The paper demonstrates seasonal changes in the content of organic carbon and phosphorus available to plants against the activity of phosphatases responsible for the transformations of that element in the soil caught by fire. The soil was sampled three times: April 2012, October 2012 and April 2013 from the surface horizon (0-15 cm) and subsurface horizon (15-30 cm), from four sites: from the site beyond the fire (control area), ecotone (border area) and from the soil burnt 150 m and 200 m away from the ecotone. The content of total organic carbon was the highest in the soil sampled 0-15 cm deep from the border area (ecotone) (16.77-23.11 g C kg^-1) as compared with the control and the area caught by fire. The highest available phosphorus content, irrespective of the sampling date, was recorded from the surface horizon 0-15 cm 200 m away from ecotone (74.08-85.02 mg P_E-R kg^-1) irrespective of the soil sampling date.

The activity of alkaline and acid phosphatase in the soil caught by fire was lower as compared with the control and ecotone in both horizons at all the research dates. There were reported significant negative values of the correlation between the content of available phosphorus in soil and the activity of alkaline (r = -0.599, p < 0.05) and acid phosphatase (r = -0.583, p < 0.05). The calculated factor of the changes in the activity of the enzymes investigated in time (TF > 1) showed that the process of soil regeneration was not completed a year after the fire. The calculated enzymatic index of soil pH (AlP/AcP) ranged from 0.35 to 0.77.

Keywords: burnt, phosphomonoesterases, physicochemical properties, soil

Fifteen-year research results of afforestation and plantation on abandoned and marginal agricultural lands have been analysed. The annual growth of different tree species has also been determined performing measurements annually in the first five years and later each 2-3 years. The environmental impacts of afforestation have been assessed in terms of changes in the aboveground vegetation and soil chemical properties. The following tree species were included in the studies: Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst.), silver birch (Betula pendula Roth.), common alder (Alnus glutinosa (L.) Gaertn.), grey alder (Alnus incana (L.) Moench.), pedunculate oak (Quercus robur l.), small-leaved lime (Tilia cordata Mill.), and wild cherry (Cerasus avium (L.) Moench syn. Prunus avium L.).

In 15 years tree species such as Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst.), silver birch (Betula pendula Roth.), common alder (Alnus glutinosa (L.) Gaertn.), and grey alder (Alnus incana (L.) Moench.) have reached maximum standing volume from 100 m³•ha^-1 (for conifers) to 248 m³•ha^-1 (for broadleaves) on soils with light and medium heavy texture and high density of stocking (2,500- 3,300 trees ha^-1). In Latvian climatic conditions lime (Tilia cordata L.), pedunculate oak (Quercus robur L.), as well as wild cherry (Cerasus avium (L.) Moench.) have reached the standing volume of 18-39 m3•ha-1 in 15 years. It implies that their suitability can be evaluated no sooner than after some 40-70 years. Soil chemical properties have changed during 15 years since forest was established on agricultural lands. In general, the humus content in the active root layer (depth 0-30 cm) has increased and the soil reaction has become more acidic. Changes were observed also in the ground cover vegetation. Before afforestation the trial sites were generally dominated by meadow or fallow plant communities. Shifts in ground cover vegetation are faster on dry lean soils, where in plantations of conifers typical forest bryophytes appear rapidly, but various nitrophyte species prevail on sites of fertile and moderately moist soils.

Keywords: afforestation of surplus and marginal farmlands, plantation of forest tree species, monocultures, mixed plantations, tree species: Pinus sylvestris, Picea abies, Betula pendula, Alnus glutinosa, Alnus incana, Quercus robur, Cerasus avium, Tilia cordata

Cordyceps militaris (L.) Link. is the type species of Cordyceps (Hypocreales, Ascomycetes), which parasitizes larva or pupa of lepidopteran insects. The aim of the present study was to examine: distribution of C. militaris in pine stands of South Lithuania, pathogenicity of the fungus, and optimal conditions for its cultivation in vitro. The efficiency of C. militaris preparations against the pine moth (Dendrolimus pini L.) was tested by artificial infection of hibernating insect larvae in forest litter under natural conditions. During 2010-2011, in pine stands of South Lithuania, a total of 4 % (on areas without pest outbreak) and 59 % (in areas with pest outbreak) of all hibernating insects were infected by C. militaris; meanwhile 99 % of insects damaged by the fungus were D. pini. A massive formation of stromata with fruitbodies of the fungus started at the third year (2011) of outbreak comprising 21% of all larvae infected by the fungus. Stromata with fruitbodies on D. pini larvae were produced after 70 – 80 days of growth under favourable conditions. The optimal conditions for cultivation of C. militaris in vitro were: temperature 18° C, daylight, inoculation with fresh pure culture fragments and cultivation on rice medium. The preparation of C. militaris biocontrol medium for pathogenicity tests was made after 35-40 days after the fungus inoculation on rice medium. Pure culture of the fungus was grown in Petri dish (diameter 9 cm) with medium made of 10 g of rice and 25 ml of distilled water. The mean 6-8 g of dry rice and the fungus mass (biocontrol medium) are possible to get from each Petri dish. The differences of larvae mortality between two treatment methods (spraying and dusting of forest litter with C. militaris preparation, when the larvae were still in crown), and the control, were statistically insignificant. It was estimated that spraying of forest litter with C. militaris preparation increased 3.7 times cordycepsmycosis disease of pine moth larvae, when they already were in forest litter.

Keywords: Cordyceps militaris, impact, infestation, Dendrolimus pini, pests, pine stands

Modern forest machines are highly effective but their availability is reduced through frequent relocation. Relocation has been estimated to constitute between 6-20% of the delivered roadside cost of cut-to-length (CTL) timber. Machine utilisation is increased when relocation frequency is reduced (larger stands), and when relocation distances are shorter. The geo-spatial structure of forests at a stand and landscape level is therefore assumed to play a role in setting the efficiency threshold of modern harvesting systems. It is further assumed that this effect varies between regions and forest ownership patterns, and that the extent of the effect is quantifiable.

Testing this assumption, the size and mutual distance between 29 000 coniferous stands constituting some 70,000 ha and divided into 4 machinery management regions in Denmark was analysed using single-linkage cluster analysis. Furthermore, benefits of using the shortest path algorithm to schedule machine deployment in an optimal way were compared with a fully randomised (customer-oriented) deployment in a simulated environment. Finally, a comparison of the advantage of sandwiching multiple (3) years of scheduled thinnings into 1 package were compared with the re-deploying of machines across the region every year.

Results showed that the geo-spatial structure at landscape level mean distances between clusters ranging from 49 km in region East, to 90 km in region North. Weighting clusters with stand size reversed this ranking, where the mean distance in North was reduced from 90 km to 17 km. This highlights the importance of using the correct statistic in planning. Furthermore, when comparing a fully randomised relocation with shortest path scheduling, the mean relocation distance in region East was reduced from approximately 49 km to under 5 km, increasing productivity for a single machine set by 900 m3 a-1. This increase was slightly larger when 3 years of thinnings were grouped into one planning parcel as compared to deploying across the whole region every year. Finally, proper scheduling of relocation was shown to be of increasing importance with increasing machine productivity.

Findings are considered to have important connotations for both the layout of administrative forest areas, and the manner in which machines are deployed. The clustering method used proved a powerful tool for generating packages of stands, for e.g. a tendering process, for finding an appropriate number of machine systems to cover a region, and for using as a method to evaluate the performance of harvesting systems, and the effectiveness of machinery managers and machine operators within these regions.

Keywords: Machinery management, spatial planning, forest topology, cluster analysis, simulation