Habitat Associations of Lepidoptera in the Ozark Mountains of Arkansas Author(S): L
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Habitat Associations of Lepidoptera in the Ozark Mountains of Arkansas Author(s): L. E. Dodd, M. J. Lacki, and L. K. Rieske Source: Journal of the Kansas Entomological Society, 84(4):271-284. 2011. Published By: Kansas Entomological Society DOI: http://dx.doi.org/10.2317/JKES110324.1 URL: http://www.bioone.org/doi/full/10.2317/JKES110324.1 BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/ terms_of_use. Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder. BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. JOURNAL OF THE KANSAS ENTOMOLOGICAL SOCIETY 84(4), 2011, pp. 271–284 Habitat Associations of Lepidoptera in the Ozark Mountains of Arkansas 1 1 2 L. E. DODD, M. J. LACKI, AND L. K. RIESKE ABSTRACT: Lepidoptera were surveyed using blacklight traps during the growing seasons of 2004 and 2005 in two counties that differed in land use patterns in the Ozark Mountains, Arkansas. Marion County is a fragmented landscape; habitats surveyed were upland forest, riparian forest, edge, and field. Crawford County lies in the Ozark National Forest; habitats surveyed were saw, pole, and sapling size classes of timber. Moths $20 mm in wingspan were identified and enumerated. A total of 8326 moths of $324 species and 22 families were identified and tabulated. The total number of species and family-level composition varied little between landscapes, but the relative occurrence of species varied between landscapes and across habitats. Dominance of common species varied between landscapes with fewer species forming the bulk of the assemblage in the fragmented landscape. Endemism of certain moths in riparian forest suggests this habitat supports many species. In contrast, few species were recorded in field habitats. These data demonstrate the importance of forest habitats for many moth species in the Ozark Mountains. Our study forms a foundation for understanding species richness patterns of Lepidoptera in the hardwood forests of central North America. KEY WORDS: Disturbance, diversity, land use, species checklist, species distributions, species richness, species survey Introduction Lepidoptera are one of the most hyperdiverse insect assemblages in the forests of North America (Hodges et al., 1983; Covell, 2005). Despite their widespread occurrence, species within this assemblage vary with forest condition (Summerville and Crist, 2008), suggesting that sensitive taxa may serve as indicators of forest quality or health (Summerville et al., 2004). The distribution and knowledge of habitat affiliations of Lepidoptera are broadly known across eastern North America. Data. exist for many areas in central and eastern North America such as the hardwood and conifer forests of Ohio (Rings and Metzler, 1988; Rings and Metzler, 1989; Rings et al., 1991; Summerville et al., 1999; Summerville and Crist, 2001; Coleman et al., 2004), the prairies of Kansas (Wright et al., 2003) and the mixed forests of Louisiana (Landau and Prowell, 1999a, b), but knowledge regarding species presence and composition of the lepidopteran assemblage is lacking for the Ozark Mountains (but see Spencer, 2006). We conducted blacklight trap surveys in the Ozark Mountains of northern Arkansas over two years to document the relative occurrence of species across habitats in two distinct forest landscapes. While the Ozark Mountains are a biodiversity hotspot for flora and fauna (Frazer et al., 1991), this region has a long history of anthropogenic disturbance (Chapman et al., 2006). By addressing the paucity of data that exists for lepidopteran assemblages in this region, we are not only bolstering our knowledge of regional species distributions in North America but 1 Department of Forestry, University of Kentucky, Lexington, KY 40546 USA. 2 Department of Entomology, University of Kentucky, Lexington, KY 40546 USA. Accepted 11 October 2011; Revised 21 October 2011 E 2011 Kansas Entomological Society 272 JOURNAL OF THE KANSAS ENTOMOLOGICAL SOCIETY also providing data pertaining to the influence of general land use patterns on the taxonomic composition of these ecologically-important insects. Materials and Methods Study Sites Surveys were conducted at two landscapes in Crawford County and Marion County, Arkansas (ca. 150 km apart). Forests in both counties consist of upland hardwoods, comprised primarily of an overstory of oak (Quercus sp.) and hickory (Carya sp.). Due to varied human disturbance, the matrices of habitat within the two landscapes differed. Marion County, hereafter referred to as ‘‘fragmented’’ landscape, is located near the Missouri border within the Ozark Highlands region (Omerik’s Level III Ecoregion) (Woods et al., 2004). The area is typical of the Elk River Hills; ridges with elevations of 300–400 m are dissected by small streams, yielding a convoluted landscape of steep valleys separated by narrow ridges. The landscape is impacted by small-scale agricultural use and timber harvests; ownership is predominantly private. Habitats surveyed in the fragmented landscape were: upland forest, riparian forest, edge, and field. ‘‘Edge’’ was defined as the interface of forested and non-forested areas. ‘‘Field’’ habitats were agricultural pastureland consisting of non-native grasses used for grazing and hay production. Riparian habitat was associated with mesic site conditions and, at a minimum, an ephemeral presence of water. Crawford County, hereafter referred to as ‘‘forested’’ landscape, is directly north of the Arkansas River along the Oklahoma border, lying both in the Arkansas Valley and Boston Mountain regions (Omerik’s Level III Ecoregion) (Woods et al., 2004). This landscape lies in the midst of the Boston Mountain Ranger District of the Ozark National Forest. The topography is rugged, with deep hollows and steep benched ridges occurring at elevations of 450–550 m. The landscape is heavily forested, and habitats surveyed were a function of the size class of given stands of timber, including sawtimber (Stand Condition Class 10, ‘‘mature,’’ .30.5 cm diameter at breast height [dbh]), poletimber (Stand Condition Class 11, ‘‘immature,’’ ,20.3 cm dbh), and sapling (Stand Condition Class 13, ‘‘adequately stocked’’) size classes, as defined by the USFS (Silvicultural Practices Handbook: FSH 2471.1 R8). Sampling and Identification Techniques Lepidoptera were surveyed during the growing seasons of 2004–2005 using 10 W blacklight traps (Universal Light Trap, Bioquip Products, Gardena, CA) (Dodd et al., 2008). Survey nights were fair, with temperatures $16uC at sunset, no precipitation, and low wind. Three replicate survey points were established for each habitat in both forested and fragmented landscapes (n 5 9andn 5 12, respectively); see Dodd et al. (2008) for additional explanation. A single replicate per habitat was considered during a single trap night at a landscape. Survey points were spaced far enough apart to ensure no overlap in effective trapping area (i.e., no two traps were visible from one another due to topographic relief and distances .100 m). Trap nights alternated between forested and fragmented landscapes. In 2004, traps were placed on the ground beginning at sunset and operated for five hours. Survey efforts were expanded in 2005; Lepidoptera were captured throughout an entire night by placing a second adjacent trap at each survey point. The resulting two traps VOLUME 84, ISSUE 4 273 per survey point were operated using timer switches (#2835 BioQuip Products, Gardena, CA). Additionally, traps in 2005 were suspended 2.5 m above ground to increase trap efficacy (Burford et al., 1999). A cotton wad soaked in ethyl acetate was placed in each trap to subdue trapped insects. Following a trap night, specimens were sorted and placed in cold storage (4uC) for identification in the laboratory. Specimens were enumerated and identified to species (or genus in rare cases) using Covell (2005) and Holland (1903), with family-level taxonomy following Covell (2005). Representative voucher specimens of selected species were retained in a collection at the University of Kentucky’s Forestry Department. We calculated Jaccard’s and Sørensen’s coefficients of similarity for comparisons between landscapes (Southwood, 1978). Additionally, we used EstimateS (v. 8.2) to generate ICE (Lee and Chao, 1994) and Chao 2 (Chao, 1987) species richness estimations. Estimations were based on 1000 randomizations (Summerville and Crist, 2005). We focused our efforts on macrolepidoptera and those microlepidoptera with wings $20 mm (i.e., some Oecophoridae, Yponomeutidae, Cossidae, Tortricidae, Zygaenidae, Megalopygi- dae, Limacodidae, and Pyralidae); thus, our study is not an exhaustive assessment of the assemblage. Results Moths were surveyed over six nights from July–August in 2004 with each replicate visited once (n 5 21 trap-nights).