Koncept geodiverzitete obstaja že več kot 20 let. Večina metod vrednotenja geodiverzitete se uporablja za ugotavljanje geokonzervatorskega ali geoturističnega potenciala. Metode, s katerimi bi lahko ...vrednotili izobraževalni potencial geodiverzitete, so zelo redke. Glavni cilj našega članka je podati novo metodo vrednotenja geodiverzitete za določanje izobraževalnega potenciala proučevanega območja. Metoda je uporabna za učne namene, ko učitelji načrtujejo organizacijo strokovnih ekskurzij ali terenskega dela.
•Large differences in floristic composition of the plant communities were found.•Hydrological gradient highly correlated with plant diversity.•Calcium content and pH negatively correlated with plant ...diversity.•Hydrological gradient significantly influenced the composition of plant communities.
Plant communities and selected environmental parameters were studied at the intermittent Lake Cerknica. Seventeen plots (16 m2) were defined down a 600-m transect on a gentle sloping shore with an elevation decrease of 2.7 m, to investigate the different types of wetland vegetation characteristic of the different habitats. Vegetation was investigated using the standard Central European method. Soil samples were measured for pH, electrical conductivity, organic matter, total nitrogen, available phosphorous and potassium, cation exchange capacity, and texture. Large differences in floristic composition of the plant communities were found. Vegetation of mesic meadows was seen for the rarely flooded most elevated plots, with transition downwards to wet grassland communities from the alliance Molinion and from the alliance Deschampsion. The lower habitats with soils waterlogged until July were colonized by marsh communities, while community of emergent hydrophytes was at the lowest end of transect. Over 100 vascular plant species were recorded in the plots. Species richness increased with elevation and decreased with moisture, with >50 taxa in three most elevated plots, and 9–15 taxa per plot for the nine most frequently flooded plots. The hydrological gradient corresponded to the elevation gradient, and together with duration of flooding had a crucial role in shaping plant community composition, distribution and diversity. The flooding arose from Ca-rich lake water, while elevated habitats were rainwater fed, which the consequent enhanced nutrient leaching and lowered pH and electrical conductivity. This produced negative correlations between plant community diversity and species richness versus pH, Ca2+ and electrical conductivity, since these influences were overridden by hydrological gradient.
Abstract
Agriculture has a great impact on biodiversity in Europe. Populations of farmland birds are declining due to both intensification and abandonment of agriculture. The purpose of this study ...was to determine the effects of overgrowing on the diversity of birds at Cerknica Polje. Six vegetation types were identified on eight survey plots (15.2-31.6 ha each): Short grass - regularly mown wet meadows; Tall herbs - stands of Common Reed Phragmites australis and Reed Canary Grass Phalaris arundinacea; Sparse bushes - stands of low woody plants; Dense bushes - dense stands of bushes; Meadows with trees - mown meadows with scattered trees; Bushes with trees - hedges, trees and dense stands of bushes. In total, 34 species were registered. The heterogeneity of vegetation types correlated positively with the heterogeneity of bird species. The highest density of breeding territories and species was established in Bushes with trees, the lowest in Short grass. No species were registered in all vegetation types, and only Tree Pipit was recorded in five out of six types. Twelve species were registered in only one vegetation type. Cerknica Polje is an important breeding locality for species with the highest breeding density at the national level (e.g. Corncrake Crex crex, Curlew Numenius arquata, Skylark Alauda arvensis, Whinchat Saxicola rubetra, Sedge Warbler Acrocephalus schoenobaenus). These species breed in specific habitats with different stages of succession. A managing plan for the area should therefore combine abandoned plots in different stages of succession and large regularly mown areas. Abandonment of agriculture at Cerknica Polje has led to the emergence of areas with bushes in different succession stages. Efforts should be directed at preserving large complexes of mown wet meadows.
The turnover of matter and through‐flow of energy in the intermittent Lake Cerknica is facilitated by the exchanging wet and dry periods, which either promote or suppress growth and development of ...organisms, depending on the season of the year. Any deviation from normal floods significantly affects the productivity of reed stands. Drainage of the lake prevents a constant presence of aquatic organisms, particularly planktonic species. Drying and wetting accelerates the decomposition of organic matter. The nutrient input into the lake by one surface tributary proved to be relatively high. The quantity of nutrients in the lake water is lower, however, because of the high buffering capacity of the densely vegetated ecosystem.
The basic hydrobiological conditions as well as the planktonic Rotifer assemblages of the Lake Cerknica (Slovenia) were investigated first time in 2004-2005. 16 taxa were found, most of them are ...frequent in Central Europe. The preliminary results suggest a pressing need for further research.
For the adequate protection of karst springs it is important to understand the functioning of karst systems in their recharge areas. Besides tracer tests with artificial tracers, tracings with ...natural tracers, such as temperature, are a very useful research tool, especially in complex karst systems with various types and sources of recharge. Detailed monitoring of water levels and temperatures of the Malenscica karst spring, as well as of the intermittent Cerknica Lake and Kotlici spring in its recharge area, indicated that temperature is a good tracer in winter and summer periods, especially when the Cerknica karst polje is flooded. High or low air temperatures influence the temperature of water, which sinks at the Cerknica polje and flows rapidly through karst channels toward the springs. Detailed analysis of selected events enabled calculation of the velocity of groundwater flow toward the Malenscica spring under different hydrological conditions. The estimated values are in accordance with the velocities previously defined in this area, based on several tracer tests with artificial tracers. From the results, it is possible to assess the transport velocities of contaminants under different hydrological conditions. This is important information for the protection of the Malenscica spring, which is captured for the public water supply.
PDF
