Sven D. Jelaska

Spatial distribution of main forest soil groups in Croatia as a function of basic pedogenetic factors

The model of spatial distribution of main forest soil groups in Croatia was developed as a function of basic pedogenetic factors: lithological substratum, macroclimate and relief. Used data about soil group, lithological substratum, terrain slope and aspect were collected on 1881 soil profiles. Macroclimatic data were estimated for each soil profile by spatial interpolation between meteorological stations. Feedforward neural networks were used as modelling tool. The final model has total classification correctness of 63.5% for training data set and 62.3% for independent test data set. The best result (86.4%) was achieved for fluvisols which are strongly spatially correlated with alluvial sediment in a flood plains. The worst result was achieved for luvisol (14.2%) which mainly comprised very old soils, probably developed under pedogenetic factors different from actual. The model was applied on entire Croatian territory aiming at construction of potential spatial distribution of main forest soils (without human impact), which was compared by the potential spatial distribution of major forest types modelled independently.

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.

Terrestrial Biodiversity Analyses in Dalmatia (Croatia): A Complementary Approach Using Diversity and Rarity

Here we present the methodology used for terrestrial biodiversity analysis and site selection in Phase B of the UNDP/GEF COAST project. The analysis was focused on the problem of biodiversity evaluation in four Croatian counties stretching from sea level to the highest mountain in Croatia. Data on habitats, vascular flora, and fauna (mammals, birds, reptiles, amphibians, butterflies, ground beetles, and underground invertebrates) were collected and analyzed for each of the four counties. Emphasis was given to the richness of endangered species and the rarity of endemic species. Based on the spatial analyses of habitat, fauna, and flora data, four to six areas were selected from each county and ranked according to their biodiversity importance. Overlap between areas important for richness and those important for rarity was highest for data on flora (65.5%) and lowest for data on fauna (16.7%). When different data sets were compared, the lowest overlap was between flora and fauna (17.1%) and largest between fauna and habitats (23.9%). Simultaneous overlap among all three data sets was found in just 6.5% of the overall selected areas. These results suggest that less specific data, with respect to taxa threat status, could better serve as surrogate data in estimating overall biodiversity. In summary, this analysis has demonstrated that Dalmatia is a region with a high overall biodiversity that is important in a broader European context.

Invasive alien plants in Croatia as a threat to biodiversity of South-Eastern Europe: Distributional patterns and range size

During the analysis of alien and invasive flora of Europe, as a threat to biodiversity, data for Croatia were missing. The aim of our research was to analyse distributional patterns and range size of all invasive alien plants (64) for the state area (57,000 km(2)). They were detected on 49% of the state territory, averaging five taxa per 35 km(2). The greatest number of invasive plants (>30 per grid cell) was recorded in the major urban centres, increasing in the south-east direction and reflecting positive correlation with temperature and negative with altitude. The most endangered areas are in the Mediterranean region, especially on islands. The number of invasive plants increased with habitat diversity and almost 75% of all sites with invasive plants are located within a few habitats with direct anthropogenic influence. The results should provide a reliable regional and global basis for strategic planning regarding invasive alien plants management.

The influence of land abandonment on farmland bird communities: a case study from a floodplain landscape in Continental Croatia

Abstract. The abandonment of less productive agricultural land and the intensification of agricultural land use are the main features of the Common Agricultural Policy (CAP) that Croatia will enforce now as new member of the EU. Due to demographic changes and the economic transition in Croatia resulting from war in the 1990s, substantial tracts of agricultural land were abandoned. We investigated two habitat types in the protected floodplain landscape of Lonjsko polje in the continental part of the country: arable land and pastures. Both habitats were maintained by agricultural management and suffered from partial abandonment. Land abandonment increased the susceptibility to encroachment by the invasive plant species Amorpha fruticosa. Data on bird communities were obtained during the breeding season in 2010 while there were high water levels in the floodplain. Data were collected from 63 points, and a total of 1447 individuals from 70 species were recorded during the study. We found that the bird community structure was primarily related to the presence/abandonment of agricultural land use and the habitat type. Further, we detected that the bird community structure in the same habitat type differed by management intensity. Open habitat specialists were most influenced by land abandonment. However, the conservation value (according to the Species of European Conservation Concern value, SPEC) of grazed pastures and abandoned pastures did not differ significantly, in part because the overgrown pastures with high water levels were found to be suitable for Acrocephalus species. The shift in bird community structure between abandoned and managed arable lands were smaller than those detected in the pastoral communities. Because land abandonment is a widespread phenomenon in Croatia, we emphasize the urgent need for a nationwide monitoring program for farmland birds to register the resulting changes in farmland bird communities and to develop appropriate agri-environment measures to mitigate the process.

Distribution and morphological variations of invasive macrophytes Elodea nuttallii (Planch.) H. St. John and Elodea canadensis Michx in Croatia

Abstract The invasive species Elodea nuttallii was recorded for the first time in the Croatian flora in 2006, in the drainage channels of Kopački rit (Baranja). After its establishment, E. nuttallii begins to spread to the eastern and northern part of the drainage channel network from 2006-2009. High water levels are responsible for the linear spreading direction of E. nuttallii, E. nuttallii and E. canadensis show a wide range of morphological variation, which is characteristic of successful invaders. To show morphological variations of two Elodea species, the most important characters indicated in the literature were measured on 24 fresh collected samples from the seven sites in Croatia. In spite of some overlap in leaf length and width between the two Elodea species, the differences of all morphological traits except internode length are statistically significant. In E. nuttallii leaf width, length and internode length show a higher morphological variability as a result of the higher adaptive strategy to environmental parameters. The most reliable morphologi-cal characters distinguishing E. nuttallii and E. canadensis are leaf width 0.5 mm below the tip and the angle at the apex. E. nuttallii can be expected to spread to other areas of Croatia.

Plant Diversity and Chemical Soil Composition of Rocky Pastures in Relation to the Sheep Grazing Intensity on the Northern Adriatic Islands (Croatia)

Abstract Optimal grazing pressure on rocky pastures is beneficial to the development of plant species and maintenance of plant diversity. Both abandonment of grazing and overgrazing gradually reduce plant diversity. This paper correlated abundance patterns of the flora on rocky pastures with the values of the chemical composition of the soil resulting from the degree of sheep grazing intensity. The study was carried out in the period from 2008 to 2010 on the islands of Pag, Krk and Cres. At 30 sites, 310 taxa of vascular plants were found. The highest plant diversity and 220 plant taxa were found on moderately grazed pastures. Abandoned pastures with a total of 93 plant taxa observed show the dominance of phanerophytes (35.5%) and the highest proportion of the Mediterranean floral element when compared to pastures of moderate and heavy grazing intensity. The highest concentration of total nitrogen in the soil (0.71%) was recorded on plots of heavy grazing intensity. The results of the study indicate that moderate grazing intensity, from 1 to 1.5 sheep ha−1, can be recommended on the northern Adriatic islands. This should contribute not only to the preservation of plant diversity, but also to the improvement of ecological sheep farming.

Alterations in the breeding habitats for two endangered raptor species along the Sava River basin, Croatia

Changes in habitat suitable for breeding of two sympatric raptor species (Haliaeetus albicilla and Aquila pomarina) were analysed along one of the most important breeding sites in Croatia for both species. The habitat suitability modelling was used to assess the influence of forestry practice during 2000–2006 using the known data on nesting places along research area. The four most important variables for lesser spotted eagle were elevation, distance from the nearest pasture, vertical distance to the nearest channel network and broadleaved forest placement (second axis from the principal component analysis of the enhanced vegetation index (EVI) index of MODIS images; November–March). The variables where white-tailed eagles showed greatest shift from overall habitat characteristics in the research area were broadleaved forest (second axis from the principal component analysis of the EVI index), height above the sea level, distance from the small settlements, vertical distance to channel network — all with negative loadings. The results clearly reveal the disproportion of suitable forests for raptors that were cut down in comparison to maturation of suitable forests.

Detecting habitat changes using MODIS EVI images: a case study of Spoonbill Platalea leucorodia in Croatia Ugotavljanje sprememb v habitatih z uporabo posnetkov MODIS EVI: vzorčna študija žličarke Platalea leucorodia na Hrvaškem

Abstract The breeding population of Spoonbill Platalea leucorodia in Croatia, estimated at 154-275 breeding pairs, is classified as Endangered. The main reason for the unfavourable status is loss of breeding/feeding habitats. The purpose of the study was to detect changes in the habitat types previously assessed as important for Spoonbill’s feeding. The study area was chosen for two reasons: (1) the alluvial wetlands of the central part of the Sava River hold the biggest colony of Spoonbills in Croatia, and (2) availability of data on feeding ecology of Spoonbills along alluvial wetlands of the Sava River. We used the MODIS (Moderate Resolution Imaging Spectroradiometer) Enhanced Vegetation Index (EVI) as the main indicator for the changes in habitat structure along critical habitats for Spoonbills. The analysis identified areas with significant changes in EVI for habitat types important for feeding of the Spoonbills during the 2000-2008 period. Pastures, especially those with high wetness potential, changed in significant percentage despite conservation efforts in this habitat type. Changes in EVI were detected on ca. 9% of the pastures. For that reason we urge for better monitoring of the Spoonbill’s feeding habitats “in situ” and more specified characterisation of the reasons for the detected changes.

SPATIAL ANALYSES OF LANDCOVER AND RELIEF DIVERSITY OF THE MEDVEDNICA NATURE PARK – POSSIBLE IMPLICATIONS FOR OPTIMISING VISITOR PRESSURE

The Nature Park Medvednica, which is V protection category, according to the IUCN categorization implies recreation beside landscape preservation management in terms of natural protection, tourism and recreation, as well as scientific research, biodiversity preservation, education and sustainable exploitation of natural resources. The forests represent basic value of this area and condition its purpose and management. It has been determined that habitat diversity indices vary dependently on data spatial resolution. The habitat map M 1:25,000 showed to be the most appropriate (compared to 1:50,000 and 1:100,000 scales) for the analyses of the Park’s management and for certain areas the data of higher spatial resolution would be desirable. Data on plant diversity, and previously calculated landforms diversity per MTB 1/64 grid units were used as well. When identifying the tourist and visiting areas of the Park it is necessary to include biodiversity value of the area in order to sustainably manage among nature and cultural protection and tourist exploitation. The GIS usage in nature protection management is justifiable and very efficient, enabling the generation and collection of multidisciplinary data as well as spatial model projection obtained using these data, helping in prompt decision making, saving time and resources.