نتایج جستجو برای: sand dune fixation
تعداد نتایج: 82294 فیلتر نتایج به سال:
Vegetation patterns are strongly influenced by sand mobility in desert ecosystems. However, little is known about the spatial patterns of Artemisia ordosica, a dominant shrub in the Mu Us desert of Northwest China, in relation to sand fixation. The aim of this study was to investigate and contrast the effects of sand dune stabilization on the population and spatial distribution of this desert s...
microbial calcium carbonate, by bridging sand particles, can play an important role in sand dune stability. a study was carried out on the cementation of sand grains and infilling of pore spaces by caco3. two bacterial species (sporosarcina pasteurii and sporosarcina ureae), three reactant concentrations (0.5, 1 and 1.5m), and six reaction times (12, 24, 48, 96, 192 and 288 hours) were tested i...
the most usual type of petroleum mulch, which has been successfully used to combat desertification in large areain iran for more than thirty years, is produced by heavy residue petroleum cuts. the petroleum mulch consists of awide range of different heavy hydrocarbons such as polycyclic aromatic hydrocarbons (pahs). pahs are present atlow level in petroleum mulch, where there is contact with wa...
Coastal sand dunes have attracted the attention of plant ecologists for over a century, but they have largely relied on correlations to explain dune plant community organization. We examined long-standing hypotheses experimentally that sand binding, inter-specific interactions, abiotic factors and seedling recruitment are drivers of sand dune plant community structure in Sardinia, Italy. Removi...
Avalanches of various sizes occur due to instability during sand dune dynamics. A physically viable equation to model sand dune dynamics is a first order nonlinear difference equation. To visualize the size distribution of avalanches, sand dune dynamics has been numerically simulated by changing the strength of nonlinearity parameter (λ) that shows different impacts on dune dynamics. An equatio...
Vegetation is the most common and most reliable stabilizer of loose soil or sand. This ancient technique is for the first time cast into a set of equations of motion describing the competition between aeolian sand transport and vegetation growth. Our set of equations is then applied to study quantitatively the transition between barchans and parabolic dunes driven by the dimensionless fixation ...
New evidence indicates that sand availability does not only control dune type but also the underlying dune growth mechanism and the subsequent dune orientation. Here we numerically investigate the development of bedforms in bidirectional wind regimes for two different conditions of sand availability: an erodible sand bed or a localized sand source on a non-erodible ground. These two conditions ...
in civil engineering concrete is a material combined of hydraulic cement, sand, gravel and water. gravel and sand compose 60 to 70 percent of concrete. these aggregates support compression force of concrete. cement paste acts as glue to stick grain together. in bushehr factories producing aggregates do not operate according to astm standards, so that fineness modulus (fm) of the produced sands ...
We investigated the variations in specific leaf area (SLA) and leaf dry matter content (LDMC) of 20 species (10 annuals and 10 perennials) that have different distributional patterns in the Kerqin Sandy Land in northern China. The main purpose of our study was to determine if SLA and/or LDMC could be used as indicators of plant resource-use strategy in sand dune environments. The selected speci...
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