Ice (glaze) storms are frequent natural disturbances in eastern deciduous forests. Two opposing hypotheses exist in the literature regarding the effect of glaze on forest succession. In the first view, succession is said to be accelerated as pioneer species sustain greater damage than equilibrium species. The resistant equilibrium species would then fill canopy gaps, shifting the stand to a more advanced stage. Alternatively, extensive canopy damage allows more light to reach the forest floor perhaps favoring the germination and establishment of pioneer seedlings. Survival of these individuals would return the community to an earlier successional stage, or maintain pioneer communities. This study examined the response of the reproduction and susceptibility of tree species (by damage and mortality) two growing seasons after an ice storm, across a moisture and successional gradient. Four stands were studied: <i>Liriodendron</i>, mesic and xeric <i>Pinus</i>, and <i>Quercus</i>. Damage for most species was consistent across stands, with larger trees generally sustaining greater damage than smaller trees or saplings. Mortality increased with increasing stem size and severity of damage for most species. However, while damage to <i>Liriodendron tulipifera</i> was very high, actual mortality was low due to its ability to sprout. Also, because seedling reproduction of pioneer species was stimulated in this stand, succession appeared to be retarded. Succession was accelerated in the mesic <i>Pinus</i> stand where mortality of canopy trees was high and where removal of the canopy stimulated growth and sprouting of understory equilibrium species. Succession of the stands on drier sites (e.g. <i>Quercus</i> and xeric <i>Pinus</i>) appeared unaffected as the composition of tree seedlings remained essentially unchanged after disturbance. Thus, the response of a community to ice damage depends on the interrelated variables of vegetation composition, successional status, and topographic position. / M. S.

A forest site quality index (FSQI) based on topographic parameters of aspect, slope inclination and slope position was used to investigate soil moisture and plant water stress relationships on the southeast face of Potts mountain in Craig County, Virginia. Topographical effects on available water are especially pronounced during low late season rainfall levels encountered in the Ridge and Valley physiographic province of Virginia. The soil moisture trends and plant water potentials demonstrated that for all forest site quality index values representing the topographically derived moisture gradient, available soil moisture and plant stress levels probably seriously decrease or inhibit tree growth from the middle of July to the end of the growing season. The Forest Site Quality Index (FSQI) delineated the soil moisture gradient within the study area most successfully in the more xeric areas, supporting its use for predicting relative site quality on those sites where soil moisture has been demonstrated as being the limiting factor of tree growth. The FSQI is a rapid and easy measure based on topographic parameters for evaluating relative site quality but is restricted in use to areas where rainfall is critical to plant growth during the growing season. / M.S.