Coastal Observations: Rapid development and colonization of a UK sand dune system

Between the years 1200 and 1600, vast quantities of sand were brought inshore from offshore bars as a result of centuries of ferocious storms, to form a series of dune systems along the South Wales coastline. Today, as a result of many housing, leisure, and industrial developments only a few remnants exist. On one such remnant at Porthcawl, Wales, UK, became a caravan site in the 1930s, which was abandoned in 1993 for political reasons. Within 27 years a minimum of 120,000 m3 of sand was transported from the adjacent beach and formed dunes >4 m in height along a 400- m frontal edge that extended some 130 m inland, approximately a third of the site. Typical vegetation found along the frontal part of the system are Ammophila arenaria (marram), Agropyron junceiforme (sand couch grass) and Euphorbia maritimum (spurge). To the rear of the system, vegetation included Agrostis tenuis and stolonifera, (bent and creeping bent grass), Cirsium avense (creeping thistle), and Caluna vulgaris (heather). A 4-m-high and c. 3000m2 area of a vigorous stand of Hippophae rhamnoides (sea buckthorn) has also formed. The rapidity of dune formation and vegetation colonization is staggering.

Gene flow in parapatric plant populations of Agrostis tenuis L.and Festuca rubra L.

The gene flow between populations of <em>Agrostis tennis</em> L. and <em>Festuca rubra</em> L. on a Zn/Pb mine and adjacent areas, which met at a distance of 150 m from the mine boundaries, was studied. It was found that the mine populations exhibit a high index of tolerance to Zn and Pb, elements encountered in the soil. Those outside the mine show relatively high indices of tolerance towards Zn and Pb, despite the fact that these elements are absent from the soil. On the other hand, the index of tolerance towards Cu, absent from the soil, of populations inside and outside the mine, was very low and did not differ from that of the control. Time difference in the flowering of these parapatric populations acts against gene flow thus resulting in a tendency for the neighbouring populations to isolate.

Assessment of the Vegetation State of Several Under-exploited Agrostis tenuis - Festuca

The study of the grassland type Agrostis tenuis - Festuca rupicola from Valea Bistrei - Otelul Rosu has been necessary due to the great surfaces covered with grasslands from the studied area and due to the social and economic climate characterised by the orientation of the rural community from the adjacent area to agriculture after the failure of the former intensive industry.There have been studied two grassland plots of about 500 hectares, res pectively Gai and Scărisoara. The purpose of this research is to assess the state of the biodiversity and pastoral value of four Agrostis tenuis - Festuca rupicola  grasslands from the hill area. Also, there has been analysed the floristic composition and a series of ecological indexes, respectively humidity, soil reaction, temperature, light, and nitrogen. Other aspects taken in account were the life-forms spectres. The analysed grasslands are placed on Bistrei Valey, in the perimeter of the locality OÅ£elul Roșu, Caraș -Severin County. The researches have been developed during 2010-2012 period. The average elevation level in the studied area is 268 square meters. The soil from the studied area is brown type, with a pH comprised between 4.79 and 5.31. The rainfall amount is about 700 mm and the average temperature is 10 Celsius degrees. The management mode of these grasslands is extensive, the grazing period being 150 days per year. The analysed surfaces are characterised by the lack of the maintenance works, there being present erosion phenomena. The method used for the vegetation analysis is the linear point quadrate method (Daget et Poissonet, 1971), the data being used for the calculation of different ecological indexes and pastoral value. The pastoral value of the species is low in both plots due to the great contribution of the low economical values of the most of the species from the analysed grasslands.

Methylation of arsenic in vitro by cell extracts from bentgrass (Agrostis tenuis): effect of acute exposure of plants to arsenate

Compared with microorganisms and mammalian tissues, information is scant on the enzymes responsible for arsenic metabolism in plants. This study investigated the arsenic methylation activities extractable from leaves and roots of Agrostis tenuis Sibth. plants grown in complete nutrient media and exposed to arsenate (135–538 M) for 3 d before harvesting. Methylation activity was determined in leaf and root extracts using an in vitro assay based onS-[3H-methyl]adenosyl-L-methionine (3H-SAM) with either arsenite or arsenate as substrate. Arsenite methylation activity was low in leaf extracts from plants not exposed to arsenate, but was greatly enhanced after acute exposure, with the induced methylation activity greatest in extracts from plants exposed to 269 M arsenate. Monomethylarsonate (MMA) was the predominant early product, but over longer assay times dimethylarsinate (DMA) accumulated at the rate of 660 amol mg protein–1 min–1 to levels exceeding MMA. With arsenate as substrate, methylation activity was much lower than with arsenite, implying that arsenite is the preferred substrate for methylation. Root extract assays exhibited no DMA, however small amounts of MMA were formed with arsenite as substrate. In contrast to leaves, the methylation activity did not increase in root extracts from plants exposed to arsenate. These findings suggest that arsenate in the plant growth medium was taken up by the roots and converted to arsenite before methylation proceeded in the leaves, accompanied by induction of arsenic methyltransferase activities.

Salinity Effects on Bentgrass Germination

Duplicate studies were conducted to determine salt tolerance during germination of eight bentgrass (Agrostis spp.) cultivars commonly used for overseeding warm-season turf species, such as bermudagrass (Cynodon spp.) putting surfaces. Bentgrass seeds were germinated on agar salinized with 0, 4000, 8000, 12,000, or 16,000 mg·liter-1, with the highest rate approaching one-half seawater salinity. Total germination decreased linearly or quadratically for specific cultivars as salinity increased. Time necessary to reach 50% germination across all salt concentrations was shortest for `Highland' colonial (Agrostis tenuis Sibth) and `Seaside' creeping (A. palustris Huds.) bentgrass (≈3.7 days); intermediate for `Kingstown' velvet (A. canina L.) and `Streaker' red top (A. alba L.) bentgrass (≈4.5 days); and longest for `Penneagle' creeping, `Penncross' creeping, `Exeter' colonial, and `Pennlinks' creeping bentgrass (≈5.3 days). Salt concentrations necessary to reduce germination to 90%, 75%, and 50% indicated that `Streaker' red top and `Seaside' creeping bentgrass were the most salt-tolerant cultivars. `Kingstown' velvet, `Exeter' colonial, and `Highland' colonial bentgrass were intermediate, while `Pennlinks', `Penncross', and `Penneagle' creeping bentgrass were the most salt-sensitive cultivars.