Andis Lazdins

Analysis of Norway spruce dieback phenomenon in Latvia – a belowground perspective

ABSTRACT In 2010, dieback of Norway spruce (Picea abies) was observed in Latvia. As mostly stands on seasonally or permanently water-saturated soils were damaged, we hypothesized that the recorded foliar damage might be associated with belowground factors. We established 48 sample plots in stands with damage symptoms for soil parameter evaluation and fine root sampling to determine the number of fine roots in different growth stages and to describe the associated fungal community. Among sample plots on organic soils, there were fewer viable older fine roots and greater number of dead fine roots in more damaged sites than in less damaged. These root parameters were significantly correlated with higher groundwater level and soil pH. The fungal community was dominated by ectomycorrhizal (ECM) species (the most common was Tylospora asterophora), the endophyte Oidiodendron maius and saprotrophic species Cryptococcus magnus. Saprotrophic species had higher abundance in more damaged sites, suggesting a shift in fungal communities from ECM fungi. In conclusion, the results of this work suggest Norway spruce root system response to short-term climatic stress, which should be considered when planning spruce forest management, especially on organic soils with a high groundwater level.

Influence of spot mounding on height growth and tending of Norway spruce: case study in Latvia

Abstract Norway spruce is commonly regenerated by planting and disc trenching is by far the most widely used soil preparation method in Latvia; however, in specific site conditions other methods might be beneficial. Therefore aim of our study was to assess influence of spot mounding on early growth and tending of Norway spruce in hemiboreal forests. Spot mounding was compared with disc trenching or no soil preparation in central part of Latvia (57° N 24° E) in five different forest types, where two-year-old containerized Norway spruce seedlings were planted. Influence of soil preparation method on tending was assessed in the same region in two different sites in a single forest type on drained fertile mineral soil. Spot mounding had positive effect on the height increment of the dominant trees at the 6th to 8th growing season. Mean height of Norway spruce at the end of 8th growing season on mounds significantly exceeded that on unprepared soil: 179 ± 6.5 and 152 ± 6.2 cm, respectively. Similarly mean height on mounds was significantly larger than on furrows: 209 ± 3.9 and 154 ± 4.0 cm, respectively. Projective vegetation cover before the tending was significantly higher in spot-mounded, but after - in disc trenched sites. Networking time for brashsaw operators in spot-mounded (478 min/ha-1) and disc trenched (462 min/ha-1) sites was similar (p > 0.05). Overall, spot mounding ensured more suitable microenvironment resulting in higher productivity of planted trees and had no negative effect on quality or efficiency of tending, therefore its wider use is recommended.

Evaluation of tree height and number of trees using LiDAR data

The aim of this study is to detect and to analyse individual trees and their heightin young and mature coniferous forest stands using local maxima method based on LiDAR (Light Detecting and Ranging) data, which are currently being obtained for the territory of Latvia. Empirical data about the tree height and number of trees for this study are obtained from the National forest inventory (NFI) sample plots and additional surveying is not conducted. LiDAR data are obtained from the Latvian Geospatial Information Agency. LiDAR surveying is done separately from NFI measurements. Sample plots are selected so that LiDAR data are obtained within 1 calendar year leeway from field measurements forNFI surveying of sample plots. Step by step instructions on the applied method are included in this paper. Average tree height and number of trees are compared between the remotely obtained and in field measurements based data sets. The best results are achieved in determination of the average tree height in mature forest stands. Remote sensing based data on the height and numberof trees in young forests is less accurate because of insufficient density of LiDAR point cloud and possible spatial offset of study plots in the NFI database.In order to obtain results with higher accuracy, LiDAR data with higher point density are needed.

Growth and Yield of 15-Year Plantations of Pine, Spruce and Birch in Agricultural Land

Abstract The growth data and the potential returns from 15-year-old plantations of pine Pinus sylvestris L. (6 trial sites), spruce Picea abies Karst L. (9 trial sites) and silver birch Betula pendula Roth (13 trial sites), established in abandoned agricultural lands in a variety of soil types (sod calcareous, anthrosols, podzolic, podzols, gley, podzolic gley, alluvial), using the planting density 2,500 and 3,300 and also 5,000 trees/ha are analysed. For tree plantations in agricultural soils (alluvial sod-gley, gley-sod podzolic, sod-podzolic gley, typic podzol) at the survival of 80-98% the stock volume for 15-year pine is as high as 102-155 m3ha−1 with the volume growth 5.72-8.94 m3ha−1 per year; the same indices for spruce in agricultural soils (gley sod-calcareous, sodpodzolic, cultivated, sod-podzolic gley, alluvial sod-gley, base-unsaturated brown) are 75-98 m3ha−1 and 10.26-15.76 m3ha−1, respectively. For 15-year plantation birch the mentioned indices may vary from 61 to 169 m3ha−1 and from 7.54 to 29.82 m3ha−1 per year. The lowest volume growth (4.66 m3ha−1 per year) is for birch in heavy clay soil (gleyic sod-podzolic), the highest (29.72-29.82 m3ha−1 per year) – in cultivated soils and pseudogley soil. Plantation cultivation of pine, spruce and birch in agricultural lands may by the age of 15 years yield with a profit such forest products as pulpwood, fire wood and woody biomass. The gross income gained from first commercial thinnings of plantation pine, utilizing pulpwood, fire wood and logging residue biomass, may vary from 679-2267 EUR ha−1, for spruce the same indices are 1644-3272 EUR ha−1, for birch - 683-2188 EUR ha−1.

Impact of feed rollers on productivity and fuel consumption

The aim of the study was to evaluate the impact of the harvester head feed roller type on the fuel consumption and productivity during the spring season. This study compares feed rollers with moving metal plates on rubber shock absorbers (Moipu plate wheel rollers, hereinafter named – gentle feed rollers) and feed rollers with large round spikes (hereinafter named – conventional feed rollers). The study was conducted in Vidusdaugava forestry (forests managed by the Joint Stock Company Latvia State Forests). A total area of 18.69 ha or 19 felling sites were logged in the final felling with gentle feed rollers and 20.29 ha or 15 felling sites – with conventional feed rollers. Harvested spruce saw logs were delivered to Rettenmeier Baltic Timber Ltd, pine sawlogs to IKEA Industry Latvia Ltd and veneer logs to Latvijas Finieris Ltd. APonsse Ergo harvester manufactured in 2008 with a standard H7 felling head was used in the study. Logging tests were carried out in the spring and early summer, using standard logging work tasks with both feed roller types.According to the data from the harvester onboard computer the productivity was 27 m 3 ·h -1 using the gentle feed rollers and 33 m 3 ·h -1 using the conventional feed rollers. However, the comparison of productivity while processing the trees of the same diameter demonstrated slightly weaker performance with the gentle feed rollers. The difference is statistically significant if the tree diameter at the breast height is below 20 cm. Further studies are necessary to investigate the productivity depending on the season and felling type. Fuel consumption using the gentle feed rollers was 18.02 l·h -1 and using the conventional feed rollers it was 16.75 l·h -1 . Fuel consumption by the roller type has a significant impact on both mean values (tStat = 2.6 > tCrit = 1.64) and data dispersion (F = 0.9 > FCrit = 0.8).