Woody species composition of disturbed forests in intermittent stream bottomlands of southern Indiana

JENKINS, M. A. (Twin Creeks Natural Resources Center, Great Smoky Mountains National Park, Gatlinburg, TN 37738) AND G. R. PARKER (Department of Fores try and Natural Resources, Purdue University, West Lafayette, IN 47907). Wo ody species composition of disturbed forests in intermittent stream bottoml ands of southern Indiana. J. Torrey Bet. Sec. 128: 165-175. - Between 1993 and 1995 we sampled understory and overstory woody vegetation on 84 plots i n Platanus/Asarum Wet-Mesic Bottomland forests to determine how these fores ts have responded to human disturbance. Four different types of disturbed s tands were sampled (abandoned agricultural areas, clearcuts, group selectio ns, and single-tree selections), and 80-100 year-old reference stands were sampled for comparison. Overstory vegetation differed in composition among these 5 stand types with abandoned agriculture, clearcut, and group selecti on plots exhibiting compositions very different from single-tree selection and reference plots. This was largely due to shirts in dominance by Acer sa ccharum and Liriodendron tulipifera across the five stand types. Although a bandoned agricultural areas experienced more severe site disturbance from y ears of cultivation, they were similar in composition to clearcuts and grou p-selection openings. The mean species richness of abandoned agriculture, c learcut, and group-selection pilots was generally greater than that of sing le-tree selection and reference plots. Abandoned agricultural areas and cle arcuts had greater overstory species richness (summed across all plots), su ggesting that larger canopy openings have allowed more shade-intolerant spe cies to establish. Total species richness was greatest on abandoned agricul ture plots due to an influx of dry-site, disturbance, and exotic species. H owever, these species did not tend to dominate sites. The dominance of A. s accharum in single-tree selection openings has led to the exclusion of othe r species, resulting in greatly reduced overstory species richness and dive rsity.