An Improved Weise’s Rule for Efficient Estimation of Stand Quadratic Mean Diameter

The main objective of this study was to explore the accuracy of Weise’s rule of thumb applied to an estimation of the quadratic mean diameter of a forest stand. Virtual stands of European beech (Fagus sylvatica L.) across a range of structure types were stochastically generated and random sampling was simulated. We compared the bias and accuracy of stand quadratic mean diameter estimates, employing different ranks of measured stems from a set of the 10 trees nearest to the sampling point. We proposed several modifications of the original Weise’s rule based on the measurement and averaging of two different ranks centered to a target rank. In accordance with the original formulation of the empirical rule, we recommend the application of the measurement of the 6th stem in rank corresponding to the 55% sample percentile of diameter distribution, irrespective of mean diameter size and degree of diameter dispersion. The study also revealed that the application of appropriate two-measurement modifications of Weise’s method, the 4th and 8th ranks or 3rd and 9th ranks averaged to the 6th central rank, should be preferred over the classic one-measurement estimation. The modified versions are characterised by an improved accuracy (about 25%) without statistically significant bias and measurement costs comparable to the classic Weise method

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

Reakcia dubov voči klimatickým extrémom v prechodnej zóne dubových a bukových lesov

Forest management might be threatened by declining health status of oaks in the transition zone between oak and beech forests, where drought is the most limiting factor. The aim of the presented paper is to assess the influence of selected climatic characteristics on the radial growth of oak trees with different stem diameter status in the beech-oak and oak-beech forest altitudinal zones within the forest growth area of Poľana Mt. and Zvolen Basin (Slovakia). Our results show that oaks with less favourable stem diameter position (Weisse’s middle stems) show slower radial growth, have less pronounced climatic precipitation signal and milder response to extreme climatic events. The findings potentially suggest that not only favourable tree species composition of stands, but also the stand structure can mitigate the negative impacts of climate change on forest growth.peerReviewe

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