Browsing by Subject "spatial distribution"

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    The spatial distribution and temporal variation of desert riparian forests and their influencing factors in the downstream Heihe River basin, China
    (2017) Ding, Jingyi; Zhao, Wenwu; Daryanto, Stefani; Wang, Lixin; Fan, Hao; Feng, Qiang; Wang, Yaping; Earth Science, School of Science
    Desert riparian forests are the main restored vegetation community in Heihe River basin. They provide critical habitats and a variety of ecosystem services in this arid environment. Since desert riparian forests are also sensitive to disturbance, examining the spatial distribution and temporal variation of these forests and their influencing factors is important to determine the limiting factors of vegetation recovery after long-term restoration. In this study, field experiment and remote sensing data were used to determine the spatial distribution and temporal variation of desert riparian forests and their relationship with the environmental factors. We classified five types of vegetation communities at different distances from the river channel. Community coverage and diversity formed a bimodal pattern, peaking at the distances of 1000 and 3000 m from the river channel. In general, the temporal normalized difference vegetation index (NDVI) trend from 2000 to 2014 was positive at different distances from the river channel, except for the region closest to the river bank (i.e. within 500 m from the river channel), which had been undergoing degradation since 2011. The spatial distribution of desert riparian forests was mainly influenced by the spatial heterogeneity of soil properties (e.g. soil moisture, bulk density and soil particle composition). Meanwhile, while the temporal variation of vegetation was affected by both the spatial heterogeneity of soil properties (e.g. soil moisture and soil particle composition) and to a lesser extent, the temporal variation of water availability (e.g. annual average and variability of groundwater, soil moisture and runoff). Since surface (0–30 cm) and deep (100–200 cm) soil moisture, bulk density and the annual average of soil moisture at 100 cm obtained from the remote sensing data were regarded as major determining factors of community distribution and temporal variation, conservation measures that protect the soil structure and prevent soil moisture depletion (e.g. artificial soil cover and water conveyance channels) were suggested to better protect desert riparian forests under climate change and intensive human disturbance.
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    Spatial Distribution of Children with an ASD Enrolled in Indiana Public Schools Compared to Quality-of-Life Indicators
    (Office of the Vice Chancellor for Research, 2014-04-11) Ashby, Jeffrey L.
    Autism Spectrum Disorder (ASD) is currently the fastest-growing developmental disability in the United States with the current prevalence rate of 1 in 88 as reported by the Centers for Disease Control and Prevention (CDC) Autism and Developmental Disabilities Monitoring (ADDM) Network. This increase has particularly impacted schools, since according to the Individuals with Disabilities Education Improvement Act [IDEA], these students must be served in the least restrictive environments that may range from special to inclusive classrooms. As such, it is important to assess the situation across the state of Indiana to better understand the areas of need and the distribution of this special population. This poster will take a spatially descriptive and quantitative approach to where and how ASDs are distributed across the state of Indiana using tools similar to those used by epidemiologist, such as crude rates and Bayesian modeling. Data were provided by the Indiana Department of Education and included a list of all public school districts in the state and the number in each district diagnosed with an ASD. A set of ten U.S. Census variables were identified from the literature and used to create a quality-of-life indicator to compare with the results of the spatial analysis. Based on the analysis, we can conclude that while autism in Indiana schoolchildren appears to be evenly distributed across the state, the more rural areas are at risk for services and should be made a priority for resources provided by the state and those NGO’s that specialize in helping those parents and families with children with ASDs.
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    Spatial Variations of Soil Moisture under Caragana korshinskii Kom. from Different Precipitation Zones: Field Based Analysis in the Loess Plateau, China
    (MDPI, 2016-02) Liu, Yuanxin; Zhao, Wenwu; Wang, Lixin; Zhang, Xiao; Daryanto, Stefani; Fang, Xuening; Department of Earth Sciences, School of Science
    Soil moisture scarcity has become the major limiting factor of vegetation restoration in the Loess Plateau of China. The aim of this study is: (i) to compare the spatial distribution of deep (up to 5 m) soil moisture content (SMC) beneath the introduced shrub Caragana korshinskii Kom. under different precipitation zones in the Loess Plateau and (ii) to investigate the impacts of environmental factors on soil moisture variability. Soil samples were taken under C. korshinskii from three precipitation zones (Semiarid-350, Semiarid-410, Semiarid-470). We found that the highest soil moisture value was in the 0–0.1 m layer with a large coefficient of variation. The soil water storage under different precipitation zones increased following the increase of precipitation (i.e., Semiarid-350 < Semiarid-410 < Semiarid-470), although the degree of SMC variation was different for different precipitation zones. The SMC in the Semiarid-350 zone initially increased with soil depth, and then decreased until it reached the depth of 2.8-m. The SMC in the Semiarid-410 zone showed a decreasing trend from the top soil to 4.2-m depth. The SMC in the Semiarid-470 zone firstly decreased with soil depth, increased, and then decreased until it reached 4.6-m depth. All SMC values then became relatively constant after reaching the 2.8-m, 4.2-m, and 4.6-m depths for Semiarid-350, Semiarid-410, and Semiarid-470, respectively. The low but similar SMC values at the stable layers across the precipitation gradient indicate widespread soil desiccation in this region. Our results suggested that water deficit occurred in all of the three precipitation zones with precipitation, latitude, field capacity, and bulk density as the main environmental variables affecting soil moisture. Considering the correlations between precipitation, SMC and vegetation, appropriate planting density and species selection should be taken into account for introduced vegetation management.