15,040 research outputs found

    Climate change: carbon losses in the Alps

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    The response of the terrestrial carbon cycle to global change is one of the main uncertainties in current climate change predictions1. Most terrestrial carbon is held in soils as organic matter derived from the decay of plant material (Fig. 1). Soil organic matter accounts for roughly three times more carbon than living vegetation, and for more carbon than vegetation and the atmosphere combined. Because elevated atmospheric CO2 concentrations have a fertilizing effect on plant growth, anthropogenic CO2 emissions have triggered increases in the land carbon sink2. However, models predict that other factors — such as water and nutrients — will eventually become limiting to plant growth, and hence to the land carbon sink. In contrast, the turnover of soil organic matter producing CO2 is expected to increase as the Earth warms. As a result, simulations using coupled carbon–climate models predict that the land surface will become a net source of CO2 before the end of the century, leading to a feedback loop between climate and soil carbon losses: increased emissions of CO2 from soil organic matter will lead to enhanced warming, which may then feedback to cause further soil organic matter losses. Prietzel and colleagues3, writing in Nature Geoscience, now provide evidence that warming has already caused a decline in soil organic matter in the German Alps

    An Annotated Checklist of Scarab Beetles (Coleoptera: Scarabaeidae) from Northeastern Iowa

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    A survey of scarab beetles (Coleoptera: Scarabaeidae) was conducted during 2009 in the geographically distinct area of Winneshiek and Allamakee counties in extreme Northeast Iowa. Four plant communities distributed among 10 locations, including tallgrass prairie, mixed grassland and forest, oak-hickory forest, and pasture were sampled during 2009 using black light traps, banana- beer traps, rodent burrow pitfalls, manure-baited pitfalls, and gleaning. Additionally, previous specimen records were examined. Forty-nine scarab species were documented for Winneshiek and Allamakee counties, including five species not previously reported in Iowa. Mixed grassland and forest habitat contained the greatest scarab species richness (n=31); black light trapping yielded the greatest number of individual beetles and collected the most species

    Butterflies (Lepidoptera) on Hill Prairies of Allamakee County, Iowa: A Comparison of the Late 1980s With 2013

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    In the late 1980s, several hundred butterflies were collected by John Nehnevaj from hill prairies and a fen in Allamakee County, Iowa. Nehnevaj’s collection included 69 species, 14 of which are currently listed in Iowa as species of greatest conservation need (SGCN). The goal of this study was to revisit sites surveyed in the 1980s and survey three additional sites to compare the species present in 2013 to the species found by Nehnevaj. A primary objective was to document the presence of rare prairie specialist butterflies (Lepidoptera), specifically the ottoe skipper (Hesperia ottoe W.H. Edwards; Hesperiidae), which was thought to be extirpated from Iowa. Twelve sites were surveyed 4 to 7 times between June and September 2013 using a meandering Pollard walk technique. A total of 2,860 butterflies representing 58 species were found; eight of these species were SGCN’s, including the hickory hairstreak (Satyrium caryaevorum McDunnough; Lycaenidae), and Leonard\u27s skipper (Hesperia leonardus Harris; Hesperiidae), species not collected in the 1980s, and the ottoe skipper and Baltimore checkerspot (Euphydryas phaeton Drury; Nymphalidae), both species also found by Nehnevaj. Species richness for the sites ranged from 14 to 33 species, with SGCNs found at 11 of the 12 sites. Significant landscape changes have occurred to hill prairies in Allamakee County over the past 25 years. Invasion by red cedar (Juniperus virginiana) has reduced hill prairie an average of 55.4% at these sites since the 1980s, but up to 100% on some of the sites surveyed by Nehnevaj. These changes in habitat may have contributed to the overall decrease in species richness. This study provides valuable information about the current status of butterflies present on northeastern Iowa hill prairies that can be used in directing future land management and conservation efforts

    The transportation depot: An orbiting vehicle support facility

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    This paper describes the details of an effort to produce conceptual designs for an orbiting platform, called a transportation depot, to handle assembly and processing of lunar, Martian, and related vehicles. High-level requirements for such a facility were established, and several concepts were developed to meet those requirements. By showing that the critical rigid-body momentum characteristics of each concept are similar to those of the dual-keel space station, some insight was gained about the controllability and utility of this type of facility. Finally, several general observations were made that highlight the advantages and disadvantages of particular design features
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