Secondary Spruce Research Articles

Soil seed banks of pure spruce (Picea abies) and adjacent mixed species stands

The soil seedbank of long living seeds of herbs, graminoids and shrubs can survive several decades in the soil and germinate after disturbances like windthrow or clearcutting. The main goal of this study was to evaluate the risk of weeds, which may limit the success of conversions of secondary pure spruce stands (Picea abies) to mixed species stands. In a first step, germination experiments were performed in the greenhouse on soil samples collected under adjacent pure spruce and mixed species stands (mainly mixtures of spruce and beech –Fagus sylvatica) on two different soil substrates (Flysch: nutrient rich, basic soil; Molasse: nutrient poor, acidic soil). Seedling density and species richness were higher on the nutrient rich soil on Flysch. Comparisons between seedlings that emerged from soil samples collected at the end of the vegetation period and in spring justify the statement of the hypothesis that mixed spruce-beech stands advance the transient seed bank while pure spruce stands stimulate the persistent seed bank. In a second step, the seed banks of different soil horizons down to 35 cm soil depth were studied in a multivariate statistical design for the most dominant species J. effusus, C. pallescens and R. idaeus, which are known to form long-term persistent seeds. Effects of bedrock material (Flysch, Molasse), species composition (pure spruce, mixed species) and treatment (control, nitrate) were tested. The total sum of these three species was significantly higher on Flysch than on Molasse. However, species composition indicated no significant differences, although there was a trend of higher amounts of germinating seeds under pure spruce. Nitrate treatments did not promote germination of viable buried seeds, indicating that the number of emerged seedlings is a realistic indicator of the seed bank density for the studied stands. It is concluded that overstorey tree species composition is not an important controlling factor for seed germination of the studied species after disturbances. The majority of emergents are the graminoids J. effusus and C. pallescens which were not present at all in the aboveground vegetation. Viable seeds were found down to 35 cm soil depth, although most seeds were concentrated in the upper 10 cm soil. Hence, care should be taken if management strategies create conditions that are generally favorable to germination. The success of forest regeneration or a conversion of pure spruce to mixed species stands could be endangered by any disturbance, which causes an immediate increase of light levels.

Dynamics of health status of forest stands on research plots in the Šumava National Park

The paper summarises an evaluation of the health status dynamics of allochthonous spruce stands in the Modrava Forest District and of natural stands in the Plešný Forest District. Analysis is based on dendroecological reactions of particular tree individuals in the stand structure. The tree damage was evaluated annually (during the period 1997–2002), based especially on defoliation. Natural and semi-natural, especially mixed forest stands with dominant beech in the Plešný Forest District territory were most tolerant, allochthonous secondary spruce stands in the Modrava Forest District area were least tolerant. The damage dynamics was limited by the activity of insect pests (bark beetle – Ips typographus). Damage caused by ozone occurred much more often in 2002 compared to 1999. The most damaged species were sycamore and rowan tree.

Occurrence of pathogens in associated living bark beetles (Col., Scolytidae) from different spruce stands in Austria

AbstractPathogen occurrence was studied in 16 099 adult specimens of 10 different bark beetle species, which live associated on Norway spruce (Picea abies (L.) Karst.). Beetles (mainly Ips typographus L. and Pityogenes chalcographus L.) were collected from 6 different localities in Austria (4 secondary spruce stands and 2 natural forest type stands, 9 sampling plots in total) in elevations between 400 m and 1600 m. Various viral, protozoan, and fungal pathogens could be diagnosed with a light microscope in the examined beetles. Numerous pathogen species were known from former studies, some pathogens were totally new or could be found in a new host species beside their type host. The most dominant pathogen species were Protozoa, Gregarina cf. typographi, Malamoeba cf. scolyti, and Chytridiopsis cf. typographi. Over the whole investigation period, the highest pathogen diversity with eight pathogen species was found in I. typographus. Differences were observed in the pathogen complex of each beetle species from the different collection sites and in different years of investigation. Several species showed an overlapping in their host range and infected various bark beetle species. Furthermore, pathogen occurrence and prevalence differed in bark beetles from 4 different sampling plots in an area (one locality) within a distance of a few kilometres.

Palaeoecological and phytosociological reconstruction of precultural vegetation in the Bílý Kříž area, the Moravskoslezské Beskydy Mts, Slovak Republic

A combined palynological and phytosociological methodological approach was used in the reconstruction of precultural forest vegetation in a small model area of Bilý Křiž-Jancik in the Moravskoslezske Beskydy mountains (northwest Slovakia). Two pollen diagrams show the predominance of Fagus sylvatica, Abies alba and Picea abies in past natural mixed forests. The present-day occurrence and distribution of forest herbs allow the differentiation of five past vegetation types with above mentioned forest climax trees covering the area before the beginning of human interference. A map of reconstructed natural vegetation is presented which can be used for revitalization of present secondary spruce plantations, heavily affected by air pollution.