Barren Sand Dunes Research Articles

Mississippi River threatens to make Dogtooth Bend peninsula in Illinois an island

T he receding floodwaters of the Mississippi River in January of 2016 left behind barren sand dunes on southern Illinois farmland reminiscent of the windswept dunes of the movie Lawrence of Arabia (figure 1). Large sand deposits up to 1.3 m (4 ft) deep covered nearly 800 ha (2,000 ac) of farmland south of Miller City, Illinois, in the Dogtooth Bend peninsula. Rainfall almost three times above average in November and December of 2015 over Missouri set in motion record flooding with the Cape Girardeau river gage breaking the 1993 record at 14.89 m (48.86 ft) and led to the breaching of Len Small levee on January 2, 2016. Floodwaters cut deep craters and scoured the landscape as they poured through the breach at mile marker 34 and then followed an old meander channel across the narrow neck of Dogtooth Bend peninsula to reconnect with the Mississippi River at mile marker 15 (figure 2). Levee breaches and land scouring are not new events for this region, occurring in 1993, 2011, and 2016; and there is high likelihood these farmlands will experience similar events in the future. Each event deepens the meander channel when the floodwaters take a 4.6 km (3.5 mi)…

Landsat Time Series Analysis of Vegetation Changes in Solar Energy Development Areas of the Lower Colorado Desert, Southern California

Land cover change from renewable energy development in southern California is receiving increasing attention due to potential impacts on protected area conservation, endangered species, and greenhouse gas emissions. This study was designed to quantify and map, for the first time, variations desert vegetation canopy density and related growth rates using 30 consecutive years of Landsat satellite image data across the Lower Colorado Desert. The time-series for mean normalized difference vegetation index (NDVI) values sampled from each of the three major land cover types (shrubland, barren sand dune, and developed urban) showed no significant positive or negative trend in vegetation canopy density. Three periods of significant decrease in NDVI were detected during the drought periods of 1989-1990, 2002-2003, and 2013-2015, indicating that annual precipitation has been the main controller of shrubland canopy growth and green cover. Shrubland canopy cover has been relatively stable in renewable energy development zones since the mid-2000s. NDVI change in the period after nearly all southern California solar energy developments were initiated (post-2010) could be attributed largely to topographic water flow pathways through canyons and desert washes, both in and around all solar energy development zones.

Degradation of seed mucilage by soil microflora promotes early seedling growth of a desert sand dune plant

In contrast to the extensive understanding of seed mucilage biosynthesis, much less is known about how mucilage is biodegraded and what role it plays in the soil where seeds germinate. We studied seed mucilage biodegradation by a natural microbial community. High-performance anion-exchange chromatography (HPAEC) was used to determine monosaccharide composition in achene mucilage of Artemisia sphaerocephala. Mucilage degradation by the soil microbial community from natural habitats was examined by monosaccharide utilization tests using Biolog plates, chemical assays and phospholipid fatty acid (PLFA) analysis. Glucose (29.4%), mannose (20.3%) and arabinose (19.5%) were found to be the main components of achene mucilage. The mucilage was biodegraded to CO(2) and soluble sugars, and an increase in soil microbial biomass was observed during biodegradation. Fluorescence microscopy showed the presence of mucilage (or its derivatives) in seedling tissues after growth with fluorescein isothiocyanate (FITC)-labelled mucilage. The biodegradation also promoted early seedling growth in barren sand dunes, which was associated with a large soil microbial community that supplies substances promoting seedling establishment. We conclude that biodegradation of seed mucilage can play an ecologically important role in the life cycles of plants especially in harsh desert environments to which A. sphaerocephala is well-adapted.

Role of fungi in litter decomposition associated with Casuarina equisetifolia L. plantations in coastal sand dunes, Orissa, India

Seasonal dynamics of soil microfungal populations, their metabolic activity and decomposition of leaf litter were studied in a monoculture plantation of Casuarina equisetifolia L. in coastal sandy belt of Orissa for a period of 2 years (June 2002–May 2004). Fungal succession of litter was also studied. Microbial isolation and soil analysis was performed using standard procedures and decomposition of leaf litter was studied using litter bag technique. Maximum population density was observed in the rainy season followed by winter and lastly summer. Larger microbial populations were encountered in plantation soil compared to barren sand, corresponding with the fluctuation of prevailing temperature, moisture and total organic carbon content. Rates of litter loss and carbon dioxide output followed the same trends as the population density. The annual K value was 0.41. The diversity index varied from 2.87 to 3.71 (Shannon) and 0.356 to 0.885 (Simpson). The similarity index showed that highly decomposed litter (HDL) is more similar to Soil A (barren sand dune) than Soil B (sand dune with monoculture plantation of Casuarina). The introduction of predominantly decomposing microorganisms isolated from samples from the present study could help to increase the nutrient status of these soils. This research will hopefully improve the monitoring and management of decomposing fungi in the study area and highlights their importance in maintaining ecosystem services which could be a valuable tool for better understanding the long-term effects of changes in soil condition of the forest floors in coastal sand dunes of Orissa, India.

A Comparative Account of the Diversity and Distribution of Fungi in Tropical Forest Soils and Sand Dunes of Orissa, India

An investigation was carried out to estimate micro fungal population and its relationship with physico- chemical properties in natural tropical forest soil, deforested soil, deforested-cum-cultivated soil, barren sand dune, sand dune with monoculture plantation of Casuarina and sand dune with monoculture plantation of Anacardium.. Microbial isolation and soil analysis was performed using standard procedures. The micro fungal population ranged from 35.5 to 1276.2 g -1 dry soil in different study sites. They corresponded to the fluctuation of prevailing temperature, moisture and total organic carbon content of the said habitat. . A total of 285 species of fungi belonging to 113 genera were enumerated. The majorities were from the genus Aspergillus; the next two in order of dominance were Penicillium and Trichoderma. The diversity values (H) show an increase as we move from barren sand dune to deforested-cum-cultivated soil. Shannon's diversity index is reasonably high varying from 3.528 to 4.144 correspondingly the dominance values are low varying from 0.0242 to 0.0499. The evenness values, however, show a different trend. The surface soil of forest has the highest species richness where as sub-surface soil of barren sand dunes shows lowest richness. The study revealed that the conversion of natural forest led to a reduction of soil organic matter. Considering the importance of microbial component in soil, we conclude that the conversion of natural forest to different land uses leads to the loss of biological stability of soil. Introduction of predominant decomposing microorganisms isolated from the present study can help to increase the nutrient status of the sandy sterile mass under focus is suggested.

N. Fraser 2007. Dawn of the Dinosaurs. Life in the Triassic. Illustrated by Douglas Henderson. xvi + 310 pp. Bloomington, Indianapolis: Indiana University Press. Price US $49.95, £27.00 (hard covers). ISBN 9780 253 34652 0.

In many ways, the Triassic is the forgotten period of the Mesozoic. Most popular accounts of Earth history refer to it only in passing, as either a transitional interval that witnessed the recovery of the Earth’s biota from the ravages of the end-Permian extinctions, or as the time in which that most charismatic of groups, the dinosaurs, first appeared. In addition, there is a widespread perception that most Triassic terrestrial environments were parched deserts that were almost devoid of life, a picture reinforced by artists’ renderings of landscapes containing a lone archosaur hunting amongst doleful, barren sand dunes. Nick Fraser’s book is a welcome …

Arbuscular Mycorrhizae in Sand Dune Plants of the North Atlantic Coast of the U.S.: Field and Greenhouse Inoculation and Presence of Mycorrhizae in Planting Stock

The ability of several sand dune-inhabiting plant species to successfully colonize dune sites appears to depend upon the presence in the soil of arbuscular mycorrhizal fungi (AMF) that form mutualistic associations with roots. Dune sites barren of vegetation lack these fungi whose large spores are not readily dispersed to the root zones. Despite the absence of these beneficial fungi from barren sites, however, plantings made in AMF-free dune soils eventually form the mycorrhizal association. Examination of planting stock of several species of plants that are used to vegetate barren sand dunes and dune flats of the eastern seaboard of the U.S.A. revealed that AMF were routinely present in the planting materials prior to outplanting. AMF occurred in planting stock of seven varieties ofAmmophila breviligulata, and inPrunus maritima,Rosa rugosa, andSpartina patens, but were absent fromMyrica pensylvanica. In a field planting in a previously barren deflation zone in the large parabolic dunes of Cape Cod National Seashore, Massachusetts, culms ofA. breviligulatathat were inoculated with native species of AMF produced more tillers and inflorescences than did non-inoculated plants, even though 78% of the latter had become mycorrhizal 47 weeks after planting. In greenhouse experiments,P. maritimawas found to have an absolute requirement for AMF andSolidago sempervirenswas not. The significance of the presence of AMF in planting stock for revegetation and restoration of previously unvegetated sites lacking in AMF is discussed.