The diversity of plant species in western Slovenia (most of the Alpine region, Slovenian submediterranean region with Kras and part of Istria) with 800 or more taxa within approximately 140 km2 (basic field of four quadrants) is considerably higher than in the central and eastern parts of Slovenia.
The trend of extinction of endangered plant species is noticeable in Slovenian Istria, in the extreme east of Slovenia in the Mura floodplain, in the extreme east of the Sava basin in Slovenia (Prilipe, Jovsi, Dobrava), partially in the western Karawanken Range and in the northern spurs of the Dinaric Mountains. Also, a slight concentration of extinction of endangered flora is noticeable in the Pohorje Massif and in the Slovenske gorice hills. An apparent improvement of conditions is dispersed throughout Slovenia with several indistinct concentrations in the upper Soča Basin, the eastern Kamnik Alps and Bela krajina.
Richness of plant species is mostly related to diversity of habitat types, which, in turn, depends on various factors ranging from natural geographic (altitude range, solar exposure, geological structure) to florogenesis-related and pure anthropogenic (intensity of impacts on nature, urbanisation, extensiveness of farming, etc.).
The indicator shows the species richness of plant species for different periods, based on the available data. All the data for the last 50 years were taken into account for the estimate of species richness of higher plants, i.e. the period 1957–2006, while comparisons were made for the periods 1987–1996 (approximately 100,000 pieces of data) and 1997–2006 (approximately 130,000 pieces of data). Threatened plant species are presented in more detail (trends showing their changing share within the flora of a certain quadrant in the periods compared).
Raw input data contained over 500,000 data points on the presence of species of vascular flora within the territory of Slovenia. Among the available data, only that with sufficient topographic accuracy was selected so it could be undisputedly placed into the grid of 35 km2 quadrants.
· To preserve a high level of biodiversity and to halt the decline of biodiversity by 2010:
· to preserve or to achieve a favourable state of species and habitat types;
· long-term stabilisation or increase in the share of threatened plant species within the flora of a certain quadrant.
Considering the fact that plants are primary producers and thus major biomass contributors, creating living environments for the majority of other organisms, they are simply indispensible for monitoring the state of the environment. However, the level of knowledge about certain plant groups and, consequently, the density of data on their occurrence, is very low in Slovenia; as a consequence, despite their known indicator values (e.g. algae and lichens), they cannot be used as indicators that would enable a good overview of the state of the environment for the entire country. On the other hand, certain groups are well studied in addition to being good indicator groups (e.g. wild orchids), but there is no systematic or regular sampling for them over a wider area. Relatively slow trends of changes represent a problem as well. All of the aforementioned information should be taken into account in the interpretation, as both figures are presented in order to provide general information and to allow comparison between them.
Species richness of plants: on approximately 140 km2, which is the size of 4 quadrants, which, together, form a basic field, there are generally 800 or more taxa in western Slovenia (most of the Alps and the Slovenian sub-Mediterranean region that includes the Kras Plateau and part of the Istria Peninsula), which is considerably more than in central and eastern Slovenia. Certain areas with notably higher sampling intensity (e.g. Ljubljana and its vicinity) deviate from the overall picture. Only a small portion of some basic fields along the border fall within Slovenia, which results in low numbers despite high biodiversity. The general impression confirms the long-known fact that plant diversity is closely related to the diversity of habitat types, which, in turn, depends on various factors ranging from natural geographic (altitude range, solar exposure, geological structure) to florogenesis-related and pure anthropogenic (intensity of impacts on nature, urbanisation, extensiveness of farming, etc.).
Changes in the share of threatened plant species within a quadrant: green squares indicate quadrants in which the share of threatened plant species in the last decade was higher than a decade earlier, while black squares indicate quadrants in which the share of threatened species was reduced or certain threatened species disappeared. The size of circles is proportional with the difference between the shares in the given periods, which means that squares with the same share of threatened species in both periods look like those species are missing, because the trend is 0 (zero).
Any other or further interpretation is delicate, as it is obvious that certain border quadrants derogate the most (in a positive or negative direction). In those quadrants, the result may be an artefact or a consequence of randomly biased sampling. Nevertheless, it is clearly evident that the trend of extinction of threatened species is noticeable in Slovenian Istria, on the Mura flood plain in the extreme east of Slovenia, in the extreme eastern part of the Slovenian Sava basin (Prilipe, Jovsi, Dobrava) and, as it seems, in the western part of the Karawanken Alps and the northern parts of the Dinaric karst plateaus. A slight concentration of extinction of threatened flora is also noticeable in the Pohorje Massif and the Slovenske gorice Hills. On the other hand, quadrants with a seemingly improved state are more dispersed all over Slovenia with certain indistinct concentrations in the upper Soča Basin, eastern Kamnik Alps and Bela krajina.