Issues

Abstract

In certificated forest ecosystems in Serbia, Bacilus thuringiensis ssp. kurstaki insecticides are well-accepted and most widely used pesticides for control of one of the most important economically harmful defoliators of Lepidoptera order - gypsy moth (Lymantria dispar Linne, 1758), in progradation phase, when number of pests is relatively small. When number is greater, it is assumed that so-called "soft" ecotoxicologically favourable preparations Avaunt^®, Alverde^®, Coragen^®, registered for application in agriculture, but not in forestry, can be used for inhibition of multiplication. The experiments of biological efficacy of those pesticides were established in the period 2009-2010, during the third larval instar of the gypsy moth. From the beginning of feeding till the end of the two groups of experiments the caterpillars were fed with natural (Pedunculate oak leaves) and synthetic food, but from the third instar the food was shortly soaked in water solutions of the analysed doses of the preparation. Results of laboratory studies of biological efficiency of above preparations showed that they have preconditions for application in forest ecosystems. The high biologic efficiency (90.52 % and 100 % for Avaunt^®, 99.53 % and 100 % for Coragen^®, 97.16 % and 100 % for Alverde^®), mechanism of rapid inhibition of larvae feeding, and thereby inhibition of leaf mass damage, resistance to water rinsing, high selectivity, and small quantities of application, anticipated a bright future for them.

Abstract

The spread of alien plants, intentionally or accidentally introduced by human activity into areas outside their native ranges, is one of the threats to natural ecosystems. Particularly the alien plant species defined as "invasive" may alter ecosystem processes and threaten the survival of native species in natural ecosystems or cause a critical economic impact in agriculture. The paper presents some data about the occurrence and the distribution of alien invasive tree species in the Italian forests derived from the Italian national forest inventory.

Abstract

The paper presents research results of morphological, physical and chemical properties of eugley soil in a protected part of alluvial plains of the Danube River. Research was conducted in the nursery "Kacka suma", where the seedlings of white willow (Salix alba L.) were produced. The following hydrological soil characteristics were studied in detail during the vegetation period: immediate moisture content by depth profile, the dynamics of movement of groundwater and its interaction with water level of Danube. In order to assess the benefits of this soil type for the production of willow seedlings, the height of seedlings of five white willow genotypes (S. alba: cl. '107/65/9', cl.'347', cl.'V-158', cl. '79/64/2' and cl. 'V-55') was measured at the end of the vegetation period. Genotype '107/65/9' exhibited the largest amount of seedlings with proper dimensions and genotype 'V-55' exhibited the smallest one. The results suggest that high quality S. alba seedlings may be successfully used on eugley soils.

Abstract

The results of three-year's research of fungi phylum Basidiomycota on Salix sp. in the area of Central Danube Basin (45°08'18" and 45°42'50" north latitude and 17°10'10" and 17°58'50" east longitude from Paris), are presented in this paper. During the research, the fruiting bodies were collected in the field and determined based on their reproductive organs. Twenty-eight species of macrofungi have been identified on the willows of which Fomes fomentarius (L.: Fr.) Fr., Phellinus igniarius (L.: Fr.) Quel. and Trametes suavealens (L.: Fr.) Fr. have the greatest pathogenic significance as wood rotting agents. Four of the above 28 species are used in human nutrition: Pleurotus ostresus (Jacquin: Fr.) Kumm., Flammulina velutipes P. Karst., Auricularia auricula-judae (Bull. :m Fr.) Wettst. and Polyporus sulphureus (Bull.) Fr.), and one is used in pharmacy (Ganoderma lucidum (Curt.: Fr.) P. Karst.). During this research, 17 species of macrofungi were first found on willow, which have not been so far identified from Serbia and Montenegro. Of 17 newly identified fungi, 7 species have never been identified from Serbia and Montenegro, and 10 have been identified, but on other hosts (e.g. poplars).

Abstract

Magnesium concentration in the needles of Douglas-fir (Pseudotsuga mensiesii /Mirb./ Franco) was investigated in a provenance test under homogeneous site conditions (Ass. Fagetum submontanum Rud. on acid brown soil on gneiss). The established quantities of magnesium in needles are indicative for different capabilities of certain Douglas-fir provenances to adopt this nutritive element from the soil. Significant differences among the examined provenances were found in mean height, mean diameter, tree volume and basal area. However, regression analysis revealed that there is no significant relation between magnesium concentration in needles of different Douglas-fir provenances and any of the examined forest stand parameters. Differences in mean height, mean diameter, tree volume and basal area are not the consequence of different capability of certain Douglas-fir provenances to adopt magnesium from the soil but are of genetic nature.

Abstract

Pinus heldreichii forests in pristine condition can still be found in Pirin National Park in Bulgaria. Although they are of high conservational value still numerous questions for their structure, the physiological and genetic peculiarities of the species exist. Here we present results for several tree ring chronologies constructed along altitudinal gradient and different exposures. We also studied the variation of anatomical leaf parameters like number of resin ducts and stomata. We found that the oldest trees in the valley reach 800 years and are situated on isolated by rock bands sites close to the local treeline. Forests on the slopes at the bottom of the valley are 200–300 years old with single older trees. Many of them are probably shaped by fires in the past. We found similar variability in tree ring chronologies from different exposures. Only one chronology constructed from a mixed coniferous forest was found to differ at certain periods from the other chronologies. The most probable reason for this is exogenous disturbance like a fire. We did not find enough evidence that the anatomical traits of the needles are altitude dependent, although number of resin ducts and the number of stomata on the outer surface were found to increase with altitude.

Abstract

As a result of the analysis performed, a genealogical network representing evolutionary relations between Rhododendron L. species was obtained. Phylogeny of Rhododendron species reconstructed on the basis of ITS1-ITS2 sequence corresponds to anatomical-morphological classification of D. Chamberlain (1996).

Abstract

Acacia senegal, the gum Arabic producing tree, is of great economic importance in Sudan. Serious biotic and abiotic factors are threatening its growth and production. Among these, the long-horned beetles (Coleoptera: Cerambycidae) are the most deleterious insect pests resulting in complete death of Acacia trees. This study was conducted in northern Kordofan state Sudan season 2007/2008 with aims to identify spectrum, relative abundance and phenology of long-horned beetle species acting as pests of A. senegal tree. Moreover, the study focuses on the assessment of tree characteristics triggering the infestation. The species spectrum and their relative abundance were determined by catch results of flight interception traps, microclimatic conditions were assessed using data loggers, tree characteristics were done by direct measurements in addition, and a questionnaire was designed to assess farmers' knowledge on long-horned beetles. The results indicated that seven species of the long-horned beetles were recorded from the flight interception traps on the study sites. The recorded species were Anthracocentrus arabicus (Thomson 1877), Crossotus subocellatus subocellatus (Fairmaire 1886) (Eisa et al. 2008), Crossotus strgifrons (Fairmaire 1886) Doesus telephoroides (Pascoe, 1862), Titoceres Jaspideus (Serville 1835) (Eisa et al. 2008), Tithoes sp. and Gasponia gaurani (Fairmaire 1892). The highest percentage of infestation (100 %) was recorded in El Demokeya site with an average tree age of 43 years, followed by on Acacia agricultural project site (23.5 %) with an average tree age of 10 years and on Elhemaira site (20 %).

Abstract

Paliurus spina-christi seeds were subjected to several treatments in order to overcome dormancy and to maximize germination. Seeds were subjected to sulphuric acid scarification for 0, 30, 60 and 90 minutes and then were stratified at 3-5 °C for 0, 4, 8 and 12 weeks (1^st experiment) or treated with 500, 1000 and 2000 ppm gibberellic acid (2^nd experiment). In the first experiment, increasing scarification of non-stratified seeds from 30 to 60 or 90 minutes germination percentage increased significantly. Moreover, cold stratification treatments of non-scarified seeds resulted in very low germination percentages. The combination of acid scarification and cold stratification treatments improved significantly germination percentages. In the second experiment, treatment with gibberellic acid, regardless of concentration, of scarified seeds improved significantly germination percentages. The concentration of gibberellic acid was found to effect germination only in 30 minutes scarified seeds. In treated seeds with 500 or 1000 ppm gibberellic acid, a significant increase of germination percentage together with the increase of time of scarification from 30 to 60 or 90 minutes was observed. The results revealed that scarification was more effective than cold stratification in improving seed germination when treatments were applied alone. The highest germination percentages were observed when acid scarification was followed by cold stratification or treatment with gibberellic acid.

Abstract

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.

Abstract

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.

Abstract

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.

Abstract

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.

Abstract

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.