Mining Contamination Disrupts Successional Change in Salt Marshes

<p>Salt marshes can generally be considered as sinks for metals. Research into salt marshes in Cornwall, UK suggests those estuaries heavily impacted by mining contamination are characterised by a less diverse vegetation compared with a significantly less-polluted site. Assessment using the National Vegetation Classification on the mid-marsh confirmed an Armeria maritima-dominated community was to be found in the most metal-enriched salt marsh of Restronguet Creek. However, this plant was co-dominant with Plantago maritima in the moderately contaminated marsh of Lelant and not present at all in the Camel, which has been subject to limited mining related contamination. Using canonical correspondence analysis, vegetation abundance data was compared with geochemical variables within the sediment. Metals were studied using extractions to signal bioavailability. P. maritima was not associated with the very high metal levels found in Restronguet Creek. A. maritima, had some association with soluble copper and was closer to the bulk of metals than P. maritima. As tolerance to adverse conditions and competitiveness are mutually exclusive, A. maritima, therefore, exists in a successional relationship with P. maritima. A. maritima then appears to be outcompeted by P. maritima in marshes with low metal loadings. Moderately high metal content results in a loss of competitiveness by P. maritima allowing A. maritima to co-dominate. In extremely metal-rich estuaries, however, P. maritima is unable to compete, allowing A. maritima to colonize the mid-marsh. Vegetation community may, therefore, be useful as an indicator of the level of metal contamination.</p>

EFFECT OF SUBSTRATE DEPTH AND TYPE ON PLANT GROWTH FOR EXTENSIVE GREEN ROOFS IN A MEDITERRANEAN CLIMATE

Although numerous examples of green roofs can be found in Turkey, limited research has been conducted on plant material and substrate type in this climate. Both plants and substrate are very important components in green roof design, it is essential to determine the proper substrates and plants in green roof systems for domestic green roof design. Two types of growing substrates: a commercial substrate consisting of crushed brick and clay (45%), pumice (45%), and organic matter (10%), and a recycled substrate including 90% coarse pumice (10–20 mm) and municipal compost (10%), were tested in three depths of 4, 7 and 10 cm. Tested plant species included Achillea millefolium , Armeria maritima , Sedum acre and Sedum album . Overall, the commercial substrate performed better than the recycled pumice. In addition, deeper substrates promoted greater survival and growth for nearly all species tested. Either A. maritima or A. millefolium survived in the recycled pumice at any depth, whereas they did survive when grown in the commercial substrate in greater than 7 cm and 10 cm, respectively. They both likely would require supplemental irrigation to be acceptable for green roofs in Istanbul or locations with a similar climate. Both Sedum species survived in all substrate types and depths. Information gained can be utilized by green roof professionals in the Istanbul region and in other parts of the world with a similar climate.

Plants accumulating heavy metals in the Sudety Mts

The Sudeten flora consists of some plants we can recognize as heavy metal accumulators. Between others there are: <em>Thlaspi caerulescens</em>, <em>Arabidopsis halleri</em>, <em>Armeria maritima</em> ssp. <em>halleri</em> s.l. and probably the endemic fern <em>Asplenium onopteris</em> var. <em>silesiaca</em>. The authors present the concentrations of some important heavy metals measured in aboveground plant dry weight. The highest concentration of zinc was 8220 ppm (<em>Thlaspi</em>), nickel - 3100 ppm (<em>Thlaspi</em>), lead - 83 ppm (<em>Armeria</em>), copper - 611 ppm (<em>Arabidopsis</em>) and cadmium - 28 ppm (<em>Thlaspi</em>). The concentrations depend rather on species or population specification than on ore deposit quality. There are no typical hyperaccumulator among plants we have examined, but some signs of hyperaccumulation of nickel, zinc and lead could be observed. There are no typical endemic taxa, only <em>Asplenium onopteris</em> var. <em>silesiaca</em> and <em>Armeria maritima</em> ssp. <em>halleri</em> may be recognized as neoendemic taxa, but still of unclear systematic position. During the study we tried to find out why some Sudeten vascular plants do not develop heavy metals hyperaccumulation and why they are rather latent hyperaccumulators. Finally, we suggest to protect some metallicolous areas in spite they are rather territories with low plant biodiversity.