Fluid turbulence drives repulsion in shifting sand dunes

Physics World ◽  
2020 ◽  
Vol 33 (4) ◽  
pp. 7-7
Author(s):  
Michael Allen
Keyword(s):  
Sand Dunes ◽  
Fluid Turbulence ◽  
Shifting Sand

Calotropis procera (apple of sodom).

2021 ◽  
Author(s):  
Julissa Rojas-Sandoval ◽  
Pedro Acevedo-Rodríguez
Keyword(s):  
Sand Dunes ◽  
Fibre Production ◽  
Calotropis Procera ◽  
Desert Grassland ◽  
Evergreen Shrub ◽  
Diameter At Breast Height ◽  
Breast Height ◽  
Shifting Sand ◽  
Pale Green

Abstract C. procera is a fleshy evergreen shrub about 1.8-5.5 m tall, with a diameter at breast height of 15-20 cm (von Maydell, 1986). The flowers are pale green to white, with purple tips. A fibre obtained from the bark is used to make lines, bow-strings and twine; it can also be spun with cotton, or used to stuff mattresses and pillows. The fibre is strengthened by soaking in water for 1-2 days, but extensive soaking may reduce durability. The wood is of small dimensions and is too light for most uses. C. procera produces a distinctive white latex, which contains cardiotoxins and hydrocarbons with many medicinal and pesticidal properties. C. procera has been widely planted for fibre production and has become naturalized on the American and Australian continents. It is often abundant on degraded areas and is an indicator of overgrazing. C. procera is a widespread pioneer in semi-desert grassland and bushland (e.g. in Africa), and it also colonizes shifting sand-dunes such as in Rajasthan, India. However, due to its properties as a pioneer, there is a risk that this species may become a weed. More research is needed on C. procera to maximize production and marketing of its many potential products.

Soil nematode community succession in stabilised sand dunes in the Tengger Desert, China

Soil Research ◽  
2009 ◽  
Vol 47 (5) ◽  
pp. 508 ◽  
Author(s):  
Dejuan Zhi ◽  
Wenbin Nan ◽  
Xiaoxia Ding ◽  
Qinjian Xie ◽  
Hongyu Li
Keyword(s):  
Sand Dune ◽  
Sand Dunes ◽  
Chemical Properties ◽  
Shannon Index ◽  
Nematode Community ◽  
Soil Nematode ◽  
Tengger Desert ◽  
Nematode Communities ◽  
Shifting Sand ◽  
The Tengger Desert

In order to examine how nematodes respond to sand dune succession after stabilisation and reclamation techniques, nematode communities were investigated in sand dunes stabilised for 0, 16, 26, 43, and 51 years in the Tengger Desert, China. Our results revealed that the abundance of nematodes; the proportion of fungivores, omnivores, and predators; maturity index (MI); Shannon index; evenness; and structure index (SI) were affected significantly by the age of stabilised sand dunes, and were correlated with soil physical and chemical properties to different degrees. There were differences in nematode abundance, the proportion of fungivores, Shannon index, and evenness between the shifting dunes and the stabilised dunes, but not within the different succession stages of the stabilised dunes. MI showed a tendency to increase with dune age and SI increased significantly with dune age. MI, and especially SI, could act as robust indicators of stabilised sand dune succession. Redundancy analysis using data on nematode community composition showed that shifting sand dunes were clearly separated from stabilised sand dunes, and younger sand dunes stabilised for 16 and 26 years were also separated from older dunes stabilised for 43 and 51 years to a lesser degree. The results indicated that changes in nematode communities could predict initial sand dune stabilisation due to the planting of artificial vegetation, and clearly differentiate sand dune succession accompanied by vegetation succession and variation of soil properties.

scholarly journals Recovery of Soil-Denitrifying Community along a Chronosequence of Sand-Fixation Forest in a Semi-Arid Desertified Grassland

Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 354
Author(s):  
Chengyou Cao ◽  
Ying Zhang ◽  
Zhenbo Cui ◽  
Hailong Li ◽  
Tingting Wang ◽  
...  
Keyword(s):  
Sand Dune ◽  
Quantitative Polymerase Chain Reaction ◽  
Sand Dunes ◽  
Soil Microbial Communities ◽  
Forest Age ◽  
Total N ◽  
Available N ◽  
Soil Microbial ◽  
Soil N Cycle ◽  
Shifting Sand

Revegetation on moving sand dunes is a widely used approach for restoring the degraded sandy land in northeastern China. The development of sand-fixation forest might improve the structures of soil microbial communities and affect soil N cycle. In the present study, the diversities of nitrite (nirS and nirK) and nitrous oxide (nosZ) reductase genes were investigated under a chronosequence of Caragana microphylla sand-fixation shrub forest (9- and 19-year), adjacent non-vegetated shifting sand-dune, and a natural forest dominated by C. microphylla. The dominant compositions and gene abundance were analyzed by a clone library technique and quantitative polymerase chain reaction, respectively. The compositions and dominant taxa of nirK, nirS, and nosZ communities under forest soil were all similar to those in the shifting sand-dune. However, the three gene abundances all linearly increased across forest age. Clones associated with known denitrifiers carrying nosZ, nirK, or nirS genes, such as members of Pseudomonas, Mesorhizobium, Rhizobium, Rhodopseudomonas, Azospirillum, and Cupriavidus, were detected. These denitrifiers were found to be abundant in soil and dominant in soil denitrification. Soil pH, total N, and available N affected the denitrifying communities by altering the relative abundance of dominant taxa. Overall, although soil attributes and forest age had no significant effects on the dominant constituents of nirK, nirS, and nosZ communities, revegetation on shifting sand-dunes facilitated the quantitative restoration of soil denitrifiers due to the increase in soil nutrients.

The Shifting Sand-Dunes

1977 ◽  
Vol 51 (3) ◽  
pp. 501
Author(s):  
Syed Amanuddin ◽  
I. K. Sharma
Keyword(s):  
Sand Dunes ◽  
Shifting Sand

scholarly journals Characteristics of Desertification and Short-Term Effectiveness of Differing Treatments on Shifting Sand Dune Stabilization in an Alpine Rangeland

2019 ◽  
Vol 16 (24) ◽  
pp. 4968
Author(s):  
Xiao Feng ◽  
Jianjun Qu ◽  
Qingbin Fan ◽  
Lihai Tan ◽  
Zhishan An
Keyword(s):  
Soil Properties ◽  
Sand Dunes ◽  
Soil Nutrient ◽  
Tibet Plateau ◽  
Short Term ◽  
Vegetation Growth ◽  
Growth State ◽  
Dune Stabilization ◽  
Planting Method ◽  
Shifting Sand

Rangeland desertification is one of the most serious problems threatening the ecological environment and socio-economic development on the eastern Qinghai-Tibet Plateau in China. To combat desertification and reduce its adverse effects, some strategies have been undertaken to stabilize the mobile sand dunes and restore the desertified land. In this study, rangeland desertification with a gradient degree of none, light, medium, severe and extreme was assessed, and short-term effectiveness of different treatments on stabilizing the shifting sand dunes was evaluated by monitoring selected vegetation and soil properties. Results showed that vegetation became thinner and sparser, and soil environment deteriorated significantly under desertification, leading to a poor and low diversity ecosystem. Applying a checkerboard protection strategy in which herb species were planted and using a shrub vegetation planting method without checkerboard protection on mobile dunes for five years, vegetation growth state and soil properties were improved. Soil particles were finer, vegetation restoration was more rapid, and soil nutrient improvement was more apparent at the lower locations of the sand dunes under the checkerboard protection planted with herbs, which performed slightly better in improving soil properties than the shrub planting method alone. A longer time period would be required for vegetation and soils on the sand dunes to be restored to sustain more intensive land use. These findings provide more insight into dune stabilization, allowing effective management in the ecological restoration of desertified rangeland.

Fixation des dunes et reboisement avec le filao (Casuarina equisetifolia) dans la zone du littoral nord du Sénégal

1994 ◽  
Vol 70 (3) ◽  
pp. 282-290 ◽  
Author(s):  
Daniel Mailly ◽  
Papa Ndiaye ◽  
Hank A. Margolis ◽  
Marius Pineau
Keyword(s):  
Rapid Growth ◽  
Sand Dunes ◽  
Climatic Conditions ◽  
Agricultural Fields ◽  
Northern Coast ◽  
Casuarina Equisetifolia ◽  
The Past ◽  
Potential Source ◽  
Dune Fixation ◽  
Shifting Sand

The northern coast of Senegal is the site of a conservation program with the objective of stabilizing shifting sand dunes in order to protect adjacent agricultural fields against the detrimental effects of wind. Casuarina equisetifolia ("filao"), a nitrogen-fixing tree species indigenous to Oceania and southeast Asia, is the favored species for these dune stabilization efforts. Over the past 40 years, the total area reforested with C. equisetifolia amounts to more than 9700 ha. Due to its rapid growth, particularly in the inter-dune depressions, it is seen as a potential source of wood for the region. Additionally, reforestation efforts have also been directed towards the semi-fixed dunes (2380 ha) and the fixed dunes (4350 ha) lying further inland. Thus, despite the severity of the climatic conditions of recent years, Senegal's dune fixation program is clearly a success in respect to its initial objectives and represents an important step forward in the fight against desertification.

Sign in / Sign up

Export Citation Format

Share Document