Search Results
Hegazy, A.K. 1996. Effects of cement-kiln dust pollution on the vegetation and seed-bank species diversity in the Eastern Desert of Egypt. Environ. Conserv. 23:249-258. Effects of
Abbadi, G.A. and M.A. El Sheikh. 2002. Vegetation analysis of Failaka Island (Kuwait). J. Arid Environ. 50:153–165. Sheikh M
. Hierarchy: Perspectives for Ecological Complexity Campetella, G., R. Canullo and S. Bartha. 2004. Coenostate descriptors and spatial dependence in vegetation - derived variables in
Abstract
A new rapid method for the determination of actinides and radiostrontium in vegetation samples has been developed at the Savannah River Site Environmental Lab (Aiken, SC, USA) that can be used in emergency response situations or for routine analysis. The actinides in vegetation method utilizes a rapid sodium hydroxide fusion method, a lanthanum fluoride matrix removal step, and a streamlined column separation process with stacked TEVA, TRU and DGA Resin cartridges. Lanthanum was separated rapidly and effectively from Am and Cm on DGA Resin. Alpha emitters are prepared using rare earth microprecipitation for counting by alpha spectrometry. The purified 90Sr fractions are mounted directly on planchets and counted by gas flow proportional counting. The method showed high chemical recoveries and effective removal of interferences. The actinide and 90Sr in vegetation sample analysis can be performed in less than 8 h with excellent quality for emergency samples. The rapid fusion technique is a rugged sample digestion method that ensures that any refractory actinide particles or vegetation residue after furnace heating is effectively digested.
Abstract
A coincidence method for measuring radium and thorium activity has been developed using the PRIPYAT-2M gamma-ray coincidence spectrometer, with six NaI(Tl) detectors and registration geometry close to 4π. It was tested by measuring soil samples from the Northern region of Montenegro, as well as vegetation samples from the same region. The results showed a good agreement with ones obtained by the HPGe spectrometer.
J. Veg. Sci. 4 157 162 Doherty, M. D. and N. C. Coops. 1995. Vegetation of the Batemans Bay study area
Fosberg, F. R. 1965. The entropy concept in ecology. In: Symposium on Ecological Research in Humid Tropics Vegetation , UNESCO and Government of Sarawak, Kuching, Sarawak. pp. 157-163. The entropy concept in
Today, native vegetation in the Valdivian Coastal Range (VCR) is restricted to areas where small-scale land use dominates resulting in a vegetation mosaic. This study (1) provides a description of the vegetation types (VT) within the vegetation mosaic, (2) identifies land use drivers that lead to either degradation or recovery processes and, (3) attempts to provide an explanation for the vegetation mosaic with a conceptual model. In two regions of the VCR we sampled 102 plots for composition of vegetation and indicators of livestock browsing, timber cutting and coppice forestry. We classified the vegetation using a flexible beta method and Bray-Curtis distance. Diagnostic species were identified by an extended indicator species analysis. The clustering results were visualized in NMDS and recursive partitioning was used to explain variations in the VTs as a function of the land use variables. Differentiating effects were tested using PERMANOVA and a conceptual model for the vegetation dynamics was developed from the results. Four VTs such as (1) extensively grazed non-native grasslands (EGN); (2), closed and semi-closed grazed Ugni and Berberis shrublands; (3) severely impacted evergreen forests; and (4) sparsely disturbed evergreen forests were recognized. The browsing indicators were important for differentiating the VTs. The EGN grasslands were differentiated by having more than 0.075 dung piles/m2. Areas with fewer dung piles but direct browsing effects had the greatest impact on vegetation. Forests were preserved when the mean browsing index was equal to or lower than 0.5. The cutting frequency was significant in determining overall floristic composition. We showed that shrublands and evergreen forests within the vegetation mosaic and the result of small-scale farming led to high native forest species richness. This makes the vegetation mosaic especially valuable in a landscape dominated by exotic tree monocultures.
characteristics of the vegetation process. Community Ecol. 3: 125-146. Some interesting characteristics of the vegetation process Community Ecol. 3
Botta-Dukát, Z., M. Chytrý, P. Hájková and M. Havlová. 2005. Vegetation of lowland wet meadows along a climatic continentality gradient in Central Europe. Preslia 77:89–111. Havlová M
