Branko Karadžić

Use of the β-function to estimate the skewness of species responses

Abstract Response of a species to an environmental variable may be modeled and predicted using a wide spectrum of different functions. Contrary to other functions (Gaussian, polynomial etc), all parameters of the β-function are interpretable in ecological terms. However, computational difficulties in the determination of the β-function parameters initiated controversial debates on the applicability and usefulness of this function in vegetation modelling and gradient analysis. We propose a simple algorithm for fitting the β-function to observed data. Analytic properties of the algorithm (its ability to recover the known species responses along gradients) are tested using a series of simulated data. In most cases the algorithm correctly estimated parameters of the simulated responses.

Indicative Status Assessment, Biodiversity Conservation, and Protected Areas Within the Sava River Basin

The aim of this chapter is to provide the overview of the water status, state of the biological diversity, and protected areas along the Sava River as well as to underline the necessity of identification and implementation of effective conservation measures. The chapter is based on historical data on environment and recent investigation on macroinvertebrate communities (2011–2012). Ecological status of water bodies within the Sava River basin ranges from high to poor, while the ecological status of the majority of water bodies is assessed as moderate, which indicates the necessity of design and implementation of relevant mitigation measures. The assessment of water quality and ecological status of the river Sava based on the macroinvertebrates community, alongside with the use of several standard biological methods and regional biotic index BNBI indicates a high correlation of the obtained results. BNBI has proven to be a method reliable enough for both the assessment of water quality and the assessment of ecological status of large rivers. Based on the results of water status assessment, the Sava River could be divided into three zones. The best water quality was recorded within the Slovenian stretch of the river, being within the limits of betamesosaprobic zone, while the ecological status was assessed as a good one. The middle part of the Sava River, stretching mainly through Croatia and Bosnia and Herzegovina, has a somewhat worse water quality, approaching the limit of betamesosaprobic zone, while the ecological status in this part of the flow was also determined as a “good” one. The lower parts of the Sava River flow through Serbia are by all indicators more heavily polluted; the water quality is on the border between beta- and alfamesosaprobic zones, while the ecological status is between “good” and “moderate.” The biodiversity of the Sava River may be considered significant, when compared to similar watercourses of Central Europe and Balkan Peninsula. The work contains a more detailed analysis of the biodiversity of aquatic macroinvertebrates and fish of the main flow of the Sava River. Based on the condition of biodiversity of these groups, the river’s ecosystem is divided into three “macrohabitats.” The first macrohabitat includes the upper rhithron parts of the river through Slovenia, with a significant diversity of stenovalent groups of macroinvertebrates (larvae EPT) and salmonid species of fish (brown trout, grayling, and huchen trout). The second macrohabitat includes the parts of the flow through Croatia and Bosnia and Herzegovina with significant diversity of invertebrates from the groups Odonata, Mollusca, Hirudinea, and Chironomidae and fish from the families of Cyprinidae, Percidae, and Gobiidae. The highest number of protected species of fish has been registered in this section. The third “macrohabitat” includes the lower part of the potamon of the Sava River and mostly flows through Serbia wherein this part of the flow represents the most important habitat of the globally endangered and fishing-wise important sturgeon species of sterlet (Acipenser ruthenus) in this river. It is characterized by a decreased biodiversity of macroinvertebrates in the main flow of the river and a significant diversity in the flood zones. In the biodiversity of fish, the highest number of allochthonous species appears. In this section, the diversity of fish in flood zones especially as the habitat of endangered species such as Umbra krameri, Misgurnus fossilis, and Carassius carassius is also important. Research has shown that in order to perform a successful conservation of large river biodiversity, the ecosystem must be observed as a complex consisting of the main flow of the river, flood zone, and its tributaries.

Aquatic and Wetland Vegetation Along the Sava River

Diverse hydrological, climate, and soil conditions along the Sava River caused significant diversification of vegetation. Therefore, the objective of this chapter is to integrate and present all the available data on variability of the aquatic and riparian plant communities along the Sava River and its main tributaries as well as to identify the environmental factors, which are related to the distribution of different vegetation types. Special attention has been also paid on the detection of threats for rare and endangered plant species and fragile wetland ecosystems along the Sava River. Based on data review, syntaxonomic revision of aquatic and riparian vegetation based on common, pan-European databank is required. Ecological studies that involve inventory, monitoring, modeling, and prediction of changes in populations, ecological communities, and ecosystems require both georeferenced databases and computational tools for application of statistical methods.

Comparative ecophysiology of seven spring geophytes from an oak-hornbeam forest

The ecophysiological traits of seven spring forest geophytes (Gagea lutea L., Scilla bifolia L., Ficaria verna L., Corydalis cava (L.) Koerte, Arum maculatum L., Dentaria bulbifera L. Crantz, and Ornithogalum pyrenaicum L.) were compared in terms of photosynthetic performance, chlorophyll content, specific leaf area, and relative water content from early spring to summer under field conditions. Light response curves were measured for each species throughout the continuum of its phenological phases to quantify the photosynthetic photon flux density at light saturation, light-saturated photosynthetic rate and light compensation point. All species showed similar seasonal dynamics of the assessed parameters, but the average seasonal values of photosynthesis, dark respiration and maximum efficiency of the photosystem II, as well as light saturation point and light compensation point, differed significantly. From the ecophysiological parameters that were determined it appears that the investigated species can be grouped in two categories: ‘early-flowering’ spring ephemerals (higher PN, Icomp, Isat, Rd, lower Fv/Fm, more shade-avoiding strategy): G. lutea, S. bifolia, F. verna, C. cava and ‘later-flowering’ spring ephemerals (lower PN, Icomp, Isat, Rd, higher Fv/Fm, more shade-tolerating strategy): A. maculatum, D. bulbifera, and O. pyrenaicum.

Soils as Natural Resources

The soil cover of Serbia is not high in terms of surface area, but it is significant due to the large number of systematic units which originated as a consequence of the diversity of the conditions for the formation and pedogenesis of certain soil types. The soils of Serbia are extremely heterogeneous as a result of the varied geological substrates, climate, vegetation, soil flora and fauna. Soils are divided into eight fertility classes, reflecting their relative suitability for agricultural production, with classes 1–4 representing higher quality soils. However, about 45% of the total land area belongs to soil classes 4–8, which are not suitable for tillage and profitable crop production, and this land is used for semi subsistence vegetable or fruit production or as meadows.

Order of Hydromorphic Soils

Soils of this order are characterized by temporary or permanent excessive wetting in part of or through the entirety of the profile. The genesis and properties of hydromorphic soils mainly depend on the hydrologic regime which includes: sources of water and the manner of excessive wetting; the zone in the profile affected by this wetting; and the duration of the excessive wetting. Soils of this order cover approximately 20,897.15 km2 or 23.7% of the land mass of Serbia.

Order of Halomorphic and Subaquatic Soils

Halomorphic soils cover approximately 1,140.29 km2 or 1.3% of the land mass of Serbia and this order is divided into two classes. Subaquatic soils occupy very small areas and have no economic significance. Only when dried out they can be used for plant cultivation, at which point these soils, in the new conditions, change drastically and lose their previous characteristics.

Order of Automorphic Soils

Automorphic soils are characterized by wetting through precipitation only with no additional wetting. Water percolates through the soil profile freely without any prolonged retention on the impermeable horizon. These soils predominate in Serbia, covering approximately 66,323.58 km2 or 74.9% of the land area and this order is divided into six classes according to the degree of profile development.