The relationship between soil fertility and deer browse nutritive quality in Nathan Bedford Forrest State Park

Habitats with infertile soils produce plants with low nutritional quality while fertile soils produce plants with high nutritional quality. Both types of habitat are found in Nathan Bedford Forrest State Park, Benton County, Tennessee and both contribute to the carrying capacity of the present over-stocked white-tailed deer (Odocoileus virginianus, Zimmerman) population in the park.

Soil samples (topsoil and subsoil) and preferred browse species were collected from ten permanent two hectare sites during the period, June 1977 through May 1978. Analysis of the soils and forage indicate differences in nutrient levels in plants growing on different soils and annual seasonal variations in soil fertility and forage nutrient quality.

The following patterns of soil fertility were found. Soil pH was less acidic in the winter months than the summer months. Soil phosphorus dropped significantly in the winter months. Soil potassium increased significantly in the winter months from the summer months. Much of the seasonal variation in soil fertility may be explained by variation in microbial activity with temperature. Increased decomposition rates in the summer months induce lower soil pH through the release of organic acids and releases more available phosphorus from organic phosphorus. . Potassium is a highly mobile cation which is cycled quickly through the environment by precipitation and leaching so that soil potassium levels are highest in winter.

A soil fertility and forage nutrient quality gradient exists corresponding to a classification of sites by moisture criteria and physiographic position. The xeric sites (uplands) had the lowest soil phosphorus and the lowest plant phosphorus and plant protein values. The mesic sites represented by alluvial lowland sites and an island had higher soil fertility and the better forage quality.

Browse is only one of many foods available to deer in this habitat. A browse survey is one index utilized by range managers to evaluate the carrying capacity of a habitat. These results indicate that alluvial bottomlands are a very important part of the habitat for a deer population. Thus the maintenance of mesic sites should be stressed in future developments within multi-purpose management areas such as Nathan Bedford Forrest State Park.