Geology topics

Noel B. Pavlovic

Publications and source records attributed to Noel B. Pavlovic.

41 records · Page 3Linked to original sources

USGS2002

Experimental restoration of native vegetation in Indiana Dunes National Lakeshore

We investigated the effects of prescribed fire, herbicide treatment, and sod removal on the eradication of exotic grasses and the establishment of native plant species in 24 experimental restoration plots in three razed residential sites within the boundary of Indiana Dunes National Lakeshore. During 1992–1995, herbicide treatment and sod removal decreased the combined cover of Poa pratensis (Kentucky blue grass) and Agropyron repens (quackgrass) significantly (from 82% to 13%, and 85% to 8%, respectively), whereas fire did not suppress such exotic lawn grasses. In 1993, several opportunistic species, represented by Cyperus spp. (umbrella sedges), Digitaria sanguinalis (crab grass), and Ambrosia artemisiifolia (common ragweed), filled the gaps left by the removal of lawn grasses. For the same period, Detrended Correspondence Analysis revealed a clear vegetation divergence between the control-fire plots and the herbicide-sod removal plots. While Poa pratensis and Agropyron repens continued to dominate the control and fire plots, the planted native species, represented by Schizachyrium scoparium (little blue-stem), Sorghastrum nutans (Indian grass), Rudbeckia hirta (black-eyed Susan), and Monarda punctata (horsemint), began to dominate in the herbicide and sod removal plots from 1994. In both herbicide and sod removal plots, the ground cover of grasses (68%) was much higher than the forbs (10%). The herbicide plots, where exotic species were removed but nitrogen-rich top soils were not removed, showed a higher diversity of planted native species than the sod removal plots (where both exotic species and top soils were removed) and the control-fire plots (where neither was removed). This finding suggests that an optimum but not excessive concentration of soil nitrogen is needed to support a maximum species diversity in such infertile substrate as sandy soil. In addition, the decrease in potassium in all plots, regardless of treatment, suggests that potassium may become a limiting factor for our restored native vegetation.

Restoration Ecology↗

USGS2000

Nectar plant selection by the Karner blue butterfly (Lycaeides melissa samuelis) at the Indiana Dunes National Lakeshore

The Karner blue butterfly, Lycaeides melissa samuelis, is an endangered species residing in savanna and barrens habitats in the Midwest and Northeast United States. To improve our understanding of nectar plant selection patterns by the Karner blue, we examined nectar plant choices made by 146 butterflies. Within observation areas of 2-m radius butterflies usually chose the nectar species with the greatest total number of flowers or flowering heads. This suggests that the Karner blue is opportunistic in selecting nectar plants. However, certain nectar species, including Arabis lyrata, Coreopsis lanceolata, Melilotus alba and Rubus flagellaris, were selected in a significant majority of cases when other nectar species were available nearby. At least in the case of R. flagellaris, this preference was not directly related to the species' local flower abundance. In a significant majority of cases (77.5%) adult Karner blues selected nectar plant species with yellow or white flowers over species with other-colored flowers. Comparison of nectar plant selections at Indiana Dunes National Lakeshore to selections from Michigan and Wisconsin suggests that the Karner blue most frequently chooses a suite of nectar plant species that includes A. lyrata, C. lanceolata, Euphorbia corollata, M. alba, Monarda punctata, Potentilla simplex, Rubus spp., Solidago speciosa and, perhaps, Asclepias tuberosa and Helianthus divaricatus. This suite includes plant species that readily flower in the sun and others that readily flower in the shade, an important consideration since Karner blues often move across the sun-shade interface.

American Midland Naturalist↗

USGS1999

A Study of Natural and Restored Wetland Hydrology

The U.S. Geological Survey and the U.S. Environmental Protection Agency are jointly studying the hydrology of a long-existing natural wetland and a recently restored wetland in the Kankakee River Valley in northwestern Indiana. In characterizing the two wetlands, project investigators are testing innovative methods to identify the analytical tools best suited for evaluating the success of wetland restoration. Investigators also are examining and comparing the relations between hydrology and restored wetland vegetation.

Indiana↗

USGS1998

The effect of canopy cover and seasonal change on host plant quality for the endangered Karner blue butterfly (Lycaeidesmelissasamuelis)

Larvae of the Karner blue butterfly, Lycaeidesmelissasamuelis , feed solely on wild lupine, Lupinusperennis , from the emergence to summer senescence of the plant. Wild lupine is most abundant in open areas but Karner blue females oviposit more frequently on lupines growing in moderate shade. Can differences in lupine quality between open and shaded areas help explain this disparity in resource use? Furthermore, many lupines are senescent before the second larval brood completes development. How does lupine senescence affect larval growth? We addressed these questions by measuring growth rates of larvae fed lupines of different phenological stages and lupines growing under different shade conditions. The habitat conditions under which lupines grew and plant phenological stage did not generally affect final larval or pupal weight but did significantly affect duration of the larval period. Duration was shortest for larvae fed leaves from flowering lupines and was negatively correlated with leaf nitrogen concentration. Ovipositing in areas of moderate shade should increase second-brood larval exposure to flowering lupines. In addition, larval growth was significantly faster on shade-grown lupines that were in seed than on similar sun-grown lupines. These are possible advantages of the higher-than-expected oviposition rate on shade-grown lupines. Given the canopy-related trade-off between lupine abundance and quality, maintenance of canopy heterogeneity is an important conservation management goal. Larvae were also fed leaves growing in poor soil conditions and leaves with mildew infection. These and other feeding treatments that we anticipated would inhibit larval growth often did not. In particular, ant-tended larvae exhibited the highest weight gain per amount of lupine eaten and a relatively fast growth rate. This represents an advantage of ant tending to Karner blue larvae.

Indiana↗

USGS1998

Habitat use by the endangered Karner blue butterfly in oak woodlands: The influence of canopy cover

The Karner blue butterfly Lycaeides melissa samuelis is an endangered species residing in the Great Lakes and northeastern regions of the United States. Increased canopy cover is a major factor implicated in the decline of the Karner blue at many locales. Therefore, we examined how the butterfly's behavior varied with canopy cover. Adult males at Indiana Dunes National Lakeshore used habitat under canopy openings for nearly 90% of their activities; females used openings and shaded areas more equally. The frequency of oviposition on the sole host plant, wild lupine Lupinus perennis , was highest under 30–60% canopy cover even though lupine was more abundant in more open areas. Larvae fed preferentially on larger lupine plants and on lupines in denser patches. However, lupines were generally larger in the shade. Therefore, shade-related trade-offs existed between lupine abundance and distribution of larval feeding and oviposition. Also, heterogeneity of shading by sub-canopy woody vegetation was greater at oviposition sites than at sites where lupine did not grow. Given the importance of shade heterogeneity, a mixture of canopy openings and shade, on a scale similar to daily adult movement range, should be beneficial for this butterfly.

Biological Conservation↗