Temporal acidity (pH) and electrical conductivity (EC) changes in runoff water determined through sediment traps established on unpaved (UPFR) and paved forest road (PFR) ditches and in an undisturbed (UA) forest land. Research was carried out one year with monthly samplings from November 2009 to October 2010. In runoff water, pH was changed between 5.15 pH and 7.32 pH, and EC was between 58.35 μS/cm and 198.09 μS/cm. Both EC and pH of runoff water showed significant variations among experiment sites and months. Runoff EC and pH sourced from PFR showed a significant relationship in regressions with same parameters of precipitation indicating that EC and pH of runoff sourced from paved forest road were related directly to precipitation chemistry. However, to indicate a definite trend or difference is difficult despite significant differences among road types and sampling times.

Key words: EC, erosion, road pavement, salinity, sediment

The objective of this study was to evaluate natural forest regeneration in cutovers on drained fens (eutrophic and mesotrophic low moor peat soils) depending on intensity of drainage characterised by depth of the ground water table, coverage of ground by vegetation and soil chemical properties (soil acidity and saturation with bases). The data were collected in 172 sample plots established in transects located perpendicular to drainage ditches at different distance to it. The assessments were carried out in 2003-2007 in the Panevėžys and Biržai state forest enterprises.

It was found that downy birch (Betula pubescens) seedlings dominated in cutovers on eutrophic and mesotrophic fens. The density of seedlings was greatest (3,700-5,300 trees per ha) on undrained and extensively drained cutovers where ground water table depth (h5) at the beginning of growth period was 1-20 cm. Black alder (Alnus glutinosa) seedlings were most abundant (1,000-1,300 trees per ha) in undrained and extensively drained cutovers on eutrophic peatlands where ground water level at the beginning of growth period is above the soil surface (10 cm) or near it (in the depth of 1-10 cm). Spruce (Picea abies) seedlings were not abundant (averaged 300 ± 101 trees per ha) in these sites. The higher density of spruce seedlings was found (more than 300 trees per ha) in drained cutovers (h5 = 10-80 cm) on mesotrophic peatlands.

It was found that the average density of seedlings of trees in cutovers on fens (eutrophic peatlands) depended significantly on the depth of the ground water table, coverage of ground vegetation and acidity of soils.It was concluded that overly intensive drainage of fens (lowering ground water table at the beginning of the growth period of trees by more than 30-40 cm) created unfavourable conditions for regeneration of trees, decreased the base saturation of soil, increased soil acidity and reduced soil fertility.

Key words: forest regeneration, cutovers, fens, ground water, chemical properties of soils.

In 2010, the spruce bud scale (Physokermes piceae Schrank.) infested 7,700 ha in Lithuania. The effect of the spruce bud scale damages like the reduction of shoot and needle growth in young spruce stands was studied in 2013. In order to determine the growth reduction in the shoots and needles, young (II-IV age class) spruce stands were examined. We have established 33 plots in stands in 9 different regions of Lithuania. Three branches from five trees were collected on each plot. The length (cm) of the shoots and the weight (g) of absolutely dried 100 needles were determined.

During the outbreak (2010), the shoot length and needle weight decreased almost twice (p < 0.05) in comparison with shoot and needle growth before the damage (2009). A direct negative effect of spruce bud scale was significantly (t ³2.91, p ≤ 0.05) higher in spruces growing in Western Lithuania (Jurbarkas, Kazlų Rūda and Šakiai) than in Central Lithuania (Kaišiadorys, Dubrava and Jonava).

Key words: needle weight, shoot length, spruce bud scale, spruce stands, Norway spruce, Picea abies

The research was conducted in the southern Poland, in mature spruce stand, where final cutting were carried out with the use of LARIX LAMAKO tower cable system combined with farm tractor and with the use of LKT 81 TURBO skidder. The tree-length system (TLS) timber harvesting technology was applied using chainsaw for felling, delimbing and cross-cutting and the above-mentioned machines for skidding to the landings. In the selected stand, four study plots were established, in which inventory of advance growth (saplings) was carried out before and after timber harvesting. In the case of technology using tower cable system, the level of damage to advance growth in individual manipulation sample plots was within the range of 21.9% – 25.4% (average 23.9%). In the case of skidder technology, damage reached the level of 55.6% – 65.9% (average 61.3%). The most commonly observed type of damage to the advance growth as a result of final cutting with the use of tower cable system technology was destroyed saplings. Most damage occurred in the lowest advance growth (up to 0.5m above the ground). As for skidder technology, the most commonly observed types of sapling damage were stem and side-branches breaks; most damage occurred in medium-sized advance growth (0.5 – 4.0 m). A few results presented in this paper may be used for long-term research consisting in, i.e., continuous observation of the growth and development of damaged advance growth or quality and spatial distribution of saplings that were not affected by timber harvesting. Conducting such observations will be possible due to fixed circular research plots, permanently marked at the current stage of the investigations.

Key words: damage to saplings, spruce stand, tower cable system, skidder, final cutting