The short-term dynamics of mixed mesophytic forest strata in West Virginia were examined using similarity analysis and linear correlation of shared ordination space. The overstory tree, understory tree, shrub/vine, and herb strata were stable over a six year interval, whereas the tree seedling and sapling strata were unstable. All strata but the shrub/vine and tree seedling strata were correlated with soil pH, elevation, P, K, Fe, Mn, Ca, and Mg, with the latter two variables being the weakest for the overstory tree, understory tree, and sapling strata. The herb stratum was also significantly correlated with the shrub/vine and tree seedling strata. The soil fertility gradient corresponded with a moisture gradient. More xeric plots tended to be less stable than more mesic plots for all strata. Successful forest management may depend on knowledge of the lower tree strata species composition, because such composition will likely vary prior to future disturbance events.

Analyses of a palaeo-channel deposit in the valley of Big Sandy Creek in northeast Texas indicate that well preserved pollen of primary origin is encountered in high concentrations. Stratigraphic pollen data derived are employed towards a reconstruction of the history of the regional pine-hardwood forest from 3500 cal. BP until present. This bio-stratigraphic sequence demonstrates that the valley has remained almost completely under forest canopy during the Middle and Late Holocene, when it is comprised of a mixture of oak, pine, and hickory. During the past 3500 yrs, the relative importance of these taxa has also varied due to drought and fire. In this respect, a differential (riparian) representation by moisture-sensitive river birch in the pollen sequence strongly suggests that periodic droughts in the valley have caused a secular variation in fire frequency and magnitude. Finally, during the past 800 yrs (Caddo period), the first significant grasslands and forbs emerge in forest clearings. The latter emergent formations are of possible anthropogenic origin after pollen data.

Dedication

The authors of this article dedicate this paper to the memory of Dr. Bruce Haines, University of Georgia, in honor of his outstanding accomplishments in the field of ecosystem ecology. A good scientist, a good mentor, and a good friend.

In the fall of 2000, a ground fire burned much of the Linville Gorge Wilderness Area, North Carolina, providing an opportunity to study the effects of fire on an oak-pine forest that had not been burned in 50 years. There was no immediate overstory mortality in our study plots. Most aboveground stems of Kalmia latifolia were killed back, but most survived and subsequently re-sprouted. Fire reduced surface organic horizons by nearly 50%, and increased light penetration ∼15%, resulting in greater soil temperature extremes. Fire increased species richness in the herb layer and allowed establishment of pine seedlings and also the exotic invasive tree species Paulownia tomentosa. Rates of soil respiration and litter decomposition were significantly lower in burned plots one year *email address: neufeldhs@appstate.edu post-fire. Changes in the microenvironment in the lower strata following fire were caused primarily by the disappearance of the Kalmia canopy. This temporary loss of the shrub layer appeared to influence composition of the ground layer as well as the re-accumulation of surface soil carbon via reduced litter decay.

Ordination and cluster analysis of 90 sampled bottomland forest stands yielded 12 groups of stands (community types). Stands and groups were arranged in a Y-shaped pattern across the ordination. A Quercus nigra group and a Q. phellos group occurred along a “less flooded” arm of the Y. A Populus deltoides-Acer negundo group, an A. negundo group, and a Celtis laevigata-Carya illinoensis-Ulmus americana group occurred along the “often flooded, flowing water” arm of the Y, with the last group overlapping a Q. texana-Fraxinus pennsylvanica group near the middle of the ordination. A Liquidambar styraciflua group extended between the “less flooded” and the “flowing water” arms of the Y. The “often flooded, standing water” base of the Y had a Taxodium distichum group and a Nyssa aquatica-Planera aquatica-T. distichum group, with Cephalanthus occidentalis important in the understory in both groups. Two overlapping groups at the center of the ordination tied together the three arms of the Y. These were a Q. lyrata group and a Carya aquatica-Forestiera acuminata group. All groups except the Acer negundo group contained stands from multiple locations in two different states, suggesting generality of these combinations of species in this region.