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Restoring the structural characteristics of secondary old-growth forests that were previously managed is increasingly debated to help increase the area of more complex forests which provide a broader array of forest services and functions. The paucity of long-term data sets in Central Europe has limited our ability to understand the ongoing ecological processes required for effective restoration programs for old-growth forests. To address this, we used repeated census data from eight permanent plots to evaluate forest structural dynamics over a 12-year period in the largest complex of European beech (Fagus sylvatica L.) forests in the Czech Highlands without intensive forestry intervention for almost 50 years. Our results showed that previously managed forests can exhibit structural qualities typically associated with old-growth forests after management has ceased for a period. The stand structural characteristics (e.g., density of large and old trees) is comparable with protected reserves of old-growth European beech-dominated forests. The average stand age was 196 years, but the oldest tree was 289 years old. The annual mortality rate was 0.43% for all species, and the U-shaped distribution indicating size-dependent mortality is likely an important process that is balanced by the turnover of new tree recruitment. During the study period, we detected that the diameter distribution tended towards a rotated sigmoid distribution. The lasting effects of the most recent forest management are evident in the scarcity of dead wood, and a prolonged process of dead wood accumulation has begun. Thus, the abandonment of all management activities in near-natural forest reserves, including dead wood removal, will ensure that the forests will develop characteristics typical of old-growth forests.

Primary forests are characterized by high vertical and horizontal stand diversity, which provides habitat for a diverse range of species with complex habitat requirements. Detailed knowledge of related ecological processes and habitat development of primary forest species are essential to inform forest management and biodiversity conservation decisions, but relationships are not well documented. We collected dendrochronological data and inventoried numerous structural elements in permanent plots throughout the primary temperate forests within the Carpathian Mountains. We fit and compared multiple predictive models to quantify the importance of 200 years of natural disturbance dynamics on the occurrence probability of an umbrella species – the capercaillie (Tetrao urogallus). We showed that a mixed-severity disturbance regime ranging from low through moderate to high severity disturbances is required to generate diverse forest habitats suitable for capercaillie. The variation in natural disturbance severity and its timing promoted key structural habitat elements, such as low natural regeneration density, low mature tree density, high ground vegetation cover, availability of forest gaps, and abundance of standing deadwood. This study demonstrates the importance of natural disturbance in maintaining the variety of conditions necessary to support primary forest specialist species. Managers of protected areas should be mindful that natural disturbances generate habitat for the capercaillie in mountain Norway spruce forests. Further intervention is unnecessary. Conservation planning and forest reserve design should shift focus to the large-scale spatial requirements needed to ensure that a wide range of forest developmental phases are represented in protected areas.

European natural mountain Norway spruce (Picea abies) forests are currently subject to extensive disturbances. An improved understanding of the self-regulated regenerative capacity of this forest type is therefore needed. We used the last remnant of natural mountain Norway spruce forests in central northwestern Europe (BNF Brocken natural forest), to analyze (1) the diversity of structure and age distribution of the tree population and (2) the effect of disturbances on self-regulated tree regeneration over the last 264 years. To this end, we combined an assessment of stand structure with dendrochronological investigations and a review of disturbance history. We hypothesized that BNF exhibits a high diversity of tree ages and dimensions and that recruitment and survival of tree regeneration were largely independent from disturbances. BNF showed a high structural and age diversity. Disturbances exhibited no regular temporal pattern. Their effect on tree regeneration was rather complex and changed with observation period. Impeding and facilitating effects of past disturbances on recruitment were significant from 1736 to 1910. From 1911 until 2000, recruitment decoupled from preceding disturbances. Subsequent disturbances facilitated survival of established trees from 1736 to 1820, while afterward no significant influence could be proved. Our study showed that in the course of self-regulated development the tree population of BNF has gradually acquired, or maintained, a diverse structure. Disturbances served as an important driver of diversification. We concluded that increasing deadwood availability and limiting browsing are the key to securing immediate regeneration.

In order to gauge ongoing and future changes to disturbance regimes, it is necessary to establish a solid baseline of historic disturbance patterns against which to evaluate these changes. Further, understanding how forest structure and composition respond to variation in past disturbances may provide insight into future resilience to climate-driven alterations of disturbance regimes. We established 184 plots (mostly 1000 m2) in 14 primary mountain Norway spruce forests in the Western Carpathians. On each plot we surveyed live and dead trees and regeneration, and cored around 25 canopy trees. Disturbance history was reconstructed by examining individual tree growth trends. The study plots were further aggregated into five groups based on disturbance history (severity and timing) to evaluate and explain its influence on forest structure. These ecosystems are characterized by a mixed severity disturbance regime with high spatiotemporal variability in severity and frequency. However, periods of synchrony in disturbance activity were also found. Specifically, a peak of canopy disturbance was found for the mid-19th century across the region (about 60% of trees established), with the most important periods of disturbance in the 1820s and from the 1840s to the 1870s. Current stand size and age structure were strongly influenced by past disturbance activity. In contrast, past disturbances did not have a significant effect on current tree density, the amount of coarse woody debris, and regeneration. High mean densities of regeneration with height >50 cm (about 1400 individuals per ha) were observed. Extensive high severity disturbances have recently affected Central European forests, spurring a discussion about the causes and consequences. We found some evidence that forests in the Western Carpathians were predisposed to recent severe disturbance events as a result of synchronized past disturbance activity, which partly homogenized size and age structure and made recent stands more vulnerable to bark beetle outbreak. Our data suggest that these events are still part of the range of natural variability. The finding that regeneration density and volume of coarse woody debris were not influenced by past disturbance illustrates that vastly different past disturbance histories are not likely to change the future trajectories of these forests. These ecosystems currently have high ecological resilience to disturbance. In conclusion, we suggest that management should recognize disturbances as a natural part of ecosystem dynamics in the mountain forests of Central Europe, account for their stochastic occurrence in management planning, and mimic their patterns to foster biodiversity in forest landscapes.

The objective of this work was to induce and detect somaclonal variation in arracacha (Arracacia xanthorrhiza) plants regenerated via indirect morphogenesis, in order to evaluate the potential of this technique to produce new genotypes for breeding purposes of this crop. Calli were induced from petiole segments on Murashige & Skoog (MS) medium supplied with 0.1 mg L-1 2,4-dichlorophenoxyacetic acid. The regeneration of plants via indirect morphogenesis was carried out on half-strength MS medium without plant growth regulators. Fifteen randomly chosen plants were subjected to flow cytometry and “inter-simple sequence repeat” (ISSR) analysis. Ploidy level remained stable in all tested regenerants (2n=4x=44), with no changes in the genome. Eighteen ISSR primers produced a total of 1,584 fragments in all samples. Two ISSR primers produced four polymorphic fragments in 26.7% of the tested samples. Somaclonal variation in arracacha is a result of plant regeneration via indirect morphogenesis and can be detected by ISSR markers. Resumo: O objetivo deste trabalho foi induzir e detectar a variação somaclonal em plantas de batata-baroa (Arracacia xanthorrhiza) regeneradas por morfogênese indireta, para avaliar o potencial dessa técnica em produzir novos genótipos para o melhoramento dessa cultura. Calos foram induzidos em segmentos de pecíolos no meio de Murashige & Skoog (MS) suplementado com 0,1 mg L-1 de ácido 2,4-diclorofenoxiacético. A regeneração de plantas pela morfogênese indireta foi realizada em meio de cultura MS meia-força, sem reguladores de crescimento de plantas. Quinze plantas escolhidas aleatoriamente foram submetidas à citometria de fluxo e à análise entre sequências simples repetidas (ISSR). O nível de ploidia manteve-se estável em todas as plantas regeneradas (2n=4x=44), sem mudanças no genoma. Dezoito iniciadores ISSR produziram um total de 1.584 fragmentos em todas as amostras. Dois iniciadores ISSR produziram quatro fragmentos polimórficos em 26,7% das amostras testadas. A variação somaclonal entre plantas de batata-baroa é resultante da regeneração de plantas pela morfogênese indireta e pode ser detectada por meio de marcadores ISSR.

In a recent opinion paper, Schulze et al. (2014) compared an-imal and plant richness of protected areas with intensivelyand extensively managed forests in Germany and in Roma-nia. Schulze et al. hypothesised that “differences in manage-ment practice have contributed to the observed differences indiversity of central versus southeastern Europe”. The studyconcludes with a hypothesis that “clear-felling followed bynatural succession may even be superior to the protectionof old-growth forests, regarding biodiversity”. We wish tocontinue the dialog on this important topic, and express oursomewhat different perspective on the conclusions and im-plications of this particular paper (Schulze et al., 2014). Weagree in principal that emulating natural disturbance regimesand creating openings via clear-fellings can be one of sev-eral management tools to introduce heterogeneity in other-wise homogenous mid-seral stands that have resulted frompast management (Franklin and Johnson, 2012). However,we believe it is misleading to compare clear-fellings to pro-tected areas dominated by old-growth or primary forests us-ing a simplistic measure of biodiversity and without a land-scape perspective on the role of different habitat types (suc-cessional stages) to sustain biodiversity over time and space.We identify some critical limitations of the original opinionpaper and offer an alternative perspective to the authors’ con-clusions regarding protected forests.We highlight three major issues of the opinion paper ofSchulze et al. (2014): limited scope, an incomplete concep-tual framework, and conjectural interpretations unsupportedby solid data.