Nadezhda Torlopova

Institute of Biology, Komi SC UB RAS, 167982, Kommunisticheskaya st., 28, Syktyvkar, Russia. E-mail: torlopova@ib.komisc.ru

The present study aimed to estimate the dynamics of vitality of ground vegetation components under air pollution by pulp and paper industry emissions. The majority of pollutants were oxides of sulfur, nitrogen, sulfur-organic compounds, and alkaline dust. The vitality determination of tree stands was carried out according to ICP-Forests program technique, which is based on ranging trees in classes depending on crowns condition. The studies were conducted in pine forests of Pinetum fruticulosum type situated along the pollution gradient. From 1998 to 2009 the share of healthy trees has increased by 1.9 times. Safety and condition of pine undergrowth has deteriorated twice, versus the double increase of the safety of spruce undergrowth has increased by 2 times. Pulp and paper industry air pollution was found to increase leaf discoloration grade and shoot density of dwarf shrubs (Vaccinium myrtillus L. and Vaccinium vitis-idea L.). For the period of researches, dwarf shrubs essentially improved their condition. Mineralization degree of above-ground parts of dwarf shrubs increased compared to the background area. Species composition of ground vegetation cover significantly changed only in pine forest situated at the shortest distance from the paper plant. Pine stands in the impact area of the pulp and paper mill underwent changes during 1998–2009 which indicated improvement of their condition. Mineralization of snow and discoloration of pine needles had the highest negative relation at far distance from the polluter, versus species composition and projective cover of mosses and epiphytic lichens had the highest direct relation. It is possible to use these parameters as indicators of forest ecological condition.

Momchil Panayotov^1,2, Dominik Kulakowski³, Heinrich Spiecker⁴, Frank Krumm², Lucinda Laranjeiro⁵, and Peter Bebi²

¹University of Forestry, Sofia, Bulgaria. E-mail: mp2@abv.bg
²WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland.
³Clark University, USA.
⁴Institute for Forest Growth, University of Freiburg, Germany.
⁵WSL Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland.

Although understanding natural disturbance regime is very important for the management of subalpine coniferous forests, studies for Southern European Mountain ecosystems are still scarce. Among the reasons are difficulties in finding unmanaged forests that could serve as reference. We studied the disturbance history of an old Norway spruce-dominated forest in the "Parangalitsa" biosphere reserve in Bulgaria. It was declared a reserve in the 1930^s, but was protected from human intervention before that. We used aerial photo interpretation to detect disturbance areas and dendroecological methods to date the occurrence moment of the disturbance events. Over the past 150 years windthrows have been the main type of disturbance. About 20 percent of the forested area was subjected to complete blowdown. The largest proportion of the affected territory was due to medium sized windthrows with dimensions of 1 to 10 ha. Although Ips typhographus populations were large enough to cause mortality of some live trees, the populations did not grow to epidemic proportions. Fire disturbance was of limited importance and only two areas (4 percent of the study area) showed evidence of fire in the 20^th century. The forest ecosystem in Parangalitsa has high resilience, which is probably due to the high landscape heterogeneity of forest structures and continuous interaction between natural disturbances.

Malgorzata Sulkowska and Justyna Nowakowska

Forest Research Institute, Department of Genetics and Physiology of Woody Plants, Sekocin Stary, Braci Leśnej, st. 3, 05-090 Raszyn, Poland. E-mails: m.sulkowska@ibles.waw.pl, J.Nowakowska@ibles.waw.pl

European Beech (Fagus sylvatica L.) is one of the main forest tree species in Poland and covers 5.2 % of the forest area. The most typical forest tree associations are formed at the lower forest belt in Carpathians and Sudety Mountains on the South of Poland and at the moraine landscape of Pomeranian Lake District of the northern Poland. In Poland, beech attains its north-eastern limit of natural range. The investigated six beech populations were classified ac-cording to phytosociogical characteristics to the following plant associations: Galio-odorati-Fagetum (Gryfino and Kwidzyn), Dentario glandulosae-Fagetum (Bieszczadzki National Park), Luzulo-luzuloides-Fagetum (Suchedniow, Tomaszow), Dentario enneaphyllidis-Fagetum (Zdroje). The genetic structure of these populations was analyzed. Thirty individuals per one generation (mother and progeny stands) in every provenance were investigated. The genetic variation and differentiation of mother stands and their open-pollinated progeny were characterized on the basis of DNA chloroplast markers: ccmp4, ccmp7 and ccmp10. Parameters of genetic diversity (H_S and H_T) and differentiation (G_ST) were counted and compared between mother and progeny generation.

Jiri Novak, Marian Slodicak, David Dusek, and Dusan Kacalek

Forestry and Game Management Research Institute, Research Station at Opocno, CZ - 51773, Opocno, Czech Republic. E-mail: novak@vulhmop.cz; slodicak@vulhmop.cz; dusek@vulhmop.cz; kacalek@vulhmop.cz

We observed the long-term effect of management (two thinning regimes: 2a - by positive selection from above and 3b - by negative selection from below compared to 1c - unthinned control) on production characteristics and forest-floor status in the stands of Scots pine in Central Bohemia (Czech Republic). We found similar effect of treatment on production during the 45-year long period of investigation, i.e. lower periodic basal area increment of both thinned stands compared to control. About 6-9 thousand kg of dry-mass was stored per hectare in humus horizon L in the stands studied in 2008, with insignificant differences among the variants. In horizon F, we found about 14-18 thousand kg of dry-mass per hectare and differences among variants were again insignificant. Significantly higher amount of dry-mass was observed in horizon H in control unthinned plot compared to both variants with thinning (103, 45 and 60 thousand kg per ha in variants 1c, 2a and 3b, respectively). The results obtained indicate that studied thinning regimes resulted in significantly decreased amount of accumulated humus in forest-floor and consequently carbon and nitrogen under treated pine stands.

Mohammed Hamed Mohammed^1,2 and Heinz Rohle¹

¹Institute of Forest Growth and Computer Sciences, TU-Dresden, Pienner Str. 8-01737 Tharandt, Germany. E-mail: hamed1705@yahoo.com, roehle@forst.tu-dresden.de
²Faculty of Natural Resources and Environmental Studies, University of Kordofan, P.O Box 160 Elobeid, Sudan.

In this study, above ground competition was assessed for individually selected Acacia seyal Del. var. seyal trees growing in natural stands of different densities. The main objective was to develop a model to estimate the competition index (CI) depending on measuring diameter at breast height (DBH). Data were collected from Umfakarin reserve forest, south Kordofan, Sudan, between September 2007 and February 2008. A total of 286 subject trees of Acacia seyal were selected in stands of three different densities, related to different number of stems per hectare. A method for identifying the competitors (adjacent trees) of the subject trees was developed. Tree dimensions such as DBH, height, height of crown base and crown radii for each subject tree and its competitors were measured. Polar coordinates were used to describe the positions of competitors to each subject tree. Eight competition indices were quantified using CroCom program for each subject tree and correlated with its dimensions. The results of the study indicated a remarkable decrease of tree dimensions, especially DBH, when the competition index increased. Regression models between selected indices and tree dimensions showed significant relationships. The results of the study could serve in defining and improving silvicultural treatments, such as thinning programs, of Acacia seyal in natural stands.