wayne Clatterbuck, Glendon Smalley

Abstract

Most oak (Quercus) regeneration research over the past two decades has focused on improving the competitive position and growth performance of established oak reproduction. Less research has been conducted on factors underlying the presence and abundance of oak advance reproduction. Oak reproduction patterns and underlying factors in east Tennessee forests are also poorly documented. The objective of the research was to investigate relationships between the abundance, size, and composition of oak advance reproduction and site factors on six soil associations and three landform positions (ridgetop, northwest slope, and southeast slope) in the Ridge and Valley Province of Tennessee.

Topography within the soil associations sampled ranged from hilly and rolling to steep ridges with rolling valleys. Soils included in this study ranged from moderately high productivity to shallow, acidic soils low in productivity and covered 68% of the land area in the Ridge and Valley Province. Two replicate transects were sampled within each soil association-landform position combination yielding a total sample size of 33 transects (transects within the J52 soil association could not be replicated). Size and abundance data were collected for four classes of oak regeneration; 1) 0 to 25 cm in height, 2) 26-50 cm in height, 3) 51-150 cm in height, and 4) greater than 150 cm in height and less than 8 cm dbh. Site factors investigated were landform position, soil association, slope, overstory and understory competitors, seed source, light regime, basal area, and litter thickness. Regression equations for predicting the abundance of oak reproduction for each size class and species of oak were developed using r2 variable selection, response surface analysis, and a general linear models procedure.

Eight species of oak were encountered: chestnut oak (Q. montana), white oak (Q. alba), black oak (Q. velutina), northern red oak (Q. rubra), southern red oak (Q. falcata), scarlet oak (Q. coccinea), chinkapin oak (Q. muehlenbergii), and post oak (Q. stellata). Chinkapin and post oak were only found on one site and, therefore, were not analyzed as individual species. Preliminary analyses suggested that both landform position and soil association were important factors influencing the presence of many of the oak species and size classes. Therefore, models for predicting oak abundance were developed within every landform position - soil association combination for all species of oak and all size classes.

Except for northern red oak, the smaller size class oak seedlings were more abundant on the more productive soils and landform positions. In contrast, the largest size class oak seedlings were more abundant on the less productive soils and landform positions. Conditions for germination and early growth may be best on northwest slopes, but chances for survival to the fourth size class were apparently greater on the drier, less productive southeast slopes. The regeneration patterns for chestnut oak, black oak, and the scarlet-southern red oak group were consistent with current hypotheses that these species perform better on the drier, poorer sites.

Variables such as oak seed source, potentially competing mature canopy trees, potentially competing saplings, and canopy depth were consistently significant throughout all species and size classes of oak. For all oak species, importance value of canopy trees (seed source) was positively related to the abundance of the smaller size classes of oak seedlings. Importance value of competing species was significantly related to the number of larger size class oak seedlings. Dogwood (Cornus florida) saplings consistently had a negative relationship with the abundance of oak seedlings of most species. Canopy depth was expected to have a negative relationship with oak abundance because less light would be available with increasing depth. However, this relationship was variable. Only northern red oak had a negative relationship, white and chestnut oak had positive relationships, and black and scarlet oak had no relationship. Land managers can use these relationships between oak regeneration and soil and site condition as guidelines for making decisions on where to concentrate oak regeneration and management efforts (silvicultural treatments) in the Ridge and Valley Province.

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