Structure and development of a Scalesia pedunculata stand in the Galapagos Islands

Stands of Scalesia pedunculata in the Galapagos Islands often develop as single-aged cohorts following episodes of mass death and regeneration. We updated earlier studies on a stand that had regenerated soon after the 1982–3 El Niño event. We quantified stem size distribution and dispersion pattern in a 0.56 ha plot near Los Gemelos on Santa Cruz Island. The plot was dominated (95% of basal area) by S. pedunculata. The stem size distribution showed the increased mean and variance for diameter (since 1987 and 1991) expected of an aging stand. Stems averaged smaller than in 1981, just before the last mass mortality episode. Large S. pedunculata stems were regularly dispersed while smaller stems were clumped and negatively associated with larger stems, implying that intraspecific competition may be important in structuring the stand. CDF Contribution Number 1008

Size Structure and Composition of Trees in Oakwood, Ohio: Historical and Environmental Determinants

Author Institution: Department of Biological Sciences, Wright State UniversityOur goal was to determine whether broad patterns could be identified in the size structure and composition of woody plants in Oakwood, OH, and to determine the influence of both natural and socio-cultural environments. We examined variation in woody species composition for 36 combinations of tree size, position within housing lots, and zones within the city. Parameters considered were development history, topography, a city tree-planting program, species characteristics, and location (front yards, tree lawns, boulevards, wild areas, and parks). Distributional patterns in species composition were examined using ordination (detrended correspondence analysis)

Prairies and Fens of Bath Township, Greene County, Ohio: 1802 and 1984

Author Institution: Department of Biological Sciences, Wright State UniversitySurveyor's records were used to determine the boundaries of prairies and fens that occurred in Bath Township, Greene Co., Ohio, in 1802. All of the old prairie sites were explored on foot in September and October 1984, to locate existing remnants. Four fen, four prairie, and four marsh remnants were located and the dominant prairie and fen species recorded. The fraction of total land area in these vegetation types went from 17% in 1802 to about 0.7% in 1984. This study illustrates the potential of using the original surveyors' records to locate existing remnants of these vegetation types

The Vascular Flora of a Transect Across the Beaver Creek Wetlands, Greene County, Ohio

Author Institution: Department of Biological Sciences, Wright State UniversityDuring the 1989 growing season we surveyed part of the Beaver Creek Wetlands in Greene County, OH, to describe and catalog the vegetation and to determine if a transect oriented through the study site satisfied the mandatory technical criteria for vegetation used by Federal agencies to delineate wetlands. We established 14 plots along the transect and compiled a list of the species occurring within the plots and throughout the rest of the study site. We identified 198 species, including five species on the Ohio list of threatened and endangered species. A majority of species occurring within the study site were classified as hydrophytes. A wetland index was calculated for each plot using weighted percentages of vegetation indicator-categories. Wetland-index values, which expressed changes in wetland character (degree and duration of soil saturation as reflected by proportions of hydrophytes and nonhydrophytes occurring in the plots), were significantly correlated with first-axis scores from a detrended correspondence analysis (DECORANA). This correlation indicated that DECORANA first-axis scores also reflected changes in wetland character along the transect. The wetland index also identified areas that showed a tendency towards seasonal or spatial transition between wetland and nonwetland. According to federal criteria, wetland areas included the 12 interior plots along the transect and part of plot 14, while nonwetland areas included plot 1 and most of plot 14

Vegetation-Site Relationships in the Lake Katharine State Nature Preserve, Ohio: A Northern Outlier of the Mixed Mesophytic Forest

Author Institution: Department of Biological Sciences, Wright State UniversityEighteen 0.1-ha plots were sampled for woody vegetation in the Lake Katharine State Nature Preserve in southeastern Ohio. These plots were selected to cover a great variety of topographic positions. Ordination (DECORANA) and classification (TWINSPAN) techniques were used to group the plots into seven site-types: ridge tops, slope edges, upper slopes, lower slopes, flood plains by small creeks, coves, and terraces by large creeks. Soil nutrients generally were higher for the lower slopes and terraces. Vegetation varied from oak-dominated upland sites to mixed mesophytic coves to floodplain stands of Platanus occidentalis, Betula nigra, and Ulmus americana. The distributions of species suggest that soil moisture is primarily responsible for determining where species occur. The low level of soil nutrients may limit the occurrence of the more nutrient-demanding mesophytic species in the area

Groundlayer Vegetation Ordination and Site-Factor Analysis of the Wright State University Woods (Greene County, Ohio)

Author Institution: Department of Biological Sciences, Wright State UniversityDetrended correspondence analysis (DECORANA) was used to examine groundlayer vegetation variation among seven locations of differing topography and successional age in the Wright State University woods (Greene County, OH). Two young sites (60 and 40 years since agricultural abandonment) and five older sites (one floodplain, one slope, and three uplands) were selected a priori and sampled four times in 1987. Taxon presences were recorded in 100 plots per location, and 12 environmental variables were measured from a subset of these plots. DECORANA ordination revealed that site age was the most important large scale factor affecting groundlayer vegetation. Topography was shown to be an important factor in the old growth sites. Stepwise linear regression with DECORANA plot scores as dependent variables and environmental factors as independent variables indicated that soil moisture content was the most important measured site factor associated with vegetation variation. This relationship was significant for vegetation along the overall successional gradient (r2 = 0.49) with soil moisture content positively correlated with site age. It was also significant along the old growth topographic gradient (r2 = 0.46) with soil moisture content negatively correlated with topographic elevation

Vegetation Release Eight Years After Removal of Lonicera maackii in West-Central Ohio

Author Institution:Dept of Biological Sciences, Wright State UniversityLonicera maackii is thought to inhibit growth of herbaceous vegetation and woody seedlings. To determine the extent of this inhibition, in April 1996, Lonicera was removed from ten 30 x 30 m areas within Sugarcreek Reserve. Paired 20 x 20 m plots were established, one of each pair in the removal area and one adjacent to that area. These plots varied in history and topographic position. Twenty 1-m2 small plots were established in each large plot and sampled for herbaceous vegetation (by species and cover class) and woody seedlings (species and number). Sampling was done summer 1996 and spring 1997. Nine of the paired plots were resampled summer 2003 and spring 2004. Few differences were found between control and treated plots the first year after Lonicera removal. Significant differences between control and treated plots were found seven to eight years after treatment in both spring and summer: treated plots had higher species richness, higher cover, and higher tree seedling densities. These results indicate that Lonicera removal can enhance ground layer species diversity and cover after a lag period of at least one year

Changes in Older and Younger Woods in West-Central Ohio

Author Institution: Dept. of Biological Sciences, Wright State University, OHThis study examines changes in two forest stands in the Quercus-Acer saccharum forest region of west central Ohio: an old-growth stand changing from Quercus-dominated to Acer saccharum-dominated and a stand established following agricultural abandonment about 1950. Both stands are in the Wright State University woods. Permanent plots were sampled in 1980 (younger stand only), 1982 (older stand only), 1993, and 2000. The older stand had more small, fewer intermediate, and more large stems than the younger stand. The plot in the new stand showed a bell-shaped distribution with most stems established shortly after land abandonment. Mortality decreased and growth increased with stem size for both stands. Acer saccharum in all sizes and large Quercus dominated the older stand. The younger stand was dominated by Robinia pseudo-acacia with Acer saccharum also important. In the older plots small stems generally were clustered, intermediate-sized stems randomly distributed, and the largest stems regularly distributed. In the younger plot small stems were aggregated while larger ones were randomly distributed. Quercus regenerated well until the late 1800s, singly or in small groups, but few stems have become established since 1900. Quercus may need fires or grazing to regenerate successfully. Both stands are changing to increased dominance by Acer saccharum and other shade-tolerant species as they lose species (Robinia pseudo-acacia in the younger stand, Quercus in the older stand) more successful under past than present conditions