Jun 2011, Volume 5 Issue 2
    

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  • RESEARCH ARTICLE
    Jim GRAHAM, Catherine S. JARNEVICH, Annie SIMPSON, Gregory J. NEWMAN, Thomas J. STOHLGREN

    Invasive species are a universal global problem, but the information to identify them, manage them, and prevent invasions is stored around the globe in a variety of formats. The Global Invasive Species Information Network is a consortium of organizations working toward providing seamless access to these disparate databases via the Internet. A distributed network of databases can be created using the Internet and a standard web service protocol. There are two options to provide this integration. First, federated searches are being proposed to allow users to search “deep” web documents such as databases for invasive species. A second method is to create a cache of data from the databases for searching. We compare these two methods, and show that federated searches will not provide the performance and flexibility required from users and a central cache of the datum are required to improve performance.

  • RESEARCH ARTICLE
    Patricia YORK, Paul EVANGELISTA, Sunil KUMAR, James GRAHAM, Curtis FLATHER, Thomas STOHLGREN

    Biologic control of the introduced and invasive, woody plant tamarisk (Tamarix spp, saltcedar) in south-western states is controversial because it affects habitat of the federally endangered South-western Willow Flycatcher (Empidonax traillii extimus). These songbirds sometimes nest in tamarisk where floodplain-level invasion replaces native habitats. Biologic control, with the saltcedar leaf beetle (Diorhabda elongate), began along the Virgin River, Utah, in 2006, enhancing the need for comprehensive understanding of the tamarisk-flycatcher relationship. We used maximum entropy (Maxent) modeling to separately quantify the current extent of dense tamarisk habitat (>50% cover) and the potential extent of habitat available for E. traillii extimus within the studied watersheds. We used transformations of 2008 Landsat Thematic Mapper images and a digital elevation model as environmental input variables. Maxent models performed well for the flycatcher and tamarisk with Area Under the ROC Curve (AUC) values of 0.960 and 0.982, respectively. Classification of thresholds and comparison of the two Maxent outputs indicated moderate spatial overlap between predicted suitable habitat for E. traillii extimus and predicted locations with dense tamarisk stands, where flycatcher habitat will potentially change flycatcher habitats. Dense tamarisk habitat comprised 500 km2 within the study area, of which 11.4% was also modeled as potential habitat for E. traillii extimus. Potential habitat modeled for the flycatcher constituted 190 km2, of which 30.7% also contained dense tamarisk habitat. Results showed that both native vegetation and dense tamarisk habitats exist in the study area and that most tamarisk infestations do not contain characteristics that satisfy the habitat requirements of E. traillii extimus. Based on this study, effective biologic control of Tamarix spp. may, in the short term, reduce suitable habitat available to E. traillii extimus, but also has the potential in the long term to increase suitable habitat if appropriate mixes of native woody vegetation replace tamarisk in biocontrol areas.

  • RESEARCH ARTICLE
    Bapi GOSWAMI, Dipsikha GHOSH

    The rocks of Triassic Panchet Formation (TPF) of West Bengal, India, predominantly include sandstones of medium to fine grain-size, with subordinate shale and pebble horizons. Textural parameter like mean, standard deviation, skewness and kurtosis are calculated using standard methods to understand the transportation and the depositional environment of the sediments in a part of Panchet Formation. Granulometric analyses indicate the presence of fluvial environment interrupted with aeolian, beach and tidal environments prevailed during the time of deposition of the sediments in this part of Gondwanaland during the Triassic time.

  • RESEARCH ARTICLE
    Khelifa HARICHANE, Mohamed GHRICI, Hanifi MISSOUM

    Soil stabilization has been practiced for quite some time by adding mixtures, such as cement, lime and fly ash. The additives of lime (L), natural pozzolana (NP) or a combination of both were investigated here on the impact on the temporal variation of geotechnical characteristics of two cohesive soils. Lime and natural pozzolana were added at the content of 0–8% and 0–20%, respectively. The soil specimens were cured for 1, 7, 28 and 90 days and then tested for shear strength. Our data show that a combination of lime with natural pozzolana causes the increase in the maximum dry density but the decrease in the optimum moisture content in the gray soil, and vice verse in the red soil. The shear stress of both cohesive soils stabilized with lime or with the combination of lime and natural pozzolana was found to increase with time. The cohesion and the internal friction angle in lime-added samples were demonstrated to increase with time. The combination of lime with natural pozzolana exhibits a significant effect on the enhancement of the cohesion and the internal friction angle at later stages. The lime-natural pozzolana combination appears to produce higher shear parameters than lime or natural pozzolana used alone.

  • RESEARCH ARTICLE
    Jie LIU, Fan CHEN, Qing CUI, Yun JIANG

    This paper summarized the main ecological impact of hydraulic engineering to the hydrology and the sediment of the river, built up the index system assessing the ecological effect of the hydraulic engineering, and structured the integrative assessment model. This model was applied using the case project to verify the feasibility of integrative assessment system.