Vladimir Hršak

Estimating plant species occurrence in MTB/64 quadrants as a function of DEM-based variables: a case study for Medvednica Nature Park, Croatia

Abstract Croatia is among those European countries without an Atlas of Flora produced till today as a result of constant lack of greater number of active botanists and inconsistency in gathering data in the field. Recently, a standard for collection of data, based on the Central European MTB (abbreviation of German term “Mestischblatter” that stands for a sheet of topographic map) grid was proposed and tested in the field on the “Medvednica Nature Park” on Medvednica mountain near the city of Zagreb. Using the data collected in 97 MTB/64 quadrants (presence/absence of plant species), we tested the potential of estimating species occurrence at the proposed grid by models in a function of the Digital Elevation Model (DEM)-based variables, namely altitude, terrain slope, terrain aspect, and flow accumulation potential. Because of significant spatial variability of environmental factors within MTB/64 quadrants, each one was represented by descriptive statistics (median, 5-, 25-, 75- and 95-percentiles) of DEM-based variables. Thirty-seven plant species were selected arbitrarily, on the basis of their frequency in the studied area (40–60% of all quadrants). Three methods for development of predictive model were used and compared: discriminant analyses, logistic regression, and classification trees. Yielded results suggest that spatial modelling could be probably applied in flora mapping, which would optimise fieldwork. However, decreasing of mapping unit area is recommended, especially for rare species. For larger areas, inclusion of other environmental predictors (macroclimatic, lithological, landuse) in models is probably needed.

Effects of CaCl2 and CaBr2 on the fecundity of Planorbarius corneus L.

Abstract Saturated water solutions of calcium chloride (481.3 g CaCl2/L) and calcium bromide (1065.9 g CaBr2/L) and their mixtures, commercially prepared as “high density brines”, are regularly used during special operations in exploration and production of natural gas and crude oil. After operations, all workover fluids are left in the environment as waste. In the present study, the effects of several sublethal concentrations of these solutions (CaCl2 1202 ppm, 2403 ppm and 4796 ppm, CaBr2 1065 ppm, 2663 ppm and 5325 ppm, 1:1 volume mixture 773.9 ppm, 1931 ppm, 3855 ppm and 5779 ppm) on the fecundity of the freshwater snail Planorbarius corneus L. were laboratory tested. During the six week exposure a considerably reduced fecundity was found. The tested CaCl2· solution concentrations reduced fecundity by 53.9–84.4 %, CaBr2 by 72.3–90.8 % and the mixture by 72.5–94.0 % compared with the control groups.

An evaluation of floristic diversity in Medvednica Nature Park (northwestern Croatia)

Abstract Mount Medvednica (northwestern Croatia), mostly consisting of slates and marls, rises to the north, above the Croatian capital of Zagreb, from 300 to 1,035 m a.s.l. A floristic research was carried out in the area of Medvednica Nature Park, which consists mainly of the western part of the mountain. On the whole, 1,352 taxa of vascular plants were recorded from all sources (field observations, literature and herbaria). Out of these, 48 taxa are strictly protected, 228 are protected, 67 taxa are considered threatened according to the IUCN categories, and 9 taxa are endemic for the Croatian flora. The life-form analysis of the investigated flora shows the predominance of hemicryptophytes, followed by therophytes and geophytes, while the chorological analysis has evidenced the prevalence of Euro-Asiatic, South European and cosmopolite geographical groups. The biological/chorological cross-spectrum was laid out by considering the percent of every life-form for each geographical element. In order to evaluate the floristic richness of the studied area, the α-index was calculated and then compared with the α-indices of similar regions in Croatia and several European countries. A floristic diversity map of Medvednica Nature Park is presented here for the first time.

Morphometric and molecular (RAPD) analysis of six Serapias taxa from Croatia

The morphometric analyses and genetic variability assessed by RAPD markers have been used to analyse relations among six Serapias taxa from Croatia (S. istriaca, S. pulae originally described as hybrid, S. ionica, S. vomeracea, S. lingua and S. cordigera). S. istriaca distributed in southern Istria and the island of Lošinj and S. pulae stenoendemic taxon distributed only in southern Istria S. ionica is endemic to the Ionian and Dalmatian islands, while the remaining taxa are more widely distributed. The obtained results shows that the endemic S. istriaca is a well characterised taxon, that S. pulae is a hybrid between S. istriaca and S. lingua and that the hybrid is morphologically and genetically more similar to S. lingua than the second parental species S. istriaca. The division into the subsections Steno-, Medio- and Platypetalae is founded based on the floral morphology while the division into the sections Serapias and Bilamellaria is not evident in the quantitative morphological and genetic analyses. Furthermore, considerable genetic resemblance between S. vomeracea and S. ionica was established.

Extreme land-cover and biodiversity change as an outcome of land abandonment on a Mediterranean island (eastern Adriatic)

Abstract Understanding land abandonment and the resulting changes in land cover provides data for suitable reaction to habitat and species losses this process brings. This study aimed to define land-cover types and their biodiversity, record spatio-temporal changes and detect the trajectories and magnitude of these changes. The study was conducted on the island of Molat in the eastern Adriatic Sea. Land cover was defined for different years (1910, 1959, 1986, 2006) using remote sensing and recent vegetation sampling. The obtained land-cover maps were used for spatio-temporal analysis of land-cover change. Open vegetation units of rocky grassland, mesophilous grasslands and farm land dominated in 1910, covering 90% of the island. The observed changes occurred in trajectories through semi-open towards closed vegetation. In 2006, closed vegetation dominated, covering approximately 70% of the island area. The overall land-cover change was extreme, occurring over 90% of the island surface. Biodiversity analysis was related to the present land-cover types and change trajectories, and showed a considerable decline of species richness towards closed vegetation types. All observed changes were correlated to island depopulation and land abandonment. Re-population and encouragement of agro-pastoral activities should reduce habitat and species loss in the process of secondary succession.

Pine reforestation of degraded sites on the island of Rab, Croatia

Abstract Degradation of forest sites on the island of Rab goes back several hundred years. The causes include in the first place negative anthropogenic impacts, followed by climatic conditions that are hostile to natural regeneration of climatozonal vegetation. In a part of the island, devastation has led to the disappearance of forests or the preservation of only degraded forms of the basic autochthonous forest vegetation, the forest of holm oak and manna ash (Fraxino orni‐Quercetum ilicis H‐ic/1956/1958). The beginning of the twentieth century saw intensive reforestation activities aimed at halting site degradation processes. The main task of the pines was to create site conditions for the return of climatozonal vegetation. The paper examines the correlation between pine cultures and the return of autochthonous vegetation. Differences were found among forest cultures of maritime (Pinus pinaster Aiton), black (Pinus nigra J.F.Arnold) and Aleppo pine (Pinus halepensis L.). Moreover, the results confirm the justifiability of reforesting degraded sites with pines, but they also reveal the absence of more pronounced effects on the sites. Today, there are about 1000 hectares of pine cultures on the island of Rab, yet climatozonal vegetation has been re‐established in only a small part of these forest cultures.

Multivariate analysis of phyto-climatic patterns of the Croatian part of the eastern Adriatic coast

ABSTRACT The present study analyses the climatic patterns of that part of the eastern Adriatic coast belonging to the Republic of Croatia and the narrow zone of the inlands. This area comprises a part of the Mediterranean phytogeographic region characterised by the Mediterranean climate type, and the transitional area towards the Eurosiberian phytogeographic region influenced by the continental climate type. The analysis was performed using multivariate numerical methods, cluster analysis following by the inertia analysis, and Principal Components Analysis with partitioning, considering the principal local climatic gradients in the data set. Six main climate classes were obtained. The results are biologically more interpretable than those obtained by using either numerical indices or the Walter climate diagram system. This suggests that multivariate numerical methods could be more efficient tools for detecting biologically significant climatic patterns on a small spatial scale.

The effects of CaCl2 and CaBr2 on the reproduction of Daphnia magna Straus.

Abstract Concentrated CaCl2 and CaBr2 salt solutions of densities up to 2.3 kg L-1 are regularly used to control hydrostatic pressure in oil wells during special operations in the exploration and production of natural gas and crude oil. Various concentrations of high density salts are frequently left in mud pits near the drilling site as waste, polluting fresh and ground waters by spillage and drainage. The toxic effects of these salts have already been observed. This study investigated the effects of CaCl2 and CaBr2 on water flea Daphnia magna Straus in a 21-day reproduction test. The three tested concentrations of CaCl2 (240, 481, and 1925 mg L-1) caused a significant dose-response decrease of reproduction (p<0.001). With CaBr2 (533 and 1066 mg L-1), only aborted eggs were produced, demonstrating the embryotoxicity of the substance. The results suggest that high concentrations of the tested chemicals are harmful to Daphnia’s reproduction and could reduce its abundance. Koncentrirane otopine soli CaCl2 i CaBr2 gustoće do 2,3 kg L-1 redovito se koriste za kontrolu hidrostatskoga tlaka u bušotinama tijekom posebnih operacija u istraživanju i proizvodnji prirodnoga plina i sirove nafte. Različite koncentracije soli visoke gustoće često su bile ostavljene u isplačnim jamama u blizini područja bušenja te su prelijevajući se ili ocjeđujući u podzemlje zagađivale slatke i podzemne vode. Iako je dosad već provedeno nekoliko istraživanja toksičnoga učinka koncentriranih otopina soli CaCl2 i CaBr2, u ovom radu istraživan je učinak CaCl2 i CaBr2 na vodenbuhu Daphnia magna u dvadesetjednodnevnom testu reprodukcije. Tri ispitane koncentracije CaCl2 (1925, 481 i 240 mg L-1) prouzročile su značajan, o dozi ovisan pad reprodukcije (p<0,001). U otopinama CaBr2 (533 i 1066 mg L-1) proizvedena su samo abortirana jaja, što pokazuje embriotoksičnost te tvari. Rezultati upućuju na to da su visoke koncentracije ispitivanih tvari štetne za razmnožavanje vodenbuhe te mogu smanjiti brojnost tih organizama.

SPONTANEOUS AND ORNAMENTAL FLORA OF THE PARK OF LUŽNICA MANOR NEAR ZAPREŠIĆ (NORTHWESTERN CROATIA)

century and laid out after the construction of the manor. The estate also comprises farm buildings, vegetable garden and orchards, which all make a func tional whole together with the main manor house. This research has established the presence of 342 plant species belonging to 233 genera and 80 families, 80 taxa of which belong to ornamental flora (a.s. planted) while 262 are spontaneous species. The flora has been analysed according to taxonomy, chorology, life forms and protected species status. It was also compared to some similar areas in the conti nental part of Croatia. According to the chorological composition and life forms, the Lužnica park flora is not significantly different from that in the compared areas. Nevertheless it is important to note that the park, although the smallest of the compared areas, abounds in a relatively large number of species, 6 of which are strictly protected by law. Therefore, we recommend that Lužnica park to be officially recognised as a protected area.

Učinak CaCl2 i CaBr2 na razmnožavanje vodenbuhe (Daphnia magna Straus)

Abstract Concentrated CaCl2 and CaBr2 salt solutions of densities up to 2.3 kg L-1 are regularly used to control hydrostatic pressure in oil wells during special operations in the exploration and production of natural gas and crude oil. Various concentrations of high density salts are frequently left in mud pits near the drilling site as waste, polluting fresh and ground waters by spillage and drainage. The toxic effects of these salts have already been observed. This study investigated the effects of CaCl2 and CaBr2 on water flea Daphnia magna Straus in a 21-day reproduction test. The three tested concentrations of CaCl2 (240, 481, and 1925 mg L-1) caused a significant dose-response decrease of reproduction (p<0.001). With CaBr2 (533 and 1066 mg L-1), only aborted eggs were produced, demonstrating the embryotoxicity of the substance. The results suggest that high concentrations of the tested chemicals are harmful to Daphnia’s reproduction and could reduce its abundance. Koncentrirane otopine soli CaCl2 i CaBr2 gustoće do 2,3 kg L-1 redovito se koriste za kontrolu hidrostatskoga tlaka u bušotinama tijekom posebnih operacija u istraživanju i proizvodnji prirodnoga plina i sirove nafte. Različite koncentracije soli visoke gustoće često su bile ostavljene u isplačnim jamama u blizini područja bušenja te su prelijevajući se ili ocjeđujući u podzemlje zagađivale slatke i podzemne vode. Iako je dosad već provedeno nekoliko istraživanja toksičnoga učinka koncentriranih otopina soli CaCl2 i CaBr2, u ovom radu istraživan je učinak CaCl2 i CaBr2 na vodenbuhu Daphnia magna u dvadesetjednodnevnom testu reprodukcije. Tri ispitane koncentracije CaCl2 (1925, 481 i 240 mg L-1) prouzročile su značajan, o dozi ovisan pad reprodukcije (p<0,001). U otopinama CaBr2 (533 i 1066 mg L-1) proizvedena su samo abortirana jaja, što pokazuje embriotoksičnost te tvari. Rezultati upućuju na to da su visoke koncentracije ispitivanih tvari štetne za razmnožavanje vodenbuhe te mogu smanjiti brojnost tih organizama.