Cementing materials in the Arahama sand dune, Japan, were studied mineralogically and biogeochemically to gain a better understanding of the cause of hardening. The cementing material is a clay-organic complex composed of noncrystalline gels and a matrix of small, poorly crystalline particles showing 14–16-Å spacings. The gel materials appear to have transformed into the poorly crystalline particles, which have a high carbon content and Al/Si ratios of 2.2 to 2.0. These particles are slightly richer in Si and poorer in Fe than the gel materials themselves. The organic portion of the complex can be removed by H2O2 treatment, leaving a noncrystalline network-structure containing a dispersed granular component. Scanning auger-depth profiles of individual particles show a high surface concentration of C and O and an increase in the Al/Si ratio with depth. The energy-intensity distribution suggests a mixture of carbon compounds having a major core-line binding energy of a hydrocarbon. The gel-cementing materials in the sand dune may have been formed from biochemical weathering products of organic matter, which subsequently controlled the formation of clay-organic complexes.

Baby’s breath (Gypsophila paniculata L.) is an invasive species in Michigan’s northern lower peninsula and is a problem in much of northern North America. It is of particular concern in coastal dune habitats of northwest Michigan, because the areas where it is most dense are also populated by several endemic and threatened species. Current removal methods include manual removal with a spade and directed spray-to-wet foliar application of glyphosate to individual plants using backpack sprayers. We assessed these methods by measuring G. paniculata density and presence–absence frequency before and after treatment using a point-intercept grid, establishing how type and timing of treatment within the growing season influences treatment efficacy and determining the proportion of plants that resprout after treatment. Our results show a consistent reduction in G. paniculata density after treatment with herbicide or manual removal (P < 0.001) but minimal impact on presence–absence frequency. These results indicate a need for quantitative data in the assessment of management efficacy to show a clearer picture of density reduction when extirpation is no longer a viable outcome of management. Through the assessment of treatment timing of manual removal and glyphosate treatments over time, we found no evidence that either treatment type was effective at reducing density when applied before plants flowered, but there was evidence that both treatments were effective when applied later in the growing season when plants were flowering. Resprouting of marked plants occurred in 14% of manually removed plants and 2% of herbicide-treated plants. Our results suggest that managers should treat G. paniculata infestations for consecutive years to remove regrowth and focus treatment during flowering for best control.

Babysbreath or perennial babysbreath (Gypsophila paniculata L.) is an aggressive invasive plant in large parts of southern Canada and the northern and western United States. It reproduces and disperses by seed, so the phenology of seed maturation is important in designing management programs. The present study provides the first quantitative assessment of G. paniculata seed-maturation phenology in a field population, as well as the first quantitative assessment of how the efficacy of herbicide treatment in preventing production of germinable seeds depends on the timing of treatment in relation to this phenology. Seeds were collected from untreated plants on five dates during July and August in both 2016 and 2017 and tested for germinability. Percent germination increased from 20% to 81% between July 22 and 28 and exceeded 90% by August 4, 2016. The seed-maturation phenology in 2017 was similar but delayed by about 4 d. On a growing degree-day scale, seed-maturation phenologies for the 2 yr were nearly identical. We also tested germinability of seeds from plants sprayed with glyphosate (23.4 ml ae L−1) on July 11, 18, and 25, 2016 (one date per plant). Percent germination increased from 0% to 13% to 20% over successive treatment dates, highlighting the importance of completing treatment early in the growing season.

This paper reports a previously unidentified paleoenvironmental record found in sand dunes of the Atacama Desert, Chile. Long-term aeolian deflation by prevailing onshore winds has resulted in the deposition of sand on the irregular surface of a Miocene-aged anhydrite outcrop. Two deposits ~25 km apart, along the prevailing wind trajectory, were hand excavated then analyzed for vertical (and temporal) changes in physical and chemical composition. Radiocarbon ages of organic matter embedded within the deposits show that rapid accumulation of sediment began at the last glacial maximum and slowed considerably after the Pacific Ocean attained its present post-glacial level. Over this time period, grain sizes are seen to increase while accumulation rates simultaneously decrease, suggesting greater wind speeds and/or a change or decrease in sediment supply. Changes in δ34S values of sulfate in the sediment beginning ~10 ka indicate an increase in marine sources. Similarly, δ2H values from palmitic acid show a steady increase at ~10 ka, likely resulting from aridification of the region during the Holocene. Due to the extreme aridity in the region, these sand dunes retain a well-preserved chemical record that reflects changes in elevation and coastal proximity after the last glacial maximum.

Leymus Racemosus, The Mammoth Wild Rye, Is A Rhizomatous Perennial Grass, Mainly Distributed In The Moving Or Semi-Stabilized Sand Dunes In Deserts Of The Junggar Basin In Xinjiang, China. The Revival Ability Of The Young Seedling After Periods Of Desiccation Can Be Influenced By Several Factors: (1) The Stage Of Seedling Development – The Later The Stage At Dehydration, The Longer The Root Length And The Lower Is The Percentage Of Seedlings That Survive; (2) The Length Of The Period Of Desiccation – The Longer The Period That The Seedlings Are Under Desiccation, The Lower Is The Percentage Of Seedlings That Survive; (3) Endosperm Size – The Smaller The Proportion Of Endosperm That Remains In The Caryopses, The Lower Is The Percentage Of Seedlings That Revive, Determined By (A) The Stage Of Seedling Development, And (B) The Proportion Of The Endosperm That Is Removed By Cutting; And (4) Caryopsis Size – The Larger The Polymorphic Caryopses, The Higher Is The Percentage Of Young Seedlings That Revive From Periods Of Desiccation. The Physiological And Ecological Implications Of L. Racemosus Seedling Desiccation Tolerance Are That Under Extreme Desert And Unpredictable Environmental Conditions, The Chances Of Seedling Establishment Are Increased.