نتایج جستجو برای: sand dune
تعداد نتایج: 29993 فیلتر نتایج به سال:
The trait-based approach shows that plant functional diversity strongly affects ecosystem properties. However, few empirical studies show the relationship between soil fungal diversity and plant functional diversity in natural ecosystems. We investigated soil fungal diversity along a restoration gradient of sandy grassland (mobile dune, semifixed dune, fixed dune, and grassland) in Horqin Sand ...
We apply a model for sand dunes to calculate formation of dunes on Mars under the present Martian atmospheric conditions. We find that different dune shapes as those imaged by Mars Global Surveyor could have been formed by the action of sand-moving winds occuring on today’s Mars. Our calculations show, however, that Martian dunes could be only formed due to the higher efficiency of Martian wind...
CA-AIV-4754 was investigated during the summer of 1997 as part of the City of La Quinta's Adams Street widening project. This well-stratified sand dune deposit was initially an encampment associated with the exploitation of fish during the last stand of ancient Lake Cahuilla. With the desiccation of the lake the site remained in use sporadically and exhibited a change in sUbsistence practices r...
Large areas of Iran are under the influence of wind erosion thus it is important that we recognize three zones ofremoval, transportation and deposition. The deposition zone is very important due to more damages and tangibleeffects. In this study we try to obtain a comprehensive idea to Persian desert with use of laboratory facilities, remotesensing, GIS and field surveying. We survey 28 ergs in...
Local adaptation may occur when selection for heritable traits differs from environment to environment and gene flow among environments is restricted. In this study, we used reciprocal transplants to explore both the existence and possible causes of local adaptation in the clonal plant Hydrocotyle bonariensis at high and low elevations of sand dunes on St. George Island, Florida. Individuals fo...
Eolian dune fields on Earth and Mars evolve as complex systems within a set of boundary conditions. A source-to-sink comparison indicates that although differences exist in sediment production and transport, the systems largely converge at the dune-flow and pattern-development levels, but again differ in modes of accumulation and preservation. On Earth, where winds frequently exceed threshold s...
Collections of gram positive bacteria from coastal sand dune vegetation, Ipomoea pes-caprae showed a predominance of orange pigmented colonies of Microbacterium arborescens-AGSB. The pigment was identified using a combination of UV/visible spectral data and HPLC retention time as a lycopene type carotenoid pigment with λmax at 468 nms. These bacteria may be accumulating carotenoids as part of t...
Sedimentation is recognized as a major factor determining the ecosystem processes of lake beaches; however, the underlying mechanisms, especially in freshwater sand dunes, have been insufficiently studied. To this end, nine belt transects from nine freshwater sand dunes, classified into low (<23.7 m), medium (25.4-26.0 m), and high-elevation groups (>28.1 m) based on their elevations in 1972, w...
Long-time evolution of models of aeolian sand dune fields: Influence of dune formation and collision
Article history: Theoretical models which a Received 18 July 2008 Received in revised form 8 December 2008 Accepted 6 February 2009 Available online xxxx
Gale Crater contains Mount Sharp, a ~5km thick stratigraphic record of Mars’ early environmental history. The strata comprising Mount Sharp are believed to be sedimentary in origin, but the specific depositional environments recorded by the rocks remain speculative. We present orbital evidence for the occurrence of eolian sandstones within Gale Crater and the lower reaches of Mount Sharp, inclu...
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