Evaluation of the effects of recent nature development measures in the Yser Estuary on ground beetle and spider assemblages

Since 1990, populations of ground beetles and spiders are continuously monitored in the coastal dune and saltmarsh habitats of the Yser Estuary (Nieuwpoort), within the context of a long-term study on invertebrate diversity, population dynamics and ecological and genetic effects of habitat fragmentation. By now, we know in detail the faunal composition of practically all available habitats in the study area. This is an ideal framework to monitor the effects of the nature development activities that started in 2001 in the area. Results of five large sampling campaigns in 2001-2003 (more than 25.000 carabid beetles and spiders, 218 species) show a number of new ground beetle and spider species and assemblages, but warrant that many of these could be rapidly lost again

Charge characteristics in relation to free iron and organic matter of soils from Bambouto Mountains, Western Cameroon

We have examined the charge characteristics, with special emphasis on the role of free Fe and organic matter, of humid tropical soils from Bambouto Mountains, Western Cameroon. The soils, which are formed from tuff, basalt and trachyte, are dominated by kaolinite and sesquioxides. The mounts of Fe oxides in them increase somewhat with depth. Open 2:1 phyllosilicates are present in trace amounts. The point of zero charge of the variable charge components, pH0, is around 4 in the topsoil (0-20 cm) and around 6 at 100-150 cm depth. In the subsoils, pH0 exceeds soil pH presumably because of large quantities of Fe oxides. Deferration increases both soil pH and pH0, but diminishes the anion exchange capacity. Oxides and oxyhydrates of Fe have positive surface charge, so their removal from the soils would result in overall loss of positive charge. Increases in soil pH would bring about an increase in the cation exchange capacity of the soils. Hence, management practices that reduce soil acidity should reduce loss of essential basic cations via leaching