The American Midland Naturalist articles from July 1997

The American Midland Naturalist archives from July 1997

Spatial variation in rates of seed removal by harvester ants (Pogonomyrmex occidentalis) in a shrub-steppe ecosystem.
July 1, 1997... INTRODUCTION Postdispersal seed predation is an important cause of seed mortality in many ecosystems (Janzen, 1971; Louda, 1989; Crawley, 1992; Sallabanks and Courtney, 1992). In arid environments of North America, granivorous rodents and...

Ground beetle (Coleoptera: Carabidae) activity density and community composition in vegetationally diverse corn agroecosystems.
July 1, 1997... INTRODUCTION Conservation tillage is increasing as a method of controlling soil erosion from agricultural land in the United States. Conservation tillage is a tillage and planting system that includes both reduced and no-tillage systems, and...

Drifting macrophytes as a mechanism for zebra mussel (Dreissena polymorpha) invasion of lake-outlet streams.
July 1, 1997... INTRODUCTION During the past decade, considerable attention has been paid to the spread of zebra mussels (Dreissena polymorpha) in North America because of their economic and ecological impacts (Nalepa and Schloesser, 1993). Some studies...

Northern redistribution of freshwater pearly mussels (Bivalvia: Unionoidea) during Wisconsin deglaciation in the southern Glacial Lake Agassiz region: a review.
July 1, 1997... INTRODUCTION Malacologists, working in the southern Glacial Lake Agassiz region (e.g., Wilson and Danglade, 1914; Dawley, 1947; Cvancara and Cvancara et al., see below; Clarke, 1973, 1981) and elsewhere (e.g., Simpson, 1896; Ortmann, 1924;...

Identification of a fish host of the inflated heelsplitter Potamilus inflatus (Bivalvia: Unionidae) with a description of its glochidium.
July 1, 1997... INTRODUCTION Potamilus inflatus is a federally threatened mussel that inhabits large rivers in the southeastern United States (U.S. Fish and Wildlife Service, 1992). The historical range of P. inflatus has decreased markedly in the last...

Effects of urbanization on brown trout Salmo trutta, other fishes and macroinvertebrates in Valley Creek, Valley Forge, Pennsylvania.
July 1, 1997... INTRODUCTION Valley Creek supports a productive naturalized population of brown trout (Salmo trutta) within the Philadelphia metropolitan area. Urbanization of the watershed threatens the integrity of this ecosystem. The term 'urbanization'...

Taxonomic status and distribution of the lamprey ichthyomyzon cf. gagei.
July 1, 1997... INTRODUCTION When Hubbs and Trautman (1957) described the southern brook lamprey, Ichthyomyzon gagei, during a revision of the genus Ichthyomyzon, they suggested that this nonparasitic species was derived from the parasitic chestnut lamprey...

An 18-year study of litterfall and litter decomposition in a Northeast Iowa deciduous forest.
July 1, 1997... INTRODUCTION As the major mechanism for nutrient recycling, litter decomposition in deciduous forests has had considerable attention (Swift et al., 1979; McClaugherty et al., 1985; Blair et al., 1990; Laskowski et al., 1995; Verhoef, 1996)....

Understory light regime, shrub layer and sand pine (Pinus clausa) regeneration in four scrub stands.
July 1, 1997... INTRODUCTION Within its present range, sand pine [Pinus clausa (Chapm. ex. Engelm.) Vasey ex. Sarg] has been separated into two geographically disjunct varieties. Ocala sand pine (Pinus clausa var. clausa D. B. Ward) occurs in the Florida...

Root system differences among species: implications for early successional changes in forests of Western Oregon.
July 1, 1997... INTRODUCTION Root systems vary greatly among species in ways that can influence species' interactions and, ultimately, changes in abundance during succession (Weaver, 1958; Parrish and Bazzaz, 1976; Fitter et al., 1988; Gleeson and Tilman,...

Demography and life history characteristics of the rare Kachina daisy (Erigeron kachinensis, Asteraceae).
July 1, 1997... INTRODUCTION The Kachina daisy (Erigeron kachinensis Welsh & Moore) is a rare endemic of the Colorado Plateau portions of southeastern Utah and southwestern Colorado. It is confined to sandy saline substrates in alcoves (recessed areas in...

Do plants derived from seeds that readily germinate differ from plants derived from seeds that require forcing to germinate? A case study of the desert mustard Lesquerella fendleri.
July 1, 1997... INTRODUCTION In many environments, within-year seed dormancy delays germination until a time which favors successful germination and subsequent plant establishment and reproduction. The time that a seed germinates within this favorable...

Polymorphic floral traits in Linaria canadensis (Scrophulariaceae).
July 1, 1997... INTRODUCTION Animal-pollinated flowers contain structures designed to attract and reward pollinators in order to disperse and receive pollen. While some of these structures may be highly canalized in appearance, others may be quite variable...

Growth and survival of Polygonum aviculare L. at a brine-contaminated site in southeastern Ohio.
July 1, 1997... INTRODUCTION Halophytes occur in coastal and inland saline areas such as salt marshes and salt deserts, or in habitats created as a result of oil drilling, salt mining, irrigation and deicing of highways (Ungar, 1987). They can tolerate high...

Historic and current amphibian and reptile distributions in the island region of western Lake Erie.
July 1, 1997... INTRODUCTION The island region of western Lake Erie includes taxa and biological communities not found elsewhere and thus makes a unique contribution to the biota of Ohio and Ontario (Clapp, 1916; Conant and Clay, 1937; Boerner, 1984;...

Growth rate, body size, sexual dimorphism and morphometric variation in four populations of painted turtles (Chrysemys picta bellii) from Nebraska.
July 1, 1997... INTRODUCTION Individual growth rates and body size are important life history traits in that they often influence, and are influenced by, other traits that directly affect reproductive success (Stearns, 1992). Within freshwater turtle...

Effects of horning and rubbing behavior by bison (Bison bison) on woody vegetation in a tallgrass prairie landscape.
July 1, 1997... INTRODUCTION Bison (Bison bison L.), like many large mammals (Snyder and Janke, 1976; Inouye et al., 1994), are capable of severely impacting woody vegetation. England and DeVos (1969) suggested that herds of bison in North American prairies...

Population characteristics of coyotes (Canis latrans) in the northern Chihuahuan Desert of New Mexico.
July 1, 1997... INTRODUCTION Coyote (Canis latrans) population dynamics are influenced by interactions between their social organization and food availability (Knowlton and Stoddart, 1983; Windberg, 1995) and by the degree of human exploitation (Knowlton,...

Changes in trumpeter swan (Cygnus buccinator) activities from winter to spring in the greater Yellowstone area.
July 1, 1997... INTRODUCTION The number of wintering trumpeter swans (Cygnus buccinator) in the greater Yellowstone ecosystem has increased sharply from approximately 700 birds in 1974 (Gale et al., 1987) to 2,200 in 1992 (Niethammer, 1992). There has also...

Aquatic seed dispersal and its implications in Cirsium vinaceum, a threatened endemic thistle of New Mexico.
July 1, 1997... INTRODUCTION Seed dispersal is a primary determinant of gene flow among plant populations. Interpretation of dispersal data is often problematic, sometimes underestimating gene flow because of erroneous assumptions about neighborhood size...

External morphology of spermatozoa and spermatozeugmata of the freshwater mussel Truncilla truncata (Mollusca: Bivalvia: Unionidae).
July 1, 1997... INTRODUCTION The gross morphology and fine structure of the spermatozoa of many marine bivalves and of a few freshwater bivalves have been described (Coe, 1931; Trimble and Gaudin, 1975; Popham, 1979; Drozdova and Kas'yanov, 1986; Peredo et...

Shell strength of mud snails (Ilyanassa obsoleta) may deter foraging by diamondback terrapins (Malaclemys terrapin).
July 1, 1997... INTRODUCTION Diamondback terrapins (Malaclemys terrapin) consume a variety of small shellfish, crustaceans and fish (Ernst et al., 1994). In South Carolina salt marshes, 76-79% of the terrapin diet is composed of periwinkles (Littorina...

Scale-dependent habitat selection by the darkling beetle Eleodes hispilabris (Coleoptera: Tenebrionidae).
July 1, 1997... INTRODUCTION Habitat selection - the nonrandom use of habitats in relation to their availability - is a scale-dependent phenomenon. Animals may occupy broad-scale habitat types (such as "beech forest," "serpentine grassland," or "alpine...

Erratum. (correction to 'A variant of the hypergeometric distribution for large or territorial organisms,' vol. 137, no. 2, pp. 195-205, 1997)(Correction Notice)
July 1, 1997... In Ghent, A. W. 1997. A variant of the hypergeometric distribution for large or territorial organisms. 137(2): 195-205. On p. 199, six lines below equation (5), the new sentence should read: "Subsequent terms for two, three and four organisms...