Smart off-line webinar for distant education

The article is devoted to searching the ways of effective development of modern electronic courses using smart presentations in teaching net technologies for university students considering difference in students’ input knowledge and their initial level

SASTOJINSKA DINAMIKA PRETPLANINSKE ŠUME SMREKE (Picea abies L. Karst) – REZULTAT PRIRODNIH POREMEĆAJA

The paper deals with the stand dynamics of subalpine Norway spruce forest in the Low Tatras Mts., Slovakia. The recent state of subalpine spruce forests is unsatisfactory because of the extensive windstorms followed by bark beetle outbreak. The study is focused on the reconstruction of historical disturbances affecting this locality in the past. The research was conducted on the model locality Mt. Veľký Bok in the Low Tatras, central Slovakia. After the harvesting of snags we cored spruce stumps (N=60). Boundary-line criteria (fig.1) were used for evaluation of growth releases. We reconstructed local disturbance chronology and tree recruitment chronology. Three distinctive peaks of growth releases were revealed, in 1860−1880; 1920−1940 and 1980−2000. The identified disturbance periods were confirmed by examination of historical sources. Regarding the tree recruitment patterns, 50 % of analyzed trees met the criterion of gap recruitment. The temporal position of recruitment waves fairly corresponds with occurrence of a major disturbance. According to obtained results, we can state that the large-scale wind disturbances are the natural part of subalpine spruce forest and the overall dynamics of investigated forest is driven by combination of gap and patch dynamics.U radu se istražuje sastojinska dinamika pretplaninske šume obične smreke u Niskim Tatrama u Slovačkoj. U posljednje je vrijeme stanje planinskih šuma smreke nezadovoljavajuće, a posljedica je to jakih olujnih vjetrova i napada potkornjaka. Istraživanje se ponajprije bavi rekonstrukcijom prirodnih poremećaja koji su utjecali na lokalitet.Istraživanje je provedeno na reprezentativnom lokalitetu na području planine Veľký Bok u Niskim Tatrama, središnja Slovačka. Nakon sječe sušaca, iz panjeva stabala smreke uzeli smo izvrtke (N=60). Koristili smo kriterij granične linije za procjenu pojave signala natprosječnog debljinskog prirasta.Rekonstruirali smo kronologiju lokalnih poremećaja i obnove sastojine. Jasno su se pokazale tri iznadprosječne kulminacije debljinskoga prirasta, u razdoblju do 1860–1880.; 1920−1940. i 1980−2000. godine. Istraživanjem povijesnih izvora potvrdili smo uočena razdoblja prirodnih poremećaja. Što se tiče obnove sastojine, 50 % analiziranih stabala zadovoljili su kriterij obnovljenih progala. Vremenski položaj prirodne obnove sastojine usko je povezan s pojavom jakih prirodnih poremećaja. Dobiveni rezultati ukazuju na činjenicu da su jaki vjetrovi prirodna pojava u pretplaninskim šumama smreke te da je ukupna tekstura istraživanih šuma posljedica djelovanja uzajamne kombinacije dinamike manjih i većih progala

Deer game, a key factor affecting population of European yew in beech forests of the Veľká Fatra Mts, Slovakia

Browsing and bark peeling by ungulates is known to affect biodiversity and may constitute the main driving factor of single tree population dynamics. In Slovakia, European yew (Taxus baccata L.) is a threatened species protected by law and present in many protected areas. In the study, we emphasize that protecting land and individual plants may not be sufficient for maintaining of yew populations, unless controlling over damage by deer game is also undertaken. Our results show that in beech forests of the Veľká Fatra Mts, browsing and bark peeling constitute the main negative factor affecting yew seedling-sapling ingrowth transition, and the mortality and vitality loss of adult yew trees. We argue that ungulates may have a larger effect on biodiversity conservation than currently realized

Gap Structure and Regeneration in the Mixed Old-Growth Forests of National Nature Reserve Sitno, Slovakia

Forest management mimicking natural processes represents an approach to maintain mixed, uneven-aged stands at small spatial scales. The reliance on natural processes, especially on natural regeneration leads to the use of gap-based regeneration as a fundamental silvicultural technique. As a baseline for such management, we investigated mixed forest in unmanaged National Nature Reserve Sitno in the Western Carpathians, which harbours extraordinary diversity on a rather small scale. To quantify the impact of gaps on gap-filling processes and to assess the role they play in recently observed changes in tree species composition we established a large (2.5 ha) permanent research plot and surveyed the status of natural regeneration, forest structure, tree species composition, and disturbance regime. Our research highlights the long-term and contemporary difficulties in the establishment of Quercus petraea (Matt.) Liebl and Fagus sylvatica (L.). Based on the provided evidence, the native tree species diversity in one of the few preserved old-growth multi-species beech-oak forest remnants is not likely to persist, what could have many implications for future ecosystem functioning. Our results suggest that variation in gap size is an important factor contributing to composition of tree species composition of natural regeneration. The recent intermediate-scale disturbance pattern dominating the old-growth beech-oak forest is beneficial to canopy recruitment of species less shade-tolerant than Fagus sylvatica, as Acer pseudoplatanus (L.), Acer platanoides (L.), and Fraxinus excelsior (L.). We discuss possible factors behind observed shifts in tree species composition and limitations for application of gap dynamics to forest practice in managed beech-oak forest systems. Overall, results of this study may help to design silvicultural measures promoting mixed-species forests to deliver a range of desired ecosystem services

Irregular Shelterwood Cuttings Promote Viability of European Yew Population Growing in a Managed Forest: A Case Study from the Starohorské Mountains, Slovakia

The increasing probability of Taxus baccata (L.) decline given climate change brings forth many uncertainties for conservation management decisions. In this article, the authors present the effects of applying regeneration cuttings since the year 2000 on the viability of the understory yew population. By collecting data from a stand located at the centre of the largest population of European yew in Slovakia, containing approximately 160,000 individuals, and analysing tree-ring records from 38 sampled trees, the improved performance of yews, including stem growth, seed production, and number of regenerated individuals, was revealed. Thinning the canopy by removing 15% of the growing stock volume per decade, combined with the subsequent irregular shelterwood cuttings, was assessed as a useful strategy. Moreover, lower radial growth of females compared to males, but simultaneously their similar response to climate, suggests a possible trade-off between reproduction and growth. Release cuttings of up to 30% of the standing volume in the vicinity of the female trees, executed in the rainy summers following warmer winters, and consistent elimination of deer browsing, can further enhance the positive effects of applied cuts on yew viability. Overall, the suggested active measures could be considered as an effective option to preserve the unique biodiversity of calcareous beech-dominated forests in Central Europe

Drought or Severe Drought? Hemiparasitic Yellow Mistletoe (Loranthus europaeus) Amplifies Drought Stress in Sessile Oak Trees (Quercus petraea) by Altering Water Status and Physiological Responses

European oak species have long been considered relatively resistant to different disturbances, including drought. However, several recent studies have reported their decline initiated by complex changes. Therefore, we compared mature sessile oak trees (Quercus petraea (Matt.), Liebl.) infested versus non-infested by hemiparasitic yellow mistletoe (Loranthus europaeus Jacq.) during the relatively dry vegetation season of 2019. We used broad arrays of ecophysiological (maximal assimilation rate Asat, chlorophyll a fluorescence, stomatal conductance gS, leaf morphological traits, mineral nutrition), growth (tree diameter, height, stem increment), and water status indicators (leaf water potential Ψ, leaf transpiration T, water-use efficiency WUE) to identify processes underlying vast oak decline. The presence of mistletoe significantly reduced the Ψ by 1 MPa, and the WUE by 14%. The T and gS of infested oaks were lower by 34% and 38%, respectively, compared to the non-infested oaks, whereas the Asat dropped to 55%. Less pronounced but significant changes were also observed at the level of photosystem II (PSII) photochemistry. Moreover, we identified the differences in C content, which probably reduced stem increment and leaf size of the infested trees. Generally, we can conclude that mistletoe could be a serious threat that jeopardizes the water status and growth of oak stands