1,070 research outputs found

    Distribution, Natural History Aspects, and Status of the Arkansas Endemic Crayfish, Fallicambarus harpi Hobbs and Robinson, 1985

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    Recent fieldwork in west central Arkansas has revealed the Arkansas endemic crayfish, Fallicambarus harpi Hobbs and Robison, to be more abundant than formerly believed. New localities and county records are provided in addition to information on the habitat preferences, sex ratio, color variation, reproductive biology, and conservation status of this burrowing crayfish

    Current frameworks for reference ET and crop coefficient calculation

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    Estimation of evapotranspiration is under continual development and evolution, with significant developments and standardizations made during the past three decades for both reference ET (ETref) and for crop coefficients (Kc). These standardizations provide consistency and reproducibility in estimating ETref and a consistent basis for determining and expressing Kc curves, especially at the local scale. The application of the dual Kc procedure is growing, and has strong potential for improving accuracy of ET estimates as compared to the single Kc approach. This article describes current structures for estimating crop coefficients including the standardized FAO-56 dual Kc approach, with example applications. Emphasis is placed on estimation of parameters and special cases to be considered. Newer bases for establishing Kcb curves include thermal units and vegetation indices

    USCID fourth international conference

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    Presented at the Role of irrigation and drainage in a sustainable future: USCID fourth international conference on irrigation and drainage on October 3-6, 2007 in Sacramento, California.Includes bibliographical references.Evapotranspiration and net irrigation water requirements were determined for 123 weather station locations across the state of Idaho for available periods of record. Estimates were made for daily, monthly and annual timesteps. Updated methods were employed for calculating reference evapotranspiration (ETr) and crop coefficients (Kc). The ET estimates cover a wide range of agricultural crops grown in Idaho and, in addition, ET estimates have been made for a number of native plant systems including wetlands, rangeland, and riparian trees. Estimates have been made for evaporation from three types of open water surfaces ranging from deep reservoirs to small farm ponds. The ET and net irrigation water requirement calculations are intended for use in design and management of irrigation systems, for water rights management and consumptive water rights transfers and for hydrologic studies. ET calculations have been made for all times during the calendar year including winter to provide design and operation information for managing land application of agriculture, food processing and other waste streams. The weather stations evaluated include 107 National Weather Service (NWS) cooperative stations measuring primarily air temperature and precipitation and 16 AgriMet agricultural weather stations. The AgriMet stations measure a full complement of weather data affecting evapotranspiration and are located primarily in the southern part of the state. Estimates at many stations cover more than 80 to 100 year periods of air temperature data. Because only maximum and minimum air temperature are observed at the NWS cooperative stations, the solar radiation, humidity and wind speed data parameters required in the ASCE Penman-Monteith equation (ASCE-PM) were estimated similar to recommendations in ASCE-EWRI (2005) where estimates for solar radiation (Rs) were based on differences between daily maximum and minimum air temperature and estimates for daily dewpoint temperature were based on daily minimum air temperature. Estimates for wind speed were based on long-term mean monthly summaries from AgriMet stations in southern Idaho and some airport locations in central and northern Idaho. Crop evapotranspiration, abbreviated ETc, was calculated on a daily timestep basis for improved accuracy. Daily calculation timesteps allowed for the calculation of evaporation of water from wet soil surfaces following precipitation or irrigation events. ETc for monthly, growing season and annual periods were summed from the daily calculations. Basal crop coefficient curves were developed or organized for 42 crop and land-cover types. Scheduling of irrigations was simulated to estimate soil evaporation from irrigation wetting events using a root-zone water balance

    Parasites of the Spotted Sucker, Minytrema melanops (Cypriniformes: Catostomidae) from Arkansas and Oklahoma

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    During October 2015, March and April 2016 and again between March and April 2017, 15 Spotted Sucker (Minytrema melanops) were collected from sites in the Ouachita (n = 5), Red (n = 1), and St. Francis (n = 5) river drainages, Arkansas, and the Arkansas River drainage, Oklahoma (n = 4), and examined for protozoan and metazoan parasites. Found were Calyptospora sp., Myxobolus sp., Pseudomurraytrema alabarrum, Biacetabulum banghami, Penarchigetes oklensis, and Acanthocephalus sp. New host and distributional records are documented for these parasites

    Fifty-four State Records of True Bugs (Hemiptera: Heteroptera) from Arkansas

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    The terrestrial true bug (Hemipterar: Heteroptera) fauna of Arkansas is poorly represented in the literature. Between 1998 and 2004, we retained Hemiptera specimens collected while conducting a few scattered entomological projects. Ninety-nine species of terrestrial Hemiptera, representing 15 families, were collected from various locations within 9 Arkansas counties. Of these 99 species, 54 are new state records for Arkansas. The majority of these 54 new state records are of common, widespread species that would be expected for Arkansas. Twenty-two of the 54 species have been reported for at least 4 states bordering Arkansas, whereas only 5 species (all Miridae) were not previously reported for any bordering state. Our specimens of Pycnoderes convexicollis (Blatchley, 1926) represent a fairly significant range extension for this species, previously known only from Indiana and Illinois
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