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Summary Sooty bark disease (SBD) caused by the pathogen Cryptostroma corticale is currently one of the risks to the population of Acer pseudoplatanus in Europe. After a number of records of symptomatic and dead trees in Prague, assessment of the latent non‐symptomatic stage of SBD was questioned as a means to forecast the health risk of the A. pseudoplatanus population. We used two methods of early detection of C. corticale in non‐symptomatic trees: cultivation from wood tissue on agar plates and a culture‐free approach based on nested PCR with newly designed species‐specific primers. The pathogen was detected in 25% of 112 examined trees from seven localities in Prague, but the disease incidence might be higher if more A. pseudoplatanus trees in Prague were included and if the crown infections were considered. The presence of C. corticale was positively correlated with discoloured wood, but its presence did not depend on the occurrence of external symptoms. Infected trees were more frequently found in groups on steep sites at higher elevations. In addition, heavier NOx pollution combined with more paths and roads increased the incidence of C. corticale.

In this study, the structure and spatial patterns of adjacent beech (Fagus sylvatica L.) forest stands, both those having undergone intensive management and those without management intervention over the last 50 years were analyzed. Data was collected from six 1ha permanent research plots. Four plots were established in varying parts of the reserve, comprising entirely of even-aged managed forest stands; two 1-ha permanent plots were located in a non-interventional stand. For each woody stem, basic dendrometrical data and coordinates were measured. The total volume of dead wood (standing and fallen) and its classes of decay were recorded. The structure and species diversity of forest stands were analyzed using skewness and the coefficient of variation of dbh distribution, the Gini index, the Shannon index, the mingling index, the Pielou index of segregation and the Hopkins-Skellam, Pielou-Mountford, Clark-Evans aggregation indices, the diameter differentiation index and Ripley K function. The diameter distribution of the managed stands was generally normal, albeit with a large diameter range and with a typical flat diameter curve. A general lack of giant trees, lower rates of coarse woody debris (from 0.2 to 0.5% of the total living volume) and random tree distribution were also confirmed. Within the investigated area, the diameter differentiation and Gini indices along with the degree of skewness and the coefficient of variation made it possible to monitor the shift from even-aged forest management to spontaneous forest development. In general, spontaneous development was marked mainly by aggregated tree distribution in the middle and lower layer, and a shift from normal to reversed J-shaped dbh distribution. The total volume of deadwood in one of the unmanaged plots amounted to 48.10 m3/ha (9.5% of living wood volume). The use of adequate structural and spatial analysis as indicators of natural forest development are discussed.

This article summarizes basic estimates of productivity and trend analysis of one of the principal introduced forest tree species in the Czech Republic, i.e. Douglas-fir (Pseudotsuga menziesii [Mirbel] Franco). As a comparison, we also examine grand fir (Abies grandis [D. Don] Lindl), northern red oak (Quercus rubra L. syn. Quercus borealis Michx.) and black locust (Robinia pseudoacacia L). This paper presents estimates of forest land area, standing volume, annual and total increments, distribution of age classes, average ages and site indexes for the period 1979-2010. All data were obtained from the national forest inventory of the Czech Republic. Korf 's growth function was used for the assessment of current and mean annual increments (CAI, MAI) of Douglas-fir compared to other tree species. Our results suggest a decline in the annual area afforested by Douglas-fir, as influenced by the State administration management choices, a low rate of an increase in the forest land area, increasing average age of the forests. On the other hand, we observed a dramatic increase in the standing volume as well as high annual increments in volume. Douglas-fir is the most productive major tree species in the Czech Republic and there is a great potential to expand its use throughout the country.

Summary The impact of ash dieback caused by Hymenoscyphus fraxineus on 17 provenances of Fraxinus excelsior and one provenance of Fraxinus angustifolia was studied in an extensive field trial established in the Czech Republic prior to the H. fraxineus invasion in 1999. A difference in the level of resistance to ash dieback between the species was found: F. angustifolia was significantly less affected by the disease than F. excelsior. Moreover, particular provenances of F. excelsior showed important differences in the level of resistance to H. fraxineus. A relationship between the impact of ash dieback and altitude was also discovered – the provenances from altitudes above 600 m a.s.l. were less affected by the pathogen than were the provenances from lower areas. No difference in the impact of the disease among provenances of F. excelsior from different ecotopes (ravine, calcareous ravine and alluvial) was found. Substantial among‐tree variability in resistance to H. fraxineus was observed throughout the trial – promising genotypes (with crown defoliation up to 5%) were identified in all 18 tested provenances. In regard to this finding, it appears that the main source of resistance to the pathogen is probably at the individual genotype level in the trial. A secondary but massive attack by Hylesinus fraxini was identified in the trees that had been greatly damaged by ash dieback, and the beetle caused their health to deteriorate significantly. A significant negative effect of the presence of collar necroses caused by H. fraxineus and browse damage was also identified.