A floristic analysis and comparison of plant communities in Harlan County, Nebraska.
Key words: Harlan County flora, mixed-grass prairie, Republican River, floristic analysis
South-central Nebraska played a major role in the early botanical history of Nebraska. The Spanish traversed this region, the traditional home of the Pawnee Tribe, as early as 1540-1542 when Coronado reached central Kansas. In 1820, the Long Expedition, with botanist Edwin James, made notable records from south-central Nebraska following the big bend of the Platte River. The Wyeth Expedition of 1834 with Thomas Nuttall also passed just to the north of the Republican River Valley and contributed many additional records to the region's flora. The J.C. Fremont expedition was next and moved through parts of the Republican Valley in 1843. Although numerous important plant collections were made, the total number of reported species was far below the number of plants that presently constitute the region's known flora. Therefore, the objective of this study was to provide additions to the flora of Harlan, County, Nebraska, from surveys of three different plant communities. These included (1) upland, grazed prairie; (2) lowland riparian forest; and (3) lowland, riparian forest/riverbank communities. Initially, this project was designed to survey only natural, undisturbed sites. However, the best available upland prairie site selected for our study was subjected to seasonal grazing, and much of the riparian community had signs of exposure to limited human activity.
Harlan County, Nebraska (Figure 1), is located in south central Nebraska and has a total area of 143,547 Ha (554 [mi.sup.2]). Of this total, 5587 Ha are occupied by Harlan County Reservoir, resulting in a land area of 137,960 Ha (~532 [mi.sup.2]) for Harlan County (Mitchell et al. 1974). With the exception of the northeastern comer, which is nearly level, approximately 90% of the county occurs in the Republican River drainage, which runs west to east, just north of the Kansas-Nebraska state line. The presettlement vegetation was mostly mixed-grass prairie accented by scattered patches of riparian forest along the river and several spring-fed tributaries. Most of the remaining prairie is either grazed by cattle or has been converted to irrigated farmland. The river valley provides riparian communities, sand bars, riverbank sites, and occasional wetlands, which enhance the potential flora of the area. In addition to the Republican River Valley, the county's uplands are described as Dissected Plains with the amount of natural vegetation estimated at 15% (Kaul et al. 2011).
As a result of the sod-busting era (-1862 into the early 20th century), much of the original mixed-grass prairie bordering the valley has been converted to cropland (Kaul et al. 2011). This has provided increased opportunities for introduced, invasive, and weedy plant species to become established in the area and has added additional, but undesirable, diversity to the region's flora.
Historically, the Harlan County flora of ~347 species, has been under-reported as compared to other counties in the region. For example, Webster County, ~40 km to the east, has a minimum flora of 604 species, and Kearney County to the northeast has a reported 586 species (Kaul and Rolfsmeier 1994; Kaul et al. 2011, Kaul and Simpson 2012). In a ranking of Nebraska's 93 counties based on each county's total flora, Harlan County originally was rated 61st (Kaul and Rolfsmeier 1994).
Over the last several decades, Harlan County has experienced environmental extremes that have affected the flora. The Republican River Basin includes parts of southwest and south central Nebraska, northeastern Colorado, and northwestern Kansas. It differs from the Platte and other western river basins because its flows rely totally on groundwater (springs) and precipitation, in contrast to the snow pack in the Rocky Mountains that feeds the Platte River headwaters. Historically, fluctuations in climate have been common, with periodic drought followed by years of above-normal precipitation. It is not unusual for daily summer temperatures in the area to exceed 38[degrees] C accompanied by periods of little or no measurable precipitation. The region was greatly affected by the Great Drought of the 1930's (Figure 2) being on the northern edge of the Dust Bowl. The drought was punctuated by Black Sunday (14 April 1935) when winds and powder-dry soil created one of the largest dust storms ever reported, suffocating people and livestock. Later that same season (30 May 1935), torrential rains in the upper part of the Republican River Basin resulted in a record flood that swept down the valley and took ~113 lives. Consequently, the vegetation has undergone several shifts in species composition in fewer than 100 years.
The present day flora reflects an increase in plant species mainly as a result of invasive species and introductions that take advantage of disturbances caused by cultivation and grazing. Irrigation has mitigated the effects of periodic drought, allowing some species to persist that otherwise would not have survived. The Republican River Valley does provide habitat and the opportunity for less adaptable plant species to inhabit an area that is known for climatic extremes and wide fluctuations in temperature and precipitation.
Material and Methods
Plants were collected at three contrasting sites in Harlan County (Figure 1; Table 1) throughout the 2009 growing season as late as 9 October to insure the inclusion of early and late season species. Plants were collected to help determine the overall diversity of the county, as well as to identify any rare or previously unrecorded species for the county. All collections were pressed and dried using a standard plant press and were deposited in the University of Nebraska at Kearney Herbarium (NEBK). Nomenclature follows the Flora of Nebraska 2nd ed. (Kaul et al. 2011). In addition to the Flora of Nebraska, field guides by Farrar (2011), Johnson and Larson (1999), and Owensby (1980) were used to assist in plant identification. A species checklist of vascular plants collected at the three sites was made and new county records were designated (Appendix 1).
Jaccard's Index of Similarity (ISj) was used to assess differences/similarities among the three sites.
[IS.sub.j] = c/(a + b + c) x 100
where "c" is the number of common species, "a" is the number of species unique to site #1, and "b" is the number of species unique to site #2. For comparison, it was useful to apply another similarity test, Sorensen's Index of Similarity (ISs),
[IS.sub.s] = 2c/a + b x 100,
where c = the number of species common to the two sites, a = the total number of species at a given site and b = the total number of species at the other site in the comparison. Coefficient of Conservatism (C) values as determined for Nebraska by Rolfsmeier and Steinauer (2003) were assigned to all native species in the study. A mean C value (Cm), and a Floristic Quality Index (FQI) were calculated for each of the three sites. The FQI serves as a point of comparison to other floristic studies and was determined using the equation
FQI = Cm x [square root of n],
where n = the total number of native species recorded at a study site (Mushet et al. 2002).
Results and Discussion
Although the 3 sites were not exceptionally diverse and each had been subjected to a degree of disturbance, a total of 48 new records for Harlan County were made, increasing the total flora to ~ 395 species of vascular plants (Appendix). Most are common throughout central Nebraska, but were not previously reported for Harlan County. One Tier 2 species listed by the Nebraska Natural Legacy Project, cut-leaf cucumber (Cyclanthera dissecta), was recorded at Site #2, a riparian area on the north side of the Republican River. Cut-leaf cucumber is known only from Harlan, Furnas, and Red Willow Counties in Nebraska but is likely more widely distributed in the Republican River Valley.
Dominant woody species in the riparian sites (#2 and #3) include plains cottonwood (Populus deltoides), green ash (Fraxinus pennsylvanica), box elder (Acer negundo) and northern catalpa (Catalpa speciosa). The understory consists of a mixture of herbaceous species, such as motherwort (Leonurus cardiaca) and poke weed (Phytolacca americana), along with shrubs and vines that are not subjected to continual inundation. River bank and sandbar habitats differ floristically, and support a number of opportunistic species, such as umbrella sedge (Cyperus odoratus), water speedwell (Veronica anagallis aquation), reed canary grass (Phalaris arundinacea), numerous sedges (Carex spp.) and rushes (Juncus spp.) that quickly colonize newly exposed substrate.
When we applied Jaccard's Index of Similarity (ISj), our results were somewhat surprising (Table 2). The most similar sites were #1 and #3 (ISj = 40.0%) but this was essentially equal to the ISj value of the two riparian sites (#2 and #3) which = 39.9%. Sites #1 and #2 were the most dissimilar (ISj = 31.3%). Sorensen's Index of Similarity was also used because it gives greater weight than Jaccard's to the species that recur in the two test areas than to those that are unique to either area (Mueller-Dombois and Ellenberg 1974). Based on ISs values, Sites #2 and #3 were the most similar (ISs = 56.6%), followed by Sites #1 and #3 (ISs = 51.9%), and Sites #1 and #2 (ISs = 47.2%) (Table 2).
Comparing the two methods, the results also indicate that there is not a great degree of separation or variability within the similarity values that were calculated. One explanation might be that the upland, grazed prairie (Site #1) does include a canyon and drainage area that seasonally contains standing water. A representative number of plant species that colonize this area are the same as those that occupy riverbank and sandbar communities (Sites #2 and #3).
A coefficient of conservatism value (C) as originally developed by Swink and Wilhelm (1979, 1994) was assigned to each native species in this study. We used values for Nebraska vascular plants as designated by Rolfsmeier and Steinauer (2003). These values rank native species in a given region on a scale of 0 to 10 and higher numbers give greater importance to native, endemic species that are limited to a narrow range of environmental characteristics. Low C values are assigned to plants that are highly reproductive and are adapted to a variety of habitats. By calculating an average or mean C for an area, this value can be used to assess the quality of vegetation present, or it may be incorporated into a Floristic Quality Index (FQI) for comparison to other sites in the region. Individually, the sites have relatively low Cm and FQI values. For Sites 1, 2, and 3, respectively, Cm values were 2.56,1.82, and 2.23 and FQI values were 25.08, 12.07, and 22.96. As expected, Site #1, consisting of mixed-prairie and a seasonal wetland is the most diverse.
These values are low in comparison to recent studies that were completed in other river valleys of central Nebraska. In a plant survey of a Loup River meadow, Veloso and Rothenberger (2008) reported a mean C of 4.14 and a FQI of 64.4. Rothenberger et al. (2010) reported a mean C of 3.73 and an FQI of 50.7 resulting from a similar study of a South Loup River meadow. Although these findings are indicative of the higher species richness and floristic quality of the Loup River Valley, this study contributes significantly to the known flora of Harlan County.
The botanical diversity of Harlan County is mainly a result of the combination of upland mixed-grass prairie and the riparian/ riverbank communities associated with the Republican River Valley that dominate the county's flora. Other plant communities of significance are the wooded uplands that extend west-east along the south side of the river, scattered wetlands, and the vegetation that borders small tributaries of the river. The Republican River Valley separates mixed-grass prairie species with both northern and southern affinities. Several species reported on limestone outcrops in Franklin and Webster Counties, such as Fendler's aster (Aster fendleri), Fremont's leather-flower (Clematis fremontii), and Fremont's evening-primrose (Oenothera macrocarpa ssp. fremontii), reach the northern edge of their range here. Therefore, additional study of prairies south of the river is recommended and the above species should be targeted. While the flora of Harlan County remains under-studied, 48 newly discovered species were collected confirming the botanical importance and significance of Harlan County.
Appendix 1. A Species Checklist for Harlan County Study Sites. (R = new county record; * = nonnative species) Scientific Name Common Name Abutilon theophrasti Medikus velvet-leaf Acer negundo L. box-elder Agrostis stolonifera L. redtop Achillea millefolium L. common yarrow Amaranthus retroflexus L. redroot pigweed Ambrosia artemisiifolia L. common ragweed Ambrosia psilostachya DC. western ragweed Ambrosia trifida L. giant ragweed Ammannia robusta Heer & Regel toothcup Amorpha fruticosa L. false indigo Antennaria neglecta Greene pussytoes Apocynum cannabinum L. Indian hemp dogbane Arctium minus (Hill) Bernh. common burdock Argemone polyanthemos (Fedde) prickly poppy G. Ownbey Aristida purpurea Nutt. purple three-awn Asclepias incamata L. swamp milkweed Asclepias pumila (A. Gray) Vail plains milkweed Asclepias syriaca L. common milkweed Astragalus crassicarpus Nutt. ground-plum Astragalus mollissimus Torr. wooly locoweed Aster ericoides L. ssp. ericoides heath aster Aster oblongifolius Nutt. aromatic aster Aster lanceolatus Willd. subsp. willowleaf aster lanceolatus Bidens cernua L. bur-marigold Bidens comosa (A.Gray) Wegand beggar-ticks Bidens frondosa L. devil's pitchfork Bolboschoenus fluviatilis (Torr.) river bulrush Sojak Bouteloua curtipendula (Michx.) side-oats grama Torr. Bouteloua gracilis (Kunth) Lag. Ex blue grama Griffiths Brickellia eupatorioides (L.) false boneset Shinners var. corymbulosa (Tory. & A. Gray) Shinners Bromus inermis Leyss. subsp. inermis smooth brome Bromusjaponicus Thunb. ex Murr. Japanese brome Bromus tectorum L. downy brome Buchloe dactyloides (Nutt.) Engelm. buffalo grass Callirhoe involucrata purple poppy mallow (Torr. & A. Gray) A. Gray Calystegia sepium (L.) R.Br. var. hedge bindweed angulata (Brummitt) N.H. Holmgren Cannabis sativa L. hemp Capsella bursa-pastoris (L.) Medik. shepherd's purse Carduus nutans L. musk thistle Carex blanda C. Dewey common wood sedge Carex brevior (C. Dewey) Mack. Ex fescue sedge Lunell Carex gravida L.H. Bailey heavy-fruit sedge Carex laeviconica C. Dewey smooth-cone sedge Carex praegracilis W. Boott clustered field sedge Catalpa speciosa (L.) Bureau northern catalpa Celtis occidentalis L. hackberry Cenchrus longispinus (Hack.) Fernald sandbur Chenopodium berlandieri Moq. pitseed goosefoot Chenopodium simplex (Torr.) Raf. maple-leaf goosefoot Chloris verticillata Nutt. windmill grass Cirsium altissimum (L.) Spreng. tall thistle Cirsium undulatum (Nutt.) Spreng. wavy-leaf thistle Cirsium vulgare (Savi) Tenore bull thistle Conium maculatum L. poison-hemlock Convolvulus arvensis L. field bindweed Conyza canadensis (L.) Cronquist horseweed Comus drummondii C.A. Mey. rough-leaved dogwood Croton texensis (Klotzsch) Mull. Texas croton Arg. Cyclanthera dissecta (Torr. & cutleaf-cucumber A. Gray) Am. Cyclachaena xanthiifolia Fresen. big marsh-elder Cyperus odoratus L. rusty flatsedge Cyperus squarrosus L. square flatsedge Delphinium virescens Nutt. prairie larkspur Descurainia pinnata (Walter) Britton tansy mustard Descurainia sophia (L.) Webb ex tansy mustard Prantl Desmanthus illinoensis (Michx.) Illinois bundleflower MacMillan ex B.L. Robinson Desmodium canadense (L.) DC. Canada tickclover Digitaria cognata (Schult.) Pilg. fall witchgrass Digitaria sanguinalis (L.) Scop. hairy crabgrass Dyssodiapapposa(Vent.)A.S.Hitchc. fetid-marigold Echinochloa crus-galli (L.) P. barnyard grass Beauv. Echinocystis lobata (Michx.) Torr. wild-cucumber & A.Gray Eclipta prostrata (L.) L. yerba de tajo Elaeagnus angustifolia L. Russian olive Eleocharis palustris (L.) Roem. & spike-rush Schultes Eleusine indica (L.) Gaertn. goosegrass Ellisia nyctelea (L.) L. waterpod Elymus canadensis L. Canada wild-rye Elymus repens (L.) Gould quackgrass Elymus smithii (Rydb.) Gould western wheatgrass Elymus virginicus L. Virginia wild-rye Eragrostis cilianensis (All.) stinkgrass Vignolo ex Janch. Eragrostispectinacea (Michx.) Nees Carolina lovegrass Erigeron strigosus Muhl. ex Wlld. prairie fleabane Euphorbia davidii Subils toothed spurge Euphorbia glyptosperma Engelm. ridge-seed spurge Euphorbia marginata Pursh snow-on-the-mountain Fraxinus pennsylvanica Marshall green ash Gaura coccinea Nutt. ex Pursh scarlet gaura Gaura parviflora Dougl. ex Lehm. velvety gaura Gleditsia triacanthos L. honey-locust Hackelia virginiana (L.) I.M. stickseed Johnst. Hedeoma hispida Pursh rough false pennyroyal Helianthus annuus L. common sunflower Helianthus maximiliani Schrad. Maximilian sunflower Hesperis matronalis L. dame's-rocket Hordeumjubatum L. foxtail barley Hordeum pusillum Nutt. little barley Juniperus virginiana L. red cedar Kochia scoparia (L.) Schrad. kochia Lactuca serriola L. prickly lettuce Lactuca canadensis L. wild lettuce Lappula redowskii (Homem.) Greene cupseed var. cupulata (A.Gray) M.E. Jones Leonurus cardiaca L. motherwort Lepidium densiflorum Schrader pepper-grass Leptochloa fusca (L.) Kunth subsp. sprangle-top fascicularis (Lam.) N. Snow Liatris punctata Hook. gayfeather Lindemia dubia (L.) Pennell false pimpernel Linum sulcatum Riddell grooved flax Lippia lanceolata Michx. fogfruit Lithospermum incisum Lehm. fringed puccoon Lygodesmiajuncea (Pursh) D. Don ex skeleton weed Hook. Malva neglecta Wallr. common mallow Medicago lupulina L. black medic Medicago sativa L. subsp. sativa alfalfa Mentha canadensis L. field mint Melilotus albus Medikus. white sweet clover Melilotus officinalis (L.) Pallas yellow sweet clover Mentzelia decapetala ten-petal stickleaf (Pursh ex Sims) Urban Mimosa quadrivalvis L. var. sensitive brier nuttallii (DC. ex Standl.) Beard ex Barneby Mirabilis nyctaginea (Michx.) common four-o'clock MacMill. Morus alba L. white mulberry Muhlenbergia mexicana (L.) Trin. wirestem muhly Muhlenbergia racemosa (Michx.) marsh muhly Britton, Sterns, & Poggenb. Nasturtium officinale WT Aiton water cress Nepeta cataria L. catnip Oenothera biennis L. common evening primrose Opuntia humifusa (Raf.) Raf. bigroot prickly-pear Oxalis dillenii Jacq. gray oxalis Oxytropis lambertii Pursh purple locoweed Panicum capillare L. witchgrass Panicum dichotomiflorum Michx. fall panicum Panicum oligosanthes Schult. var. Scribner panicum scribnerianum (Nosh) Fernald Panicum virgatum L. switchgrass Parthenocissus vitacea (Knerr) woodbine A. Hitchc. Pediomelum digitatum (Nutt. Ex palm-leaf scurfpea Torr. & A.Gray) Isely Phalaris arundinacea L. reed canarygrass Physalis heterophylla Nees clammy ground cherry Physalis longifolia Nutt. common ground-cherry Phytolacca americana L. pokeweed Plantago patagonica Jacq. wooly plantain Poa pratensis L. Kentucky bluegrass Polygonum aviculare L. subsp. knotweed depressum (Meissn.) Arcang. Polygonum bicome Raf. pink smartweed Polygonum lapathifolium L. pale smartweed Polygonum pensylvanicum L. Pennsylvania smartweed Polygonum persicaria L. lady's thumb Polygonum scandens L. climbing false buckwheat Populus deltoides Bartr. Ex Plains cottonwood Marsh.subsp. monilifera (Aiton) Eckenwalder Prunus virginiana L. choke cherry Psoralidium tenuiflorum (Pursh) slender-flowered scurf-pea Rydb. Ranunculus sceleratus L. var. cursed crowfoot sceleratus Rhus glabra L. smooth sumac Ribes missouriense Nutt. Missouri gooseberry Ribes odoratum H.L. Wend]. buffalo currant Rorippa palustris (L.) Bess. var. bog yellow cress glabra (O.E. Schulz) Roy L. Taylor & MacBryde Rosa woodsii Lindl. western wild rose Rudbeckia hirta L. var. pulcherrima black-eyed susan Farw. Rumex altissimus A.W. Wood pale dock Rumex crispus L. curly dock Salix amygdaloides N.J. Andersson peach-leaf willow Salix exigua Nutt. subsp. Interior coyote willow (Rowlee) Cronquist Salsola tragus L. Russian thistle Salvia reflexa Homem. Rocky Mountain sage Sambucus canadensis L. elderberry Schizachyrium scopanium (Michx.) little bluestem Nash Setaria faberi R.A.W. Herrm. Chinese foxtail Setaria pumila (Poir.) Roem. & yellow foxtail Schult. Setaria verticillata (L.) P.Beauv. bristly foxtail Setaria viridis (L.) P. Beauv. green foxtail Sicyos angulatus L. bur-cucumber Sisymbrium loeselii L. tall hedge mustard Solanum carolinense L. Carolina nightshade Solanum interius Rydb. plains black nightshade Solanum rostratum Dunal buffalo-bur Solidago canadensss L. Canada goldenrod Solidago gigantea Aiton late goldenrod Solidago missouriensis Nutt. Missouri goldenrod Sonchus asper (L.) Hill prickly sow-thistle Sorghastrum nutans (L.) Nash Indian grass Spartina pectinata Link prairie cordgrass Sporobolus compositus (Poir.) Merr. rough dropseed Sporobolus cryptandrus (Torr.) A. sand dropseed Gray Stipa viridula Trin. green needle grass Symphoricarpos orbiculatus Moench coralberry Taraxacum officinale F.H. Wigg. common dandelion Teucrium canadense L. var. American germander occidentale (A.Gray) McClint.& Epling Thelesperma megapotamicum (Spreng.) greenthread Kuntze Toxicodendron radicans (L.) Kuntze poison ivy var. rydbergii (J.K. Small ex Rydb.) Erskine Tragopogon dubius Scop. goatsbeard Tribulus terrestris L. puncture-vine Tridens flavus (L.) A.S. Hitchc. purpletop Ulmus americana L. American elm Ulmus pumila L. Siberian elm Urtica dioica L. subsp. Gracilis stinging nettle (Aiton) Selander Verbascum thapsus L. mullein Verbena bipinnatifida Nutt. fernleaf vervain Verbena bracteata Lag. & J.D. prostrate vervain Rodriguez Verbena hastata L. blue vervain Verbena stricta Vent. hoary vervain Verbena urticifolia L. white vervain Vemonia baldwinii Torr. western ironweed Veronica anagallis-aquatica L. water speedwell Vitis riparia Michx. river-bank grape Vulpia octoflora (Walter) Rydb. sixweeks-fescue Xanthium strumarium L. var. cocklebur canadense (P. Mill.) Torr. & A. Gray Site New county Scientific Name 1 2 3 record C-value Abutilon theophrasti Medikus X X * Acer negundo L. X X X 3 Agrostis stolonifera L. X * Achillea millefolium L. X 2 Amaranthus retroflexus L. X X 0 Ambrosia artemisiifolia L. X X R 0 Ambrosia psilostachya DC. X X 1 Ambrosia trifida L. X X X 0 Ammannia robusta Heer & Regel X 4 Amorpha fruticosa L. X X R 5 Antennaria neglecta Greene X R 3 Apocynum cannabinum L. X 2 Arctium minus (Hill) Bernh. X X * Argemone polyanthemos (Fedde) X 1 G. Ownbey Aristida purpurea Nutt. X 5 Asclepias incamata L. X X R 4 Asclepias pumila (A. Gray) Vail X R 4 Asclepias syriaca L. X 1 Astragalus crassicarpus Nutt. X R 7 Astragalus mollissimus Torr. X 3 Aster ericoides L. ssp. ericoides X X 3 Aster oblongifolius Nutt. X 5 Aster lanceolatus Willd. subsp. X X R 2 lanceolatus Bidens cernua L. X X 3 Bidens comosa (A.Gray) Wegand X 2 Bidens frondosa L. X R 1 Bolboschoenus fluviatilis (Torr.) X R 3 Sojak Bouteloua curtipendula (Michx.) X X 5 Torr. Bouteloua gracilis (Kunth) Lag. Ex X X 4 Griffiths Brickellia eupatorioides (L.) X R 4 Shinners var. corymbulosa (Tory. & A. Gray) Shinners Bromus inermis Leyss. subsp. inermis X X * Bromusjaponicus Thunb. ex Murr. X X * Bromus tectorum L. X * Buchloe dactyloides (Nutt.) Engelm. X 2 Callirhoe involucrata X 2 (Torr. & A. Gray) A. Gray Calystegia sepium (L.) R.Br. var. X 1 angulata (Brummitt) N.H. Holmgren Cannabis sativa L. X X X Capsella bursa-pastoris (L.) Medik. X X X Carduus nutans L. X X Carex blanda C. Dewey X R 2 Carex brevior (C. Dewey) Mack. Ex X X 4 Lunell Carex gravida L.H. Bailey X 4 Carex laeviconica C. Dewey X 4 Carex praegracilis W. Boott X 4 Catalpa speciosa (L.) Bureau X X Celtis occidentalis L. X R 4 Cenchrus longispinus (Hack.) Fernald X 0 Chenopodium berlandieri Moq. X X X R 0 Chenopodium simplex (Torr.) Raf. X X 1 Chloris verticillata Nutt. X 0 Cirsium altissimum (L.) Spreng. X X 1 Cirsium undulatum (Nutt.) Spreng. X 4 Cirsium vulgare (Savi) Tenore X X * Conium maculatum L. X * Convolvulus arvensis L. X X X * Conyza canadensis (L.) Cronquist X X X 0 Comus drummondii C.A. Mey. X X X 3 Croton texensis (Klotzsch) Mull. X X 1 Arg. Cyclanthera dissecta (Torr. & X R 0 A. Gray) Am. Cyclachaena xanthiifolia Fresen. X X 0 Cyperus odoratus L. X 3 Cyperus squarrosus L. X 2 Delphinium virescens Nutt. X R 6 Descurainia pinnata (Walter) Britton X R 0 Descurainia sophia (L.) Webb ex X * Prantl Desmanthus illinoensis (Michx.) X 5 MacMillan ex B.L. Robinson Desmodium canadense (L.) DC. X 5 Digitaria cognata (Schult.) Pilg. X R 4 Digitaria sanguinalis (L.) Scop. X * Dyssodiapapposa (Vent.) A.S. Hitchc. X R 0 Echinochloa crus-galli (L.) P. X R * Beauv. Echinocystis lobata (Michx.) Torr. X 3 & A.Gray Eclipta prostrata (L.) L. X 2 Elaeagnus angustifolia L. X * Eleocharis palustris (L.) Roem. & X 4 Schultes Eleusine indica (L.) Gaertn. X X X * Ellisia nyctelea (L.) L. X 0 Elymus canadensis L. X 5 Elymus repens (L.) Gould X R * Elymus smithii (Rydb.) Gould X R 3 Elymus virginicus L. X X 4 Eragrostis cilianensis (All.) X X X * Vignolo ex Janch. Eragrostispectinacea (Michx.) Nees X 0 Erigeron strigosus Muhl. ex Wlld. X X R 2 Euphorbia davidii Subils X 0 Euphorbia glyptosperma Engelm. X 0 Euphorbia marginata Pursh X X 0 Fraxinus pennsylvanica Marshall X X X 2 Gaura coccinea Nutt. ex Pursh X 4 Gaura parviflora Dougl. ex Lehm. X X X 1 Gleditsia triacanthos L. X 1 Hackelia virginiana (L.) I.M. X 2 Johnst. Hedeoma hispida Pursh X 2 Helianthus annuus L. X R 0 Helianthus maximiliani Schrad. X R 4 Hesperis matronalis L. X Hordeumjubatum L. X X 1 Hordeum pusillum Nutt. X 1 Juniperus virginiana L. X X X R 1 Kochia scoparia (L.) Schrad. X X X * Lactuca serriola L. X X X * Lactuca canadensis L. X X R 2 Lappula redowskii (Homem.) Greene X 2 var. cupulata (A.Gray) M.E. Jones Leonurus cardiaca L. X X * Lepidium densiflorum Schrader X X X 0 Leptochloa fusca (L.) Kunth subsp. X 1 fascicularis (Lam.) N. Snow Liatris punctata Hook. X 5 Lindemia dubia (L.) Pennell X 5 Linum sulcatum Riddell X R 6 Lippia lanceolata Michx. X 3 Lithospermum incisum Lehm. X 5 Lygodesmiajuncea (Pursh) D. Don ex X 4 Hook. Malva neglecta Wallr. X R * Medicago lupulina L. X * Medicago sativa L. subsp. sativa X R * Mentha canadensis L. X 4 Melilotus albus Medikus. X Melilotus officinalis (L.) Pallas X Mentzelia decapetala X R 5 (Pursh ex Sims) Urban Mimosa quadrivalvis L. var. X 6 nuttallii (DC. ex Standl.) Beard ex Barneby Mirabilis nyctaginea (Michx.) X X X 1 MacMill. Morus alba L. X X X * Muhlenbergia mexicana (L.) Trin. X X 4 Muhlenbergia racemosa (Michx.) X 4 Britton, Sterns, & Poggenb. Nasturtium officinale WT Aiton X R * Nepeta cataria L. X X * Oenothera biennis L. X X X R 1 Opuntia humifusa (Raf.) Raf. X 5 Oxalis dillenii Jacq. X X 0 Oxytropis lambertii Pursh X 6 Panicum capillare L. X X X R 0 Panicum dichotomiflorum Michx. X X X 0 Panicum oligosanthes Schult. var. X 4 scribnerianum (Nosh) Fernald Panicum virgatum L. X X X 4 Parthenocissus vitacea (Knerr) X X X 4 A. Hitchc. Pediomelum digitatum (Nutt. Ex X R 6 Torr. & A.Gray) Isely Phalaris arundinacea L. X X X 0 Physalis heterophylla Nees X 4 Physalis longifolia Nutt. X X 0 Phytolacca americana L. X X R 0 Plantago patagonica Jacq. X 1 Poa pratensis L. X X X * Polygonum aviculare L. subsp. X * depressum (Meissn.) Arcang. Polygonum bicome Raf. X X 0 Polygonum lapathifolium L. X X 2 Polygonum pensylvanicum L. X X X R 0 Polygonum persicaria L. X * Polygonum scandens L. X X 1 Populus deltoides Bartr. Ex X X X 3 Marsh.subsp. monilifera (Aiton) Eckenwalder Prunus virginiana L. X R 3 Psoralidium tenuiflorum (Pursh) X 5 Rydb. Ranunculus sceleratus L. var. X * sceleratus Rhus glabra L. X 2 Ribes missouriense Nutt. X R 4 Ribes odoratum H.L. Wend]. X 4 Rorippa palustris (L.) Bess. var. X X 4 glabra (O.E. Schulz) Roy L. Taylor & MacBryde Rosa woodsii Lindl. X X R 4 Rudbeckia hirta L. var. pulcherrima X R 4 Farw. Rumex altissimus A.W. Wood X 0 Rumex crispus L. X X Salix amygdaloides N.J. Andersson X X 4 Salix exigua Nutt. subsp. Interior X 3 (Rowlee) Cronquist Salsola tragus L. X * Salvia reflexa Homem. X R 0 Sambucus canadensis L. X X X 2 Schizachyrium scopanium (Michx.) X 4 Nash Setaria faberi R.A.W. Herrm. X R * Setaria pumila (Poir.) Roem. & X X * Schult. Setaria verticillata (L.) P.Beauv. X X X * Setaria viridis (L.) P. Beauv. X X X * Sicyos angulatus L. X 1 Sisymbrium loeselii L. X R * Solanum carolinense L. X X 2 Solanum interius Rydb. X X 0 Solanum rostratum Dunal X X X 0 Solidago canadensss L. X X X 2 Solidago gigantea Aiton X X X 3 Solidago missouriensis Nutt. X 5 Sonchus asper (L.) Hill X * Sorghastrum nutans (L.) Nash X X X 5 Spartina pectinata Link X X 5 Sporobolus compositus (Poir.) Merr. X X 3 Sporobolus cryptandrus (Torr.) A. X 2 Gray Stipa viridula Trin. X R 4 Symphoricarpos orbiculatus Moench X X X 2 Taraxacum officinale F.H. Wigg. X X X R * Teucrium canadense L. var. X 4 occidentale (A.Gray) McClint.& Epling Thelesperma megapotamicum (Spreng.) X 4 Kuntze Toxicodendron radicans (L.) Kuntze X X X 2 var. rydbergii (J.K. Small ex Rydb.) Erskine Tragopogon dubius Scop. X R * Tribulus terrestris L. X X X * Tridens flavus (L.) A.S. Hitchc. X R 2 Ulmus americana L. X X X 3 Ulmus pumila L. X X X * Urtica dioica L. subsp. Gracilis X X X 1 (Aiton) Selander Verbascum thapsus L. X X X * Verbena bipinnatifida Nutt. X 4 Verbena bracteata Lag. & J.D. X 0 Rodriguez Verbena hastata L. X 4 Verbena stricta Vent. X X 2 Verbena urticifolia L. X 3 Vemonia baldwinii Torr. X R 3 Veronica anagallis-aquatica L. X * Vitis riparia Michx. X X X 3 Vulpia octoflora (Walter) Rydb. X 3 Xanthium strumarium L. var. X X X 1 canadense (P. Mill.)Torr. & A. Gray
The authors wish to thank the private landowners who gave permission for our study. We are also grateful for support and assistance from Dr. John Hastings, Department of Information Technology and Dr. Joseph Springer, Department of Biology at the University of Nebraska at Kearney. Thanks to Rick Simonson for preparing the map of the study area.
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Naomi D. Hastings and Steven J. Rothenberger
Department of Biology, University of Nebraska at Kearney, Kearney, Nebraska 68849-1140
Correspondence: Steve Rothenberger, email@example.com
Table 1. The locations of the three study sites, Harlan County, Nebraska. Site 1 Upland/Lowland The W 1/2 SEC 36, T3N, R20W Prairie Site 2 Riparian The NW 1/4 of the SW 1/4 SEC 6, T2N, R19W Site 3 Riparian The SW 1/4 SEC 36, T3N, R20W Table 2. Index of Similarity Values Comparing the Three Study Sites. Jaccard's (ISj) Sorensen's (ISs) Sites 1 and 3 40.0% 51.9% Sites 2 and 3 39.9% 56.6% Sites 1 and 2 31.3% 47.2%
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|Author:||Hastings, Naomi D.; Rothenberger, Steven J.|
|Publication:||Transactions of the Nebraska Academy of Sciences|
|Date:||Jun 1, 2013|
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