Elm as Deer Browse

Abstract

Sprouts and tops of American elm (Ulmus americana) were preferred woody deer browse on the Allegheny National Forest in northwestern Pennsylvania. More than 90 percent of the succulent sprouts and two-thirds of the available twigs in the tops of trees felled in winter were utilized in the growing season after cutting. Elm was found to sprout vigorously from stumps, and from the boles of trees that were successfully hinged to the stumps. These results are in general contrast to reports in the literature on deer browse in which elm is listed as low in use. The white-tailed deer (Odocoileus virgianus) has the reputation of being a highly selective feeder, browsing heavily on some plants, nibbling lightly or not at all on others. This paper reports on heavy utilization of American elm twigs as browse in northwestern Pennsylvania during spring and summer. Observations of the use of elm by deer were made in the late summer of 1964 in a northern hardwood poletimber stand, 40 to 60 years old, on the Allegheny National Forest in northwestern Pennsylvania. About 12 acres had been thinned the previous winter in one of the blocks used to study a method for increasing deer-browse production in poletimber stands (Jordan et al. 1965). Before cutting, elm was common in the stand, comprising up to 10 percent of the stems. Associated species were sugar maple (Acer saccharum), black cherry (Prunus serotina), basswood (Tilia americana), white ash (Fraxinus americana), yellow birch (Betula alleghaniensis), hop-hornbeam (Ostrya virginiana), and blue beech ( Carpinus caroliniana). Slippery elm (Ulmus rubra), beech (Fagus grandifolia), quaking aspen (Populus tremuloides), black birch (Betula lenta), eastern hemlock (Tsuga canadensis), red maple (Acer rubrum), and striped maple (A. pensylvanicum) were less common, occurring mainly as isolated trees. Under the stand-improvement method used, all stems except selected future crop trees were cut to produce browse. Wellformed sugar maple, white ash, and black cherry were favored in the residual stand. In the late summer following cutting, a randomized sample of woody browse production and utilization yielded the following number of twigs per acre and percent of browsing by species: sugar maple 183,900, 6.4; yellow birch 52,900, 15.7; hophornbeam 28,800, 6.6; basswood 14,400, 59.0; white ash 11,000, 23.6; black cherry 8,700, 21.8; blue beech 6,800, 0.0; beech 1,700, 11.8; and striped maple 300, 0.0. In felling, an effort was made to hinge the stem to the stump so that the top would remain alive to produce browse in succeeding years. Thus browse was produced by both the stumps and tops, and in many instances along the bole of the tree. American elm was found to sprout vigorously from the stumps, and from the boles of trees that were successfully hinged. To determine the extent to which American elm was browsed, individual trees accessible to deer were selected, and all browsed and unbrowsed twigs 2 inches or more in length to 5 ft in height were recorded. The twigs were grouped into three categories: stump sprouts, stem sprouts, and tops.